Novel VO (IV) complexes derived from a macrochelates: Synthesis, characterization, molecular modeling andin vivoinsulin-mimic activity studies

For the development of extensive investigations into a potential medicinal application of vanadium coordination compounds for the oral treatment of diabetes, new mono and bimetallic VO (IV) complexes with N,N '-(2,2 '-(9,10-dihydro-9,10-ethanoanthracene-11,12-dicarbonyl) bis (hydrazine-1-carbonothioyl)) dibenzamide (H6EBT) and 2,2 '-((9S,10S,11R,12R)-9,10-dihydro-9,10-ethanoanthracene-11, 12-dicarbonyl) bis (N-phenylhydrazine-1-carboxamide) (H6EPH) have been isolated and characterized. The FTIR and NMR spectral data revealed that H6EBT acts as neutral tridentate and dibasic hexadentate while H6EPH as dibasic tridentate and tetrabasic hexadentate. The electronic and ESR spectra indicated that complexes has octahedral geometry. ESR spectrum of [(VO)(H6EBT)(SO4)].5H(2)O gives a well resolved hyperfine eight-line pattern typical spectrum for mononuclear vanadyl complexes with g> g(perpendicular to)= 1.9 suggesting that the ligand donor atoms ONS are coplanar with the two chelate rings forming octahedral geometry. Also, the high parallel hyperfine splitting value, A = 0.0108, than perpendicular one (A(perpendicular to)= 0.0087) indicated that the single d- electron is in a sigma-nonbonding orbital and aiming away from the equatorial ligands. On the other hand, the EPR spectra of the binuclear [(VO)(2)(H4EBT)(SO4)]3H(2)O and [(VO)(2)(H2EPH)(H2O)(2)].10H(2)O complexes gave a single broad line centered at g = 2.05 and 2.07, respectively, without resolved hyperfine structure paramagnetic triplet (S = 1) is consistent with the anomalous value of the magnetic moment value (mu(eff)= 1.100 and 0.99 B.M.) supporting a binuclear nature. The TG analyses confirmed the existence of solvent molecules inside and/or outside the coordination sphere. The DFT molecular modeling of ligands and its VO (IV) complexes supported the suggested geometries. Also, all compounds were screened forin vivoinsulin-mimetic activity.