Synthesis, spectral characterization and crystal structure of Ni(II) pyridoxal thiosemicarbazone complexes and their recyclable catalytic application in the nitroaldol (Henry) reaction in ionic liquid media

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.

Synthesis, Crystal Structure, Theoretical Calculations, Antibacterial Activity, Electrochemical Behavior, and Molecular Docking of Ni(II) and Cu(II) Complexes with Pyridoxal-Semicarbazone

New Ni (II) and Cu (II) complexes with pyridoxal-semicarbazone were synthesized and their structures were solved by X-ray crystallography. This analysis showed the bis-ligand octahedral structure of [Ni(PLSC-H)₂]·H₂O and the dimer octahedral structure of [Cu(PLSC)(SO₄)(H₂O)]₂·2H₂O. Hirshfeld surface analysis was employed to determine the most important intermolecular interactions in the crystallographic structures. The structures of both complexes were further examined using density functional theory and natural bond orbital analysis. The photocatalytic decomposition of methylene blue in the presence of both compounds was investigated. Both compounds were active toward E. coli and S. aureus, with a minimum inhibition concentration similar to that of chloramphenicol. The obtained complexes led to the formation of free radical species, as was demonstrated in an experiment with dichlorofluorescein-diacetate. It is postulated that this is the mechanistic pathway of the antibacterial and photocatalytic activities. Cyclic voltammograms of the compounds showed the peaks of the reduction of metal ions. A molecular docking study showed that the Ni(II) complex exhibited promising activity towards Janus kinase (JAK), as a potential therapy for inflammatory diseases, cancers, and immunologic disorders.

Synthesis, Crystal Structure, Quantum Chemical Analysis, Electrochemical Behavior, and Antibacterial and Photocatalytic Activity of Co Complex with Pyridoxal-(S-Methyl)-isothiosemicarbazone Ligand

New complex Co(III) with ligand Pyridoxal-S-methyl-isothiosemicarbazone, (PLITSC) was synthesized. X-ray analysis showed the bis-ligand octahedral structure of the cobalt complex [Co(PLITSC-H)₂]BrNO₃·CH₃OH (compound 1). The intermolecular interactions governing the crystal structure were described by the Hirsfeld surface analysis. The structure of compound 1 and the corresponding Zn complex (([Zn(PLTSC)(H₂O)₂]SO₄·H₂O)) were optimized at the B3LYP/6–31 + G (d,p)/LanL2DZ level of theory, and the applicability was assessed by comparison with the crystallographic structure. The natural bond orbital analysis was used for the discussion on the stability of formed compounds. The antibacterial activity of obtained complexes towards S. aureus and E. coli was determined, along with the effect of compound 1 on the formation of free radical species. Activity of compound 1 towards the removal of methylene blue was also investigated. The voltammograms of these compounds showed the reduction of metal ions, as well as the catalyzed reduction of CO₂ in acidic media.

Electrocatalytic hydrogen evolution upon reduction of pyridoxal semicarbazone and thiosemicarbazone-based Cu(II) complexes

The growing global demand for renewable energy sources has pushed renewable, green energy sources to the forefront, among which the production of hydrogen gas from water occupies a significant place. To realize this goal, researchers across the globe are developing various systems that could swiftly catalyze the hydrogen evolution reaction (HER) in the highest possible yield. In the present work, the electrocatalytic HER performances of pyridoxal semicarbazone- and thiosemicarbazone-based Cu(II) complexes, i.e., ([Cu(PLSC)Cl2] and [Cu(PLTSC-H)H2O]Br?H2O) are reported. It has been unambiguously demonstrated that the complexes exhibit enviable level of HER catalytic activity. The catalytic activity of the complexes was not only the function of central metal but it was also controlled by the nature of the coordinating ligand.

Recent reports on Pyridoxal derived Schiff base complexes

Pyridoxal and Pyridoxal 5-phosphate are two among the six aqua soluble vitamers of vitamin B6. They can form Schiff bases readily due to the presence of aldehyde group. Schiff bases can offer diverse coordination possibilities for many transition metals as has been found in a large volume of research till now. The coordination complexes thus formed gives insight into the active core structure and enzymatic activities of vit B6 containing enzymes. Apart from that, these complexes have been found useful as catalysts for synthesis of fine chemicals, as sensors and for their diverse biological activities.

Thiosemicarbazone Complexes of Transition Metals as Catalysts for Cross-Coupling Reactions

Catalysis of cross-coupling reactions under phosphane-free conditions represents an important ongoing challenge. Although transition metal complexes based on the thiosemicarbazone unit have been known for a very long time, their use in homogeneous catalysis has been studied only relatively recently. In particular, reports of cross-coupling catalytic reactions with such complexes have appeared only in the last 15 years. This review provides a survey of the research in this area and a discussion of the prospects for future developments.

Synthesis and structure of nickel(ii) thiocarboxamide complexes: effect of ligand substitutions on DNA/protein binding, antioxidant and cytotoxicity

Four Ni(ii) thiocarboxamide complexes were synthesized and characterized. The effect of ligand substitution on DNA and protein binding is described. The complexes exhibit excellent radical scavenging abilities and show better cytotoxicity against HeLa and MG-63 cell lines.

Synthesis of high surface area mixed metal oxide from the NiMgAl LDH precursor for nitro-aldol condensation reaction

NiMgAl mixed oxide catalyzes nitro-aldol condensation reaction at room temperature under solvent free conditions exhibiting 99% conversion.