Co existence of isomeric binuclear tetrahedral Cu(I) complexes and their reaction with [NiCl2(PPh3)2]

Reaction between 2-hydroxy-1-naphthaldehyde thiosemicarbazone and square planar dichloro bis triphenylphosphine Cu(II) resulted in two structurally different binuclear Cu(I) tetrahedral complexes which are co-crystallized together by exhibiting bonding isomerism. The reaction of co-crystallized complexes with [NiCl2(PPh3)2] led to C–S and Cu–S activation of coordinated ligand to form [Cu2(μ2-Cl2)(PPh3)3] and [Cu2(μ2-S2)(PPh3)3] respectively along with a square planar [Ni(nap-tsc)(PPh3)] (where, nap-tsc =2-hydroxy-1-naphthaldehyde thiosemicarbazone) and triphenylphosphine sulfide

New palladium metallacycles containing 4(N,N′)-diethylaminosalicylaldehyde-4(N)-thiosemicarbazones: Synthesis, spectral, structural and DNA/protein binding studies

International audienceThe versatile coordination behavior of 4(N, N')-diethylaminosalicylaldehyde-4(N)-substituted thiosemicarbazones (H2L1-4) was examined in 1 : 1 stoichiometric reactions with [PdCl2(AsPh3)(2)]. All the new complexes (1-4) were characterized by analytical, IR, absorption and H-1 NMR spectroscopic studies. The complexes [Pd(DeaSal-tsc)(AsPh3)] (1), [Pd(H-DeaSal-mtsc)(AsPh3)] (2) and [Pd(H-DeaSal-etsc)(AsPh3)] (3) were structurally characterized by single crystal X-ray diffraction studies. Crystallographic results showed that the ligand H2L1 is coordinated as mono negative tridentate ONS donor ligand in the complex 1 by forming six and five member rings. Whereas, the ligands H2L2 and H2L3 bound to palladium in 2 and 3 as mono negative bidentate NS donor by forming a five member chelate ring by leaving the third potential donor atom, phenolic oxygen remain intact without being participated in bonding. The non-participation of the phenolic oxygen may be due to the intra molecular hydrogen bonding between phenolic hydrogen and N2 nitrogen. The interaction of the palladium(II) precursor [PdCl2(AsPh3)(2)], ligands ((H2L1-H2L4)) and their corresponding complexes (1-4) with calf-thymus DNA (CT DNA) has been explored by absorption and emission titration methods. Based on the observations, an intercalative binding mode of DNA has been proposed. The protein binding abilities of the new complexes along with their precursor were monitored by quenching of tryptophan and tyrosine residues using BSA as model protein. From the studies, it was found that the new palladium metallacycles exhibited better affinity than their precursors

Versatile Coordination Behavior of Salicylaldehydethiosemicarbazone in Ruthenium(II) Carbonyl Complexes: Synthesis, Spectral, X‑ray, Electrochemistry, DNA Binding, Cytotoxicity, and Cellular Uptake Studies

The reaction of salicylaldehydethiosemicarbazone, [H₂-(Sal-tsc)], with an equimolar amount of [RuHCl­(CO)­(PPh₃)₃] has afforded two complexes, namely [Ru­(H-Sal-tsc)­(CO)­Cl­(PPh₃)₂] (<b>1</b>) and [Ru­(Sal-tsc)­(CO)­(PPh₃)₂] (<b>2</b>), in one pot. The new complexes were separated and characterized by elemental analyses, various spectroscopic techniques (NMR, UV–vis, IR), X-ray crystallography, and cyclic voltammetry. In complex <b>1</b>, the ligand coordinated in a bidentate monobasic fashion by forming an unusual strained NS four-membered ring in 32% yield. However, in <b>2</b>, the ligand coordinated in a tridentate dibasic fashion by forming ONS five- and six-membered rings in 51% yield. Comparative biological studies such as DNA binding, cytotoxicity (MTT, LDH, and NO), and cellular uptake studies have been carried out for new ruthenium­(II) complexes (<b>1</b> and <b>2</b>). From the DNA binding studies, it is inferred that the complex <b>1</b> exhibited electrostatic binding and <b>2</b> exhibited intercalative binding modes. On comparison of the cytotoxicity of the complexes in human lung cancer cells (A549) and liver cancer cells (HepG2), complex <b>2</b> exhibited better activity than <b>1</b>; this may be due to the strong chelation and subsequent electron delocalization in <b>2</b> increasing the lipophilic character of the metal ion into cells