Co-reporter:Alexander Schade, Ivan Tchernook, Mirko Bauer, Alexander Oehlke, Martin Breugst, Joachim Friedrich, and Stefan Spange
The Journal of Organic Chemistry August 18, 2017 Volume 82(Issue 16) pp:8476-8476
Publication Date(Web):July 17, 2017
DOI:10.1021/acs.joc.7b01223
Second-order rate constants (k2) of the reactions of various barbiturate anions such as the parent barbiturate, 1,3-dimethylbarbiturate, 2-thiobarbiturate, and 1,3-diethyl-2-thiobarbiturate with diarylcarbenium ions and Michael acceptors have been determined in dimethyl sulfoxide solution at 20 °C. The reactivity parameters N and sN of the barbiturate anions were derived from the linear plots of log k2 versus the electrophilicity parameters E of these reference electrophiles, according to the linear-free-energy relationship log k2 (20 °C) = sN (E + N). Several reactions of these nucleophiles with benzylidenemalononitriles and quinone methides proceeded with reversible formation of the new C–C-bond followed by rate-determining proton shift. No evidence for initial attack of the electrophiles at the enolate oxygens of these nucleophiles was found by the kinetic measurements, in line with quantum chemical DFT calculations, which showed that in all cases C-attack is kinetically and thermodynamically preferred over O-attack. The nucleophilic reactivities of barbiturate anions were compared with those of structurally related carbanions, e.g., Meldrum’s acid and dimedone anions.
Co-reporter:Gabi Thielemann
New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 16) pp:8561-8567
Publication Date(Web):2017/08/07
DOI:10.1039/C7NJ00443E
Solvatochromic measurements and 1H NMR spectroscopy have been used to investigate the overall polarity of tetraalkylammonium (R3N+–CH3 with R = n-C4H9; n-C8H17) based ionic liquids (IL) and low temperature molten salts (LTMS), respectively, as function of the counter anion. Solvent acidity (SA), solvent basicity (SB), polarizability (SP) and dipolarity (SdP) parameters have been determined according to the Catalán scale. [FeII(1,10-phenanthroline)2(CN)2] (Fe), 3-(4-amino-3-methylphenyl)-7-phenylbenzol[1,2-b:4,5-b′]difuran-2,6-dione (ABF), 3-(4-N,N-dimethylaminophenyl)-7-phenylbenzol[1,2-b:4,5-b′]-difuran-2,6-dione (DMe-ABF), 4-tert-butyl-2-(dicyanomethylene)-5-[4-(dimethylamino)benzylidene]-Δ3-thiazoline (Th), and 2-[4-(N,N-dimethylamino)benzylidene]malononitrile (BMN) have been used as solvatochromic polarity indicators. Significant correlations of the SB parameter of anion X− as a function of the chemical shift of the H-atoms of R3N+–CH3X− are presented and discussed. Thus, IL solvent basicity (SB) of the anion determines the interaction strength towards those CH-bonds in the direct vicinity of the ammonium nitrogen atom.
Co-reporter:L. Wöckel;A. Seifert;C. Mende;I. Roth-Panke;L. Kroll;S. Spange
Polymer Chemistry (2010-Present) 2017 vol. 8(Issue 2) pp:404-413
Publication Date(Web):2017/01/03
DOI:10.1039/C6PY01572G
Acid induced step-growth polymerizations of bis(p-methoxybenzyl) carbonate (pMBC), bis(m-methoxybenzyl) carbonate (mMBC) and difurfuryl carbonate (DFC) have been performed to produce resin-foams, because controlled release of carbon dioxide takes place during polymerization of those organic carbonates. The monomers are polymerized in bulk using p-toluene sulfonic acid (pTS) as a catalyst. The volume development of the foams is assisted by use of an appropriate surfactant and the crosslinking agent 1,3,5-trioxane as co-components. A portion of carbon dioxide release is a function of the carbenium stability of the reactive intermediate derived from the monomer; DFC > pMBC ≫ mMBC. Resins derived from mMBC can be post-treated to release carbon dioxide after polymerization. The molecular structures of the resulting materials are investigated by solid state 13C-NMR spectroscopy and IR spectroscopy. Scanning electron microscopy was used to study foam morphology. The carbon dioxide release was monitored with TG-MS analysis. Finally, the polymer foams have been converted into carbon foams and investigated by means of mercury porosimetry.
Co-reporter:My Göring;Katja Schreiter;Alexra Schuberth;Tina Windberg;Heike Jung;Susann Anders;Philipp Müller;Daniela Nickel;Daisy Nestler;Lothar Kroll;Bernhard Wielage;Thomas Lampke
Advanced Materials Interfaces 2017 Volume 4(Issue 16) pp:
Publication Date(Web):2017/08/01
DOI:10.1002/admi.201601115
The production of metal-based hybrid laminates, such as aluminum combined with thermoplastics like polyamide 6, requires a precise and purposeful design of the interface between the two components. The utilization of twin polymerization has been successfully examined and an improved adhesion behavior is shown. By utilizing the monomers 2,2′-spirobi[4H-1,3,2-benzodioxasiline] and 2-(3-amino-n-propyl)-2-methyl-4H-1,3,2-benzodioxasiline in a molar ratio of 15:85, medial tensile shear strength values of 12.9 ± 3.9 MPa are achieved in tests according to DIN EN 1465. Electron microscopic and atomic force microscopic investigations give further structural details of the hybrid material. Additionally, the results of nanoindentation and microscratch tests clearly demonstrate that the choice of an adhesion promoter depends on its chemical as well as its mechanical characteristics.
Co-reporter:Matthias Birkner, Katja Schreiter, Katja Trommler, Andreas Seifert, Stefan Spange
Polymer 2017 Volume 121(Volume 121) pp:
Publication Date(Web):14 July 2017
DOI:10.1016/j.polymer.2017.06.015
•Synthesis of a new ternary hybrid material composed of phenolic resin, polydialkylsiloxane and epoxide/amine composites.•The reaction mechanism of functional twin monomer and bisepoxide was investigated by time dependent NMR experiments.•Consecutive reaction of amine and epoxide followed by twin polymerization of a functional twin monomer in one process.•The network structure is adjustable by variation of the monomer ratio.•13C and 29Si Solid state NMR spectroscopy was used for structure determination.Homogeneous hybrid materials composed of phenolic resins, crosslinked polydialkylsiloxane moieties with linear epoxide/amine composites have been synthesized by twin polymerization of 2-(3-amino-n-propyl)-2-methyl-4H-1,3,2-benzodioxasiline (APSI) combined with addition polymerization of bisphenol-A-diglycidylether (BADGE). The ternary formation of three different polymer structures within one procedure in the melt process occurs smoothly as evidenced by solid state 13C and 29Si NMR spectroscopy. The formation of in situ generated twin monomer moieties with higher functionalities f = n • 2 (n > 2, n is the assumed average degree of polymerization of the linear chain fragments resulting intermediately from APSI and BADGE), compared to the primary reactant APSI (f = 2, n = 1), triggers the polysiloxane network formation. A novel type of polysiloxane resin is produced by this methodology. Highly thermally stable materials are accessible by appropriate adjustment of reaction conditions and the molar ratio of the reactants. Potential applications are inter alia in the field of glue adhesives, veneers, and casting resins.Download high-res image (227KB)Download full-size image
Co-reporter:T. Windberg, T. Ebert, D. Uhlig, S. Schulze, S. Spange
Microporous and Mesoporous Materials 2017 Volume 246(Volume 246) pp:
Publication Date(Web):1 July 2017
DOI:10.1016/j.micromeso.2017.03.012
•Synthesis of hierarchically structured porous carbon materials by surface twin polymerization.•Mesoporous carbon materials with a microporous shell were prepared by twin polymerization on carbon black particles.•The shell thickness is adjustable by the amount of twin monomer used for polymerization.•Consecutive polymerization of two different twin monomers on Stöber particles leads to double-shelled carbon hollow spheres.•The hierarchically structured porosity was investigated by nitrogen sorption measurement and mercury porosimetry.Carbon materials with a complex core-shell structure and adjustable porosity are fabricated by subsequent surface polymerization of twin monomers on carbon black and silica particles. The twin monomers 2,2’-spirobi[4H-1,3,2-benzodioxasiline] (Spiro) and tetrafurfuryloxysilane (TFOS) are polymerized in one step to an inorganic/organic hybrid material, which contains nanostructured silica and phenolic resin or poly(furfuryl alcohol), respectively, as organic polymer. After carbonization and the removal of silica, a porous carbon shell with defined porosity is obtained. In this process, Spiro based materials produce microporous carbon and TFOS based materials produce a mesoporous carbon. Quantities of monomer, catalyst and substrate can be varied. This allows to create a library of porous carbon materials with different properties such as controlled porosity, morphology and hierarchically structuring. Thus, mesoporous carbon with a microporous shell can be achieved by using carbon black particles as substrate and Spiro as twin monomer. Furthermore, carbon hollow spheres with a double shell with hierarchically structuring can be synthesized by subsequent polymerization of TFOS and Spiro on silica particles. The porous carbon materials were characterized by quantitative elemental analysis, thermogravimetric measurements, SEM/EDX, TEM, nitrogen sorption isotherms and mercury porosimetry.Download high-res image (258KB)Download full-size image
Co-reporter:J. Weißhuhn, T. Mark, M. Martin, P. Müller, A. Seifert and S. Spange
Polymer Chemistry 2016 vol. 7(Issue 31) pp:5060-5068
Publication Date(Web):25 Jul 2016
DOI:10.1039/C6PY00903D
The acid and base catalyzed simultaneous twin polymerization (STP) of various 2,2′-disubstituted 4H-1,3,2-benzodioxasiline derivatives 2a–d with 2,2′-spirobi[4H-1,3,2-benzodioxasiline] (1) are presented in this paper. The products are nanostructured ternary organic–inorganic hybrid materials consisting of a cross-linked organic polymer, silica and a disubstituted polysiloxane. It can be demonstrated whether and in which extent the copolymerization of the two inorganic fragments of 1 and 2 takes place among the STP and how the molar ratio of the two components determines the structure formation of the resulting hybrid material. Steric and electronic effects of the substituents at the silicon center of 2 on the molecular structure formation and the morphology of the resulting hybrid material were investigated by means of solid state CP MAS 29Si and 13C NMR spectroscopy as well as high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The mechanical properties (hardness and Young's modulus) of the hybrid materials were analyzed by means of nanoindentation measurements.
Co-reporter:Sindy Oschatz;Arno Lange;Szilard Csihony;Gerhard Cox;Oliver Gronwald;Andreas Seifert
Journal of Polymer Science Part A: Polymer Chemistry 2016 Volume 54( Issue 15) pp:2312-2320
Publication Date(Web):
DOI:10.1002/pola.28102
ABSTRACT
Internal polymeric soft templates are used for the polymerization of twin monomers (TM) to achieve nanostructured hybrid materials of desired morphology. For this purpose, oligomeric groups such as oligo(ethylene glycol) (OEG) or polymerizable ethenyl-substituents were covalently linked to the silicon atom of TMs of the 4H-benzo-1,3,2-dioxasiline type. These functionalized TMs are used in simultaneous twin polymerization in combination with the ideal TM 2,2'-spirobi[4H-1,3,2-benzodioxasiline]. Nanostructure dimension can be adjusted in the range from 2 to 20 nm by the composition of the components used in hybrid material synthesis. Inorganic/organic hybrid material disks of interpenetrating networks with hierarchical nanostructures are available by polymerization in the melt which are potentially suitable as membrane devices. Physical properties such as brittleness, transparency, electrolytic stability, and barrier properties of the hybrid material could potentially be adjusted by changing both monomer composition and monomer structure. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2312–2320
Co-reporter:Alexer Schade;Dr. Katja Schreiter;Dr. Tobias Rüffer;Dr. Heinrich Lang;Dr. Stefan Spange
Chemistry - A European Journal 2016 Volume 22( Issue 16) pp:5734-5748
Publication Date(Web):
DOI:10.1002/chem.201504932
Abstract
The specific barbituric acid dyes 1-n-butyl-5-(2,4-dinitro-phenyl) barbituric acid and 1-n-butyl-5-{4-[(1,3-dioxo-1H-inden-(3 H)-ylidene)methyl]phenyl}barbituric acid were used to study complex formation with nucleobase derivatives and related model compounds. The enol form of both compounds shows a strong bathochromic shift of the UV/Vis absorption band compared to the rarely coloured keto form. The keto–enol equilibria of the five studied dyes are strongly dependent on the properties of the environment as shown by solvatochromic studies in ionic liquids and a set of organic solvents. Enol form development of the barbituric acid dyes is also associated with alteration of the hydrogen bonding pattern from the ADA to the DDA type (A=hydrogen bond acceptor site, D=donor site). Receptor-induced altering of ADA towards DDA hydrogen bonding patterns of the chromophores are utilised to study supramolecular complex formation. As complementary receptors 9-ethyladenine, 1-n-butylcytosine, 1-n-butylthymine, 9-ethylguanidine and 2,6-diacetamidopiridine were used. The UV/Vis spectroscopic response of acid–base reaction compared to supramolecular complex formation is evaluated by 1H NMR titration experiments and X-ray crystal structure analyses. An increased acidity of the barbituric acid derivative promotes genuine salt formation. In contrast, supramolecular complex formation is preferred for the weaker acidic barbituric acid.
