Synthesis and crystal structure of bis(m-hydroxybenzoato(1-))bis(benzimidazole) copper(II) dihydrate

The crystal structure of the title complex was determined by single-crystal X-ray diffraction methods. The unit cell contains two independent molecules, A and B. B is a mononuclear Cu(II) complex with square-planar coordination geometry formed by two benzimidazole molecules and two hydroxylbenzoate anions. A is a dimer of B, formed by bridging hydroxybenzoate, and copper assumes square-pyramidal geometry. Aromatic π–π stacking is observed between parallel benzimidazole rings of neighboring A molecules. IR spectra of the compound are assigned in line with the crystal structure.     

Syntheses and molecular structures of four inorganic–organic hybrid compounds from N-containing aromatic bases and perchlorometallates of Zn,Cu, Sn,and Fe

Four organic–inorganic crystals, [(HL1)₂(ZnCl₄)]·H₂O (1) (L1?=?2-methylquinoline), [(HL1)₂(CuCl₄)] (2), [(HL2)₂SnCl₆] (3) (L2?=?6-bromobenzo[d]thiazol-2-amine), and [(HL3)FeCl₄] (4) (L3?=?5,7-dimethyl-1,8-naphthyridine-2-amine), derived from N-containing aromatic Brønsted bases and metal(II) chlorides (zinc(II) chloride, copper(II) chloride dihydrate, tin(II) chloride dihydrate, and iron(III) chloride hexahydrate) were prepared at room temperature and characterized by IR, X-ray structure analysis, elemental analysis, and TG analysis. The crystals are built up by perchlorometallates (Zn, Cu, Sn, and Fe) associated with organic cations through multiple non-covalent associations. X-ray diffraction analysis reveals that 1 and 2 have 3-D network structures built from hydrogen bonds between the cations and chlorometallates. Water molecules play an important role in structure extension in 1. Anhydrous 3 and 4 produced from 2-aminoheterocyclic derivatives display 2-D sheet structures. Arrangements of anions and cations are dominated by shape and size of cations, and also by the different structures of the chlorometallates as well as non-bonding interactions in the crystal structures. Except for 1, the other compounds are thermally stable below 240°C.     

Triphenyltin chloride complexes containing bidentate organodiimines as effective antitumor agents

Three triphenyltin chloride complexes, [(Ph₃SnCl)₂?·?(bpy)_1.5] (1), [(Ph₃SnCl)₂.tbpe] (2), and [(Ph₃SnCl)₂?·?bpe] (3), were synthesized by reaction of triphenyltin chloride with 4,4′-bipyridine (bpy), trans-1,2-bis(4-pyridyl)ethylene (tbpe), and 1,2-bis(4-pyridyl)ethane (bpe) in water/acetonitrile. Both 2 and 3 are binuclear; each consists of two Ph₃SnCl molecules bridged by the bidentate ligand. Complex 1 consists of two crystallographically independent and chemically different coordination complexes, mononuclear and binuclear in equal proportion. The structures of these complexes were investigated by single-crystal X-ray analysis, elemental analyses, NMR spectroscopy as well as electronic absorption and emission spectroscopy. The three complexes exhibit in vitro antitumor activity against human breast cancer cell line, MCF7.     

Direct Synthesis of a Dimeric Mixed-Anions Bismuth(III) Complex: Synthesis and Structural Characterization of [Bi2(Phen)4(No3)4.4I0.6]I3 (A New Dimeric Compound)

A direct synthetic method of mixing Bi(NO₃)₃ and NaI with 1,10-phenanthroline yielded red crystals of [Bi₂(phen)₄(NO₃)_4.4I_0.6]I₃. In this complex the cationic part is in fact binuclear and contains two [Bi(phen)(NO₃)_1.7I_0.3] groups linked via a bridging NO^? ₃ anion. The I^? ₃ anion was not coordinated to bismuth(III) and the lone pair of valence electrons of the bismuth(III) ions appears to be stereochemically inactive. There are two independent NO^? ₃ anions, one coordinated to bismuth but another shares a position with I^? anion. The final results of crystallography show that 40% of these positions are occupied by NO^? ₃ anions and 60% by I^? anions that are coordinated to bismuth atom in bidentate fashion (NO^? ₃) and in unidentate fashion (I^?). An interesting point is that the I^? ₃ anion was produced by direct synthetic method (Branched tube method). There is a π-π stacking interaction between the parallel aromatic rings around the Bi(III) ion.     

