Palladium (II) complexes with thione and thioalkylated thiosemicarbazones: Electrochemical, antimicrobial and thermogravimetric investigations

Efficient treatment of palladium from wastewater by acrolein cross-linked chitosan hydrogels: Adsorption, kinetics, and mechanisms

Herein we present a study on the preparation and properties of a hydrogel adsorbent for treatment of wasted palladium souring from actial petrochemical industrial wastewater. Chitosan was used as the raw material and acrolein as the cross-linking agent for the hydrogel (A/CS). The adsorption behaviors of the hydrogel for Pd(II) ions were characterized and analyzed. The effect of pH, temperature, adsorption kinetics, and thermodynamics were investigated. Langmuir models were employed to describe the adsorption isotherms, while the pseudo-second-order equation was applied to describe the adsorption kinetics. The experimental results demonstrated that the adsorption was a monolayer chemical adsorption, and the adsorption capacity was found to reach 505.05 mg/g under optimal conditions. In addition, FT-IR and XPS analyses, combined with MS calculations confirmed that chelation and electrostatic attraction were dominated in the adsorption process. Overall, the development of this hydrogel adsorbent will provide a practical approach to the treatment of industrial wastewater containing palladium and have great potential for practical applications.

Bioactive Thiosemicarbazone Coordination Metal Complexes: Synthesis, Characterization, Theoretical analysis, Biological Activity, Molecular Docking and ADME analysis

Mn(II) and Cu(II) complexes having the formula [M(L)2 ]X2 of ligand, i. e., 2-acetyl-5-methylfuranthiosemicarbazone were synthesized. Various analytical and spectroscopic techniques described the structure of synthesized complexes. Molar conductance confirmed the electrolytic nature of the complexes. The theoretical study of the complexes explained the structural property and reactivity. The chemical reactivity, interaction and stability of the ligand and metal complexes were studied with the help of global reactivity descriptors. MEP analysis was used to investigate the charge transfer in the ligand. The biological potency was evaluated against two bacteria and two fungi. Complexes demonstrated superior inhibitory action to ligand. The inhibitory effect was also checked at the atomic scale using molecular docking, which confirmed the experimental results. Cu(II) complex was shown to have the most inhibitory effect in experimental and theoretical studies. To check the bioavailability and drug-likeness, ADME analysis was also done.

Antimicrobial Resistance Challenged with Platinum(II) and Palladium(II) Complexes Containing 1,10-Phenanthroline and 5-Amino-1,3,4-Thiadiazole-2(3H)-Thione in Campylobacter jejuni

This work describes the synthesis and characterization of two metal complexes of the type [M(L1)2(phen)], where M = Pt2+ (complex I) or Pd2+ (complex II), L1 = 5-amino-1,3,4-thiadiazole-2(3H)-thiolate and phen = 1,10-phenanthroline. The in vitro antibacterial activity of these complexes was investigated in isolation and synergistically with ciprofloxacin (CIP) and erythromycin (ERY) in three strains of Campylobacter jejuni (MIC = 32 mg/L for CIP and ERY), selected from a bank of 235 strains representative of three poultry exporting states of the country (A, B and C), previously analyzed for epidemiology and resistance to CIP and ERY. A total of 53/235 (22.55%) strains showed co-resistance to CIP and ERY. Isolated resistance to CIP was higher than to ERY. Epidemiological analysis showed that resistance to CIP was more evident in state B (p < 0.0001), as well as a higher susceptibility to ERY in state C (p = 0.0028). Co-resistance was expressive in state A and in the spring and fall seasons. The evaluation of I alone and in synergy with CIP and ERY found values up to 0.25 mg/L not significant for ERY. Complex II did not show an antimicrobial effect on the three strains of tested C. jejuni. The effect provided by complex I represents a promising alternative for control of resistant strains of C. jejuni.

New Pd(II) complexes of the bisthiocarbohydrazones derived from isatin and disubstituted salicylaldehydes: Synthesis, characterization, crystal structures and inhibitory properties against some metabolic enzymes

Pd(II) complexes (Pd1, Pd2, and Pd3) were synthesized for the first time using asymmetric isatin bisthiocarbohydrazone ligands and PdCl₂(PPh₃)₂. All complexes were characterized by a range of spectroscopic and analytical techniques. The molecular structures of Pd1 and Pd3 have been determined by single-crystal X-ray diffraction analysis. The complexes are diamagnetic and exhibit square planar geometry. The asymmetric isatin bisthiocarbohydrazone ligands coordinate to Pd(II) ion in a tridentate manner, through the phenolic oxygen, imine nitrogen and thiol sulfur, forming five- and six-membered chelate rings within their structures. The fourth coordination site in these complexes is occupied by PPh₃ (triphenylphosphine). The free ligands and their Pd(II) complexes were evaluated for their carbonic anhydrase I, II (hCAs) and acetylcholinesterase (AChE) inhibitor activities. They showed a highly potent inhibition effect on AChE and hCAs. K_i values are in the range of 9 ± 0.6 - 30 ± 5.4 nM for AChE, 7 ± 0.5 - 16 ± 2.2 nM for hCA I and 3 ± 0.3-24 ± 1.9 nM for hCA II isoenzyme. The results clearly demonstrated that the ligands and their Pd(II) complexes effectively inhibited the used enzymes.

