Azo-benzoic acid derivatives directed dinuclear and tetranuclear association of trimethyltin(IV) complex components and their biological activities

Two new trimethyltin(IV) complexes including dinuclear-[(H2O)Me3Sn-mu -OH-SnMe3(HL1)] (1) and tetranuclear-[(Me3Sn)(2)(HOMe)H2L2](2) (2) were synthesized by the reaction of 2-[2-{8-oxoquinolin-5(8H)-ylidene}hydrazinyl]benzoic acid (H2L1) and 2-[{4-hydroxy-3-(4-hydroxy-3-carboxyphenyliminomethyl)phenylazo}]benzoic acid (H4L2), respectively with trimethyltin(IV) chloride. The complexes were characterized using sophisticated spectroscopic tools and single crystal X-ray crystallographic analysis. The structure of the complex 1 is dinuclear and is made up of two Me3Sn(IV) centres connected by a hydroxyl (mu -OH) group. The carboxylate group from the H2L1 ligand and a water molecule are each responsible for coordinating the terminal edges of the two distinct tin centres. In the structure of complex 2, which is tetranuclear in nature, a cyclic loop containing two symmetry-related Me3Sn(IV) units is confined by the alternate carboxylate-O and phenoxide-O atoms from the two H4L2 ligands. The remaining carboxylate groups from H4L2 ligands are attached to the other two terminal symmetry-related Me3Sn(IV) units, which are further bound by the methanol-O atoms, thereby preventing extended molecular structure. According to Hirshfeld surface and DFT topological analysis, the weak noncovalent interactions involving H-bonding are substantially responsible for the molecular packing. According to the Sn-119-NMR spectra, the hydroxo-bridge bonds of 1 in the solid state break to form two dissimilar tetrahedral environment about two Sn(IV) units in solution. Whereas, in complex 2, the phenolate-O-Sn bonds in the solid state break to form a trigonal bipyramidal and a tetrahedral geometries around Sn(IV) linked by the H4L2 ligand in the solution, as if the ligand H4L2 holds Me3Sn(IV) and Me3Sn(IV)(OMe) units by its two carboxylate hands. The study of antidiabetic activities of the synthesized compounds against alpha-glucosidase and alpha-amylase reveal that the ligand H4L2 and complex 1 have efficient alpha-amylase inhibitory characteristics. In addition, the results of antioxidant activities indicate that complex 2 possesses promising activity and thus could be employed as an excellent antioxidant.