液晶投影电视技术的研究

本文介绍了国外液晶投影电视的发展动态,结合对典型液晶彩色投影机特性的介绍,剖析了液晶投影电视机的结构和原理,并进一步探讨了研究液晶投影电视技术的有关技术要点,阐述了在我国进行这项技术研究的有关问题。     

PDLC膜制备及响应特性研究

本文从ＰＩＰＳ法制备ＰＤＬＣ膜出发，探讨了工艺条件对响应特性，尤其是响应时间的影响。并对制备工艺提出一些改进措施。     

多片LPE生长AlxGa1—xAs／GaAs单晶薄膜

介绍了一种新的“分离三室水平推挤式多片外延舟”，可在国产水平外延炉中实现多片单晶薄膜外延。同时，研究了适合于多片外延的各种工艺条件。用于研制的ｐ－ＡｌｘＧａ１－ｘＡｓ／ｐ－ｎ－ｎ＾＋－ＧａＡｓ太阳通电池，ＡＭ０．２５℃，１２０ｍＷ．ｃｍ＾－２的转换室１９．８％。     

Field-induced phase transitions and reversible field-induced inversion of chirality in tilted smectic phases of bent-core mesogens

Three homologous achiral five-ring bent-core mesogens are presented where 4-chlororesorcinol is the central core and the aromatic rings are linked by ester groups. These compounds form smectic phases with a tilted arrangement of the molecules (tilt angle ≈ 45^°). On cooling the isotropic liquid this phase adopts a fan-like texture which shows for two homologues at relatively high electric fields ( 25-35V μm^-1) an antiferroelectric electro-optical response based on the collective rotation of the molecules around their long axes. At lower temperature the application of a sufficiently high electric field leads to a continuous transition into a non-birefringent texture which exhibits randomly distributed domains of opposite handedness. These domains can be reversibly switched into a state of opposite chirality by reversal of the field polarity. This switching is bistable and shows a current response typical for a ferroelectric ground state. The possible mechanism of the field-induced phase transition, of the ferroelectric switching and of the field-induced inversion of the chirality is discussed on the base of XRD, ¹³C- and ¹H-NMR investigations, dielectric and electro-optical measurements.     

Frustrated structure of an anticlinic-like smectic-C phase

We present a polarising optical microscopy study of the low-temperature anticlinic-like tilted mesophase of the liquid-crystal compound octylphenyl-2-chloro-4-(p-cyano-benzoyloxy) (DB₈Cl). This mesophase has been described as a bilayer smectic structure in which the molecules within each layer are organised in an anticlinic way. The optical textures observed in samples with planar orientation show a double stripe pattern, with the lines aligned parallel to the rubbing direction, characteristic of a double periodic modulation of the refractive index of the material. The long-period modulation is temperature dependent and disappears for thin sample cells (< 5μm). The short-period modulation is nearly independent of the thickness of the cells. The experimental results are analysed in terms of a model which considers that there is a special distribution of the principal optical axis which may be in or out of the polariser-analyser plane. The observed periodic variation of the principal optical axis could not be interpreted in terms of the original structure proposed for this phase. DB₈Cl presents a structure formed by dimers that can be viewed as flexible bent-core-like molecules, showing similarities with phases found in banana-like systems, but exhibiting a much more complex structure.     

Fiber Optic Excitation of Silicon Microspheres in Amorphous and Crystalline Fluids

ABSTRACT

This study investigates the optical resonance spectra of free-standing monolithic single crystal silicon microspheres immersed in various amorphous fluids, such as air, water, ethylene glycol, and 4-Cyano-4’-pentylbiphenyl nematic liquid crystal. For the various amorphous fluids, morphology-dependent resonances with quality factors on the order of 10⁵ are observed at 1428 nm. The mode spacing is always on the order of 0.23 nm. The immersion in various amorphous fluids affects the spectral response of the silicon microsphere and heralds this technique for use in novel optofluidics applications. Even though the nematic liquid crystal is a highly birefringent, scattering, and high-index optical medium, morphology-dependent resonances with quality factors on the order of 10⁵ are observed at 1300 nm in the elastic scattering spectra of the silicon microsphere, realizing a liquid-crystal-on-silicon geometry. The relative refractive index and the size parameter of the silicon microsphere are the parameters that affect the resonance structure. The more 4-Cyano-4’-pentylbiphenyl interacting with the silicon microsphere, the lower the quality factor of the resonances is. The more 4-Cyano-4’-pentylbiphenyl is interacting with the silicon microsphere, the lower the mode spacing Δλ of the resonances is. The silicon microspheres wetted with nematic liquid crystal can be used for optically addressed liquid-crystal-on-silicon displays, light valve applications, or reconfigurable optical networks.