Template Synthesis, Spectral and Thermal Properties of Nd(III) Metformin Schiff-Base Complexes As Potential Hypoglycemic Agents

ND(III) complexes with Schiff-bases obtained by condensation of metformin with each of salicylaldehyde (HL1); 2,3- dihydroxybenzaldehyde (H2L2); 2,4-dihydroxybenzaldehyde (H2L3); 2,5- dihydroxybenzaldehyde (H2L4) and 3,4-dihydroxybenzaldehyde (H2L5); and 2-hydroxynaphthaldehyde (HL6) have been synthesized using the template reaction. The complexes were characterized by elemental analysis, conductivity and magnetic moment measurements, IR, UV-Vis., emission, GC-MS and XRD spectroscopy and thermal analysis. The complexes are eight coordinated structure with formulae [NdL1-4,6(NO3)(2)(H2O)(3)]center dot nH(2)O where n = 2, 3, 3, 4, 5 and [NdL5(NO3)(H2O)(5)]center dot 2H(2)O. The nitrate appears to coordinate in the monodentate fashion to the metal ion.The complexes have hexagonal bipyramide stereochemistry as shown by the UV-Vis spectra and molecular modeling calculations. The thermal stabilities of the complexes have been studied by TGA, DTG and DTA and Coats-Redfern method was used to calculate their kinetic parameters. The mechanism of thermal decomposition was suggested using IR spectra at different temperatures. The association constants (K-b) for the interaction of glucose with the complexes were calculated at physiologically relevant pH (phosphate buffer) using UV-Vis and fluorescence spectroscopy as well as viscosity measurements.