Structure, biological and electrochemical studies of transition metal complexes from N,S,N ' donor ligand 8-(2-pyridinylmethylthio)quinoline

摘要

The semirigid tridentate 8-(2-pyridinylmethylthio)quinoline ligand (Q1) is shown to form the structurally characterized transition metal complexes [Cu(Q1)Cl-2] (1), [CO(Q1)(NO3)(2)] (2). [Cd(Q1)(NO3)(2)] (3). [Cd(Q1)I-2] (4). [Cu(Q1)(2)](BF4)(2)center dot(H2O)(2) (5), [Cu(Q1)(2)](ClO4)(2)center dot(CH3COCH3)(2) (6). [Zn(Q1)(2)](CiO(4))(2)(H2O)(2) (7). [Cd-2(Q1)(2)Br-4] (8), [Ag-2(Q1)(2)(ClO4)(2)] (9), and [Ag-2(Q1)(2)(NO3)(2)] (10). Four types of structures have been observed: ML-type in complexes 1-4, in which the anions Cl-, NO3- or I- also participate in the coordination; ML2- type in complexes 5-7 Without direct coordination of the anions BF4- or ClO4- and with more (Cu2+) or less (Zn2+) distorted bis-fac coordinated Q1: M2L2-type in complex 8. in which two Br- ions act as bridges between two metal ions; and M-2(mu-L)(2)-type in complexes 9 and 10, in which the ligand bridges two anion binding and Ag-Ag bonded ions. Depending on electron configuration and size, different coordination patterns are observed with the bonds from the metal ions to N-pyridyl longer or shorter than those to N-quinoline. Typically Q1 acts as a facially coordinating tridentate chelate ligand except for the compounds 9 and 10 with low-coordinate silver(I). Except for 6 and 8. the complexes exhibit distinct constraining effects against both G(+) and G(-) bacteria. Complexes 1, 3, 4, 5, 7 have considerable antifungal activities and complexes 1, 5, 7, and 10 show selective effects to restrain certain botanic bacteria. Electrochemical studies show quasi-reversible reduction behavior for the copper(II) complexes 1, 5 and 6.