Crystal structure and photochromism of 1-phenyl-3-methyl-4-benzyl-5-one-pyrazole S-methyl thiosemicarbazone

A new organic photochromic compound containing pyrazolone-ring photochromic functional unit: 1-phenyl-3-methyl-4-benzyl-5-one pyrazole S-methyl thiosemicarbazone (PMBP-smtsc) was synthesized. The photochromic properties and photochemical kinetics of PMBP-smtsc have been studied by UV reflectance spectra under irradiation of 365 nm light. The crystal structure analyses of photocolored product show the photochromism is due to the photoisomerization from enol form to keto form through an intermolecular proton transfer.     

Oxorhenium(V) Complexes with Thiosemicarbazones

Neutral oxorhenium(V) complexes with thiosemicarbazones derived from 2‐pyridine formamide, HL¹, are formed when [ReOCl₃(PPh₃)₂] reacts with equimolar amounts of the ligands. Reduction of the metal and the formation of rhenium(III) complexes of the composition [Re(L¹)₂]⁺ occurs when an excess of thiosemicarbazones is used and the reaction is performed in boiling toluene for a prolonged period of time. The thiosemicarbazones deprotonate and act as tridentate ligands as has been confirmed by an X‐ray structure of [ReOCl₂(L^1b)], where HL^1b is 2‐pyridineformamide‐N(4)‐ethylthiosemicarbazone and the ligand occupies the equatorial coordination sphere of the complex together with one of the chloro ligands.     

Thermodynamic and voltammetric studies of salicylaldehyde-4-(2-pyridyl)-3-thiosemicarbazone

Summary UV spectra, dc polarograms, cyclic voltammetry and coulometry measurements of salicylaldehyde-4-(2-pyridyl)-3-thiosemicarbazone (H₂ SPT) were recorded inBritton-Robinson buffer solutions ofpH 2–12. The dissociation constants of H₂ SPT evaluated spectrophotometrically and potentiometrically in a 5% (v/v)DMF-water mixture are concordant. The dc-polarograms in solutions ofpH<8.5 exhibit a single 4-electron diffusion-controlled polarographic wave, whereas in solutions ofpH>8.5 two waves are observed. The cyclic voltammograms give a single cathodic peak in acidic and neutral solutions, whereas two cathodic peaks can be identified in alkaline ones. An electrode mechanism is proposed and discussed. The effect of temperature on the dissociation constants and the polarographic data was also investigated; the corresponding thermodynamic parameters were derived and are discussed.

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Thermodynamische und voltammetrische Untersuchungen an Salicylaldehyd-4-(2-pyridyl)-3-thiosemicarbazon

Zusammenfassung UV-Spektroskopische, dc-polarographische, voltammetrische und coulometrische Messungen an Salicylaldehyd-4-(2-pyridyl)-3-thiosemicarbazon (H₂ SPT) inBritton-Robinson-Pufferlösungen (pH 2–12) wurden durchgeführt. Die spektrophotometrisch und potentiometrisch ermittelten Dissoziationskonstanten von H₂ SPT in 5% (v/v)DMF/Wasser stimmen überein. In Lösungen mit einempH-Wert unter 8.5 zeigen die dc-Polarogramme eine einzelne diffusionskontrollierte polarographische Welle (4e^–), während in Lösungen mit einempH-Wert von über 8.5 zwei Wellen zu beobachten sind. Die cyclischen Voltammogramme weisen in sauren und neutralen Lösungen einen, in basischen Lösungen hingegen zwei kathodische Peaks auf. Ein Elektrodenmechanismus wird vorgeschlagen und diskutiert. Der Effekt der Temperatur auf die Dissoziationskonstanten und die polarographischen Ergebnisse wurde ebenfalls untersucht. Die entsprechenden thermodynamischen Größen wurden bestimmt und werden diskutiert.

     

Syntheses and spectroscopic studies on zinc(II) and mercury(II) complexes of isatin-3-thiosemicarbazone

Zinc(II) and mercury(II) complexes were prepared by reacting isatin-3-thiosemicarbazone (ISTSCH) with zinc(II) acetate or mercury(II) bromide. The complexes were characterized by IR, Raman, diffuse reflectance, ¹H and ¹³C NMR spectra and elemental analysis. Tetrahedral structures for Zn(ISTSC)₂ and Hg(ISTSCH)Br₂ are suggested.     

