A compound {[Co(azpy)2(NCS)2]·1/4EtOH·1/2H2O}n(1), where azpy=4,4’-azobispyridine, was synthesized and characterized by means of IR, TGA-DTA, magnetic susceptibility and X-ray single crystal diffraction. It consists of two independent sets of fully interlocked two-dimensional networks with the dihedral angle 61.7°, organized in parallel stacks of the sheets which are made of edge-shared [Co(Ⅱ)]4squares separated by 0. 9062nm, and defined size rhombic channels. The thermal gravimetric analysis indicates that the framework is stable up to 198℃. The variable-temperature magnetic susceptibility measurements indicated that there is a weak antiferromagnetic interaction between the cobalt(Ⅰ) ions in the complex (1).
By using photoacoustic calorimetry, a photoacoustic measurement system is applied to determine the Co-C bond dissociation energy of n C4H9Co(Salen)H2O, which is 116±8kJ·mol-1. This value is in agreement with the activation enthalpy of the Co-C bond homolytic cleavage reaction that obtained by the kinetic method.
Electrospray mass spectrometry investigation shows that denatured oxidized insulin B chain can be selectively cleaved by simple Cu(II) ion and the site of cleavage is at Gly8 - Ser9 bond which is second amide bond left from His 10 in the sequence of oxidized insulin B chain.
Xue Mei LUOWei Jiang HEYu ZHANGZi Jian GUOLong Gen ZHU
The interaction of oxidized insulin B chain (B) with cis-[Pd(en)Cl2] (en=ethylenediamine), cis-[Pd-(dtco-3-OH)Cl2] (dtco-3-OH= dithiacyclooctan-3-ol) and CuCl2 was studied by electrospray mass spectrometry. It is discovered that the binding of Pd(II) complexes and the sites of cleavage are highly dependent on the secondary structure and local environment of B. The hydrolytic cleavage of denatured B by Pd(II) complexes was monitored by HPLC. The reaction is regioselective and follows first order kinetics with half-life of 4.8 days at 40oC. Two amide bonds, i. e. at Leu6-Cys7 and at Gly8-Ser9, which are dose to the two potential Pd(II) binding sites His5 and His10, are selectively cleaved. In the case of Cu(II) ion as promoter, only one cleavage site was observed which is located at Gly8-Ser9 bond. These results provide improved understanding on the design of artificial metallopeptidase.
Two long carbon chain alkyl (aqua) Costa type organocobalt complexes (R=C 6H 13 and C 8H 17 ) have been synthesized for the first time and characterized by elemental analysis, UV Vis and 1H NMR. Their inclusion behavior with β cyclodextrin was studied by 1H NMR methods. It was indicated that in aqueous solution supramolecular adducts have been formed, in which the alkyl groups of the guests were included into the cavity of β CD. Cyclic voltammetry methods was also used to study the electrochemical properties of organocobalt complexes in the absence and presence of β CD. [WT5HZ]
