A novel AB type of clickable monomer, (S)-2-[(2-azido-1-phenylethylimino)methyl]-5-propargyloxyphenol (AMPP) was designed and polymerized to yield a class of main-chain chiral poly(imine-triazole)s through the metal-free click reaction. With the thermally induced polymerization, the desired polytriazoles can be easily prepared in high yields by a stepwise heating-up process and have the number-average molecular masses ranging from 5.1 × 10³ to 58.1 × 10³ (polydispersity indices = 1.38−1.68). The polymers were characterized by Fourier Transform Infrared spectroscopy (FTIR), ¹H Nuclear Magnetic Resonance (NMR), and gel permeation chromatography, and their optical properties were studied by fluorescence and circular dichroism (CD) spectroscopies. As a chemosensor, these polymers exhibited a selective “turn-on” fluorescence enhancement response toward Zn²⁺ ion over other cations such as Na⁺, K⁺, Mg²⁺, Ca²⁺, Ag⁺, Pb²⁺, Cd²⁺, Hg²⁺, Mn²⁺, and Ni²⁺ in dimethyl sulfoxide. However, the Zn²⁺-induced fluorescence signal was subject to serious interference by Al³⁺, Cu²⁺, Cr³⁺, and Fe³⁺ ions. Interestingly, the chiral polymer showed distinctive changes in the CD spectra on complexation with Zn²⁺, which allowed for the discrimination of this ion in the presence of other species tested including those interfering ions observed in the fluorescent detection. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2248–2257

A new kind of polymeric chemosensor containing chiral naphthaldimine moiety in the side chain was synthesized by the reversible addition-fragmentation chain transfer polymerization of N-{[2-(4-vinylbenzyloxy)-1-naphthyl]-methylene}-(S)-2-phenylglycinol (VNP). The resulting polymers (PVNP) showed high selectivity for hydrogen sulfate relative to other anions including F⁻, Cl⁻, Br⁻, H₂PO, CH₃CO, and NO in tetrahydrofuran (THF) solution as judged from UV−vis, fluorescence, and circular dichroism spectrophotometric titrations. Compared with its monomer, the polymer has proven to be more attractive for detection of HSO in terms of sensitivity and reproducibility. Upon addition of the anion it gives remarkable spectral responses concomitant with detectable color change from colorless to pale yellow. Furthermore, the HSO-induced CD or fluorescence signal can be totally reversed with addition of base and eventually recovered the initial state, leading to a reproducible molecular switch with two distinguished “on” and “off” states. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