Co-reporter:L. Kaßner, K. Nagel, R.-E. Grützner, M. Korb, T. Rüffer, H. Lang and S. Spange
Polymer Chemistry 2015 vol. 6(Issue 35) pp:6297-6304
Publication Date(Web):10 Jul 2015
DOI:10.1039/C5PY00815H
Polyamide 6/SiO2 hybrid materials were produced by a coupled polymerization reaction of three monomeric components namely 1,1′,1′′,1′′′-silanetetrayltetrakis-(azepan-2-one) (Si(ε-CL)4), 6-aminocaproic acid (ε-ACA) and ε-caprolactam (ε-CL) within one process. Si(ε-CL)4 together with ε-ACA has been found suitable as a precursor monomer for the silica and PA6 components. The accurate adjustment of the molar ratio of both components, as well as the combination of the overall process for producing the polyamide 6/SiO2 hybrid material with the hydrolytic ring opening polymerization of ε-caprolactam is of great importance to achieve homogeneous products with a low extractable content. Water in comparison with ε-ACA has been found unsuitable as an oxygen source to produce uniformly distributed silica. The procedure was carried out in a commercial laboratory autoclave at 8 bar initial pressure. The molecular structure and morphology of the hybrid materials have been investigated by solid state 29Si and 13C NMR spectroscopy, DSC and FTIR spectroscopy and electron microscopy measurements.
Co-reporter:Thomas Ebert;Andreas Seifert
Macromolecular Rapid Communications 2015 Volume 36( Issue 18) pp:1623-1639
Publication Date(Web):
DOI:10.1002/marc.201500182
Co-reporter:Nadine Friebe, Katja Schreiter, Joachim Kübel, Benjamin Dietzek, Norbert Moszner, Peter Burtscher, Alexander Oehlke and Stefan Spange
New Journal of Chemistry 2015 vol. 39(Issue 7) pp:5171-5179
Publication Date(Web):05 May 2015
DOI:10.1039/C5NJ00256G
A series of para-substituted acetophenones bearing a furanyl or a thiophenyl moiety show a large Stokes-shift, which is a function of various solvent properties. Photophysical properties such as emission lifetime of the compounds have been determined using time-correlated-single photon counting to secure the intrinsic fluorescence behaviour. The solvent dependent position of the UV/Vis emission band max,em of the compounds has been measured in 26 various solvents. The influence of the solvent on max,em is of very complex nature and mathematically analysed by multiple square linear solvation energy (LSE)-correlation analysis using Catalán's four-solvent parameter set. Solvent acidity has a strong influence on the bathochromic shift of 2,5-disubstituted furan derivatives compared to the non-5-substituted furan and thiophene derivatives, which show a contrary behaviour. Therefore, the 5-cyanofuranyl-substituted acetophenone derivative is useful as a probe for measuring environmental properties by fluorescence spectroscopy.
Co-reporter:Ingmar Polenz;Ivan Tchernook;Joachim Friedrich;Friedrich Georg Schmidt
Macromolecular Chemistry and Physics 2015 Volume 216( Issue 4) pp:386-394
Publication Date(Web):
DOI:10.1002/macp.201400469
Co-reporter:Dr. Alexer Oehlke;Dr. Alexer A. Auer;Dr. Katja Schreiter;Nadine Friebe;Dr. Stefan Spange
Chemistry - A European Journal 2015 Volume 21( Issue 49) pp:17890-17896
Publication Date(Web):
DOI:10.1002/chem.201500835
Abstract
A series of boronate-π-acceptor compounds containing different types of π bridges (1,4-phenylen or thien-2,5-diyl or furan-2,5-diyl) that link the switchable boronate ester group with the efficient TCF acceptor group (TCF=2-dicyanomethylen-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran) has been synthesized. A TCF chromophore of this type undergoes transition to a donor-π-acceptor compound upon coordination of Lewis bases at the Lewis acidic boron center, which is accompanied by an enhanced intramolecular charge-transfer interaction. The Lewis acid character has been investigated by spectroscopic measurements (UV/Vis, NMR spectroscopies) as well as DFT and ab initio-based calculations. It is shown that the TCF acceptor group and thiophene or furan π-bridges directly bound to the boron atom cooperatively increase the Lewis acidity. UV/Vis titration experiments confirm fluoride binding constants in the range of up to 108 M−1 in CH2Cl2. In addition to the strong boron fluoride binding motif, Lewis interactions also occur with weaker Lewis bases, such as pyridine or aliphatic alcohols. The unique combination of chromophoric and Lewis acidic properties is responsible for the intense colorimetric turn-on response detectable after complex formation.
Co-reporter:M. Göring, A. Seifert, K. Schreiter, P. Müller and S. Spange
Chemical Communications 2014 vol. 50(Issue 68) pp:9753-9756
Publication Date(Web):07 Jul 2014
DOI:10.1039/C4CC03640A
Amino-functionalized organic–inorganic hybrid materials with a narrow distributed nanostructure of 2–4 nm in size were obtained by means of a template-free and non-aqueous procedure. Simultaneous twin polymerization of novel amino group containing twin monomers with 2,2′-spirobi[4H-1,3,2-benzodioxasiline] has been applied for this purpose. The amino groups of the organic–inorganic hybrid material are useful for post derivatization.
Co-reporter:Thomas Schönfelder, Joachim Friedrich, Janett Prehl, Steffen Seeger, Stefan Spange, Karl Heinz Hoffmann
Chemical Physics 2014 440() pp: 119-126
Publication Date(Web):31 August 2014
DOI:10.1016/j.chemphys.2014.06.003
•Modeling electrophilic substitution of twin polymerization with ReaxFF.•ReaxFF parametrization from literature fail to reproduce this chemical reaction step.•Development of appropriate ReaxFF parametrization for this chemical reaction step.•Comparison with PW6B95-D3 DFT reference calculation for analyzed systems.Twin polymerization is a new synthesis concept, which enables the formation of two different macromolecular structures from organic–inorganic hybrid materials in one single process step. To gain insights into formation processes we implement a first-principles-based ReaxFF reactive force field for C/H/O/Si for the initial electrophilic substitution of an aromatic system. We show that established parametrizations that have been developed to model chemical reactions of (hydro) carbon or carbon nanotubes systems successfully cannot reproduce this reaction although they include the same chemical elements and in parts same reaction mechanisms. Thus, we develop a new parametrization being capable in reproducing this aromatic reaction properly and compare it to the established ones to identify the differences.Download full-size image
Co-reporter:Alexer Schade;Nicole Behme ;Dr. Stefan Spange
Chemistry - A European Journal 2014 Volume 20( Issue 8) pp:2232-2243
Publication Date(Web):
DOI:10.1002/chem.201304069
Abstract
The four empirical solvent polarity parameters according to the Catalán scale—solvent acidity (SA), solvent basicity (SB), solvent polarizability (SP), and solvent dipolarity (SdP)—of 64 ionic liquids (ILs) were determined by the solvatochromic method. The SA parameter was determined solely by using [FeII(1,10-phenanthroline)2(CN)2] (Fe), the SB parameter by using the pair of structurally comparable dyes 3-(4-amino-3-methylphenyl)-7-phenylbenzo[1,2-b:4,5-b′]difuran-2,6-dione (ABF) and 3-(4-N,N-dimethylaminophenyl)-7-phenylbenzo[1,2-b:4,5-b′]-difuran-2,6-dione (DMe-ABF), and the SP and SdP parameters by using the homomorphic pair of 4-tert-butyl-2-(dicyanomethylene)-5-[4-(diethylamino)benzylidene]-Δ3-thiazoline (Th) and 2-[4-(N,N-dimethylamino)benzylidene]malononitrile (BMN). The separation of SP and SdP for a set of 64 various ILs was performed for the first time. Correlation analyses of SP with physicochemical data related to ionization potentials of anions of ILs as well as with theoretical data show the correctness of the applied method. The found correlations of the Catalán parameters with each other and with the alkyl-chain length of 1-alkyl-3-methylimidazolium-type ILs gives new information about interactions within ILs. An analytical comparison of the determined Catalán parameters with the established Kamlet–Taft parameters and the Gutmann acceptor and donor numbers is also presented.
Co-reporter:Patrick Kempe;Dr. Tina Löschner; Alexer A. Auer;Dr. Andreas Seifert;Dr. Gerhard Cox;Dr. Stefan Spange
Chemistry - A European Journal 2014 Volume 20( Issue 26) pp:8040-8053
Publication Date(Web):
DOI:10.1002/chem.201400038
Abstract
The twin monomer 2,2′-spirobi[4H-1,3,2-benzodioxasiline] (1) can be polymerized to nanostructured SiO2/phenolic-resin composite material by thermally induced twin polymerization. Thermally induced twin polymerization represents a way to produce nanocomposites simply by thermal induction of twin monomers. Besides 1, the thermal reaction of several related salicylic (2-oxybenzylic) silicon molecules has been investigated. The thermal cleavage of the molecules is studied by using several trapping reagents (e.g., vinyl compounds). A significant occurrence of quinone methide adducts indicates that the thermal mechanism proceeds not only by a ring opening at the oxymethylene position, but also with the ortho-quinone methide as a central or alternative intermediate. This is supported by product analyses of thermally initialized reactions of 1 and its substituted analogues as well as by quantum chemical calculations.
Co-reporter:Ingolf Kahle, Oliver Tröber, Hannes Richter and Stefan Spange
New Journal of Chemistry 2013 vol. 37(Issue 5) pp:1479-1485
Publication Date(Web):21 Feb 2013
DOI:10.1039/C3NJ41130C
The synthesis of new 3H-naphtho[2,1-b]pyran dyes substituted at position 8 of the naphthalene ring by either a stilbazolium or an 4-ethenyl-quinolinium group and their photochemical properties are described. In non-polar media the naphthopyran–stilbazolium conjugates do not show any photochromic response while the formation of the ring opened species is promoted in strong polar media. Additional investigations of the new dyes within the pores of mesoporous MCM 41 particles showed a significant enhancement of the photochromism compared with that in solution. The generation of the ring-opened species upon irradiation with UV-light is accompanied by a decrease of the fluorescence intensity, which could be recovered by illumination with visible light.
Co-reporter:Alexer Schade;Roberto Menzel;Helmar Görls;Dr. Stefan Spange;Dr. Rainer Beckert
Asian Journal of Organic Chemistry 2013 Volume 2( Issue 6) pp:498-503
Publication Date(Web):
DOI:10.1002/ajoc.201300085
Co-reporter:Alexander Mehner, Tobias Rüffer, Heinrich Lang, Maik Schlesinger, Michael Mehring and Stefan Spange
New Journal of Chemistry 2013 vol. 37(Issue 5) pp:1290-1293
Publication Date(Web):07 Mar 2013
DOI:10.1039/C3NJ40775F
The tetranuclear titanium oxido cluster (μ4-oxido)-hexakis(μ-thiophene-2-methoxido)-octakis(thiophene-2-methoxido)-tetra-titanium (1), which has been obtained by the reaction of Ti(OiPr)4 with thiophene-2-methanol in the presence of moisture, consists of a Ti4(μ4-O)(μ-O)6-core and crystallizes as a racemic mixture of two different chiral enantiomers. Compound 1 undergoes a reversible phase transition at 163–168 K in the solid state as evidenced by Powder X-Ray Diffraction (PXRD) and Differential Scanning Calorimetry (DSC). Single-crystal X-ray diffraction studies have been carried out to establish the molecular structure of the high and low temperature phase of 1.
Co-reporter:Alexer Mehner;Andreas Pohlers;Walter Hoyer;Gerhard Cox
Macromolecular Chemistry and Physics 2013 Volume 214( Issue 9) pp:1000-1010
Publication Date(Web):
DOI:10.1002/macp.201200629
Co-reporter:Ingmar Polenz;Friedrich Georg Schmidt;Joachim Friedrich;Ivan Tchernook
Macromolecular Chemistry and Physics 2013 Volume 214( Issue 13) pp:1473-1483
Publication Date(Web):
DOI:10.1002/macp.201300200
Co-reporter:Falko Böttger-Hiller;Patrick Kempe;Dr. Gerhard Cox;Dr. Alexer Panchenko;Dr. Nicole Janssen;Dr. Albrecht Petzold;Dr. Thomas Thurn-Albrecht;Lars Borchardt;Dr. Marcus Rose;Dr. Stefan Kaskel;Colin Georgi;Dr. Heinrich Lang;Dr. Stefan Spange
Angewandte Chemie 2013 Volume 125( Issue 23) pp:6204-6207
Publication Date(Web):
DOI:10.1002/ange.201209849
Co-reporter:Falko Böttger-Hiller;Patrick Kempe;Dr. Gerhard Cox;Dr. Alexer Panchenko;Dr. Nicole Janssen;Dr. Albrecht Petzold;Dr. Thomas Thurn-Albrecht;Lars Borchardt;Dr. Marcus Rose;Dr. Stefan Kaskel;Colin Georgi;Dr. Heinrich Lang;Dr. Stefan Spange
Angewandte Chemie International Edition 2013 Volume 52( Issue 23) pp:6088-6091
Publication Date(Web):
DOI:10.1002/anie.201209849
Co-reporter:Katharina Ladewig, Andreas Seifert, Harald Hahn, Michael Hietschold, Norbert Moszner, Peter Burtscher and Stefan Spange
Journal of Materials Chemistry A 2012 vol. 22(Issue 9) pp:3839-3852
Publication Date(Web):23 Jan 2012
DOI:10.1039/C2JM15407B
An advanced procedure for the one-pot synthesis of organic–inorganic hybrid materials via combination of sol–gel process and nucleophilic aromatic substitution reaction (SNAr) of 4-fluoronitrobenzene and 3-aminopropyltrimethoxysilane is described. With this advanced procedure both SNAr-reaction and sol–gel process can be accomplished in the same reaction vessel due to the sol–gel precursor tetraethoxysilane (TEOS) acting as solvent during the first reaction step. Via extensive NMR spectroscopic studies it is proven for the first time that—contrary to common belief—hydrogen fluoride (HF), which is formed as a by-product in the SNAr-reaction, is not trapped by any bases present but is rather trapped by both of the silane species and serves as a catalyst during the subsequent sol–gel process. The chromophoric system of the resulting xerogels is well protected against aggressive chemicals, i.e. strong acids, by the silica matrix, which predestines these materials for pigment applications. Given that a high chromophore content is highly desirable in these applications, we show that the chromophore content of the final xerogel can be varied by modification of the organosilicon precursor:TEOS ratio or by using trialkoxy-silanes bearing two or three amino functions, whereby the latter option is more favourable. Monodisperse core–shell particles with identical chromophore content but consisting of a pure silica-core and a p-nitroaniline functionalized shell with a diameter of about 200 nm can also be prepared using this advanced procedure.
