Ruthenium(II) carbonyl complexes containing thiourea ligand

What is it about?

The ligand H2L (N-(N,N-diethylaminothiocarbonyl) benzimidoylchloride-2-aminoacetophenone-N-methylthiosemicarbazone) reacts with ruthenium(II) building blocks [RuHCl(CO)(EPh3)3] (E = P or As) to form new complexes [Ru(1,1-DT)(Cl2)(CO)-(EPh3)2] (E = P or As; 1,1-DT = 1,1-diethylthiourea). The ligand H2L in these reactions undergoes C=N bond break and coordinates through a sulfur atom of C=S group. Analytical and spectral (IR, UV–Vis, NMR, ESI-MS) methods were used to characterize the compounds. A distorted octahedral geometry for complexes has been furnished by X-ray crystallography, which confirmed the coordination mode of the ligand with the metal precursor. The binding affinity and mode of binding of the complex towards some important biomolecules such as calf thymus DNA and bovine serum albumin protein were determined using absorption and emission spectra and found intercalative binding with calf thymus DNA and static interaction with bovine serum albumin. The in the vitro cytotoxic activity of complex was assessed using human cervical cancer (HeLa), human hepatocellular carcinoma (HepG2), and normal Vero cells. Furthermore, the complex was found to possess significant enzyme mimic catalytic activity in oxidation and hydrolysis reactions.

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Why is it important?

In conclusion, the ruthenium complexes 1 and 2 bearing thiourea ligand have been synthesized and characterized by analytical, spectral, and single crystal X-ray crystallographic techniques. The characteristic results reveal the C=N bond cleavage in ligands and monodentate coordination via the C=S group with the ruthenium metal ion. The results of single crystal XRD analysis of complexes confirm ligand cleavage, monodentate coordination mode, and octahedral geometry. The binding properties of the ruthenium complex with CT-DNA were evaluated by emissive titrations, fluorescence quenching, viscosity measurements, and the results show that the complex interacts with CT-DNA through intercalative mode. Furthermore, the complex BSA protein interactions were examined by UV–Vis and emissive titrations reveal that complex has shown high binding affinity and acts as the static quencher. The in the vitro cytotoxic study demonstrates the substantial cytotoxicity of the complex. Moreover, the complex was effectively used for aerial oxidation of catechol and phosphate hydrolysis. On the basis of Michaelis–Menton approach of enzyme kinetics, the complex shows good catalytic efficiency in catechol-oxidase functional mimic in the conversion of 3,5-DTBC to 3,5-DTBQ and ester hydrolysis functional mimic in the hydrolysis of 4-NPP to 4-NP in aerobic conditions.

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