Bidentate Chelating Research Articles

Divergent Synthesis of Chelating Aziridines and Cyclic(Alkyl)(Amino)Carbenes (CAACs) from Pyridyl-Tethered Robust Azomethine Ylides.

Azomethine ylides are typically in situ generated synthons for making N-heterocycles through cycloaddition reactions. But an offbeat aspect about them is the isomeric nature of aldiminium-based azomethine ylides and (alkyl/aryl)(amino)carbenes, interconvertible by a formal 1,3-H+ transfer. Herein, two thermally robust azomethine ylides with a N-appended picolyl sidearm are isolated, which cyclize to py aziridines at 80 °C but unprecedentedly result N-pico CAAC-CuCl (CAAC=cyclic(alkyl)(amino)carbene) complexes when heated with CuCl at merely 60 °C. The pendant Npy , as revealed by computational analysis, plays a crucial role in this unusual 1,3-H+ shift using a deprotonation-protonation sequence, as well as in placing the CuCl at the carbenic site in tandem. The softer nature of Cu(I) is also critical. Chelating CAACs are rare and one with a N-tethered additional donor is priorly unknown. Both N-pico CAAC and py aziridine are bidentate chelators giving highly active cationic Rh(I) catalysts for hydrosilylating unactivated olefins by Et3 SiH. Notably, the py aziridine-Rh(I) is superior than the N-pico CAAC-Rh(I) catalyst.

Divergent Synthesis of Chelating Aziridines and Cyclic(Alkyl)(Amino)Carbenes (CAACs) from Pyridyl‐Tethered Robust Azomethine Ylides

AbstractAzomethine ylides are typically in situ generated synthons for making N‐heterocycles through cycloaddition reactions. But an offbeat aspect about them is the isomeric nature of aldiminium‐based azomethine ylides and (alkyl/aryl)(amino)carbenes, interconvertible by a formal 1,3‐H+ transfer. Herein, two thermally robust azomethine ylides with a N‐appended picolyl sidearm are isolated, which cyclize to pyaziridines at 80 °C but unprecedentedly result N−picoCAAC‐CuCl (CAAC=cyclic(alkyl)(amino)carbene) complexes when heated with CuCl at merely 60 °C. The pendant Npy, as revealed by computational analysis, plays a crucial role in this unusual 1,3‐H+ shift using a deprotonation‐protonation sequence, as well as in placing the CuCl at the carbenic site in tandem. The softer nature of Cu(I) is also critical. Chelating CAACs are rare and one with a N‐tethered additional donor is priorly unknown. Both N‐picoCAAC and pyaziridine are bidentate chelators giving highly active cationic Rh(I) catalysts for hydrosilylating unactivated olefins by Et3SiH. Notably, the pyaziridine‐Rh(I) is superior than the N‐picoCAAC‐Rh(I) catalyst.

Tetravalent Terbium Chelates: Stability Enhancement and Property Tuning.

Coordination chemistry of rare-earth elements has been dominated by the +3 oxidation state. Complexes with higher-valence lanthanide ions are synthetically challenging but are of fundamental research interest and significance as advanced molecular materials. Herein, four tetravalent terbium complexes (2-5) of the common formula [Tb(OSiPh3)4L] (L = ethylene glycol dimethyl ether (DME), 2,2'-bipyridine (bpy), 2,2'-bipyrimidine (bpym), and 1,10-phenanthroline (phen)) are reported. Crystallographic analyses reveal in each of these complexes a hexacoordinate Tb(IV) ion situated in a distorted octahedral coordination environment formed by four triphenylsiloxido ligands and a bidentate chelating ligand. The use of chelating ligands enhances the stability of the resulting complexes over their THF solvate precursor. More significantly, the aromatic N-chelating ligands have been found to tune effectively the electronic structures of the complexes, as evidenced by the sizable potential shifts observed for the quasi-reversible redox Tb(IV/III) process and by the changes in their absorption spectra. The experimental findings are augmented with quantum theoretical calculations in which the ligand π-donation to the 5d orbitals of the Tb(IV) center is found to be primarily responsible for stability enhancement and the corresponding changes of physical properties observed. Magnetic measurements and results from electron paramagnetic resonance studies produced small absolute values of zero-field splittings of these complexes, ranging from 0.1071(22) to 1.1484(112) cm-1 and comparable to the values reported for analogous Tb(IV) complexes.

