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)] <bold>(1)</bold> and tetranuclear-[(Me3Sn)(2)(HOMe)H2L2](2) <bold>(2)</bold> were synthesized by the reaction of 2-[2-{8-oxoquinolin-5(8H)-ylidene}hydrazinyl]benzoic acid (<bold>H2L1</bold>) and 2-[{4-hydroxy-3-(4-hydroxy-3-carboxyphenyliminomethyl)phenylazo}]benzoic acid (<bold>H4L2</bold>), 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 <bold>1</bold> is dinuclear and is made up of two Me3Sn(IV) centres connected by a hydroxyl (mu -OH) group. The carboxylate group from the <bold>H2L1</bold> ligand and a water molecule are each responsible for coordinating the terminal edges of the two distinct tin centres. In the structure of complex <bold>2</bold>, 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 <bold>H4L2</bold> ligands. The remaining carboxylate groups from <bold>H4L2</bold> 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 <bold>1</bold> in the solid state break to form two dissimilar tetrahedral environment about two Sn(IV) units in solution. Whereas, in complex <bold>2</bold>, 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 <bold>H4L2</bold> ligand in the solution, as if the ligand <bold>H4L2</bold> 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 <bold>H4L2</bold> and complex <bold>1</bold> have efficient alpha-amylase inhibitory characteristics. In addition, the results of antioxidant activities indicate that complex <bold>2</bold> possesses promising activity and thus could be employed as an excellent antioxidant.