A Dual-Functional Fluorescent Chemosensor Derived from Naphthalene Dithiouryl for Cu2+: Applications in Water Analysis, Logic Gates, Swab Tests, and Pesticide Monitoring

A chemosensor (CNS) built on a naphthalene fluorophore was developed, featuring a disulfide-bridged dimer structure. The probe CNS was completely characterized by the usual spectral analysis methods like 1H NMR, 13C NMR, and HR-MS. The CNS probe selectively detects Cu2+ ions and subsequently recognizes the amino acid tryptophan in a semi-aqueous medium of DMF:H2O solution. The detection of Cu2+ ions occur via three distinct mechanisms: suppression of the photoinduced electron-transfer process (PET), arrested rotation of diuryl groups leading to conformational change, and a blue-shifted fluorescence enhancement through intramolecular charge-transfer (ICT). With a 1:1 complexation ratio and a detection limit of 2.14 x 10-4 M, the CNS probe has been successfully applied in various practical scenarios, including real water sample analysis, glyphosate detection, smartphone-based color detection, and Cu2+ ion testing using a cotton-swab method.

Nicotine sensing behavior of nickel(II) complexes catalyzed oxidation and coupling reactions

One of the main source of demise during the next ten years will be coronary heart disease and stroke, which are brought on by smoking (nicotine). To identify the percentage (%) of nicotine consumption by electrocatalytic sensor towards nicotine for target-specific prevent stroke, four uninuclear Ni2+ complexes of substituted butanimidamide Schiff base ligands [H2L1-4] was prepared. All the complexes were thoroughly analyzed by using several spectroscopic techniques such as CHNS analysis, FT-IR, NMR (1H & 13C) UV-Vis and NMR. The analyses showed tetradentate binding mode of ligand around nickel(II) metal ion leads to the structure of square planar with N2X2 (X = O, S) donor fashion. In addition, the well-defined nickel(II) complexes were utilized for oxidation of various alcohols such as cyclohexanol, and benzyl alcohol were produced to the assorted oxidized products with high yield respectively using greener co-oxidant (molecular oxygen). In addition, Nickel(II) complexes was further utilized as catalyst for aryl-aryl coupling reaction via Suzuki-Mayura method to obtain biphenyl compound. Furthermore, nickel(II) complexes were exploited for electrochemical detection of nicotine sensing in μM concentration.

Synthesis, Structural Characterization, Cytotoxicity, and Protein/DNA Binding Properties of Pyridoxylidene-Aminoguanidine-Metal (Fe, Co, Zn, Cu) Complexes

Pyridoxylidene-aminoguanidine (PLAG) and its transition metal complexes are biologically active compounds with interesting properties. In this contribution, three new metal-PLAG complexes, Zn(PLAG)(SO4)(H2O)].∙H2O (Zn-PLAG), [Co(PLAG)2]SO4∙2H2O (Co-PLAG), and [Fe(PLAG)2]SO4∙2H2O) (Fe-PLAG), were synthetized and characterized by the X-ray crystallography. The intermolecular interactions governing the stability of crystal structure were compared to those of Cu(PLAG)(NCS)2 (Cu-PLAG) within Hirshfeld surface analysis. The structures were optimized at B3LYP/6-31+G(d,p)(H,C,N,O,S)/LanL2DZ (Fe,Co,Zn,Cu), and stability was assessed through Natural Bond Orbital Theory and Quantum Theory of Atoms in Molecules. Special emphasis was put on investigating the ligand's stability and reactivity. The binding of these compounds to Bovine and Human serum albumin was investigated by spectrofluorometric titration. The importance of complex geometry and various ligands for protein binding was shown. These results were complemented by the molecular docking study to elucidate the most important interactions. The thermodynamic parameters of the binding process were determined. The binding to DNA, as one of the main pathways in the cell death cycle, was analyzed by molecular docking. The cytotoxicity was determined towards HCT116, A375, MCF-7, and A2780 cell lines. The most active compound was Cu-PLAG due to the presence of PLAG and two thiocyanate ligands.

