Synthesis and Properties of a One-Dimensional Mixed-Ligand Cd(Ⅱ) Complex with Helical Structure

The title complex,[[Cd(Him)(OH-BDC)(H2O)2]·3H2O]n(1) (Him is imidazole,OH-H2BDC is 5-hydroxyisophthalic acid),was synthesized by liquid/liquid diffusion method at room temperature.The complex crystallizes in orthorhombie,space group P212121,with a = 0.671 6(7),b = 1.380 6(2),c =1.7421(2) nm,V = 1.615 2 (3) nm3,C11 H18 CdN2O10,Mr = 450.67,Dc = 1.853 g/cm3,μ =1.407 mm-1,F(000) = 904,Z = 4,the final R1 = 0.020 9 and wR 2 = 0.045 3 for 3 211 observed reflections (Ⅰ＞ 2σ (Ⅰ)).In the structure of 1,the OH-BDC ligands exhibiting bis-bidentate coordimtion mode bridge the adjacent Cd centers to form a one-dimensional helical chain and the second ligand Him acting as terminal ligands are attached to the helical chain.It is notable that a series of complicated hydrogen bonds (e.g.,N-H ...O,O-H...O) exist in the structure,which link neighboring helices into a three-dimensional supramolecular architecture.An observed intense blue luminescence with an emission band peaking at 390 nm for 1 may be resulted from ligand-to-metal charge transfer (LMCT).     

Polyoxometalates Pillared Hydrotalcite： Synthesis and Catalysis in Transesterification of Dimethyl Carbonate and Phenol

The salts of para-tungstic and para-molybdic were heterogenized for their effective use as solid catalysts in the transesterification reaction of dimethyl carbonate and phenol by inserting them between the layers of Mg₂Al-hydrotalcite. These catalysts were characterized by FT-IR spectra and X-ray powder diffraction. Polyoxometalates (POMs) clusters were intercalated into the interlayer of layered double hydroxide (LDH) via anion exchange with organic acid precursor in Mg₂Al-LDH, and the integrity of the clusters ^6- and ^6- was maintained. The intercalated para-molybdic cluster showed high catalytic activity and reusability in the transesterification under mild reaction conditions. When the reaction was carried out at 180?℃, with a molar ratio of phenol to DMC of 1∶1, a reaction time 10?h, and a catalyst amount 1%(wt), the conversion of phenol was 10.0%, the selectivities of diphenyl carbonate and methyl phenyl carbonate were 10.7% and 86.1%, respectively.