Co-reporter:Falko Böttger-Hiller, Alexander Mehner, Susann Anders, Lothar Kroll, Gerhard Cox, Frank Simon and Stefan Spange
Chemical Communications 2012 vol. 48(Issue 85) pp:10568-10570
Publication Date(Web):21 Sep 2012
DOI:10.1039/C2CC35112A
Sulphur-doped carbon was synthesized using a thiophene-based twin monomer. While tetra(thiophene-2-ylmethoxy)-silane can be converted into sulphur containing nanocomposites, which lead to microporous sulphur-doped carbon, it is possible to produce additional mesopores by the use of templates. Thus, a variety of sulphur-doped carbon materials with tailored pore texture are available.
Co-reporter:Thomas Ebert, Gerhard Cox, Evgeniya Sheremet, Ovidiu Gordan, Dietrich R. T. Zahn, Frank Simon and Stefan Spange
Chemical Communications 2012 vol. 48(Issue 79) pp:9867-9869
Publication Date(Web):16 Aug 2012
DOI:10.1039/C2CC34775J
Defect-free microporous carbon layers on graphite can be produced by DABCO-catalyzed twin polymerization of 2,2′-spirobi[4H-1,3,2-benzodioxasiline] in a slurry polymerization and subsequent thermal transformation of the resulting phenolic resin into carbon.
Co-reporter:Katja Hofmann, Susann Brumm, Carola Mende, Kevin Nagel, Andreas Seifert, Isabelle Roth, Dieter Schaarschmidt, Heinrich Lang and Stefan Spange
New Journal of Chemistry 2012 vol. 36(Issue 8) pp:1655-1664
Publication Date(Web):13 Jun 2012
DOI:10.1039/C2NJ40313G
Nucleophilic substitution of fluoroaromatics with poly(vinyl amine) (PVAm) is a suitable method for producing various azobenzene-functionalized PVAms. The solubility of the fluoroaromatic reagents in water was mediated by complexation with 2,6-O-dimethyl-β-cyclodextrin (DMCD). The degree of functionalization has been determined using model compounds as reference system. The solvatochromic properties of the polymers and the model compounds have been studied and interpreted using the well-established linear solvation energy relationships (LSER) of Kamlet–Taft and Catalán. The most dominant effect on the solvatochromic behavior is caused by interactions with solvents of a different dipolarity/polarizability. Also the basicity of the solvents is assumed to play an important role in the solvatochromism of the azobenzene-functionalized PVAms which shows the influence of the polymer chains. Furthermore, the UV/vis absorption spectra show a bathochromic shift with increasing acid strength of the medium. The impact of the PVAm backbone on the color of the chromophore bonded is highlighted.
Co-reporter:Susan Seifert, Andreas Seifert, Gunther Brunklaus, Katja Hofmann, Tobias Rüffer, Heinrich Lang and Stefan Spange
New Journal of Chemistry 2012 vol. 36(Issue 3) pp:674-684
Publication Date(Web):12 Dec 2011
DOI:10.1039/C2NJ20835K
The solid state complexes, solvatochromic and acidochromic behaviour of four merocyanine-type dyes derived from barbituric and thiobarbituric acid and their use as solvatochromic probe molecules for coloured surfaces are described. The dyes were obtained by condensation reaction of barbituric, N-methylbarbituric, N,N′-dimethylbarbituric and thiobarbituric acid with 4-N,N-dimethylaminocinnamaldehyde. The dyes were characterised by means of liquid and solid state NMR techniques (1H MAS NMR, 1H–1H DQ MAS NMR, 13C CPMAS NMR), single-crystal X-ray analysis, UV/vis and IR measurements. The solvatochromism has been investigated in 43 solvents and interpreted in terms of Kamlet–Taft parameters α, β, and π*. Altogether, the solvatochromic properties of these four dyes were determined mainly by the hydrogen bond donating (HBD) ability and the polarisability/dipolarity of a solvent. The interactions of the dyes with oxidic and metal surfaces were studied. Their perichromic behaviour was compared with that of established solvatochromic dyes for the determination of α, β, and π*, namely dicyano-bis-(1,10-phenanthroline)-iron(II)-complex (1), 3-(4-amino-3-methylphenyl)-7-phenyl-benzo-[1,2-b:4,5-b′]-difuran-2,6-dione (2) and 4-tert-butyl-2-(dicyanomethylene)-5-[4-(diethylamino)benzylidene]-Δ3-thiazoline (3). The barbituric acid dyes were used to probe the surface polarity of coloured oxides like tungsten(VI) oxide and iron(III) oxide. The interactions between the dyes and metals like zinc and aluminium were also investigated.
Co-reporter:Petra Schönherr, Andreas Seifert, Ralf Lungwitz, Frank Simon, Norbert Moszner, Peter Burtscher, Stefan Spange
Progress in Organic Coatings 2012 Volume 75(Issue 4) pp:335-343
Publication Date(Web):December 2012
DOI:10.1016/j.porgcoat.2012.07.018
The interaction of 4-(4-nitrobenzyl)pyridine (NBP) with electrophile reagents results in an intensive colored product. This process occurs rapidly and serves as an indication reaction for several electrophilic reagents which is known as Preussmann-test (PT). In this study the application of the PT is firstly presented for surface bonded epoxy groups. 3-Glycidoxypropyltrimethoxysilane (Glymo) has been used for surface functionalization of various solids such as alumo silicate, MgO, Ba-glass, Sr-glass, and various silicas such as Aerosil® 300, OX 50, Sunspheres and silica gel KG 60. The covalent bonding of the epoxy moieties on the particle's surface by the silane function has been demonstrated by solid state NMR spectroscopy. The detection of active epoxy groups was implemented by the use of 13C–{1H}-CP-MAS-NMR and XPS investigations. These both analytical methods require a large demand of time. Advantageously, the PT, which is applied to Glymo functionalized surfaces, enables a fast and certain assignment of the presence of active epoxy groups. The indicator reaction for detection of epoxy groups is the blue coloration of the samples. The reversible switching of the epoxy particles coloration is attributed to residual acid surface groups from the alumo silicates due to the protonation of the alkylated NBP product.Highlights► Surface functionalization of solids is made with 3-glycidoxypropyltrimethoxysilane. ► Detection of surface bonded epoxy groups is achieved by solid state NMR and XPS. ► The Preussmann-test enables a fast and certain evidence of epoxy groups. ► For the Preussmann-test 4-(4-nitrobenzyl)pyridine is used. ► Surface bonds epoxy groups are indicated by a blue coloration of the material.
Co-reporter:Katja Hofmann;Isabelle Roth
Macromolecular Chemistry and Physics 2012 Volume 213( Issue 16) pp:1655-1662
Publication Date(Web):
DOI:10.1002/macp.201200115
Abstract
The nucleophilic aromatic substitution (NAS) reaction of various fluoroaromatic/2,6-O-dimethyl-β-cyclodextrin complexes with poly(vinyl amine) (PVAm) has been studied in water at different pH. Increasing pH lowers the notable negative activation entropy of those types of NAS due to the PVAm chain segments becomes better accessible in basic media. At pH > 7, the zwitterionic intermediate in the course of NAS seems stabilized by intermolecular hydrogen bonds, which has an influence on the increase of activation energy for elimination the fluoride ion. As a consequence, the counter balance between activation entropy and activation energy determines the rate of the NAS with PVAm, which is shown for several functional fluoroaromatic compounds including fluoronitrobenzenes, fluoronitroanilines, and imine bases.
Co-reporter:Katja Hofmann;Isabelle Roth
Macromolecular Chemistry and Physics 2012 Volume 213( Issue 16) pp:
Publication Date(Web):
DOI:10.1002/macp.201290049
Co-reporter:Franziska Riedel
Journal of Physical Organic Chemistry 2012 Volume 25( Issue 12) pp:1261-1268
Publication Date(Web):
DOI:10.1002/poc.3003
The solvatochromism of nine push–pull substituted catechol derivatives has been studied in a set of 39 various solvents. The influence of successive methyl substitution at the catechol OH groups on the extent of the solvatochromic shift has been investigated. The positive solvatochromism of 2-(3,4-dihydroxybenzylidene)-2H-indene-1,3-dione amounts 4360 cm–1, which ranges from toluene to hexamethyl-phosphoric triamide. To the best of our knowledge, it is one of the largest positive solvatochromic extent measured for a positive solvatochromic dye, comparable with Brooker's thiobarbituric acid with an extent of 4400 cm–1. The detailed analyses of the solvatochromism were carried out by alternatively using the Kamlet–Taft and Catalán solvent parameters to achieve information of dipolarity versus polarizability effects of solvent upon solvatochromic properties. In solvents with high β values such as alcohols (0.66 < β < 0.90), amides (0.48 < β < 0.80), dimethyl sulfoxide (β = 0.76), tetramethyl urea (β = 0.80) and hexamethyl-phosphoric triamide (β = 1.05) UV–Vis absorption spectra show two separate λmax, which are caused by a deprotonation reaction. The solvatochromic behaviour of the anionic species is compared with those of the catechol derivatives. Copyright © 2012 John Wiley & Sons, Ltd.
Co-reporter:Dr. Ralf Lungwitz ;Dr. Stefan Spange
ChemPhysChem 2012 Volume 13( Issue 7) pp:1910-1916
Publication Date(Web):
DOI:10.1002/cphc.201100832
Abstract
Hydrogen-bond-accepting (HBA) and -donating (HBD) parameters of ionic liquids (ILs) with halogeno complex anions are determined by means of 1H NMR spectroscopy. Thereby, the imidazolium cation serves both as part of the IL and as 1H NMR probe. The HBA and HBD strength are calculated in terms of the empirical polarity parameters β and α according to the Kamlet–Taft equation. The study includes 1-butyl-3-methylimidazolium ILs with chloroaluminates of various mole fractions from 0 to 0.67 of AlCl3, anions of the general chemical formula MtXn− (Mt=metal, X=halide) as well as tri- and pentaiodide. The 1H NMR chemical shift of the hydrogen atom in the two position of the imidazolium cation is a function of the HBA ability of the corresponding anion. For the chloroaluminates the HBA ability decreases and the HBD ability increases with increasing mole fraction of the Lewis acid. In general, the HBA strength of the studied ILs increases in the following order: MoCl6−<Al2Cl7−<AlCl4−<WCl7−<I5−<SnCl5−<I3−<SbCl6−<TiCl5−<BBr4−<SnCl3−. The corresponding HBD ability shows a reverse trend.
Co-reporter:Tina Löschner;Alexer Mehner;Dr. Silke Grund;Dr. Andreas Seifert;Dr. Andreas Pohlers;Dr. Arno Lange;Dr. Gerhard Cox;Dr. Hans-Joachim Hähnle;Dr. Stefan Spange
Angewandte Chemie 2012 Volume 124( Issue 13) pp:3312-3315
Publication Date(Web):
DOI:10.1002/ange.201108011
Co-reporter:Tina Löschner;Alexer Mehner;Dr. Silke Grund;Dr. Andreas Seifert;Dr. Andreas Pohlers;Dr. Arno Lange;Dr. Gerhard Cox;Dr. Hans-Joachim Hähnle;Dr. Stefan Spange
Angewandte Chemie International Edition 2012 Volume 51( Issue 13) pp:3258-3261
Publication Date(Web):
DOI:10.1002/anie.201108011
Co-reporter:Susan Seifert, Susanne Höhne, Frank Simon, Christian Hanzelmann, René Winkler, Thomas Schmidt, Ralf Frenzel, Petra Uhlmann, and Stefan Spange
Langmuir 2012 Volume 28(Issue 42) pp:14935-14943
Publication Date(Web):October 4, 2012
DOI:10.1021/la302855f
The adsorption of poly(vinylformamide) (PVFA) and its derivative statistical copolymer poly(vinyl-formamide-co-vinylamine) (PVFA-co-PVAm) on metallic copper and copper oxide particles as well as planar copper surfaces was studied as a function of the degree of hydrolysis of PVFA, the pH, and the polymer concentration in solution. The chemical composition and molecular structure of the PVFA-co-PVAm layers were investigated by surface-sensitive spectroscopic methods such as XPS, DRIFT spectroscopy, and ellipsometry. The findings allowed us to explain the adsorption mechanisms and the forces driving the PVFA-co-PVAm adsorption. It was shown that PVFA-co-PVAm layers thicker than 30 nm are able to protect the planar copper surface against corrosive attack.
