Discotic salicylaldimato metal complexes exhibiting columnar mesophases and their mixtures with rod-like salicylaldimato complexes

The synthesis and mesomorphism of a series of discotic metal complexes of salicylaldimine ligands is reported. None of the ligands was mesomorphic, but the longer chain length complexes showed a Col_h phase as evidenced by optical microscopy. Phase diagrams were constructed using rod- and disk-like salicylaldimato complexes, where one was designed to have Lewis acid characteristics and the other Lewis base properties. It was hoped that an associative Lewis acid/base interaction would prevent phase separation of the two components, which may point a way to the realization of a mixture with a biaxial nematic phase. The form of the phase diagrams is discussed.     

Novel near-infrared fluorescent liquid crystal: Bodipy bearing multiple alkyl chains with columnar mesophase

By the typical Knoevenagel condensation of Bodipy with aldehyde derivatives, two novel Bodipy derivatives 3 and 6 with symmetric three and six alkyl chains were designed and prepared. The Bodipy derivative 3 with three alkyl chains showed no mesophase but the Bodipy derivative 6 with six alkyl chains possessed the orderly hexagonal columnar mesophase at room temperature. Both samples 3 and 6 exhibited the near-infrared fluorescence with high fluorescence quantum yields and larger Stokes shifts than their Bodipy precursors. Sample 6 was the first near-infrared fluorescent columnar liquid crystal with Bodipy core. This research presented a good strategy on constructing the near-infrared columnar Bodipy liquid crystal.     

Self-assembly of coil-rod-coil molecules into bicontinuous cubic and oblique columnar assemblies depending on coil chain length

Coil-rod-coil molecules 1–3, consisting of four biphenyls and a p-terphenyl unit linked together with ether bonds as a rod segment and poly(propylene oxide) (PPO) with a degree of polymerization (DP) of 7, 12, 17 as coil segments were synthesized. These molecules contain lateral methyl groups at 2 and 5 positions of the middle benzene ring of p-terphenyl. The self-assembling behavior of molecules 1–3 was investigated by means of DSC, POM and SAXS in the bulk state. Molecule 1 self-organizes into a lamellar structure in the bulk state and transfers into a bicontinuous cubic structure in the liquid crystalline phase. While, molecules 2, 3 containing longer coil chains than 1 self-assemble into the hexagonal perforated lamellar (HPL) structures and the oblique columnar structures in the solid state and liquid crystalline phase, respectively. These results reveal that self-organizing behavior of such molecules is dramatically influenced by the length of the coil chains connected with the rod building block, as well as the lateral methyl groups incorporating in the middle of the rod segment.     

Achiral bent-core salicylaldimine compounds exhibiting dark conglomerate and B2 mesophases: effect of linkage groups and lateral substituents

Four new series of achiral bent-core compounds and two biphenyl derivatives of them have been synthesised and their mesomorphic properties are studied. These mesogens are salicylaldimine derivatives, designed with an aim to study the effect of salicylaldimine group and lateral substituents, viz., ?F and ?Cl at different locations of the molecular structure, on the mesomorphic properties. The newly synthesised compounds are characterised using organic spectroscopy and elemental analysis (EA). The liquid crystalline properties of these compounds are studied using polarising optical microscopy, differential scanning calorimetry, X-ray diffraction and electro-optical studies. They are found to exhibit dark conglomerate (DC) and B₂ mesophases. The DC phases are of sponge and HNC type, and the B₂ is SmC_aP_A in nature. The compounds, wherein the salicylaldimine group is present at the centre of the bent-core, mainly exhibit DC mesophases and when this group is present in one of the wings of the bent-core molecule, the compounds tend to show only a B₂ mesophase, irrespective of the nature of lateral substituents. Many of the DC liquid crystals synthesised here retained the chirality even in their crystalline states which are confirmed by the circular dichroism spectroscopic studies.     

