Binuclear zinc(II) complexes of N(4)-substituted bis(thiosemicarbazone) ligands incorporating hydroxyl group and their non-hydroxyl analogues.

We have reported the synthesis and physical and chemical studies of the new zinc complexes of N(4)-substituted bis(thiosemicarbazones). The complexes characterized by spectroscopic methods. The crystal structures of the compounds [Zn 2 L2 (CH 3 COO)]·EtOH and [Zn 2 L4 (CH 3 COO)]·MeOH is determined. Bis(thiosemicarbazones) involving a pendant OH group having SNONS donor sequences can hold two metal ions in close proximity. The coordination sphere has been formed by the imine nitrogen and sulfur atom, and the remaining positions, in a square-based pyramid, has been occupied by three oxygen atoms derived of pendant OH, ether group and acetate ligand. Acetate ligand and alkoxide oxygen are bridged between two metal centers. Whereas, their non-hydroxyl analogues are dimer. In dimer complexes, two ligands are tetradentate coordinated via N 2 S 2 donor atoms. The presence of bulky groups on the nitrogens of thiosemicarbazide enforce an s-trans conformation for the H 2 L1 and H 2 L3 ligands in [Zn L1 ] 2 ·MeOH and [Zn L3 ] 2 ·MeOH. Fluorescence studies suggest that the [Zn L1 ] 2 ·MeOH complex can be utilized as a fluorescent imaging agent. [ABSTRACT FROM AUTHOR]