Co-reporter:Katja Hofmann and Stefan Spange
The Journal of Organic Chemistry 2012 Volume 77(Issue 11) pp:5049-5055
Publication Date(Web):May 8, 2012
DOI:10.1021/jo300530k
Para-nitroaniline derivatives with peripheral 1,2- and 1,3-diol functionalities [O2N–C6H4–NR1–CH2CH(OH)CH2OH; O2N–C6H4–NR1–CH(CH2OH)2; R1 = −H, −CH3] covalently bonded to the amino group are esterified with various para-substituted phenylboronic acids [R2–C6H4–B(OH)2; R2 = −OCH3, −CH3, −H, −Br, −CHO, −NO2, −B(OH)2], and the solvatochromic properties of these esters are investigated in 33 solvents of different polarity. To interpret the solvent effects, the established linear solvation energy (LSE) multiparameter equations of Kamlet–Taft and the improved Catalán scales are used. Although the boron atom is separated by two or three sp3-hybridized carbon atoms from the actual chromophore, solvation effects have a significant positive solvatochromic effect on the nitroaniline unit (R1 = −CH3) as result of the solvent acting as a donor at the boron atom. The influence of the substituent R2 on the coefficient b of the LSE relationship according to Kamlet–Taft and Catalán, which reflects the quantitative influence of the hydrogen-bonding acceptor or the electron-pair donor capacity of the solvent on the position of the UV–vis absorption maximum, can be determined via a linear Hammett relationship [b = f(σp)]. The interpretation of the effects is based on the electronic influence of the solvated boronic acid ester unit on the 4-nitroaniline group, predominantly through inductive interactions.
Co-reporter:Ingolf Kahle, Oliver Tröber, Sabine Trentsch, Hannes Richter, Bernd Grünler, Steffen Hemeltjen, Maik Schlesinger, Michael Mehring and Stefan Spange
Journal of Materials Chemistry A 2011 vol. 21(Issue 13) pp:5083-5088
Publication Date(Web):21 Feb 2011
DOI:10.1039/C0JM03986A
Precisely nano-sized aluminosilicate particles (average diameter size 50 to 80 nm) with tailor-made internal surface polarity are suitable as host material for photochromic dyes of the chromene type in order to produce optical transparent photoswitchable polymer films. The sophisticated host material does accomplish two important requirements for a technical application, appropriate internal space for the light induced reversible switching process of the adsorbed dye and suppression of disturbing chemical reactions. The adjustment of the internal surface polarity of the host material was achieved by silane reagents which could be observed by means of specific solvatochromic probes.
Co-reporter:Patrick Kempe, Tina Löschner, David Adner and Stefan Spange
New Journal of Chemistry 2011 vol. 35(Issue 12) pp:2735-2739
Publication Date(Web):10 Oct 2011
DOI:10.1039/C1NJ20654K
4H-1,3,2-Benzodioxasilines represent a class of monomers, which are suitable for the recently developed concept of twin polymerization. Relating to the prediction of quantum chemical calculations we are now able to confirm the results for the first step of the reaction: the selective ring opening of 4H-1,3,2-benzodioxasilines. An electrophilic attack of iodotrimethylsilane leads firstly to a bond cleavage at the oxymethylene group and not at the more stable Si–O–aryl bond, yielding ring-opened species.
Co-reporter:Mirko Bauer ;Dr. Stefan Spange
Angewandte Chemie 2011 Volume 123( Issue 41) pp:9901-9904
Publication Date(Web):
DOI:10.1002/ange.201103585
Co-reporter:Susan Seifert, Frank Simon, Giesela Baumann, Michael Hietschold, Andreas Seifert, and Stefan Spange
Langmuir 2011 Volume 27(Issue 23) pp:14279-14289
Publication Date(Web):November 10, 2011
DOI:10.1021/la203479n
The adsorption of poly(vinyl formamide) (PVFA) and the statistic copolymers poly(vinyl formamide-co-vinyl amine) (PVFA-co-PVAm) onto zinc and iron metal particles as well as their oxides was investigated. The adsorbates were characterized by means of XPS, DRIFT spectroscopy, wet chemical analysis, and solvatochromic probes. Dicyano-bis-(1,10-phenanthroline)-iron(II) (1), 3-(4-amino-3-methylphenyl)-7-phenyl-benzo-[1,2-b:4,5-b′]difuran-2,6-dione (2), and 4-tert-butyl-2-(dicyano-methylene)-5-[4-(diethylamino)-benzylidene]-Δ3-thiazoline (3) as solvatochromic probes were coadsorbed onto zinc oxide to measure various effects of surface polarity. The experimental findings showed that the adsorption mechanism of PVFA and PVFA-co-PVAm strongly depends on the degree of hydrolysis of PVFA and pH values and also on the kind of metal or metal oxide surfaces that were employed as adsorbents. The adsorption mechanism of PVFA/PVFA-co-PVAm onto zinc oxide and iron oxide surfaces is mainly affected by electrostatic interactions. Particularly in the region of pH 5, the adsorption of PVFA/PVFA-co-PVAm onto zinc and iron metal particles is additionally influenced by redox processes, dissolution, and complexation reactions.
Co-reporter:Mirko Bauer ;Dr. Stefan Spange
Angewandte Chemie International Edition 2011 Volume 50( Issue 41) pp:9727-9730
Publication Date(Web):
DOI:10.1002/anie.201103585
Co-reporter:Katja Schreiter, Katja Hofmann, Andreas Seifert, Alexander Oehlke, Katharina Ladewig, Tobias Rüffer, Heinrich Lang and Stefan Spange
Chemistry of Materials 2010 Volume 22(Issue 9) pp:2720
Publication Date(Web):April 6, 2010
DOI:10.1021/cm903048u
Novel donor−acceptor-substituted stilbenes were synthesized by means of nucleophilic aromatic substitution starting from 1-fluoro-2-nitro-4-[(E)-2-(4-nitrophenyl)vinyl]benzene and n-propylamine, L-proline, and 2-aminopropane-1,3-diol as model compounds for the study of molecular interactions in the solid-state and liquid environments of different polarity. The solvatochromic behavior of the chromophoric building blocks has been studied and interpreted using the empirical Kamlet−Taft solvent parameters π* (dipolarity/polarizability), α (hydrogen bond donating capacity), and β (hydrogen bond accepting ability) in terms of the well-established linear solvation energy relationship (LSER): νmax = νmax,0 + sπ* + aα + bβ. The most dominant effect on the solvatochromic behavior of nitrostilbenes is caused by interactions with solvents of different polarity/polarizability. To evaluate the environmental effects the nitrostilbenes are subjected to, we also investigated the UV/vis spectroscopic behavior as pure crystal powders and as an organic component in class II xerogels. Starting from these chromophores we were able to use three different synthetic routes in order to bind the chromophore covalently to the trialkoxysilane via an amine, amide or urethane function, respectively. The precursors thus obtained were converted into the corresponding xerogels in situ in a one-pot procedure. Two routes can be followed−one involving incorporation of the chromophore in the main chain, and the other involving incorporation in the side chain. All obtained organic−inorganic hybrid materials were characterized in detail using solid-state NMR, FT-IR, and UV/vis spectroscopy.
Co-reporter:Ralf Lungwitz, Thomas Linder, Jörg Sundermeyer, Igor Tkatchenko and Stefan Spange
Chemical Communications 2010 vol. 46(Issue 32) pp:5903-5905
Publication Date(Web):07 Jul 2010
DOI:10.1039/C0CC00797H
The reaction of four different basic ionic liquid precursors with Aerosil®300 is presented. Chemisorbed imidazolium and phosphonium cations, with silanolate anions as part of the silicatic support, were obtained and investigated with various solid state NMR techniques.
Co-reporter:Mirko Bauer
European Journal of Organic Chemistry 2010 Volume 2010( Issue 2) pp:259-264
Publication Date(Web):
DOI:10.1002/ejoc.200901066
Abstract
The supramolecular complex formation by cooperativehydrogen bonding of a highly dipolar barbiturate dye and 2,6-diacetamidopyridine is shown to have a marked effect on the reactivity of the barbiturate. The increase of both Lewis acidity and electrophilicity by hydrogen bonding is demonstrated by thermodynamic and kinetic studies using the electrophile–nucleophile recombination reaction with cyanide.
Co-reporter:Ralf Lungwitz, Veronika Strehmel and Stefan Spange
New Journal of Chemistry 2010 vol. 34(Issue 6) pp:1135-1140
Publication Date(Web):25 Feb 2010
DOI:10.1039/B9NJ00751B
Based on the developed tool to measure Kamlet–Taft polarity parameters α (hydrogen bond donating ability), β (hydrogen bond accepting ability), and π* (dipolarity/polarisability) for ionic liquids (ILs), it is now possible to precisely determine the influence of both cation and anion structure on π*. α, β, and π* values of 38 1-alkyl-3-methylimidazolium ILs ([Rmim]X) are presented in this work to give a solid background for the discussion. The dipolarity/polarisability of [Rmim]X determined by means of the established π*-sensitive solvatochromic probe 4-tert-butyl-2-(dicyanomethylene)-5-[4-(diethylamino)benzylidene]-Δ3-thiazoline is a blend of dipolarity and polarisability in equal parts. The large π* parameters of ionic liquids are attributed to two cumulative effects: the ion pairing strength and the individual polarisabilities of both the cation and anion. This is shown by the influence of anion and cation structures (alkyl chain length of R) on the dipolarity/polarisability. For all studied ionic liquids we observed a general trend. The stronger the ion pairing effect, the greater is the determined π* value.
Co-reporter:Susann Anders;Wolfgang Schrepp;Lysann Kaßner;Andreas Pohlers;Walter Hoyer
Macromolecular Chemistry and Physics 2010 Volume 211( Issue 14) pp:1550-1558
Publication Date(Web):
DOI:10.1002/macp.201000071
Co-reporter:Ina Bolz;Mirko Bauer;Anja Rollberg
Macromolecular Symposia 2010 Volume 287( Issue 1) pp:8-15
Publication Date(Web):
DOI:10.1002/masy.201050102
Abstract
Summary: The barbituric acid moiety of the presented dyes shows multifunctional properties like acidochromism, solvatochromism, and adjustable hydrogen-bonding pattern for molecular recognition. Hydrogen-bonding ability, acidity and solvatochromic effects are studied for a series of N-alkyl substituted 5-(4-nitrophenyl)-barbiturates. Solvatochromism and metal ion complexation are also investigated using chromophoric thiobarbituric acid derivatives.
Co-reporter:Ingolf Kahle
The Journal of Physical Chemistry C 2010 Volume 114(Issue 36) pp:15448-15453
Publication Date(Web):August 23, 2010
DOI:10.1021/jp1048106
The adsorption of the photochromic 1,3,3-trimethyl-6′-nitroindoline-2-spiro-2′-benzopyran (SP) on Y-zeolites from dichloromethane solution and the ship in the bottle reaction (SIBOR) of SP have been studied by measuring the UV/vis absorption of the resulting materials to achieve information on polarity of the internal and external surface environments. The acidity and α values (hydrogen bond donating ability) of the faujasites significantly differ whether the probe is located at the external surface or inside the Y-zeolite. Additionally, dicyanobis(1,10-phenanthroline)iron(II) [Fe(phen)2(CN)2] (1) and 4-tert-butyl-2-(dicyanomethylene)-5-[4-(diethylamino)benylidene]-Δ3-thiazoline (2) were used as solvatochromic probes for the external surface. The empirical Kamlet−Taft polarity parameter α (hydrogen bond donating (HBD) ability) and π* (dipolarity/polarizability) have been determined for the faujasites surfaces using the linear solvation energy relationship (LSER).
Co-reporter:Stefan Spange;Silke Grund
Advanced Materials 2009 Volume 21( Issue 20) pp:2111-2116
Publication Date(Web):
DOI:10.1002/adma.200802797
Abstract
Forming two structurally different but associated polymer structures in a single step is a possible route for the production of nanostructured materials. By means of twin polymerization of specially constructed monomers consisting of two different covalently bonded building blocks (hybrid monomers), this route is realized. What is important is that two different macromolecular structures are formed from one monomer in a single process. The two polymers formed can be linear, branched, or cross-linked structures. The molecular composition of the hybrid monomer defines the degree of cross-linking of the corresponding macromolecular structures that is theoretically possible.
