Organic crystals constructed by pi-conjugated molecules have been paid great attention to in the field of organic optoelectronic materials. The superiorities of these organic crystal materials, such as high thermal stability, highly ordered structure, and high carrier mobility over the amorphous thin film ma-terials, make them attractive candidates for optoelectronic devices. Single crystal with definite struc-ture provides a model to investigate the basic interactions between the molecules (supramolecular interaction), and the relationship between molecular stacking modes and optoelectronic performance (luminescence and carrier mobility). Through modulating molecular arrangement in organic crystal, the luminescence efficiency of organic crystal has exceeded 80% and carrier mobility has been up to the level of 10 cm2·V?1·s?1. Amplified stimulated emission phenomena have been observed in many crys-tals. In this paper, we will emphatically introduce the progress in optoelectronic functional organic crystals and some correlative principle.
The twisted aromatics, functional dibenzo[d,f][1,3]dioxepine derivatives were synthesized in high yields from reactions of 5,5′-dibromo-2,2′-biphenol with corresponding ketal or ketone compounds under acid catalysis. The structures of these compounds were characterized by 1H NMR, elemental analysis, UV-Vis absorption spectrum and X-ray diffraction analysis. The conformation of O―C―O bridged biphenyl derivatives with varied substitute groups on 6,6′-position was studied by X-ray crystallography and force-field simulation. The result of calculations by UNIVERSAL 1.02 force field in Cerius2 package(4.6) indicates that dibenzo[d,f][1,3]dioxepine derivatives show twisted conformations and the twisted angle between the phenyl rings is about 40°, which is accordant with the result from crystal structure determination, though the obtained angles in the crystal of dibenzo[d,f][1,3]dioxepine derivatives with the varied substitute groups on 6,6′-position are shown to be slightly shifted to 40° owing to intermolecular interactions in crystal stacking. DSC studies exhibit that the substitute groups on 6,6′-position can induce a large variation of endothermic peaks ranging from 80 to 135 °C. The conjugated polymers based on dibenzo[d,f][1,3]dioxepine derivatives, which have ultraviolet emitting with a quantum efficiency of 10%, were obtained by Yamamoto coupling.
A novel blue luminescent mercury(Ⅱ) complex of 2,6-bis(benzimidazolyl)pyridine( L ) was synthesized. In solid state, this complex has the formula [Hg( L )Cl2]52DMF([STHZ]1[STBZ]). The molecular structures of both the ligand and the complex were determined by using single-crystal X-ray diffraction. Crystallographic studies of the mercury(Ⅱ) complex reveal that the complex possesses a five-coordinated geometry that can be best described as a distorted trigonal-bipyramidal. The luminescent properties of ligand L and complex [STHZ]1[STBZ] both in solution and in solid state were also studied.
LIU Xiao-mingMU Xiao-yueXIA HongSU QingYE LingCHEN ChaoGAO WeiMU Ying
A soluble poly(meta-phenylene)derivative with rigid twisted biphenyl unit was synthesized by the Yamamoto coupling reaction.The polymer is soluble in common organic solvents,and the number-average molecular weight is about 6500.The UV-Vis and quantum chemical calculation indicate that the different conformation segments named "conformers" exist in the polymer backbones;it was also further confirmed by the single crystal X-ray diffraction study of the dimeric model compound.The π-π transition of biphenyl segments of twisted and planar conformations made the polymer exhibit a strong absorption around 256 nm and a weak absorption at about 300 nm.Furthermore,the polymer exhibits a strong UV photoluminescence at 372 nm when the excitation wavelengths are longer than 300 nm.The ultraviolet-emitting electroluminescence(EL)device with the single layer structure shows EL λmax of the derivative at 370 nm.
ZHENG Yan YANG Bing ZHANG Hai-quan LU Ping SHEN Fang-zhong LIU Lin-lin XU Hai YANG Guang-di MA Yu-guang