Synthesis and antioxidant activities of new nickel(II) complexes derived from 4-benzyloxysalicylidene-S-methyl/propyl thiosemicarbazones

Six nickel(II) complexes of the N₂O₂ chelating thiosemicarbazones were synthesized using N¹-4-benzyloxysalicylidene-S-methyl/propyl thiosemicarbazone and methoxy-substitute-salicylaldehydes in the presence of Ni(II) ion by template reaction. The structures of thiosemicarbazones and nickel(II) complexes were characterized by elemental analysis, UV-Vis, IR, and ¹H-NMR spectroscopies. The structure of the N¹-4-benzyloxysalicylidene-S-propyl thiosemicarbazone ( 2 ) was determined by X-ray single-crystal diffraction method. The total antioxidant capacities of synthesized compounds were evaluated by using cupric reducing antioxidant capacity (CUPRAC) method. The thiosemicarbazones exhibited more potent antioxidant capacity than Ni(II) complexes. Trolox equivalent antioxidant capacity (TEAC) of 1c was found highest in tested nickel(II) complexes. In addition, antioxidant activities of tested compounds were evaluated by using the hydroxyl radical, DPPH radical, and ABTS radical scavenging abilities of these compounds.

Synthesis, characterization of ruthenium(II), nickel(II), palladium(II), and platinum(II) triphenylphosphine-based complexes bearing an ONS-donor chelating agent: Interaction with biomolecules, antioxidant, in vitro cytotoxic, apoptotic activity and cell cycle analysis

Four new transition metal complexes, [M(PPh₃)(L)]^.CH₃OH (M = Ni(II) (1), Pd(II) (2)) [Pt (PPh₃)₂(HL)]Cl (3) and [Ru(CO)(PPh₃)₂(L)] (4) (H₂L = 2,4-dihydroxybenzaldehyde-S-methyldithiocarbazate, PPh₃ = triphenylphosphine) have been synthesized and characterized by elemental analyses (C, H, N), FTIR, NMR (¹H, ³¹P), ESI-MS and UV-visible spectroscopy. The molecular structure of (1) and (2) complexes was confirmed by single-crystal X-ray crystallography. It showed a distorted square planar geometry for both complexes around the metal center, and the H₂L adopt a bi-negative tridentate chelating mode. The interaction with biomolecules viz., calf thymus DNA (ct DNA), yeast RNA (tRNA), and BSA (bovine serum albumin) was examined by both UV-visible and fluorescence spectroscopies. The antioxidant activity of all compounds is discussed on basis of DPPH^• (2,2-diphenyl-1-picrylhydrazyl) scavenging activity and showed better antioxidant activity for complexes compared to the ligand. The in vitro cytotoxicity of the compounds was tested on human (breast cancer (MCF7), colon cancer (HCT116), liver cancer (HepG2), and normal lung fibroblast (WI38)) cell lines, showing that complex (1) the most potent against MCF7 and complex (4) against HCT116 cell lines based on IC₅₀ and selective indices (SI) values. So, both complexes were chosen for further studies such as DNA fragmentation, cell apoptosis, and cell cycle analyses. Complex (1) induced MCF7 cell death by cellular apoptosis and arrest cells at S phase. Complex (4) induced HCT116 cell death predominantly by cellular necrosis and arrested cell division at G2/M phase due to DNA damage.

Synthesis, Crystal Structure, Biological Evaluation and in Silico Studies on Novel (E)-1-(Substituted Benzylidene)-4-(3-isopropylphenyl)thiosemicarbazone Derivatives

A series of (E)-1-(substituted benzylidene)-4-(3-isopropylphenyl)thiosemicarbazone derivatives were synthesized and characterized by FT-IR spectrum, elemental analysis, NMR spectrum, HR-MS spectrum, and X-ray single crystal diffraction technology. The crystal structures and packing of (E)-1-(4-fluorobenzylidene)-4-(3-isopropylphenyl)thiosemicarbazone and (E)-1-(3-fluorobenzylidene)-4-(3-isopropylphenyl)thiosemicarbazone were maintained through the intramolecular hydrogen bond (N3-H6⋅⋅⋅N1) and intermolecular hydrogen bonds (N2-H4⋅⋅⋅S1, C14-H14⋅⋅⋅F1 and C7-H7⋅⋅⋅S1). The results obtained by employing the DPPH free radicals scavenging assay indicated that (E)-1-(4-methoxylbenzylidene)-4-(3-isopropylphenyl)thiosemicarbazone had a more significant antioxidant activity compared with other compounds. The results measured by adopting the disc diffusion method elucidated that (E)-1-(4-trifluoromethylbenzylidene)-4-(3-isopropylphenyl)thiosemicarbazone possessed a more prominent antifungal activity than other compounds. Molecular docking showed that (E)-1-(4-chlorobenzylidene)-4-(3-isopropylphenyl)thiosemicarbazone had the highest affinity with receptor protein (1NMT). Moreover, the drug-likeness characteristic, physicochemical properties, pharmacokinetic profiles, and bioactivity scores of all the compounds were predicted through in silico studies. The results illustrated that (E)-1-(4-fluorobenzylidene)-4-(3-isopropylphenyl)thiosemicarbazone had the drug-likeness characteristic and all the compounds were considered as moderately biological active molecules.