Mercury complexes with the ligand benzaldehyde-N(4),N(4)-dimethylthiosemicarbazone

E- or Z-Isomers Arising from the Geometries of Ligands in the Mercury Complex of 2-(Anthracen-9-ylmethylene)-N-phenylhydrazine Carbothioamide

An anionic mercury(II) complex of 2-(anthracen-9-ylmethylene)-N-phenylhydrazine carbothioamide (HATU) and two isomers of a neutral mercury(II) complex of the anion of the same ligand (ATU) were reported. The anionic complex [Hg(HATU)2Cl2]·CH2Cl2 had a monodentate HATU ligand (a neutral form of the ligand) and chloride ligands. The two conformational isomers were of the neutral mercury(II) complex Hg(ATU)2·2DMF. The two isomers were from the E or Z geometry of the ligands across the conjugated C=N-N=C-N scaffold of the coordinated ligand. The two isomers of the complex were independently prepared and characterized. The spectroscopic properties of the isomers in solution were studied by 1H NMR as well as fluorescence spectroscopy. Facile conversion of the E-isomer to the Z-isomer in solution was observed. Density functional theory (DFT) calculations revealed that the Z-isomer of the complex was stable compared to the E-isomer by an energy of 14.35 kJ/mol; whereas, E isomer of the ligand was more stable than Z isomer by 8.37 KJ/mol. The activation barrier for the conversion of the E-isomer to the Z-isomer of the ligand was 167.37 kJ/mol. The role of the mercury ion in the conversion of the E-form to the Z-form was discussed. The mercury complex [Hg(HATU)2Cl2]·CH2Cl2 had the E-form of the ligand. Distinct photophysical features of these mercury complexes were presented.

Transition Metal Complexes of Thiosemicarbazides, Thiocarbohydrazides, and Their Corresponding Carbazones with Cu(I), Cu(II), Co(II), Ni(II), Pd(II), and Ag(I)-A Review

This review focuses on some interesting and recent applications of transition metals towards the complexation of thiosemicarbazides, thiocarbohydrazides, and their corresponding carbazones. We started the review with a description of the chosen five metals, including Cu[Cu(I), Cu(II], Co(II), Ni(II), Pd(II), and Ag(I) and their electronic configurations. The stability of the assigned complexes was also discussed. We shed light on different routes describing the synthesis of these ligands. We also reported on different examples of the synthesis of Cu(I), Cu(II), Co(II), Ni(II), Ag(I), and Pd(II) of thiosemicarbazide and thiocarbohydrazide complexes (until 2022). This review also deals with a summary of the fruitful use of metal complexes of thiosemicarbazones and thiocarbazones ligands in the field of catalysis. Finally, this recent review focuses on the applications of these complexes related to their biological importance.

Thiosemicarbazonecopper/Halido Systems: Structure and DFT Analysis of the Magnetic Coupling

Experimental magnetic studies performed on the [{CuLX}2] system (HL = pyridine-2-carbaldehyde thiosemicarbazone, X = Cl−, Br−, I−) point to the larger electronegativity in X, the lower magnitude of the antiferromagnetic interactions. In order to confirm this and other trends observed and to dip into them, computational studies on the [{CuLX}2] (X = Cl− (1), I− (2)) compounds are here reported. The chemical and structural comparisons have been extended to the compounds obtained in acid medium. In this regard, chlorido ligands yield the [Cu(HL)Cl2]∙H2O (3) complex, whose crystal structure shows that thiosemicarbazone links as a tridentate chelate ligand to square pyramidal Cu(II) ions. On the other hand, iodido ligands provoke the formation of the [{Cu(H2L)I2}2] (4) derivative, which contains pyridine-protonated cationic H2L+ as a S-donor monodentate ligand bonded to Cu(I) ions. Crystallographic, infrared and electron paramagnetic resonance spectroscopic results are discussed. Computational calculations predict a greater stability for the chlorido species, containing both the neutral (HL) and anionic (L−) ligand. The theoretical magnetic studies considering isolated dimeric entities reproduce the sign and magnitude of the antiferromagnetism in 1, but no good agreement is found for compound 2. The sensitivity to the basis set and the presence of interdimer magnetic interactions are debated.

Mimicking Peroxidase Activity by a Manganese(II) Complex Involving a New Asymmetric Tetradentate Ligand Containing Both Amino and Imino Groups

The asymmetric ligand (E)-4-bromo-2-(((2-((5-bromo-2-hydroxybenzyl)(methyl)amino)ethyl)imino)methyl)phenol has been prepared by a novel seven-step route. All organic compounds isolated in each step have been characterised by elemental analysis, infrared and1H NMR spectroscopy, and mass spectrometry. Interaction of this ligand with manganese has been investigated employing an electrochemical method. This method leads to the formation of a neutral manganese(II) complex7in high yield and purity. The complex has been thoroughly characterised by elemental analysis, infrared spectroscopy, mass spectrometry, magnetic susceptibility measurements, and cyclic voltammetry. Complex7behaves as peroxidase mimic in the presence of the water-soluble trap ABTS, probably due to its ease to coordinate the substrate molecule.

A mechanosynthesized, sequential, cyclic fluorescent probe for mercury and iodide ions in aqueous solutions

A fluorescent Hg(2+)-selective chemosensor, 2,5-dimethoxybenzaldehyde thiosemicarbazone (1), was quantitatively prepared by grinding 2,5-dimethoxybenzaldehyde and thiosemicarbazide together in a ball mill for 15min. The excitation and emission maxima of compound 1 are 347 and 450nm, respectively. The reaction of this ligand with Hg(2+) was investigated by FT-IR, (1)H NMR, and fluorescence titration. Results show that the composition of the resulting Hg complex 1-Hg is 2:1 1:Hg, and that the S and imino N atoms serve as the binding sites of the ligand to the Hg(2+) ions. Coordination-assisted fluorescence quenching results show that compound 1 exhibits a highly selective fluorescence response to trace amounts of Hg(2+) in water. More importantly, the resulting complex 1-Hg can be used as a turn-on fluorescence probe for I(-) at a detection limit of 8.4×10(-8)M. Thus, compound 1 is a relatively stable, sequential, cyclic fluorescent probe for Hg(2+) and I(-).