Dual switchable six-ring bent-core liquid crystals with azo linkages exhibiting B1 and B2 mesophases

A new series of asymmetric bent-core compounds were synthesised using azo linkages with equal as well as unequal terminal alkyl chains and their photo and electrical switching properties investigated. The mesomorphic properties were characterised using polarised optical microscopy, X-ray diffraction and differential scanning calorimetry. The lower homologues of the series of compounds show a B₁ phase whereas higher homologues exhibit a B₂ phase. The B₂ phase shows an anticlinic-antiferroelectric switching behaviour during electro-optic measurements. The photo-switching properties of the azobenzene containing bent-core molecules were investigated using ultraviolet-visible spectroscopy. The trans to cis photo isomerisation was observed at 25 s whereas reverse processes took 14 h in chloroform.     

Synthesis and mechanism of polyaniline nanotubes with rectangular cross section via in situ polymerization

Polyaniline (PANI) nanotubes with rectangular cross section, which had 90–500 nm in outer diameter and 30–400 nm in inner diameter, were synthesized via a self‐assembly process in the presence of chiral acid (1S)‐(+)‐10‐camphorsulfonic (D‐CSA) and non‐chiral hydrochloric acid (HCl) coordinating with sodium dodecylbenzenesulfonate (SDBS), respectively. By using SEM, TEM, OM, FTIR, and WAXD, the as‐prepared PANI nanotubes with diversified morphologies were also characterized so as to investigate the formation mechanism of such tubular nanostructures with square cross sections. The results showed that the bilayer‐lamellar micelles formed by anilinium cations and CSA anions acted as the primary templates in the formation of the flat oligomer flakes, and the flakes finally united together to form rectangular nanotubes initiated by the reaction of the active centers on their edges. This study sheds light on the formation process of the PANI nanotubes with rectangular holes and outer contours and may be instructive to the controllable growth of certain nanostructures with unique morphologies. Copyright © 2011 John Wiley & Sons, Ltd.     

Novel correlation of Schottky constants with lattice energies for II-VI and I-VII compounds

Correlations of computed Schottky constants () with structural and thermodynamic properties showed linear dependences of log K_S on the lattice energies for the Zn-, Cd-, Hg-, Mg-, and Sr-chalcogenides and for the Na- and K-halides. These findings suggest a basic relation between the Schottky constants and the lattice energies for these families of compounds from different parts of the Periodic Table, namely, =−(2.303nRT log K_S)+2.303nRm_b+2.303nRTi_b. is the experimental (Born-Haber) lattice energy (enthalpy), n is a constant approximately equal to the formal valence (charge) of the material, m_b and i_b are the slope and intercept, respectively, of the intercept b (of the log K_S versus linear relation) versus the reciprocal temperature. The results of this work also provide an empirical correlation between the Gibbs free energy of vacancy formation and the lattice energy.     

钼铁硫原子簇化合物的合成与结构化学IV: 双类立方烷化合物与酰氯的反应

报导了双类立方烷簇状化合物(Et4N)4[Mo2Fe7S8(SC6H5)12]与乙酰氯在乙腈中的反应, 结果获得不含Fe(SC6H5)3桥的双类立方烷化合物(Et4N)4[Mo2Fe6S8(SC6H5)9]. 反应用^1H NMR和元素分析表征. 这种类型的结构转换为首次所见, 从而对化合物中桥的松散结构提供了新的实验证据.     

Novel superalkali superhalogen compounds (Li3)+(SH)- (SH=LiF2, BeF3, and BF4) with aromaticity: new electrides and alkalides.

Optimized structures, with all real frequencies, of superalkali superhalides (Li(3))(+)(SH)(-) (SH=LiF(2), BeF(3), and BF(4)), are obtained, for the first time, at the B3LYP/aug-cc-pVDZ and MP2/aug-cc-pVDZ computational levels. These superalkali superhalides possess three characteristics that are significantly different from normal alkali halides. 1) They have a variety of structures, which come from five bonding mode types: edge-face, edge-edge, face-face, face-edge, and staggered face-edge. We find that the bonding mode type closely correlates with the Li(3)-SH bond energy. 2) The valence electrons on the Li(3) ring are pushed out by the (SH)(-) anion, and become excess electrons, conferring alkalide or electride characteristics on these Li(3)-SH species, depending on the bonding mode type. 3) The highest occupied molecular orbital of each Li(3)-SH species is a doubly occupied delocalized sigma bonding orbital on the Li(3) ring, which indicates its aromaticity. It is noticeable that the maximum negative nucleus-independent chemical shift value (about -10 ppm) moves out from the center of the Li(3) ring, owing to repulsion by the SH(-) anion. We find that these superalkali superhalides are not only complicated "supermolecules", but are also a new type of alkalide or electride, with aromaticity.     

