64849-53-2

Upstream product

• 6342-56-9 Pyruvic aldehyde dimethyl acetal 
• 5351-69-9 4-Phenyl-3-thiosemicarbazide 
• 78-98-8 2-oxopropanal 

Relevant academic research and scientific papers

Copper complexes with dissymmetrically substituted bis(thiosemicarbazone) ligands as a basis for PET radiopharmaceuticals: Control of redox potential and lipophilicity

Copper(ii) bis(thiosemicarbazone) derivatives have been used extensively in positron emission tomography (PET) to image hypoxia and blood flow and to radiolabel cells for cell tracking. These applications depend on control of redox potentials and lipophilicity of the bis(thiosemicarbazone) complexes, which can be adjusted by altering peripheral ligand substituents. This paper reports the synthesis of a library of new dissymmetrically substituted bis(thiosemicarbazone) ligands by controlling the condensation reactions between dicarbonyl compounds and 4-substituted-3-thiosemicarbazides or using acetal protection. Copper complexes of the new ligands have been prepared by reaction with copper acetate or via transmetallation of the corresponding zinc complexes, which are convenient precursors for the rapid synthesis of radio-copper complexes. Well-defined structure-activity relationships linking ligand alkylation patterns with redox potential and lipophilicity of the complexes are reported.

Binuclear and tetranuclear Zn(ii) complexes with thiosemicarbazones: Synthesis, X-ray crystal structures, ATP-sensing, DNA-binding, phosphatase activity and theoretical calculations

Two Zinc(ii) complexes [Zn4(L1)4]·2H2O (1) and [Zn2(L2)2]·2H2O (2) of pyruvaldehydethiosemicarbazone ligands are reported. The complexes were characterized by elemental analysis, IR, NMR, UV-vis spectroscopy and by single-crystal X-ray crystallography. X-ray crystal structure determinations of the complexes show that though Zn : ligand stoichiometry is 1 : 1 in both the complexes, the molecular unit is tetranuclear for 1 and binuclear for 2. Both the complexes show selective sensing of ATP at pH 7.4 (0.01 M HEPES) in CH3CN-H2O (9 : 1) medium in the presence of other anions like AcO-, NO3-, F-, Cl-, H2PO4-, HPO42- and P2O72-. The UV-titration experiments of complexes 1 and 2 with ATP results in binding constants of 2.0(±0.07) × 104 M-1 and 7.1(±0.05) × 103 M-1 respectively. The calculated detection limits of 6.7 μM and 1.7 μM for 1 and 2 respectively suggest that the complexes are sensitive detectors of ATP. High selectivity of the complexes is confirmed by the addition of ATP in presence of an excess of other anions. DFT studies confirm that the ATP complexes are more favorable than those with the other inorganic phosphate anions, in agreement with the experimental results. Phosphatase like activity of both complexes is investigated spectrophotometrically using 4-nitrophenylphosphate (NPP) as a substrate, indicating the complexes possess significant phosphate ester hydrolytic efficiency. The kinetics for the hydrolysis of the substrate NPP was studied by the initial rate method at 25 °C. Michaelis-Menten derived kinetic parameters indicate that rate of hydrolysis of the P-O bond by complex 1 is much greater than that of complex 2, the kcat values being 212(±5) and 38(±2) h-1 respectively. The DNA binding studies of the complexes were investigated using electronic absorption spectroscopy and fluorescence quenching. The absorption spectral titrations of the complexes with DNA indicate that the CT-DNA binding affinity (Kb) of complex 1 (2.10(±0.07) × 106 M-1) is slightly greater than that of 2 (1.11(±0.04) × 106 M-1). From fluorescence spectra the apparent binding constant (Kapp) values were calculated and they are found to be 5.41(±0.01) × 105 M-1 for 1 and 3.93(±0.02) × 105 M-1 for 2. The molecular dynamics simulation demonstrates that the Zn(ii) complex 1 is a good intercalator of DNA.

Ruthenium(II/III) complexes of redox non-innocent bis(thiosemicarbazone) ligands: Synthesis, X-ray crystal structures, electrochemical, DNA binding and DFT studies

Six tetradentate bis-thiosemicarbazone ligands formed by condensation of pyruvaldehyde with 4-(aryl) thiosmicarbazides and their Ru(II) complexes are reported. The complexes are of formula [Ru(PPh3)2(L)], where L is the dianionic form of the bis-thiosemicarbazone ligands. X-ray crystal structures of two of the complexes suggest that the thiosmicarbazone ligands act in a tetradentate fashion occupying the basal plane of the Ru(II) coordination octahedron and each of the two thiosemicarbazone moiety forms five membered chelate ring involving deprotonated thiolato sulfur and the imine nitrogen atoms; the two triphenylphosphine ligands are trans to each other. The complexes undergo Ru(II)/Ru(III) oxidation at a relatively low potential of 0.05–0.12?V versus Ag/AgCl. One of the Ru(II) complex has been chemically oxidized to the corresponding Ru(III) complex [Ru(PPh3)2(L)]PF6 using ferrocenium hexafluorophosphate as an oxidizing agent. E.P.R. spectra of the Ru(III) complex and DFT calculations on the Ru(III) as well as two of the Ru(II) complexes suggest that there is extensive mixing between the ligand and metal valence orbitals. The DNA-binding properties of the Ru(II) complexes were studied by both UV–Vis spectroscopy and fluorescence quenching of ethidium bromide-DNA complex. The complexes showed strong DNA-binding ability with Kapp of the order of 106?M?1.