Low-dimensional compounds containing bioactive ligands. Part VI. Spectral and structural characterizations of a unique zinc(II) compound with biologically active ligand — clioquinol

The investigated compound of {[Zn(CQ)2(H2O)2]2[Zn(CQ)2(H2O)]3}·5DMF·2H2O (1) composition (where CQ = 5-chloro-7-iodo-quinolin-8-ol, DMF = N,N-dimethylformamide) was prepared by simple mixing of ZnCl2 and CQ. Infrared spectroscopy confirmed the presence of CQ, DMF and H2O molecules in the prepared compound. X-ray structural analysis revealed that the structure of the title compound consists of five independent Zn(II) atoms, which are coordinated by two bidentately coordinated molecules of CQ. Three of these central atoms are also coordinated by one water molecule, while the other two have two water molecules in the coordination sphere. The structure of 1 also includes five solvated DMF and two water molecules involved in thirteen hydrogen bonds, which interconnect different complex species to form four “triplets”, in the centre of which are units with hexacoordinated Zn atoms surrounded by two units with pentacoordinated Zn atoms. These triplets are linked together to chains parallel with the b axis by two kinds of π–π interactions.