Novel coordination compounds: Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) cations with acesulfame/N,N-diethylnicotinamide ligands

Abstract

Five coordination complexes with Mn²⁺ (1), Co²⁺ (2), Ni²⁺ (3), Cu²⁺ (4), and Zn²⁺ (5) containing acesulfame (ace) and N,N-diethylnicotinamide (dena) ligands were synthesized and structural binding properties investigated. Four compounds (1, 2, 4, and 5) were examined with single crystal X-ray diffraction methods. The structures containing Mn(II), Co(II), and Zn(II) were iso-structural. Six-coordination of metal cations were completed with two moles dena and four aqua ligands. The dena ligands were coordinated via pyridine nitrogen as neutral-monodentate. Charge stabilities of the complexes are complemented by two moles monoanionic ace ligands, located outside of the coordination unit. In the Cu(II) complex, the coordination is completed by acidic nitrogen and carbonyl oxygen atoms of two ace ligands and pyridine nitrogen of two moles dena ligands. The coordination to Cu(II) for ace ligands was monoanionic-bidentate. All metal cations in the structure are distorted octahedral. Thermal decomposition of complexes begins with removal of the aqua molecules from the structures and is completed by combustion of organic ligands. The final decomposition products of all structures have been identified as corresponding metal oxides. Some biological applications (anti-fungal/anti-bacterial) were studied using 1–5.     

Synthesis and structural characterization of A3In2Ge4 and A5In3Ge6 (A=Ca, Sr, Eu, Yb)—New intermetallic compounds with complex structures, exhibiting Ge-Ge and In-In bonding

Reported are the synthesis and the structural characterization of four new polar intermetallic phases, which exist only with mixed alkaline-earth and rare-earth metal cations in narrow homogeneity ranges. (Sr_1-xCa_x)₅In₃Ge₆ and (Eu_1-xYb_x)₅In₃Ge₆ (x≈0.7) crystallize in the orthorhombic space group Pnma with two formula units per unit cell (own structure type, Pearson symbol oP56). The lattice parameters are as follows: a=13.109(3)-13.266(3) Å, b=4.4089(9)-4.4703(12) Å, and c=23.316(5)-23.557(6) Å. (Sr_1-xCa_x)₃In₂Ge₄ and (Sr_1-xYb_x)₃In₂Ge₄ (x≈0.4-0.5) adopt another novel monoclinic structure-type (space group C2/m, Z=4, Pearson symbol mS36) with lattice parameters in the range a=19.978(2)-20.202(2) Å, b=4.5287(5)-4.5664(5) Å, c=10.3295(12)-10.3447(10) Å, and β=98.214(2)-98.470(2)°, depending on the metal cations and their ratio. The polyanionic sub-structures in both cases are based on chains of InGe₄ corner-shared tetrahedra. The A₅In₃Ge₆ structure (A=Sr/Ca or Sr/Yb) also features Ge₄ tetramers, and isolated In atoms in nearly square-planar environment, while the A₃In₂Ge₄ structure (A=Sr/Ca or Eu/Yb) contains zig-zag chains of In and Ge strings with intricate topology of cis- and trans-bonds. The experimental results have been complemented by tight-binding linear muffin-tin orbital (LMTO) band structure calculations.     

Novel supramolecular compounds with three-dimensional hydrogen-bonded network [M(H2O)6][H2L] (H4L=1,2,4,5-benzenetetracarboxylic acid, M=Mn and Co): syntheses, characterization and crystal structures

Two hydrogen-bonded supramolecular compounds having the general formula [M(H₂O)₆][H₂L] (M=Mn^II or Co^II and H₄L=1,2,4,5-benzenetetracarboxylic acid), have been newly prepared by the reaction of [M(H₂O)₆](ClO₄)₂ and [C₆H₂(COOH)₄] (H₄L), and structurally characterized by X-ray diffraction. The metal center in each compound is six-coordinated, forming an ideal octahedral geometry. Both neutral formula units make unique three-dimensional supramolecular architectures through hydrogen bonds and stabilized by electrostatic force.