Synthesis, spectral characterization, and antiproliferative studies of mixed ligand titanium complexes of adamantylamine

Comparative In Vitro Binding Studies of TiCl2(dpme)2, Ti(ada)2(bzac)2, and TiCl2(bzac)(bpme) Titanium Complexes with Calf-Thymus DNA

The binding of TiCl2(dpme)2 (1), (dpme = 6,6'-dimethyl-2,2'-bipyridine), Ti(ada)2(bzac)2 (2), (ada = adamantylamine; bzac = benzoylacetone), and TiCl2(bzac)(bpme) (3), (bpme = 4,4'-dimethyl-2,2'-bipyrdine) with calf thymus (ct) DNA has been studied by UV-visible spectroscopy, thermal denaturation, and circular dichroism spectroscopy. In UV-visible study complexes 1, 2, and 3 showed red, blue, and red shifts, respectively, upon the addition of ct-DNA along with a significant hyperchromism. The intrinsic binding constants (K b ) calculated from UV-visible absorption studies were 2.3 × 10(3) M(-1), 3.3 × 10(3) M(-1) and, 7.1 × 10(3) M(-1) for complexes 1, 2, and 3, respectively. The change in melting temperature (ΔT m ) was calculated to be 2-3°C for each complex. Circular dichroism (CD) study showed blue shift for complex 2 and red shift for complexes 1 and 3 along with rise in molecular ellipticity upon the addition of complexes. Results suggest a binding mode of complex 2 different than 1 and 3.

Synthesis, DFT Calculation, and Antimicrobial Studies of Novel Zn(II), Co(II), Cu(II), and Mn(II) Heteroleptic Complexes Containing Benzoylacetone and Dithiocarbamate

Heteroleptic complexes of zinc(II), copper(II), manganese(II), and cobalt(II) of the types [MLL'(H2O)2]·nH2O and [MLL']·nH2O have been synthesized using sodium N-methyl-N-phenyldithiocarbamate (L) and benzoylacetone (L'). The metal complexes were characterized by elemental analysis, electrical conductance, magnetic susceptibility, infrared (IR), and UV-visible spectroscopic studies. The electrical conductance measurements revealed the nonelectrolytic nature of the synthesized complexes. The results of the elemental analyses, magnetic susceptibility measurements, and electronic spectra inferred that the Zn(II) complex adopted a four-coordinate geometry while the Co(II), Cu(II), and Mn(II) complexes assumed octahedral geometries. The IR spectra showed that the metal ions coordinated with the ligands via the S- and O-donor atoms. The geometry, electronic, and thermodynamic parameters of the complexes were obtained from density functional theory (DFT) calculations. The spin density distributions, relative strength of H-bonds, and thermodynamic parameters revealed that the order of stability of the metal complexes is Mn < Co < Cu > Zn. The agar diffusion methods were used to study the antimicrobial activity of the complexes against two Gram positive bacteria (S. aureus and S. pneumoniae), one Gram negative bacterium (E. coli), and two fungi organisms (A. niger and A. candida) and the complexes showed a broad spectrum of activities against the microbes.