Polynuclear Silver(I) Triazole Complexes: Ion Conduction and Nanowire Formation in the Mesophase.

Examples of polynuclear metallomesogens are few. Herein,1,2,4-triazole ligands were used to prepare mono- and polynuclear silver(I) triazole metallomesogens. Besides showing an SmA phase in the mesophase, two interesting properties were observed.

Labile imidazolium salt protected palladium nanoparticles.

An imidazolium (Im) salt with two long alkyl substituents at N atoms is employed to prepare cubelike palladium nanoparticles (PdNPs). The bilayer nature of the capped Im salts is characterized by thermogravimetric analysis and NMR studies. These capped Im salts are labile, as evidenced by their displacement reaction with dimethylaminopyridine, and the observation of fast exchange between those free and capped Im salts on the NMR time scale.

Tetranuclear silver(I) clusters showing high ionic conductivity in a bicontinuous cubic mesophase.

The synthesis and characterization of tetranuclear silver triazole metallomesogens, [Ag4(L(4)-C(n))6][BF4]4 (L(4)-C(n) = 4-alkyl-1,2,4-triazoles where C(n) stands for C(n)H(2n+1) with n = 12, 14, 16, and 18), are reported. Upon heating, a phase transition sequence of Cr → SmC → Cub → SmA → isotropic liquid is observed for all of these compounds. Depending on the alkyl chain length, two types of cubic phases are found in this series of compounds.

Strong tendency of homeotropic alignment and anisotropic lithium ion conductivity of sulfonate functionalized zwitterionic imidazolium ionic liquid crystals.

Here, we report the first attempt to investigate the liquid crystal (LC) behavior of SO3(-) functionalized imidazolium zwitterionic (SO3(-)ImZI) salts, which display homeotropic alignment on a glass slide without the aid of any aligning approach. Doping lithium salt to ImZI salts lowers the melting temperatures and raises the clearing temperatures substantially to form room temperature ImZILCs. Excellent anisotropic lithium ion conductivity is achieved; which is strengthened by their tendency for homeotropic alignment.

A triple helical structure supported solely by C-H···O hydrogen bonding.

A novel triple helical structure that is self-assembled by cationic molecules, 1-acetamido-3-(2-pyrazinyl)-imidazolium, is reported. The computational analysis underpins that the formation of the triple helix is driven by C-H···O hydrogen bonding.

Self-assembly of silver(I) and gold(I) N-heterocyclic carbene complexes in solid state, mesophase, and solution.

The assembly of silver(I) and gold(I) complexes of functionalized N-heterocyclic carbenes (NHCs) of the type [M(C(n),amide-imy)(2)][anion] were studied, in which C(n),amide-imy stands for an NHC of imidazol-2-ylidene having one N-alkyl substituent (C(n)H(2n+1)) and one N-acetamido substituent, while the anions are Br(-), NO(3)(-), BF(4)(-) or PF(6)(-). A single crystal X-ray diffraction study reveals that self-assembly of [Ag(C(10),amide-imy)(2)][PF(6)] through Coulombic, hydrogen bonding, and hydrophobic interactions gives a lamellar structure with tubular architecture around the metal ion head core. Self-assembly of these functionalized NHC complexes also leads to the formation of the first example of thermotropic liquid crystals of silver(I)-NHCs and gels of gold(I)-NHC.

Liquid crystals of gold(I) N-heterocyclic carbene complexes.

Three types of Au(I) N-heterocyclic carbene (NHC) and imidazole (Im) complexes, namely [Au(NHC)Cl], [Au(NHC)(Im)][NO(3)], and [Au(NHC)(2)][NO(3)], with two-, three-, and four-N-long alkyl chains, respectively, were synthesized and their mesomorphic properties investigated. Only the [Au(NHC)(Im)][NO(3)] series of compounds, adopting an m-shaped conformation in the solid state, showed liquid crystalline properties. For the molecules with three alkyl chains in particular, the Coulombic and hydrogen bonding interactions between the cationic head core and anionic NO(3)(-), and the hydrophobic chain-chain interactions facilitate in sustaining the partially ordered motion, which is not observed for those with two and four arms.

Vertex and edge truncated octahedron gold crystals. N-alkylimidazole and silver(I) ion controlled morphology transformation.

Two interesting morphology transformations of Au crystals are observed through reacting a mixture of N-alkylimidazole (denoted as C(n)-im, where C(n) = C(n)H(2n+1), and n = 18 and 1), AgNO(3), and HAuCl(4) at 200 degrees C. The long chain C(18)-im with increasing AgNO(3) concentration leads to a progressive truncation of octahedrons at {100} vertices to produce cubes. On the other hand, increasing the concentrations of C(1)-im and AgNO(3), results in a progressive truncation of octahedrons at {110} edges to give rhombic dodecahedrons, which further transform to the unprecedented tetrahexahedrons.

