Optical quality tetragonal phase quasi one-dimensional single-crystalline fibers of potassium di-hydrogen phosphate with a large length-to-diameter ratio and high flexibility have been grown. Efficient guided-wave optical second harmonic generation is achieved along the growth axis. The single-crystal fibers open great potential of potassium di-hydrogen phosphate crystals in micro-photonic applications.

•The growth of Alq3 in several organic solvents has been investigated.•Two new solvated single crystals of Alq3(HCON(CH3)2) and Alq3((CH2OH)2) have been grown and solved.•The two solvated Alq3 crystals possess strong photoluminescence properties.•One-dimensional Alq3(HCON(CH3)2) microstructures have excellent optical wave guide features.Tris(8-hydroxyquinoline)aluminum(III) (Alq3) is characterized by crystallization in polymorphism both under vapor deposition and solvent evaporation. In this article, crystal growth of Alq3 in several organic solvents is studied. High quality bulk single crystals or crystalline microstructures are obtained, which depends on the varied conditions of crystallization. Two new crystalline solvates of Alq3(HCON(CH3)2) and Alq3((CH2OH)2) growing in N,N-dimethylformamide (DMF) and ethylene glycol (EG) have been obtained. X-ray diffraction analysis shows that their structures belong to new polymorphism bearing identical crystal symmetry, which is different to any solvated crystal phases reported before. The photoluminescent (PL) properties of the crystalline Alq3(HCON(CH3)2) and Alq3((CH2OH)2) are measured. Both crystals exhibit high quantum yield and long PL lifetime. In addition, the optical waveguide properties of Alq3(HCON(CH3)2) microstructures are investigated. It shows that solvated single-crystals or microstructures can be used as excellent light-emitting and propagation materials in miniaturized optoelectronic devices.

This paper describes the crystal growth, structure and properties of a new semi-organic hybrid crystal with an accurate molecular formula of ZnMnCl4(TPPO)4 by a guest–host combination of ZnCl2(TPPO)2 and MnCl2(TPPO)2 for the first time and its formation is bidirectional. It crystallizes in the acentric space group Fdd2. The 3D framework of the crystal structure is formed by triphenylphosphine oxide (TPPO), linked with a mixture of zinc(II) chloride and manganese(II) chloride. A mixed occupancy of zinc and manganese atoms was designed to form a noncentrosymmetric coordination compound, which exhibits relatively strong second-order nonlinear properties. The powder of this crystal shows a phase-matchable SHG effect that is twice that of KH2PO4 (KDP). The crystal has a broad optical transmission range, relatively good stability and a wide band gap. It is also magnetic and luminescent. The properties of this new crystal make it a potential candidate for improved or even novel devices.

•A series of new organic salts based on imidazolium are developed for second-order nonlinear applications.•Nine single crystals have been obtained, among which two crystals show acentric crystal structure.•DITMS crystal exhibits a large macroscopic optical nonlinearity and excellent crystal growth characteristic.•The growth of the bulk DITMS crystal has been investigated.We have developed a new organic cation core structure, trans-1-[p-(N, N-dimethylamino) styryl]-3-methylimidozalium for second order nonlinear optical (NLO) applications. Among the eight crystals of imidozalium salts with various counter anions, trans-1-[p-[(N, N-dimethylamino) styryl]-3-methylimidozalium 1-naphthalenesulfonate (II) (DINS-1(II)) and trans-1-[p-(N, N-dimethylamino) styryl]-3-methylimidozalium mesitylenesulfonate (DITMS) exhibit acentric crystal structures. The former belongs to Pna21 space group, while the latter crystallizes in Pn phase. The macroscopic optical nonlinearity of the acentric crystals have been estimated by Kurtz and Perry powder test at various grain sizes. Compared to DINS-1(II), DITMS exhibits a relatively large second order nonlinearity benefiting from the almost parallel arrangement of the main molecular charge–transfer axis in lattice. The growth of the bulk DITMS crystal has been investigated.

Indolocarbazole derivatives have already been reported to be good organic semiconductor candidates. The knowledge of the relationship between the structure and packing of molecules in crystal is indispensable in design of high performance organic semiconductor materials. Two new indolocarbazole derivatives, 2,8-dibromo-5,11-di-[4-(isoindole-1,3-dione-2-yl)butyl]indolo[3,2-b]carbazole (I) and 2,8,6,12-tetrabromo-5,11-di-(4-chlorobutyl)indolo[3,2-b]carbazole (II) have been synthesized and the crystal structures have been studied. The dichloromethane solvate of (I), C42H32Br2N4O4 · 2CH2Cl2, is monoclinic, space groups P21/n. Unit cell parameters are a = 11.6847(2), b = 12.6942(2), c = 13.7899(2) Å, β = 91.8220(10)°. Unlike other indolo[3,2-b]carbazole derivatives, there is no any π–π stacking between the indolocarbazole backbone of two adjacent molecules in the crystal. Since the isoindole-1,3-dione-2-yl is introduced in 5- and 11-positions in the molecule, the intermolecular short contacts mainly localize in between the pendant groups of the neighboring indolocarbazole molecules. The compound (II) is also monoclinic with P21/c space groups. Unit cell parameters are a = 4.6427(9), b = 11.425(2), c = 24.511(4) Å, β = 93.47(1)°. In contrast with compound (I), the molecules of (II) possess strong face-to-face π–π stacking. The crystal structures were studied in detail. It is concluded that linear pedant groups benefit to co-facial π–π interaction. Additionally, the molecule electronic spectra were studied by quantum chemistry theoretical calculation.