A new styryl-type monomer, 2-(4-vinylbenzyloxy)-1-naphthaldehyde thiosemicarbazone (VNT), was synthesized and then copolymerized with methyl methacrylate (MMA) by reversible addition fragmentation chain transfer polymerization affording a series of poly(MMA-co-VNT)s with different functional unit content, predetermined molecular weight, and narrow molecular-weight distribution. The desired copolymers were structurally confirmed by various spectroscopic characterizations. Colorimetric and fluorescent titration spectra revealed that the copolymers are highly selective toward fluoride anions over other competitive species including Cl⁻, Br⁻, I⁻, H₂PO₄⁻, AcO⁻, and HSO₄⁻. On addition of F⁻, a remarkable colorless-to-yellow color change is easily observed by naked eyes. The influence of the copolymer composition and molecular weight on its sensing capacity was then carefully investigated. The results showed that higher VNT-incorporation amount within the copolymer chains leads to higher sensitivity toward F⁻ ions. Interestingly, the chromogenic process of the polymeric sensor can be switched back and forth by successively adding F⁻ and HSO₄⁻ anions into the dimethyl sulfoxide solution of the polymer, which may be represented by a complementary “IMPLICATION/INHIBIT” logic gate at molecular level using both the ions as the chemical inputs. Based on such a reversible and reproducible sensing system, we designed a molecular-scale sequential information processing circuit displaying “writing–reading–erasing–reading” behavior and “multiwrite” function in the form of binary logic. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Enantiopure acrylamide derivatives, (S)-N-[o-(4-methyl-4,5-dihydro-1,3-oxazol-2-yl)phenyl]acrylamide and (R)-N-[o-(4-phenyl-4,5-dihydro-1,3-oxazol-2-yl)phenyl]acrylamide, were synthesized through the acylation of chiral 2-oxazolinylanilines. The radical polymerization of the chiral monomers was carried out with (3-mercaptopropyl)trimethoxysilane as a chain-transfer agent to obtain the corresponding optically active prepolymers with a trimethoxysilyl group. By immobilizing the prepolymers on porous silica gel via the grafting-to method, we prepared a new chiral stationary phase (CSP) and characterized it by elemental analysis, thermogravimetry, and Fourier transform infrared spectroscopy. The enantioseparation capacities of the CSPs were evaluated with high-performance liquid chromatography toward several racemic compounds, including 1,1′-bi-2-naphthol, benzoin, 2-amino-1-butanol, and loxoprofen sodium under the normal-phase mode. The results indicate that the CSPs exhibited improved chromatographic performances compared to their brush-type analogs obtained by the alternative grafting-from approach. Also, the column packed with poly{(R)-N-[o-(4-phenyl-4,5-dihydro-1,3-oxazol-2-yl)phenyl]acrylamide}-bonded silica was found to have an extent of enantioselectivity in the chiral resolution of some unmodified amino acids with reversed-phase eluents. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Enantiopure acrylamide derivatives, N-[o-(4-methyl-4,5-dihydro-1,3-oxazol-2-yl) phenyl]acrylamide (MeOPAM), N-[o-(4-isopropyl-4,5-dihydro-1,3-oxazol-2-yl)phenyl]acrylamide (PrⁱOPAM), and N-[o-(4-phenyl-4,5-dihydro-1,3-oxazol-2-yl)phenyl]acrylamide (PhOPAM), were synthesized and radically polymerized in the presence of rare earth metal trifluoromethanesulfonates (Ln(OTf)₃, Ln = La, Nd, Sm, and Y) to yield corresponding optically active polymers. Among these Lewis acids, Y(OTf)₃ was found to be most effective for increasing the isotactic specificity during the radical polymerizations when using n-butanol as solvent. Also, the effect of the Lewis acids was significantly influenced by the ratio of Ln(OTf)₃ to monomer. The relationship of both chiroptical property and the chiral recognition with the stereoregularity was then examined for the resulting polymers having various tacticity by spectroscopic techniques such as NMR, fluorescence, and circular dichroism. The results indicated that the polymers rich in isotacticity exhibited a favorable enantioselective discrimination ability toward 1,1′-bi-2-naphthol as evidenced by ¹H NMR study, where the characteristic hydroxyl proton signal was split into two peaks that ascribed respectively to the levo- and dextro-isomer; furthermore, the splitting magnitude was linearly correlated with the diad isotacticity of the polymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

A series of optically active amphiphilic block copolymers were synthesizedby using potassium alkoxide of poly(ethylene glycol) monomethyl ether (MeOPEGO⁻K⁺) to initiate the anionic polymerization of N-{o-(4-phenyl-4,5-dihydro-1,3-oxazol-2-yl)phenyl}maleimide [(R)-PhOPMI]. The PEG-macroinitiators generated in situ in the reaction between MeOPEGOH and potassium naphthylide in tetrahydrofuran. The synthetic procedure may provide the PEG-b-PPhOPMI copolymers with well-defined structure, as evidenced by gel permeation chromatography, ¹H NMR, FTIR, and elemental analysis. In particular, the preparation of block copolymers having a laevorotation or dextrorotation activity was accomplished by changing the feed composition. The micellization was examined for the amphiphilic block copolymers in aqueous milieu by fluorescence spectroscopy, dynamic light scattering, and circular dichroism. The results indicate that the copolymers could form regular spherical micelles with core-shell structure when the hydrophilic component was long enough; in contrast, the copolymers containing shorter PEG segments formed aggregates in large dimension due to the considerable interaction between hydrophobic PPhOPMI components. Also, it was found that the aggregated structure of the polymeric micelles is strongly dependent on the medium nature and the polymer concentration. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1025–1033, 2008