Au(i)-benzimidazole/imidazole complexes. Liquid crystals and nanomaterials.

Three series of Au(I)-imidazole complexes with stoichiometries of [Au(Cn-bim)Cl], [Au(Cn-im)Cl], and [Au(Cn-im)2][NO3] x 2H2O (Cn-bim = N-CnH2n+1 -substituted benzimidazole and Cn-im = N-CnH2n+1-substituted imidazole) together with the compound of [Au(C18-bim)2][NO3] are synthesiszed. Typical structures of each series are determined by single crystal X-ray diffraction. The last series of compounds, are liquid crystals, and exhibit a wider mesophase range than their Ag(I) analogues.

Structural, photophysical, and catalytic properties of Au(I) complexes with 4-substituted pyridines.

Ionic gold(I) complexes with general formula of [Au(Py)2][AuCl2] and [Au(Py)2][PF6] (Py = 4-substituted pyridines) have been synthesized. Structures of five Au(I) complexes and a Ag(I) complex were determined by single crystal X-ray diffraction. Evidence for cationic aggregation of [Au(py)2][PF6] complexes in solution was obtained by conductivity measurements and by the isosbestic point observed from variable temperature UV-visible absorption spectra.

New hexatic liquid phase observed in lyotropic thin films.

An intermediate surface hexatic phase between the liquid and the crystalline phases has been found for the first time in a lyotropic lamellar liquid-crystal system. This phase is highly unusual in that it has long-range sixfold bond-orientational order but liquidlike nearest-neighbor positional correlations, and could represent a significant departure from our current understanding of defect-mediated melting in two dimensions.

Probing C-H...X hydrogen bonds in amide-functionalized imidazolium salts under high pressure.

We have probed under high pressure the C-H hydrogen bonds formed by N,N(')-disubstituted imidazolium ions having PF(6) (-) and Br(-) counterions. High-pressure infrared spectral profiles, x-ray crystallographic analysis, and ab initio calculations allow us to make a vibrational assignment of these compounds. The appearance of a signal for the free-NH unit (or weakly bonded N-H.

Liquid crystals of silver complexes derived from simple 1-alkylimidazoles.

A homologous series of silver complexes of 1-alkylimidazoles (R-im, R = CnH(2n+1), where n= 10, 12, 14, 16 and 18) was synthesized. All the CnH(2n+1)-im ligands are non-mesomorphic. Upon complexation, all the [Ag(CnH(2n+1)-im)2]-[NO3], except for n = 10, exhibit liquid crystalline properties.

C[bond]H- - -O hydrogen bonds in beta-sheetlike networks: combined X-ray crystallography and high-pressure infrared study.

Close interactions of the C(alpha)[bond]H- - -O type have been analyzed via X-ray crystallography and high-pressure infrared spectroscopy. The results demonstrate that the C(alpha)[bond]H- - -O interactions can offer an additional stability to the beta-sheet formation. X-ray structural data suggest that while 1-acetamido-3-(2-pyrimidinyl)-imidazolium bromide exhibits a bilayer stacking, the PF(6)(-) salt reveals a beta-sheetlike pattern.

Molecular Aggregation of Annular Dinuclear Gold(I) Compounds Containing Bridging Diphosphine and Dithiolate Ligands.

A series of annular dinuclear Au(I) complexes containing diphosphine (R(2)P(CH(2))(n)()PR(2); R = Me, n = 1, dmpm; R = Me, n = 2, dmpe; R = Ph, n = 1, dppm; R = Ph, n = 2, dppe) and dithiolate (dtc = S(2)CNEt(2)(-), i-mnt = S(2)C(2)(CN)(2)(2)(-)) ligands were synthesized: [Au(2)(P-P)(S-S)]X (S-S = dtc: P-P = dmpm, X = Cl, 1; P-P = dppm, X = PF(6), 2; P-P = dppe, X = PF(6), 3; P-P = PPh(3), X = PF(6), 4) and [Au(2)(P-P)(S-S)] (S-S = i-mnt: P-P = dmpm,5; P-P = dppm, 6; P-P = dmpe, 7; P-P = dppe, 8). Crystal structures of two complexes are reported. Pertinent crystallographic data: [Au(2)(dmpm)(i-mnt)] (5), space group Fdd2, with a = 19.