Comparative Studies of 1,4-Bis[2-(4-Pyridyl)ethenyl]-benzene Using Density Functional Theory

The optimized molecular structure and harmonic vibrational frequencies of a 1,4-bis [ 2-（4-pyridyl）ethenyl]- benzene（BPENB） molecule were calculated via five popular density functional theory（DFI＇） methods. On the basis of the comparison between calculated and experimental results, it is concluded that the B3PW91 and B3LYP methods are superior to the others in optimizing structures, and the BPW91 method reproduces the observed fundamental fre-quencies most satisfactorily.

Synthesis, Structural Characterization and Fluorescent Properties of a Cadmium Coordination Polymer with 4-Nitrophthalate and 1,4-Bis(imidazol-1-yl)-benzene

A new complex[Cd(nph)(bix)]n(1,H2nph=4-nitrophthalic acid,bix=1,4-bis(imidazol-1-yl)-benzene)has been successfully synthesized under hydrothermal conditions.Its structure has been characterized by elemental analysis,IR spectrum,TG,single-crystal and powder X-ray diffractions.The Cd^2+ion has a distorted octahedral environment with four O atoms from two nph ligands and two N atoms from two bix ligands.Each bix acts as a cis-conformation bridging ligand to link the neighboring[Cd2(nph)]subunit to form tetranuclear subunits with 42-ring,which are bridged again by bix ligands to yield a two-dimensional network structure.It was stabilized by C–H···O hydrogen bonding andπ-πinteractions,and extended into a 3D supramolecular architecture.Moreover,the luminescent properties of complex 1 have been investigated in the solid state.

Catalyst-free 2+2 Photodimerization of l,4-Bis[2-(4-pyridyl)ethenyl]-benzene in Solution Under Low Power UV Irradiation

Two different kinds of configurations of 1,4-bis[2-(4-pyridyl)etheny 1]-benzene(trans-bpeb and c/5-bpeb)were achieved,and a bpeb dimer was synthesized in dimethyl sulfoxide(DMSO).Compared with the previous work that synthesized the bpeb dimer or polymer in crystal with a template agent needed,the reaction occurred in a solu・tion phase in the present method.A hand-held ultraviolet lamp(365 nm)with the power of 12 W and the Watt density of 0.35 mW/cm2 can realize the photodimerization of bpeb,instead of the high-power mercury lamp in most previous studies.Unlike other 2+2 cycloaddition in liquid state using catalysts even noble metals,no catalysts were required here,which is cost-saving.Only the trans-pbeb can start the cycloaddition and the formation of the close J-aggregations of Zra≪5-pbeb in DMSO is a precondition for explaining the 2+2 photodimerization.The productivity for the 2+2 cycloaddition product was achieved as 55.6%.

Syntheses,Crystal Structures and Fluorescent Properties of Two Zinc Complexes Assembled by Bis(imidazol)Ligands

Two new complexes[Zn(nph)(bix)]n·nH2O(1)and[Zn(nba)2(bix)]n(2)(H2nph=4-nitrophthalic acid,Hnba=4-nitrobenzoic acid,bix=1,4-bis(imidazol-1-yl)-benzene)have been hydrothermally synthesized and structurally characterized by elemental analysis,IR spectrum,fluorescence spectrum,single-crystal and power X-ray diffraction.Complex 1 exhibits a three-dimensional(3D)framework,which is stabilized through C–H…O hydrogen bonds andπ-πstacking interactions.Complex 2 shows a zero-dimensional structure,which is further extended into a three-dimensional supramolecular structure through C–H…O and C–H…N hydrogen bonding interactions.