Co-reporter:Franziska Riedel
Journal of Physical Organic Chemistry 2009 Volume 22( Issue 3) pp:203-211
Publication Date(Web):
DOI:10.1002/poc.1468
Abstract
Solvatochromism of 4-nitrocatechol (1), tetra-n-butylammonium 2-hydroxy-4-nitrophenolate (2), sodium tris(4-nitrobenzene-1,2-diolato)silicate (3a), tetra-n-butylammonium tris(4-nitrobenzene-1,2-diolato)silicate (3b), pyrrolidinium tris(4-nitrobenzene-1,2-diolato)silicate (3c), (3-amino-1-propyl)-bis(4-nitrobenzene-1,2-diolato)silicate (4a), and (N,N-diethyl-3-amino-1-propyl)-bis(4-nitrobenzene-1,2-diolato)silicate (4b) as well as potassium bis(4-nitrobenzene-1,2-diolato)borate (5) has been studied in a set of common solvents. The origin of the solvent-induced UV/vis band shifts of 1–3c, and 5 has been determined by means of Linear Solvation Energy Relationship (LSER) using the empirical Kamlet–Taft and Catalán solvent parameter sets, respectively. The solvent-induced UV/vis band shift of the negatively charged moiety of all solvatochromic dyes studied is mainly a function of the hydrogen-bond donor (HBD) strength and the dipolarity/polarizability of the solvent as shown by multiple regression analyses. HBD solvents cause a hypsochromic shift of the UV/vis band due to specific solvation of the anion site. Oppositely, increasing dipolarity/polarizability of the solvent induces a bathochromic shift of the UV/vis absorption band. The donor strength of the solvent has an influence on the UV/vis band shift since ion pair formation occurs in solvents of low relative permittivity. This is shown by the impact of the counter ion of sodium tris(4-nitrobenzene-1,2-diolato)silicate (3a) compared to tetra-n-butylammonium tris(4-nitrobenzene-1,2-diolato)silicate (3b). The influence of the counter ion on the position of the UV/vis absorption band occurs in the same way as HBD solvents do. Na+ and the pyrrolidinium ion, respectively, have a stronger influence than the tetra-n-butylammonium ion on the solvatochromic band shift due to the stronger cation–anion interaction. Copyright © 2008 John Wiley & Sons, Ltd.
Co-reporter:Stefan Spange Dr.;Patrick Kempe;Andreas Seifert Dr.;AlexerA. Auer Dr.;Petra Ecorchard Dr.;Heinrich Lang Dr.;Meiken Falke Dr.;Michael Hietschold Dr.;Andreas Pohlers Dr.;Walter Hoyer Dr.;Gerhard Cox Dr.;Emanuel Kockrick;Stefan Kaskel Dr.
Angewandte Chemie 2009 Volume 121( Issue 44) pp:8403-8408
Publication Date(Web):
DOI:10.1002/ange.200901113
Co-reporter:Falko Böttger-Hiller;Ralf Lungwitz;Andreas Seifert Dr.;Michael Hietschold Dr.;Maik Schlesinger;Michael Mehring Dr. Dr.
Angewandte Chemie 2009 Volume 121( Issue 47) pp:9039-9043
Publication Date(Web):
DOI:10.1002/ange.200903636
Co-reporter:Ina Bolz;Dieter Schaarschmidt;Tobias Rüffer Dr.;Heinrich Lang Dr. Dr.
Angewandte Chemie 2009 Volume 121( Issue 40) pp:7576-7579
Publication Date(Web):
DOI:10.1002/ange.200902860
Co-reporter:Alexander Oehlke, Alexander A. Auer, Katja Schreiter, Katja Hofmann, Franziska Riedel and Stefan Spange
The Journal of Organic Chemistry 2009 Volume 74(Issue 9) pp:3316-3322
Publication Date(Web):April 3, 2009
DOI:10.1021/jo9000383
The electrophilic substituent constant σ+ was derived from the relative rate constants of the solvolysis of substituted α-cumyl chlorides in an acetone/water solvent mixture in the original work by Brown and Okamoto (J. Am. Chem. Soc. 1958, 80, 4979). As an extension of this procedure, we were looking for methods to determine σ+ values in nonpolar media. We have calculated the exocyclic charges q(R) for α-cumyl cations (R-C6H4CMe2+) as a measure of the electron-donating capacity of meta and para substituents. The UV−vis absorption ν̃max of the analogously substituted nitrobenzene derivatives has been used for the experimental measurement of the electron donating capacity of substituents R in nonpolar media. A linear relationship between ν̃max and Δq(R) (= q(R-C6H4CMe2+) − q(C6H5CMe2+)) was obtained. A description of the electron-donating capacity in nonpolar media can be achieved both for substituents investigated already and for those for which the experimental determination of σ+ has previously been difficult. Special interest was directed to boron-based substituents in which the electron-donating ability is dependent on the coordinational environment of the boron atom.
Co-reporter:Ina Bolz;Dieter Schaarschmidt;Tobias Rüffer Dr.;Heinrich Lang Dr. Dr.
Angewandte Chemie International Edition 2009 Volume 48( Issue 40) pp:7440-7443
Publication Date(Web):
DOI:10.1002/anie.200902860
Co-reporter:Stefan Spange Dr.;Patrick Kempe;Andreas Seifert Dr.;AlexerA. Auer Dr.;Petra Ecorchard Dr.;Heinrich Lang Dr.;Meiken Falke Dr.;Michael Hietschold Dr.;Andreas Pohlers Dr.;Walter Hoyer Dr.;Gerhard Cox Dr.;Emanuel Kockrick;Stefan Kaskel Dr.
Angewandte Chemie International Edition 2009 Volume 48( Issue 44) pp:8254-8258
Publication Date(Web):
DOI:10.1002/anie.200901113
Co-reporter:Falko Böttger-Hiller;Ralf Lungwitz;Andreas Seifert Dr.;Michael Hietschold Dr.;Maik Schlesinger;Michael Mehring Dr. Dr.
Angewandte Chemie International Edition 2009 Volume 48( Issue 47) pp:8878-8881
Publication Date(Web):
DOI:10.1002/anie.200903636
Co-reporter:Doreen Piasta, Cornelia Bellmann, Stefan Spange and Frank Simon
Langmuir 2009 Volume 25(Issue 16) pp:9071-9077
Publication Date(Web):July 9, 2009
DOI:10.1021/la900407n
A readily synthetic route to endow the surface of hydrophobic carbon black (CB) particles with primary amino groups has been developed. The adsorption of the water-borne polyelectrolyte copolymer poly(vinyl amine-co-vinyl amide) (PVAm) on CB was studied as function of pH and polyelectrolyte concentration. The amino-functionalization process of CB with PVAm strongly depends on pH. As shown by electrokinetic measurement as function of pH, the content of accessible primary amino groups on the surface of CB increases with increasing the OH− concentration. The alternative functionalization of the CB surface with an anionic polyelectrolyte is demonstrated for the adsorption of poly(ethylene-alt-maleic anhydride) (PEMSA). About 50 mg of PVAm can be adsorbed on 1.0 g of CB, which is sufficient to completely alter the surface net charge. The aim of the introduced functional amino groups is their ability to act as anchoring groups for subsequent surface reactions improving the CB’s process ability, compatibility, and adhesion properties.
Co-reporter:Alexer Mehner;Tobias Rüffer;Heinrich Lang;Andreas Pohlers;Walter Hoyer
Advanced Materials 2008 Volume 20( Issue 21) pp:4113-4117
Publication Date(Web):
DOI:10.1002/adma.200801376
Co-reporter:Ralf Lungwitz and Stefan Spange
New Journal of Chemistry 2008 vol. 32(Issue 3) pp:392-394
Publication Date(Web):24 Jan 2008
DOI:10.1039/B714629A
A hydrogen bond accepting (HBA) ability scale for anions of room temperature ionic liquids (RTILs) has been determined by means of 1H NMR spectroscopy and a solvatochromic UV/vis probe.
Co-reporter:Mirko Bauer;Anja Rollberg;Anina Barth
European Journal of Organic Chemistry 2008 Volume 2008( Issue 26) pp:4475-4481
Publication Date(Web):
DOI:10.1002/ejoc.200800355
Abstract
Barbiturate dyes containing either a dipolar or polarizable chromophoric system have been synthesized and their solvatochromism investigated. The effect of specific and non-specific solvent interactions on the position of their UV/Vis absorption bands has been evaluated by using the Kamlet–Taft and Catalán solvent parameter sets. Furthermore, the effect on the solvatochromic behaviour of different substitution patterns on the barbiturate moiety has been examined. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Co-reporter:Katja Hofmann, Katja Schreiter, Andreas Seifert, Tobias Rüffer, Heinrich Lang and Stefan Spange
New Journal of Chemistry 2008 vol. 32(Issue 12) pp:2180-2188
Publication Date(Web):08 Sep 2008
DOI:10.1039/B809055F
New donor–acceptor-substituted azo dyes, such as 2-({4-[(E)-(2,4-dinitrophenyl)diazenyl]-2-nitrophenyl}amino)propane-1,3-diol, (2S)-1-{4-[(E)-(2,4-dinitrophenyl)diazenyl]-2-nitrophenyl}-pyrrolidine-2-carboxylic acid and methyl-(2S)-1-{4-[(E)-(2,4-dinitrophenyl)diazenyl]-2-nitrophenyl}pyrrolidine-2-carboxylate have been obtained in a single step by nucleophilic aromatic substitution of (E)-1-(2,4-dinitrophenyl)-2-(4-fluoro-3-nitrophenyl)diazene with 2-aminopropane-1,3-diol, (S)-proline and (S)-proline methyl ester hydrochloride. The solvatochromism of the diol- and (S)-proline-methyl-ester-containing azo dye was studied and analysed using the empirical Kamlet–Taft and Catalán solvent parameter set. The dyes undergo a reversible protonation–deprotonation equilibrium in a concentration range of 5–12 M hydrochloric acid. The UV/Vis absorption spectra show a bathochromic shift with increasing acid strength of the medium.
Co-reporter:Ralf Lungwitz, Manfred Friedrich, Wolfgang Linert and Stefan Spange
New Journal of Chemistry 2008 vol. 32(Issue 9) pp:1493-1499
Publication Date(Web):17 Jul 2008
DOI:10.1039/B805932B
Improved hydrogen bond donor (HBD) strength parameters of 1-butyl-3-methylimidazolium room temperature ionic liquids (RTILs), acceptor number (AN) of Gutmann and α of Kamlet–Taft, have been determined using [Fe(phen)2(CN)2]ClO4 as an original solvatochromic probe. Each of the parameters shows an excellent correlation with the independently determined HBA strength β (Kamlet–Taft) of the anion which demonstrates that empirical polarity parameters of RTILs can be utilized independently of each other.
Co-reporter:Katja Schreiter
Journal of Physical Organic Chemistry 2008 Volume 21( Issue 3) pp:242-250
Publication Date(Web):
DOI:10.1002/poc.1306
Abstract
N-(4-nitrophenyl)-L-proline (2) has been obtained by a nucleophilic aromatic substitution reaction of 4-fluoronitrobenzene with L-proline. The corresponding amide derivatives 3–5 have been synthesized by peptide coupling of 2 with different amino acid derivatives and chiral amines. Solvatochromism of the long-wavelength UV/Vis band in the electronic absorption spectra of the compounds 2–5 has been studied and analyzed using the empirical Kamlet–Taft solvent polarity parameters π* (dipolarity/polarizability), α (hydrogen bond donating ability), and β (hydrogen bond accepting ability). Reasonable Kamlet–Taft solvatochromic correlations (r > 0.95) were established for the three amide derivatives 3–5 in a range of common solvents and three room temperature ionic liquids (RTILs). The UV/Vis absorption of the 4-nitroaniline derivative 2 showed a hypsochromic shift with increasing concentration due to intermolecular hydrogen bonded aggregate formation in protic solvents, which is not observed for compounds 3–5. Copyright © 2008 John Wiley & Sons, Ltd.
Co-reporter:Ralf Lungwitz and Stefan Spange
The Journal of Physical Chemistry C 2008 Volume 112(Issue 49) pp:19443-19448
Publication Date(Web):November 14, 2008
DOI:10.1021/jp806422g
The adsorption of N-methylimidazolium chloride ([Hmim]Cl) on Aerosil300 from dichloromethane solution has been studied by measuring the UV/vis absorption spectra of co-adsorbed solvatochromic probes. Additionally, solid state 29Si-{1H}-CP-MAS, 1H-HR-MAS NMR, and DRIFT spectroscopy studies show that physisorption of [Hmim]Cl on Aerosil300 takes place. Fe(phen)2(CN)2 (1), 3-(4-amino-3-methylphenyl)-7-phenyl-benzo-[1,2-b:4,5b′]-difuran-2,6-dione (2), and 4-tert-butyl-2-(dicyanomethylene)-5-[4-(diethylamino)benylidene]-Δ3-thiazoline (3) were used as solvatochromic surface polarity probes. The UV/vis absorption spectra of the probes 1, 2, and 3 co-adsorbed on the adsorbates were measured as function of the surface loading with [Hmim]Cl in reflection technique. The Kamlet−Taft’s α (hydrogen bond donating ability), β (hydrogen bond accepting ability), and π* (dipolarity/polarizability), respectively, parameters of the [Hmim]Cl/Aerosil300 phase boundary have been calculated using the linear functions of υmax(probe) with the solvent parameter of solvents, which serve as the reference system. The α value of Aerosil300 significantly decreases with an increasing amount of adsorbed [Hmim]Cl. β values are specified by the adsorbed chloride ion. Increasing salt loading of the solid surface increases β. The calculated β values range between those of pure Aerosil300 and [Hmim]Cl. The dipolarity/polarizability of the [Hmim]Cl-loaded silica particles goes through a maximum as a function of the loading and decreases below the value of pure Aerosil300 and [Hmim]Cl. This result is a clear indication for a lowering of the anion−cation interaction of [Hmim]Cl due to the physisorption onto the surface silanol groups.