Thiosemicarbazone(s)-anchored water soluble mono- and bimetallic Cu(ii) complexes: enzyme-like activities, biomolecular interactions, anticancer property and real-time live cytotoxicity

The reactions of CuCl2·2H2O with chromone thiosemicarbazone ligands containing a -H or -CH3 substituent on terminal N yielded monometallic Cu(ii) complexes [Cu(HL1)Cl2] (1) and [Cu(HL2)Cl2] (2), whereas bimetallic Cu(ii) complexes [Cu(μ-Cl)(HL3)]2Cl2 (3), [Cu(μ-Cl)(HL4)]2Cl2 (4) and [Cu(μ-Cl)(L5)]2 (5) were obtained when a -C2H5, -C6H11 or -C6H5 substituent was present, respectively, in the ligands. The complexes were characterized using elemental analyses, UV-Vis, FT-IR, EPR, mass and TGA studies. The structures of neutral monometallic and dicationic bimetallic complexes were confirmed by single crystal X-ray diffraction, and they exhibited a distorted square pyramidal geometry around Cu(ii) ions. The catecholase-mimicking activity of complexes 1-5 was examined spectrophotometrically, and the results revealed that all the complexes except 5 had the ability to oxidize 3,5-di-tert-butylcatechol (3,5-DTBC) to 3,5-di-tert-butylquinone (3,5-DTBQ) under aerobic conditions with moderate turnover numbers. In order to find the possible complex-substrate intermediates, a mass spectrometry study was carried out for complexes 1-4 in the presence of 3,5-DTBC. The phosphatase-like activity of 1-5 was also investigated using 4-nitrophenylphosphate (4-NPP) as a model substrate. All the complexes exhibited excellent phosphatase activity in DMF-H2O medium. The complexes displayed significant biomolecular interactions and antioxidant potential. Complex 3 showed good interaction with apoptotic CASP3 protein, VEGFR2 and PIM-1 kinase receptors as revealed by a molecular docking study. Complexes (3-5) exhibited promising cytotoxicity against HeLa-cervical cancer cells with IC50 values of 2.24 (3), 2.25 (4) and 3.77 (5) μM, respectively, and showed a two-fold higher activity than cisplatin. The active complex 3 showed complete inhibition of colony formation at 10 μM concentration. In addition, the acridine orange (AO)/ethidium bromide (EB) staining and real-time live cell imaging results confirmed that complex 3 induced cell death in HeLa cells.

Metal Complexes as Promising Agents for Biomedical Applications

Background::

In this review article, a brief overview of novel metallotherapeutic agents (with an emphasis on the complexes of essential biometals) promising for medical application is presented. We have also focused on the recent work carried out by our research team, specifically the development of redox-active antimicrobial complexes of sterically hindered diphenols with some essential biometals (copper, zinc, nickel).

Results::

The complexes of essential metals (manganese, iron, cobalt, nickel, copper, zinc) described in the review show diverse in vitro biological activities, ranging from antimicrobial and antiinflammatory to antiproliferative and enzyme inhibitory. It is necessary to emphasize that the type of organic ligands in these metal complexes seems to be responsible for their pharmacological activities. In the last decades, there has been a significant interest in synthesis and biological evaluation of metal complexes with redox-active ligands. A substantial step in the development of these redox-active agents is the study of their physicochemical and biological properties, including investigations in vitro of model enzyme systems, which can provide evidence on a plausible mechanism underlying the pharmacological activity. When considering the peculiarities of the pharmacological activity of the sterically hindered diphenol derivatives and their nickel(II), copper(II) and zinc(II) complexes synthesized, we took into account the following: (i) all these compounds are potential antioxidants and (ii) their antimicrobial activity possibly results from their ability to affect the electron-transport chain.