Structures,DNA binding,DNA cleavage,and antitumor investigations of a series of molybdenum(VI) complexes with some N(4) methyl and ethyl thiosemicarbazone ligands

Four dioxomolybdenum(VI) complexes were synthesized by reaction of [MoO₂(acac)₂] with thiosemicarbazones derived from 5-allyl-2-hydroxy-3-methoxybenzaldehyde (1), 2-hydroxynaphthaldehyde (2), 2,3-dihydroxybenzaldehyde (3), or 5-tert-butyl-2-hydroxybenzaldehyde (4). The ligands were coordinated to molybdenum as tridentate ONS donors. X-ray crystallography showed that the distorted octahedral coordination of molybdenum is completed by methanol (D) in 1a, 3a, and 4a or H₂O in 2a. The molecular structures of 1, 3, and 4, and the complexes were determined by single-crystal X-ray crystallography. Binding of the ligand and complexes with calf thymus DNA were investigated by UV, fluorescence titrations, and viscosity measurements. Gel electrophoresis revealed that all the complexes can cleave pBR322 plasmid DNA. The cytotoxic properties of the complexes against human colorectal (HCT 116) cell line showed strong antiproliferative activities in relative order 4a?>?3a?>?1a?>?2a with IC₅₀ values of 1.6, 4.0, 4.8, and 6.7?μM, respectively. The complexes exhibited more activity than the standard reference drug, 5-fluorouracil (IC₅₀ 7.3?μM). These studies show that dioxomolybdenum(VI) complexes have potential use in chemotherapy.     

Ni(II) and Cu(II) complexes of bidentate thiosemicarbazone ligand: Synthesis,structural, theoretical,biological studies and molecular modeling

The conventional condensation and refluxing process was employed to synthesize Ni(II) and Cu(II) complexes of Methylcarbamatethiosemicarbazone ligand. Reactions were carried out at the pH of 7. The molar ratio of the ligand and metal salt was 2:1. The structures of the synthesized metal complexes were suggested by different analytical techniques such as magnetic susceptibility, molar conductance, IR, EPR and UV spectroscopy. Experimental studies confirmed the octahedral geometry for all the complexes. The geometry of the ligand and complexes were also confirmed by theoretical studies. The complexes were investigated for biological action against pathogenic fungi (C. krusei, C. albican) and bacteria (S. aureus, E. coli). The antimicrobial results confirmed superior inhibition potential of the metal complexes as compared with the parent ligand. The enhanced antimicrobial activities might be due to the chelation. Molecular-docking assays confirmed the strong interaction of ligand with target antimicrobial protein DNA gyrase-B.     

Synthesis and molecular modeling study of Cu(Ⅱ) complexes derived from 2-(diphenylmethylene)hydrazinecarbothioamide derivatives with cholinesterase inhibitory activities

Thiosemicarbazones of 2-amino-5-chlorobenzophenone and 3-aminobenzophenone（L¹-L⁴） have been synthesized and their Cu（Ⅱ） complexes（1-4） were afforded via coordination with cupric chloride.All these compounds were characterized by UV-vis and IR spectroscopy together with CHN elemental analysis.NMR spectroscopy was also applied to characterize the ligands.In vitro chohnesterase inhibitory assays for the complexes（1-4） showed IC₅₀ values less than 10μmol/L,with complex 1 exhibiting the most activity,IC₅₀=2.15μmol/L and 2.16μmol/L for AChE and BuChE,respectively. Molecular modeling simulation revealed the binding interaction template for complex 1 with the AChE and BuChE receptors.In DPPH assay,the complexes also showed more in vitro antioxidant activities in comparison to their parent ligands.     

Synthesis of new bis(thiosemicarbazone) derivatives and DFT analysis of antioxidant characteristics in relation to HAT and SET reactions

A series of new bis(thiosemicarbazones) have been synthesized from terephthalaldehyde and various thiosemicarbazides. IR, ¹H NMR, ¹³C NMR spectroscopic methods, and elemental analysis were used to characterize the identification of the synthesized compounds. The in vitro antioxidant activity determinations were made using the 1,1-Diphenyl-2-Picryl Hydrazil (DPPH) method. The compounds exhibited very different inhibition activities with the change of groups attached to the bis(thiosemicarbazone) structure. The spectral and electronic properties of the compounds were investigated by DFT calculation. Intramolecular interactions were analyzed by QTAIM and IRI calculations. Intrinsic bond strength index values of the N–H bonds, Fukui indices and the local electron affinities of the compounds were calculated, and the relationships between the compounds and their antioxidant activity properties were investigated. The SET and HAT mechanisms in the reactions of the compounds with DPPH were affected by the concentration of the compounds, and the possible effects of the parameters supporting the dominant characteristics in these reactions were examined using theoretical data.     

Synthesis and structural characterization of Pd(II) thiosemicarbazonato complex: Catalytic evaluation in synthesis of diaryl ketones from aryl aldehydes and arylboronic acids

A simple route to synthesize triphenylphosphinopalladium(II) thiosemicarbazonato complex has been described. Elemental analysis, spectral (IR, NMR) and single crystal X-ray diffraction techniques were employed for the complete characterization of the complex. The latter was found to be effective catalyst for carbon–carbon cross-coupling reaction of aryl- and heteroarylboronic acids with aromatic and heteroaromatic aldehydes to form the corresponding diaryl ketones. The influence of reaction parameters such as solvent, base, reaction temperature and catalyst loading was also investigated.