Co-reporter:Ina Bolz Dr.
Chemistry - A European Journal 2008 Volume 14( Issue 30) pp:9338-9346
Publication Date(Web):
DOI:10.1002/chem.200800626
Abstract
The use of hydrogen-bonding patterns in the same way as is known from DNA building blocks is a challenge for the construction of novel types of suitable chromophoric probes. This feature has been utilised for the construction of a novel type of UV/Vis probe for detection of supramolecular AAD or DAD sequences (A=hydrogen bond acceptor, D=hydrogen bond donor). Here we report on the structure of the enolisable chromophore 1-n-butyl-5-(4-nitrophenyl)barbituric acid (1), which has an adjustable hydrogen-bonding pattern. The position of the keto–enol equilibrium of this dye is strongly influenced both by the solvent polarity and by the chemical environment. Furthermore, the recognition properties of the barbiturate were examined by the use of seven artificial receptors: the pyridine bases 2,6-diaminopyridine (DAP), 2,6-diacetamidopyridine (DAC) and 2,6-bis(trifluoroacetamido)pyridine (TFA), as well as the nucleic acid bases 9-ethyladenine (EtAd), 9-ethylguanine (EtGu), 1-n-butylcytosine (BuCy) and 1-n-butylthymine (BuTy). It was found that 1 can interact with these bases either through acid–base interaction or by hydrogen-bonding complexation. The balance between the interactions is dependent both on the basicity strength and on the presence of a suitable recognition sequence in the base. The induced formation of the enol form of 1 thus causes a significant UV/Vis shift as function of the nature of the base.
Co-reporter:Silke Grund;Patrick Kempe;Gisela Baumann;Andreas Seifert Dr.
Angewandte Chemie 2007 Volume 119(Issue 4) pp:
Publication Date(Web):7 DEC 2006
DOI:10.1002/ange.200504327
Von gleicher Herkunft: Eine neuartige Polymerisationsmethode (Zwillingspolymerisation) liefert organisch-anorganische Nanokomposite ausgehend von einem einzigen Monomer. Zum Beispiel ergibt Tetrafurfuryloxysilan sich durchdringende Netzwerke aus Polyfurfurylalkohol und SiO2 (siehe Bild). Durch Herauslösen der organischen Komponente sind poröse Silicate und möglicherweise auch andere Metalloxide zugänglich.
Co-reporter:Martha Príncipe;Heidi Suárez;Guillermo H. Jimenez;Ricardo Martínez
Polymer Bulletin 2007 Volume 58( Issue 4) pp:619-626
Publication Date(Web):2007 April
DOI:10.1007/s00289-006-0701-5
Composites of furfuryl alcohol and silica gel or Aerosil were prepared using p-toluenesulphonic acid as catalyst at room temperature. The molar ratio furfuryl alcohol/p-toluensulphonic acid was varied between 64.7 and 10. The surface of silica gel was partially coated when composite was prepared with the lower quantity of acid while the use of the higher proportion of acid produces the start of particle agglutination. The thickness of the polymer layer completely coating the surface of the composites ranged between around 10 to 39 Å. Preliminary results suggest that composites could be used as adsorbent of organic pollutants from water.
Co-reporter:Silke Grund;Patrick Kempe;Gisela Baumann;Andreas Seifert Dr.
Angewandte Chemie International Edition 2007 Volume 46(Issue 4) pp:
Publication Date(Web):7 DEC 2006
DOI:10.1002/anie.200504327
A common source: In a novel twin polymerization, a single monomer is transformed into an organic–inorganic nanocomposite. For example, tetrafurfuryloxysilane polymerizes to form a dense interpenetrating network of poly(furfuryl alcohol) and SiO2 (see picture). Nanoporous silicate, and potentially other metal oxides, can be obtained when the organic components are removed.
Co-reporter:Rudolf Holze;Isabelle Roth;Manfred Friedrich;Abdel Aziz Jbarah
Macromolecular Rapid Communications 2006 Volume 27(Issue 3) pp:193-199
Publication Date(Web):23 JAN 2006
DOI:10.1002/marc.200500722
Summary: Nucleophilic aromatic substitution of 2,6-O-dimethyl-β-cyclodextrin (β-DMCD)-complexed 4-fluoro-3-nitroaniline derivatives with poly(vinyl amine) (PVAm) in water results in 2-nitro-1,4-benzenediamine-functionalized water-soluble PVAms in one step. The 2-nitro-1,4-benzenediamine moiety linked to the polymer is solvatochromic and undergoes protonation and deprotonation as function of pH as shown by UV-Vis spectroscopy. The occurrence of an isosbestic point in the UV-Vis spectrum is suitable to directly determine the pKa value using the Henderson-Hasselbalch equation. The influence of the methyl group substitution of the polymer and the 2-nitro-1,4-benzenediamine moiety on the pKa is discussed.
Co-reporter:Alexander Oehlke, Katja Hofmann and Stefan Spange
New Journal of Chemistry 2006 vol. 30(Issue 4) pp:533-536
Publication Date(Web):07 Mar 2006
DOI:10.1039/B516709D
Kamlet–Taft solvatochromic polarity parameters β and π* of ionic liquids with 1-alkyl-3-methylimidazolium cations are determined in two ways by the counter anion X−: the β value represents the hydrogen bond basicity and the π* value depends on the polarizability of X−.
Co-reporter:S. Grund, A. Seifert, G. Baumann, W. Baumann, G. Marx, M. Kehr, S. Spange
Microporous and Mesoporous Materials 2006 Volume 95(1–3) pp:206-212
Publication Date(Web):18 October 2006
DOI:10.1016/j.micromeso.2006.05.019
The sol–gel process of tetraethoxysilane involving the simultaneously occurring cationic polymerization of furfuryl alcohol has been used to fabricate large amounts of monolithic silica having hierarchical bimodal pore size distribution with regular arrayed mesopores. In the key step of the sol–gel polymerization a phase separation on micrometer scale takes place and two different poly(furfuryl alcohol)/silica composite material portions are formed. Each phase consists of a poly(furfuryl alcohol)/silica composite of different quantitative elemental compositions as determined by electron probe microanalysis. The final step involves the thermal decomposition of the poly(furfuryl alcohol)/silica composite material at 900 °C. The discovery of the phase separation among the sol–gel process demonstrates that morphological control can be achieved without additional templates, but under limited molar ratio of tetraethoxysilane/furfuryl alcohol used. The specific advantage of this synthesis is that large amounts in the 100 g scale can be produced using this procedure.
Co-reporter:Silvio Prause;Herbert Barthel
Macromolecular Chemistry and Physics 2005 Volume 206(Issue 3) pp:
Publication Date(Web):25 JAN 2005
DOI:10.1002/macp.200400399
Summary: The surface polarity of dimethylsiloxane-grafted silica particles (DMS/silica) has been studied as a function of surface coverage by measuring the UV/Vis spectra of coadsorbed solvatochromic probes. Fe(phen)2(CN)2 [cis-dicyano-bis-(1,10)-phenanthroline-iron(II), (1)] Michler's ketone [4,4′-bis(N,N-dimethylamino)-benzophenone, (2)], coumarine 153 (3) and 3-(4-amino-3-methylphenyl)-7-phenylbenzo[1,2b:4,5b′]difuran-2,6-dione (4) were used as solvatochromic surface polarity indicators. Kamlet–Taft's α (hydrogen bond acidity), β (hydrogen bond basicity), and π* (dipolarity/polarizability) parameters of the DMS/solid acid interfaces were calculated using different LSE relationships of data sets of the probes 1 and 2 or 3 (for α and π*) as well as 1 and 4 (for β). The values for α decrease significantly with increasing conversion of silanol groups with grafted DMS chains. Then, α asymptotically approachs a constant value when more than about 75% of the residual silanols on the surface are grafted with DMS when measured in 1,2-dichloroethane slurry. The π* values of DMS/silica solvent interfaces seems unaffected by the degree of surface functionalization. The β values of DMS and grafted DMS/silica are clearly lower than the values for α and π*.
Co-reporter:Mohamed El-Sayed;Bernhard Walfort;Heinrich Lang;Wolfgang Poppitz
Journal of Physical Organic Chemistry 2005 Volume 18(Issue 11) pp:1086-1098
Publication Date(Web):16 AUG 2005
DOI:10.1002/poc.980
A series of N-substituted phenyl-2-thienyl ketones including 2-(4-fluorobenzoyl)thiophene (FLBT, 1a), 2-(4-piperidinobenzoyl)thiophene (PIBT, 1b), 2-(4-morpholinobenzoyl)thiophene (MOBT, 1c), 2-(4-thiomorpholinobenzoyl)thiophene (THBT, 1d), 2-(4-phenylpiperazinobenzoyl)thiophene (PHBT, 1e), 2-(4-pyrrolidinobenzoyl)-thiophene (PYBT, 1f), 2-(4-hydroxyethylpiperazinobenzoyl)thiophene (HYBT, 1g), 1,4-bis(4-benzoyl-2-thienyl)piperazine (BBTP, 2) and 1,6-bis(4-benzoyl-2-thienyl)-N,N′-dimethylhexamethylenediamine (BBDA, 3) have been investigated regarding solvatochromism and solid-state structure. Solvatochromic properties have been analyzed using the Kamlet–Taft linear solvation energy relationship. The influence of the dipolarity/polarizability (π*) and hydrogen-bond acidity (α) of the solvent, respectively, on the portions of the bathochromic UV–Vis band shift as a function of substituent is discussed. The solid-state structures of 1b (C16H17NOS), 1c (C15H15NO2S) and 1f (C15H15NOS) have been determined by single-crystal x-ray structure analysis. Crystallochromic effects are discussed comparatively with regard to the linear solvation energy relationships and the results of the solid-state structures. Copyright © 2005 John Wiley & Sons, Ltd.
Co-reporter:Susanne Höhne;Rudolf Holze;Manfred Friedrich;Andreas Seifert
Macromolecular Chemistry and Physics 2004 Volume 205(Issue 12) pp:1667-1676
Publication Date(Web):3 AUG 2004
DOI:10.1002/macp.200400098
Summary: 2-Vinylthiophene (2-VT) has been cationically polymerized using chloroarylmethane derivatives as the surface polymerization initiator on silica. By applying this procedure a soluble fraction of poly(vinylthiophene) (PVT) and PVT/silica composites can be simultaneously synthesized. The mass balance of the products (soluble fraction and hybrid particle fraction) depends significantly on temperature and 2-VT/silica ratio. The hydride abstraction reaction of PVT both in solution and immobilized on silica particle surface has been studied using 2,3-dichloro-5,6-dicyano-1,4-quinone (DDQ), tetrachloro-1,4-quinone (chloranile = ClA) and triphenylmethylium as reagents. The transformation process of PVT towards conjugated polymers has been studied with UV-vis spectroscopy and ESR spectroscopy. Cyclic voltammetry shows that chloranil is complexated with the formed polymer. Radical formation increases with increasing degree of conversion. The soluble fraction of the conjugated PVT sections formed is capable of reacting with each other as evidenced by GPC data. Structure of PVT/silica and resulting hybrid materials have been investigated by solid state 13C {1H} CP MAS NMR-spectroscopy showing a reaction of methine and methylene hydrogen atoms after treatment with DDQ or chloranil as hydride acceptors. For all poly-(2-vinylthiophene)/hydride acceptor systems studied, chloranil has been found to be the best reagent for the transformation of PVT towards conjugated polymers.
Co-reporter:Torsten Meyer, Stefan Spange, Frank Simon
Journal of Colloid and Interface Science 2003 Volume 266(Issue 1) pp:93-98
Publication Date(Web):1 October 2003
DOI:10.1016/S0021-9797(03)00581-2
Novel gold/poly-(1,3-divinyl-imidazolid-2-one)/silica [poly-bisvinylethyleneurea (poly-BVU)/silica)] hybrid particles have been produced by adsorption and spontaneously occurring in situ reduction of Au3+ cations on the surface of poly-BVU/silica hybrid particles. The successful functionalization of the poly-BVU/silica particles with gold nanoclusters has been evidenced by UV/vis and XPS spectroscopy as well as scanning electron microscopy. The size of the resulting gold clusters, estimated by means of the Mie–Drude theory on the full peak width at half-maximum of the surface plasmon UV/vis absorbance, correlates with the polymer content of the poly-BVU/silica hybrid particles used for the modification. Therefore, it is possible to control the size of the gold clusters simply by adjusting the monomer/silica ratio in the polymerization process, which corresponds with the polymer content of the hybrids.
