Structural Diversity in Oxadiazole-Containing Silver Complexes Dependent on the Anions.

Two coordination polymers, namely [Ag2(L)(SO3CF3)(H2O)](SO3CF3)•CH2Cl2 (1) and [Ag5(L)4(H2O)2](SbF6)5•5THF (2), were obtained by reacting oxadiazole-containing tri-armed ligand 1,3,5-tri(2-methylthio-1,3,4-oxadiazole-5yl) ben-zene (L) and silver salts in CH2Cl2/THF medium. The two complexes crystallized in the tetragonal space group I41/a and orthorhombic space group Fdd2, respectively. The Single-crystal X-ray diffraction revealed that the two complexes ex-hibit strikingly different 3D polymeric structures, which can be ascribed to the different counter anions. L in compound 1 acted as a hexa-dentate ligand, binding to two types of Ag+ atoms to form a 3D polymeric structure. L in compound 2acted as a hexa- and penta-dentate ligand, binding to three types of Ag+ atoms to form the 3D polymeric structure. The antibacterial activity of the complexes was also investigated.

Synthesis, structure and bioactivity of Ni2+ and Cu2+ acylhydrazone complexes.

Two acylhydrazone complexes, bis{6-methyl-N'-[1-(pyrazin-2-yl-κN1)ethylidene]nicotinohydrazidato-κ2N',O}nickel(II), [Ni(C13H12N5O)2], (I), and di-µ-azido-κ4N1:N1-bis({6-methyl-N'-[1-(pyrazin-2-yl-κN1)ethylidene]nicotinohydrazidato-κ2N',O}nickel(II)), [Cu2(C13H12N5O)2(N3)2], (II), derived from 6-methyl-N'-[1-(pyrazin-2-yl)ethylidene]nicotinohydrazide (HL) and azide salts, have been synthesized. HL acts as an N,N',O-tridentate ligand in both complexes. Complex (I) crystallizes in the orthorhombic space group Pbcn and has a mononuclear structure, the azide co-ligand is not involved in crystallization and the Ni2+ centre lies in a distorted {N4O2} octahedral coordination environment. Complex (II) crystallizes in the triclinic space group P-1 and is a centrosymmetric binuclear complex with a crystallographically independent Cu2+ centre coordinating to three donor atoms from the deprotonated L- ligand and to two N atoms belonging to two bridging azide anions. The two- and one-dimensional supramolecular structures are constructed by hydrogen-bonding interactions in (I) and (II), respectively. The in vitro urease inhibitory evaluation revealed that complex (II) showed a better inhibitory activity, with the IC50 value being 1.32±0.4 µM. Both complexes can effectively bind to bovine serum albumin (BSA) by 1:1 binding, which was assessed via tryptophan emission-quenching measurements. The bioactivities of the two complexes towards jack bean urease were also studied by molecular docking. The effects of the metal ions and the coordination environments in the two complexes on in vitro urease inhibitory activity are preliminarily discussed.

Synthesis and in vivo Anti-inflammatory Evaluation of Piperazine Derivatives Containing 1,4-Benzodioxan Moiety.

Six piperazine derivatives 6a-f containing 1,4-benzodioxan moiety have been synthesized and characterized by 1H NMR, ESI-MS and elemental analysis. The structure of 6d was further confirmed by single crystal X-ray diffraction. All these novel compounds were screened for their in vivo anti-inflammatory activity employing classical para-xylene-induced mice ear-swelling model. The results revealed that most of the target compounds showed significant anti-inflammatory activities, especially compound 6a with ortho-substituted methoxy group on the phenylpiperazine ring exhibited the best activity among the designed compounds.