Conclusion::

We obtained novel data demonstrating that the level of antibacterial and antifungal activity in the series of the above-mentioned metal-based antimicrobials depends not only on the nature of the phenolic ligands and complexing metal ions, but also on the lipophilicity and reducing ability of the ligands and metal complexes, specifically regarding the potential biotargets of their antimicrobial action – ferricytochrome c and the superoxide anion radical. The combination of antibacterial, antifungal and antioxidant activity allows one to consider these compounds as promising substances for developing therapeutic agents with a broad spectrum of activities.

Bioactivity of a radical scavenger bis(pyrazolium p-toluenesulphonate) on ctDNA and certain microbes: a combined experimental and theoretical analysis

A small organic molecule, bis(pyrazolium p-toluenesulphonate) (BPPTS), was crystallized, characterized and used to scavenge free radicals in biological systems. SXRD and spectroscopic analyses were used to confirm the structure of BPPTS. Methanolic and ethanolic solutions of BPPTS were used to assess the stability of the proposed drug using the UV-vis spectrophotometric technique. Optimization of the molecular structure was carried out by DFT with B3LYP/6-311++G(d,p) level of basis set. MEP and Fukui functions that elaborate theoretically the predominant electrophilic, nucleophilic and radical sites in BPPTS were correlated with experimental biological screening. BPPTS exhibits strong activity against Bacillus subtilis and Escherichia coli, comparable with all other analyzed pathogens. The free radical scavenging activity of BPPTS was assessed by both experimental studies and theoretical calculations. The binding sites of DPPH, which can bind to BPPTS, were also predicted by Fukui functions. DNA binding of BPPTS in UV-vis studies revealed the groove mode of binding due to the occurrence of hyperchromism. The phenomenon of hyperchromism was established by the Hirshfeld surface analysis of BPPTS, which confirmed the presence of π···π interactions (2.4%). Molecular docking established a positive correlation between experimental bio-screening reports and simulated data. ADMET properties were also calculated.

Synthesis and Characterization of a Rare Transition-Metal Oxothiostannate and Investigation of Its Photocatalytic Properties

The new transition-metal oxothiostannate [Ni(cyclen)(H₂O)₂]₄[Sn₁₀S₂₀O₄]·∼13H₂O (1) was prepared under hydrothermal conditions using Na₄SnS₄·14H₂O as the precursor in the presence of [Ni(cyclen)(H₂O)₂](ClO₄)₂·H₂O. Compound 1 comprises the [Sn₁₀S₂₀O₄]^8- anion constructed by the T3-type supertetrahedron [Sn₁₀S₂₀] and the [Sn₁₀O₄] anti-T2 cluster. Channels host the H₂O molecules, and the sample can be reversibly dehydrated and rehydrated without significantly affecting the crystallinity of the material. ¹¹⁹Sn NMR spectroscopy of an aqueous solution of Na₄SnS₄·14H₂O evidences that between 25 and 120 °C only [SnS₄]^4- and [Sn₂S₆]^4- anions are present. In further experiments, hints were found that the formation of tin oxosulfide ions depends on the Ni²⁺-centered complexes. Compound 1 exhibits promising photocatalytic properties for the visible-light-driven hydrogen evolution reaction, with 18.7 mmol·g^-1 H₂ being evolved after 3 h.

One new azido bridged dinuclear copper(ii) thiosemicarbazide complex: synthesis, DNA/protein binding, molecular docking study and cytotoxicity activity

Biological potential of a copper(ii) complex found to exhibit in vitro antiproliferative activity towards two cell lines, AGS and A549 cancer cells.

Exploration of biological activities of alkyne arms containing Cu(ii) and Ni(ii) complexes: syntheses, crystal structures and DFT calculations

Several mononuclear Cu(ii) and Ni(ii) Schiff base (N,O-donor) complexes were synthesized and characterized. The binding ability with DNA and BSA and catecholase activity of the complexes were investigated.