Co-reporter:Torsten Meyer;Stephanie Hesse;Christian Jäger;Cornelia Bellmann
Macromolecular Chemistry and Physics 2003 Volume 204(Issue 4) pp:725-732
Publication Date(Web):31 MAR 2003
DOI:10.1002/macp.200390042
Two different radical polymerization techniques have been applied to covalently graft vinylformamide (VFA) onto silica particles. Grafting by the polymerization of VFA using an immobilized azo initiator on silica has been found less effective, because monomer conversion is limited in non-aqueous solvents and grafting yields are low in water. Radical copolymerization of VFA with vinyltriethoxysilane (VTS)-functionalized silica particles is suitable to produce poly(vinylformamide) (PVFA) silica hybrid particles in respectable yield. The VFA/VTS-silica ratio determines the degree of grafting. The PVFA-VTS-co-grafted silica particles can be acidically hydrolyzed into poly(vinylamine)-grafted silica particles. Molecular structures of the surface groups and grafted polymer chains have been confirmed by means of solid state 13C{1H} cross-polarization magic-angle spinning (CP MAS) NMR spectroscopy. Zeta potential measurements show the altering of the former silica particles surface charges arising from the introduction of basic groups on the surface.
Co-reporter:Kristin Fischer;Thomas Heinze
Macromolecular Chemistry and Physics 2003 Volume 204(Issue 10) pp:1315-1322
Publication Date(Web):30 JUN 2003
DOI:10.1002/macp.200390105
Kamlet-Taft's α (hydrogen-bond donor acidity), β (hydrogen-bond acceptor basicity) and π* (dipolarity/polarizability) values of carboxymethyl celluloses (CMCs) and cellulose tosylates (CTs) with different degrees of substitution are reported. Fe(phen)2(CN)2 [cis-dicyanobis(1,10-phenanthroline)iron(II)] (1), Michler's ketone [4,4′-bis(N,N-dimethylamino)benzophenone] (2), and 4-aminobenzophenone (3) have been used as solvatochromic surface polarity indicators. The three probes 1, 2, and 3, respectively, have been adsorbed onto polymer samples from 1,2-dichloroethane (1) and cyclohexane (2, 3) solution for the UV/Vis measurements. The probe-loaded samples have been measured by means of a special reflectance technique. Apparent ET(30) values are calculated by applying linear solvation energy relationships (LSER) using the independently determined α and π* values of the samples according to ET(30) = [ET(30)]0 + aα + sπ*, because ET(30) values are not directly available for these materials. α values of CMCs and CTs significantly decrease with increasing degree of substitution due to the decrease of the number of cellulosic OH groups (Cell-OH). The dipolarity/polarizability π* values of the CMCs show no linear dependence on the degree of substitution. A slight increase of π* with DS is observed for CTs. The β term using 3 as the probe for CTs is not determinable, because 3 also interacts, via the carbonyl oxygen, with acidic sites of the cellulose OH groups.
Co-reporter:Stefan Spange Dr.
Angewandte Chemie 2003 Volume 115(Issue 37) pp:
Publication Date(Web):25 SEP 2003
DOI:10.1002/ange.200301654
Verkabelt: Durch einen Sol-Gel-Prozess werden MCM-41-Zeolithgerüste erhalten, deren Kanäle gleichmäßig mit Pyrrol- oder Thiophen-Templatmonomeren beladen sind. Redoxinitiierte Polymerisation in den Kanälen verknüpft die Monomereinheiten zu potenziell leitfähigen molekularen Drähten. Diese Strategie ermöglicht die gezielte Synthese organisch-anorganischer Hybridmaterialien.
Co-reporter:Stefan Spange Dr.;Dagmar Kunzmann Dipl.-Chem.;Rüdiger Sens Dr.;Isabelle Roth Dipl.-Chem.;Andreas Seifert Dipl.-Chem.;Werner R. Thiel Dr.
Chemistry - A European Journal 2003 Volume 9(Issue 17) pp:
Publication Date(Web):28 AUG 2003
DOI:10.1002/chem.200304844
Azamethine dyes of the merocyanine type [4-(N,N-di-n-butylamino)-2-methylphenyl]{2,4-di-keto-3-[N′-(n-hexyl)]-5-cyano-6-methyl-3-pyridinio}-1-azamethine (1) and [4-(N,N-diethylamino)-2-(N′-tert-butylcarboxy)-amidophenyl]-{2,4-diketo-3-[N″-(n-hexyl)]-5-cyano-6-methyl-3-pyridinio}-1-azamethine (2) have been used as surface-polarity indicators for gold-cluster-functionalized silica particles. Their UV/Vis absorption maxima range from about λ=600 to 700 nm as a function of solvent polarity and are clearly separated from the surface plasmon UV/Vis absorption band of gold (λ≈520–540 nm). Solvatochromism of both dyes has been investigated in 26 solvents of different polarity. The positive solvatochromic band shifts of 1 and 2 can be well expressed in terms of the empirical Kamlet–Taft solvent polarity parameters α and π*. They are mainly sensitive to the dipolarity/polarizability (π* term; 70–75 %) and HBD (hydrogen-bond donating) acidity (α term) of the solvent. Both dyes adsorb readily on functionalized silica samples from solutions in 1,2-dichloroethane or cyclohexane. The surface polarities of gold-cluster-functionalized silica particles, with and without co-adsorbed L-cysteine and poly(ethylenimine), have been investigated by using these solvatochromic dyes. The specific interaction of dye 2 with cysteine has been examined independently by quantum-chemical calculations by using the AM1 and PM3 methods.
Co-reporter:Stefan Spange Dr.
Angewandte Chemie International Edition 2003 Volume 42(Issue 37) pp:
Publication Date(Web):25 SEP 2003
DOI:10.1002/anie.200301654
Conducting research and wiring zeolites: By a sol–gel process MCM-41 zeolite scaffolds are prepared, the channels of which are evenly loaded with pyrrole or thiophene template monomers. Redox-initiated polymerization leads to linking of the monomer units in the channels to form insulated potentially conducting molecular wires. These strategies increase the synthetic palette available for the targeted preparation of organic–inorganic hybrid materials.
Co-reporter:Frank Cichos;Silvio Prause;Kristin Fischer;Christian Von Borczyskowski
Journal of Polymer Science Part B: Polymer Physics 2003 Volume 41(Issue 11) pp:1210-1218
Publication Date(Web):23 APR 2003
DOI:10.1002/polb.10475
Solvent-dependent ultraviolet–visible (UV–vis) absorption and Stokes shifts including strong hydrogen-bond-donating (HBD) solvents such as 2,2,2-trifluoroethanol and 1,1,1,3,3,3-hexafluoro-2-propanol of two coumarine dyes (Co 151 and Co 153) were analyzed with multiple-square analyses of linear solvation energy relationships and the Kamlet–Taft solvent parameter set to α (HBD capacity), β (hydrogen-bond-accepting capacity), and π* (dipolarity/polarizability). The UV–vis absorption and emission spectra of Co 151 and Co 153 were measured when adsorbed on various polysaccharides such as different cellulose batches, carboxymethylcelluloses with different degrees of substitution, and chitine. As a result of this evaluation, Co 153 is recommended as an alternative UV–vis probe for evaluating the dipolarity/polarizability of cellulose and cellulose derivates. Multiple adsorption of Co 153 on Linters cellulose took place indicating a wide-surface polarity distribution, which makes the determination of a rigid polarity parameter questionable. Thus, fluorescence measurements of adsorbed Co 153 are suitable to detect inhomogenities on a surface but not for the determination of empirical polarity parameters. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1210–1218, 2003
Co-reporter:Stefan Spange;Mohamed El-Sayed;Hardy Müller;Gerd Rheinwald;Heinrich Lang;Wolfgang Poppitz
European Journal of Organic Chemistry 2002 Volume 2002(Issue 24) pp:
Publication Date(Web):26 NOV 2002
DOI:10.1002/1099-0690(200212)2002:24<4159::AID-EJOC4159>3.0.CO;2-H
The solvatochromism (νmax) of N-substituted Michler’s ketones − including 4′-[bis(2-acetoxyethyl)amino]-4-(dimethylamino)benzophenone [MK(OAc)2, 1a], 4,4′-bis(diethylamino)benzophenone [MK(NEt2)2, 1e], 4,4′-bis(4-ethoxycarbonylpiperazino)benzophenone [MK(pipOEt)2, 2a], 4,4′-bis(piperidino)benzophenone [MK(pip)2, 2b], 4,4′-bis(morpholino)benzophenone [MK(mor)2, 2c], 4,4′-bis(piperazino)benzophenone [MK(pipaz)2, 2d], 4,4′-bis[4-(2-hydroxyethyl)piperazino]benzophenone [MK(pipazOH)2, 2e] and 1,4-bis(4-benzoylphenyl)piperazine (BBP, 3) − has been studied at 298 K in various solvents with wide ranging dipolarities and hydrogen-bonding abilities. The solvatochromic properties (νmax)s = (νmax)0 + sπ* + aα + bβ have been analysed in terms of the Kamlet−Taft linear solvation energy (LSE) relationship. The effect of the solvent on the UV/Vis spectral characteristics (νmax) has been determined quantitatively for all compounds in terms of the Kamlet−Taft solvent-independent correlation coefficients s, a, and b. It was found to be mainly the dipolarity/polarizability (π*) and hydrogen bond acidity (α) of the solvent that contribute to the bathochromic UV/Vis band shift. As strongly basic sites are present as substituents at the peripheries of the molecules, protonation takes place at the secondary nitrogen atom of, for example, MK(pipaz)2 (2d) in strongly hydrogen bond-donating (HBD) solvents. This specific type of substitution therefore gives rise to an ambiguous solvatochromic property, which makes the basicity (β term) of the solvent important. The solid-state structures of 2b (C23H28N2O), 2c (C21H24N2O3), and 3 (C30H26N2O2) have been determined by single-crystal X-ray structure analysis. Compound 2b crystallizes in the trigonal space group P3121 with a = 948.11(11), b = 948.11(11), c = 1818.0(3) pm, α = β = 90, γ = 120° and Z = 3, whereas 2c crystallizes in the orthorhombic space group Pna21 with a = 1259.9(2), b = 910.16(17), c = 1586.2(3) pm, α = β = γ = 90° and Z = 4. Compound 3 crystallizes in the triclinic space group P with a = 1034.0(2), b = 1079.9(2), c = 1127.2(2) pm, α = 72.062(4), β = 73.361(4), γ = 74.549(4)° and Z = 2. The UV/Vis band shifts are comparatively discussed with regard to the LSE relationships and the results of the solid-state structure determinations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2002)
Co-reporter:Stefan Spange Dr.;Andreas Seifert Dipl.-Chem.;Hardy Müller Dr.;Stephanie Hesse Dipl.-Phys.;Christian Jäger Dr.
Angewandte Chemie 2002 Volume 114(Issue 17) pp:
Publication Date(Web):30 AUG 2002
DOI:10.1002/1521-3757(20020902)114:17<3214::AID-ANGE22223214>3.0.CO;2-Z
Co-reporter:Stefan Spange Dr.;Andreas Seifert Dipl.-Chem.;Hardy Müller Dr.;Stephanie Hesse Dipl.-Phys.;Christian Jäger Dr.
Angewandte Chemie 2002 Volume 114(Issue 10) pp:
Publication Date(Web):15 MAY 2002
DOI:10.1002/1521-3757(20020517)114:10<1805::AID-ANGE1805>3.0.CO;2-I
Durch Kombination einer nucleophilen aromatischen Substitution von Fluor durch Aminogruppen mit einem Sol-Gel-Prozess gelingt die Eintopfsynthese von organisch funktionalisierten Hybridgelen auf Silicatbasis. Die bei der Substitution gebildete Fluorwasserstoffsäure katalysiert dabei die anschließende Sol-Gel-Reaktion, die durch Zugabe von Wasser und Alkohol gestartet wird. Das Bild zeigt eine Auswahl der erhaltenen Gele in getrockneter Form.
Co-reporter:Stefan Spange Dr.;Andreas Seifert Dipl.-Chem.;Hardy Müller Dr.;Stephanie Hesse Dipl.-Phys.;Christian Jäger Dr.
Angewandte Chemie International Edition 2002 Volume 41(Issue 17) pp:
Publication Date(Web):30 AUG 2002
DOI:10.1002/1521-3773(20020902)41:17<3085::AID-ANIE11113085>3.0.CO;2-X
Co-reporter:Stefan Spange Dr.;Andreas Seifert Dipl.-Chem.;Hardy Müller Dr.;Stephanie Hesse Dipl.-Phys.;Christian Jäger Dr.
Angewandte Chemie International Edition 2002 Volume 41(Issue 10) pp:
Publication Date(Web):15 MAY 2002
DOI:10.1002/1521-3773(20020517)41:10<1729::AID-ANIE1729>3.0.CO;2-V
A combination of nucleophilic aromatic substitution of fluorine by amino groups with a sol–gel process leads to the synthesis of organic-functionalized hybrid gels by a one-pot method based on silicates. The sol–gel reaction is catalyzed by hydrofluoric acid formed after addition of ethanol and water. The picture shows a selection of the dried gels.
Co-reporter:Torsten Meyer;Thomas Hellweg;Stephanie Hesse;Christian Jäger;Cornelia Bellmann
Journal of Polymer Science Part A: Polymer Chemistry 2002 Volume 40(Issue 18) pp:3144-3152
Publication Date(Web):30 JUL 2002
DOI:10.1002/pola.10400
Polyvinylamine hydrogels with silica particles encapsulated (PVAm/silica) were produced by a two-step synthesis. In the first step, polyvinylformamide/silica (PVFA/silica) hybrids were synthesized from vinylformamide (VFA) and 1,3-divinylimidazolidin-2-one (1,3-bisvinylethyleneurea, BVU), as the crosslinker, by radical copolymerization in silica/water suspensions using different compositions of VFA/BVU. The target product PVAm/silica was obtained by acidic hydrolysis of the PVFA/silica hydrogels in a second step. The chemical structures of both hydrogels, PVFA/silica and PVAm/silica, respectively, were revealed by solid-state 13C(1H) cross-polarity/magic-angle spinning NMR spectroscopy. Both hydrogels swelled significantly in water. The swelling capacity of the two systems was characterized by the correlation length ξ (or hydrodynamic blob size) of the network meshes with small-angle neutron scattering experiments. ξ is significantly larger for PVAm/silica than for PVFA/silica, which corresponds to the observed higher swelling capacity of this polyelectrolyte material. Furthermore, the swelling behavior of the hybrid hydrogels was quantitatively described in terms of free swell capacity, centrifuge-retention capacity, adsorption against pressure, and free swell rate as compared with values of the corresponding copolymer hydrogels. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3144–3152, 2002
Co-reporter:Isabelle Roth
Macromolecular Rapid Communications 2001 Volume 22(Issue 15) pp:
Publication Date(Web):17 OCT 2001
DOI:10.1002/1521-3927(20011001)22:15<1288::AID-MARC1288>3.0.CO;2-Z
Polyvinylamine (PVAm) can be readily functionalized by means of a nucleophilic substitution reaction with 4-fluoro-substituted aromatic compounds having a substituent with negative mesomeric effect in ortho and/or para position. PVAm is soluble in water only in which aromatic fluoro compounds are usually sparingly soluble. However, the solubility of aromatic compounds in water can be mediated in particular by cyclodextrin derivatives. This first report on the nucleophilic substitution reaction of 4-fluoronitrobenzene with PVAm provides an elegant method towards the preparation of chromophoric water-soluble polymers by means of a one-pot procedure.
Co-reporter:Stefan Spange;Annett Fährmann;Anett Reuter;Ralph Walther;Yvonne Zimmermann
Journal of Physical Organic Chemistry 2001 Volume 14(Issue 5) pp:271-283
Publication Date(Web):12 MAR 2001
DOI:10.1002/poc.360
Spectral characteristics of two different types of electron donor–acceptor (EDA) complexes with charged components (arene–carbenium and anion–π acceptor) are presented. The UV–Vis absorption maxima of the charge-transfer (CT) band (νmax,CT) of the EDA complexes were measured in various solvents and after adsorption on silica. Tropylium, triarylmethylium and diarylmethylium ions in combination with aromatic π donors, e.g. pyrene, acenaphthene and methoxy-substituted benzene derivatives and also the tetraethylammonium iodide–1,3,5-trinitrobenzene complex have been investigated by means of a special UV–Vis technique in transparent slurries of silica nanoparticles in 1,2-dichloroethane. Multiple linear regression analyses of the νmax,CT values of the EDA complexes in various solvents and on silica with the Kamlet–Taft solvent parameters and structure–reactivity terms of the complex components, e.g. the oxidation potential of the arene component or the Hammett substituent constant, σp+, of the arylmethyl component, show their related properties to the solution complexes. The influence of the electron-pair donating capacity of a solvent on νmax,CT of carbenium/arene complexes was compared with the property of the silica surface in order to link EDA complexes. For the diarylmethyl carbenium ion–pyrene complexes on silica, the presence of a σ-like structure is discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Co-reporter:Stefan Spange Dr.;Annett Gräser Dr.;Andreas Huwe;Friedrich Kremer Dr.;Carsten Tintemann;Peter Behrens Dr.
Chemistry - A European Journal 2001 Volume 7(Issue 17) pp:
Publication Date(Web):8 AUG 2001
DOI:10.1002/1521-3765(20010903)7:17<3722::AID-CHEM3722>3.0.CO;2-J
The synthesis of poly(vinyl ether)s or polyvinylcarbazole under the conditions of constricted geometry can be achieved by means of cationic host–guest polymerisation of the corresponding monomers in the pores of MCM-41 (pore diameter 3.6 nm), MCM-48 (pore diameter 2.4 nm) and in nanoporous glasses (Gelsil® with a pore diameter of 5 nm) with bis(4-methoxyphenyl)methyl chloride (BMCC) or triphenylmethyl chloride as the internal surface initiator. The reaction products are new polymer/MCM-41, polymer/MCM-48 etc., host–guest hybrid materials. The molecular mass of the enclosed polymer and the degree of loading of the host compounds can be adjusted within certain limits. The molecular dynamics were investigated by using broad-band dielectric spectroscopy. Under the conditions of constricted geometry, molecular fluctuation is observed as well as a secondary β-relaxation, which is hardly affected (in comparison with the free melt) and which corresponds to the relaxation between structural substates (dynamic glass transition). This process is several orders of magnitude faster in its relaxation rate than in the free melt and thus follows a confinement effect. This is already well known in lower molecular weight systems with constricted geometry.
Co-reporter:Petra Rehak;Christian Jäger;Ina Voigt;Frank Simon;Torsten Meyer
Macromolecular Symposia 2001 Volume 163(Issue 1) pp:87-96
Publication Date(Web):13 MAR 2001
DOI:10.1002/1521-3900(200101)163:1<87::AID-MASY87>3.0.CO;2-9
The use of vinylformamide and 1,3-divinylimidazolidin-2-one, bisvinylethylene-urea (BVU), as well as of the poly(vinylformamide-vinylamine) copolymer (PVFA-co-PVAm) for silica surface functionalization has been investigated. Various procedures such as grafting from, crosslinking surface polymerization, and post-functionalization of adsorbed PVAm chains have been experimentally applied. The advantage of the different synthetic methods is discussed with regard to the resulting surface structure of the organic/inorganic hybrid materials.
Co-reporter:S. Spange
Progress in Polymer Science 2000 Volume 25(Issue 6) pp:781-849
Publication Date(Web):August 2000
DOI:10.1016/S0079-6700(00)00014-9
Modification reactions of bare silica particles with cationically polymerizable monomers are reported. Suitable monomers for silica surface functionalization are p-methoxystyrene, cyclopentadiene, 2-furfuryl alcohol, 2-vinylfurane and 1,3-divinyl-imidazolidin-2-one. It is of importance that the initiating surface group and the propagating chain are mediated on to surface silanol groups by basic counter ions, e.g. chloride, bromide, hydrogen sulfate or trifluoroacetate. A general mechanism of cationic surface polymerization on acidic surfaces is discussed based on model reactions of 1,4-cyclohexadiene upon surface linked carbenium intermediates, electrokinetic measurements, UV/Vis spectroscopy and various MAS NMR spectroscopic methods. The formation of silicon oxygen carbon bonds and their occurrence on the polymer silica interface of the novel solid hybrid materials is investigated by solid state 13C NMR spectroscopy and DRIFT spectroscopy. The surface properties of silica can be widely controlled by grafting and post functionalization as demonstrated by zetapotential, NMR spectroscopy and XPS measurements.
Co-reporter:H. Müller;P. Rehak;C. Jäger;J. Hartmann;N. Meyer;S. Spange
Advanced Materials 2000 Volume 12(Issue 22) pp:
Publication Date(Web):1 DEC 2000
DOI:10.1002/1521-4095(200011)12:22<1671::AID-ADMA1671>3.0.CO;2-M
Co-reporter:Stefan Spange;Annett Graeser;Marcus Schulz;Christian Jäger;Petra Rehak;Annett Graeser;Petra Rehak;Christian Jäger;Marcus Schulz
Macromolecular Rapid Communications 2000 Volume 21(Issue 3) pp:146-150
Publication Date(Web):31 JAN 2000
DOI:10.1002/(SICI)1521-3927(20000201)21:3<146::AID-MARC146>3.0.CO;2-P
Cationic polymerization of cyclohexyl vinyl ether (CHVE) within mesoporous, siliceous molecular sieves (MCM-41) yields novel MCM-41-polyCHVE host-guest hybrid materials. Initiation within the channel can be achieved by triphenylmethylium or bis(4-methoxyphenyl)methylium silanolate ion pairs, as well as by mobile acidic silanols to a certain extent. Generation of the carbenium ions on MCM-41 is investigated by a special UV/VIS technique. The structure of poly(vinyl ether) generated within the channels of MCM-41 depends on the mechanism of initiation as shown by means of solid state 13C{1H} and 29Si{1H} CP MAS NMR spectroscopy.
Co-reporter:Falko Böttger-Hiller, Alexander Mehner, Susann Anders, Lothar Kroll, Gerhard Cox, Frank Simon and Stefan Spange
Chemical Communications 2012 - vol. 48(Issue 85) pp:NaN10570-10570
Publication Date(Web):2012/09/21
DOI:10.1039/C2CC35112A
Sulphur-doped carbon was synthesized using a thiophene-based twin monomer. While tetra(thiophene-2-ylmethoxy)-silane can be converted into sulphur containing nanocomposites, which lead to microporous sulphur-doped carbon, it is possible to produce additional mesopores by the use of templates. Thus, a variety of sulphur-doped carbon materials with tailored pore texture are available.
Co-reporter:Katharina Ladewig, Andreas Seifert, Harald Hahn, Michael Hietschold, Norbert Moszner, Peter Burtscher and Stefan Spange
Journal of Materials Chemistry A 2012 - vol. 22(Issue 9) pp:NaN3852-3852
Publication Date(Web):2012/01/23
DOI:10.1039/C2JM15407B
An advanced procedure for the one-pot synthesis of organic–inorganic hybrid materials via combination of sol–gel process and nucleophilic aromatic substitution reaction (SNAr) of 4-fluoronitrobenzene and 3-aminopropyltrimethoxysilane is described. With this advanced procedure both SNAr-reaction and sol–gel process can be accomplished in the same reaction vessel due to the sol–gel precursor tetraethoxysilane (TEOS) acting as solvent during the first reaction step. Via extensive NMR spectroscopic studies it is proven for the first time that—contrary to common belief—hydrogen fluoride (HF), which is formed as a by-product in the SNAr-reaction, is not trapped by any bases present but is rather trapped by both of the silane species and serves as a catalyst during the subsequent sol–gel process. The chromophoric system of the resulting xerogels is well protected against aggressive chemicals, i.e. strong acids, by the silica matrix, which predestines these materials for pigment applications. Given that a high chromophore content is highly desirable in these applications, we show that the chromophore content of the final xerogel can be varied by modification of the organosilicon precursor:TEOS ratio or by using trialkoxy-silanes bearing two or three amino functions, whereby the latter option is more favourable. Monodisperse core–shell particles with identical chromophore content but consisting of a pure silica-core and a p-nitroaniline functionalized shell with a diameter of about 200 nm can also be prepared using this advanced procedure.
Co-reporter:Ingolf Kahle, Oliver Tröber, Sabine Trentsch, Hannes Richter, Bernd Grünler, Steffen Hemeltjen, Maik Schlesinger, Michael Mehring and Stefan Spange
Journal of Materials Chemistry A 2011 - vol. 21(Issue 13) pp:NaN5088-5088
Publication Date(Web):2011/02/21
DOI:10.1039/C0JM03986A
Precisely nano-sized aluminosilicate particles (average diameter size 50 to 80 nm) with tailor-made internal surface polarity are suitable as host material for photochromic dyes of the chromene type in order to produce optical transparent photoswitchable polymer films. The sophisticated host material does accomplish two important requirements for a technical application, appropriate internal space for the light induced reversible switching process of the adsorbed dye and suppression of disturbing chemical reactions. The adjustment of the internal surface polarity of the host material was achieved by silane reagents which could be observed by means of specific solvatochromic probes.
Co-reporter:Thomas Ebert, Gerhard Cox, Evgeniya Sheremet, Ovidiu Gordan, Dietrich R. T. Zahn, Frank Simon and Stefan Spange
Chemical Communications 2012 - vol. 48(Issue 79) pp:NaN9869-9869
Publication Date(Web):2012/08/16
DOI:10.1039/C2CC34775J
Defect-free microporous carbon layers on graphite can be produced by DABCO-catalyzed twin polymerization of 2,2′-spirobi[4H-1,3,2-benzodioxasiline] in a slurry polymerization and subsequent thermal transformation of the resulting phenolic resin into carbon.
Co-reporter:M. Göring, A. Seifert, K. Schreiter, P. Müller and S. Spange
Chemical Communications 2014 - vol. 50(Issue 68) pp:NaN9756-9756
Publication Date(Web):2014/07/07
DOI:10.1039/C4CC03640A
Amino-functionalized organic–inorganic hybrid materials with a narrow distributed nanostructure of 2–4 nm in size were obtained by means of a template-free and non-aqueous procedure. Simultaneous twin polymerization of novel amino group containing twin monomers with 2,2′-spirobi[4H-1,3,2-benzodioxasiline] has been applied for this purpose. The amino groups of the organic–inorganic hybrid material are useful for post derivatization.
Co-reporter:Ralf Lungwitz, Thomas Linder, Jörg Sundermeyer, Igor Tkatchenko and Stefan Spange
Chemical Communications 2010 - vol. 46(Issue 32) pp:NaN5905-5905
Publication Date(Web):2010/07/07
DOI:10.1039/C0CC00797H
The reaction of four different basic ionic liquid precursors with Aerosil®300 is presented. Chemisorbed imidazolium and phosphonium cations, with silanolate anions as part of the silicatic support, were obtained and investigated with various solid state NMR techniques.
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