TEMPO oxidized cellulose nanocrystal (TOCNC) scaffolded nanoscale zero-valent iron (nZVI) for enhanced chromium removal

The conventional carboxymethyl cellulose (CMC) stabilization hampered available active sites of adsorption and reduction, due to irregular shape of nanoscale zero-valent iron (nZVI) particles with augmented average size and passivated surface, leading to insufficient removal and poor resistance against complex environmental conditions. Herein, we presented (2,2,6,6-Tetramethylpiperidine-1-oxyl)-mediated (TEMPO-mediated) oxidation of cellulose nanocrystal (TOCNC) scaffolded nZVI (nZVI@TOCNC) with enhanced efficiency for chromium removal in comparison with CMC stabilized nZVI (nZVI@CMC). The anchoring of nZVI at the functional sites of TOCNC was initiated by liquid-phase chemical reduction method. The nZVI@TOCNC showed improved nZVI distribution with uniform particle size and thinner shell (∼1 nm). Characterizations using FT-IR, XPS and XRD demonstrated that bindings between TOCNC and nZVI were through hydrogen bonds, electrostatic attractions, coordination-covalent bonds and bidentate chelation. TOCNC with shorter branch-chain (–COC–) surrounding the nZVI could potentially form a porous and compact “mesh” to rigidly encapsulate nZVI, while CMC wrapped around nZVI in the way of traditional polymeric stabilizers. Thus, 0.5 g/L nZVI@TOCNC achieved 99.96% Cr (Ⅵ) removal efficiency (20 mg/L) at pH = 7 and the removal capacity were up to 55.86 mg/g. The nZVI@TOCNC consistently presented higher removal efficiency than nZVI@CMC under wide pH range (3–7). Cr (Ⅵ) was reduced to Cr (Ⅲ) by nZVI@TOCNC with deposition of CrxFe1-x (OH)3 and Cr2O3. The predominant mechanisms of removal probably consisted of electrostatic attractions, reduction, co-precipitation and surface complexation. The pseudo-second-order kinetic model well-fitted the sorption kinetic, indicating TOCNC scaffold stabilized nZVI for efficient reduction of Cr (Ⅵ) through multi-layer adsorption. As a template and delivery carrier, TOCNC shows promising potential to further improve the capability and practice of nZVI for in situ treatment of industrial waste water with heavy metal pollution.

Synthesis, Crystal Structure, and Optical Properties of Mononuclear Eu(III) and Tb(III) Complexes Containing a Chalcone Ligand

Chalcones are α,β-unsaturated ketones with great structural diversity and various applications. A chalcone produced by condensation of 2-acetylpyridine with 2-naphthaldehyde (L) was employed for synthesis of two mononuclear complexes: [Eu(L)(hfac)3(H2O)]·0.5CHCl3 and [Tb(L)(hfac)3], where hfac is the hexafluoroacetylacetonate anion. The chalcone and complexes were structurally characterized by single-crystal X-ray diffraction. The chalcone acts as a chelating bidentate ligand. Luminescent properties of the ligand L and the complexes were investigated in the solid state. For these heteroleptic mononuclear complexes, the emission of the Eu(III) and Tb(III) ions was influenced by the excitation wavelength.

Magnetic polyacrylonitrile-melamine nanoadsorbent (PAN-Mel@Fe3O4) for effective adsorption of Cd (II) and Pb (II) from aquatic area

A magnetic polyacrylonitrile-melamine nanoadsorbent (PAN-Mel@Fe3O4) has been developed as a polymer-based adsorbent in three steps involving the preparation of polyacrylonitrile (PAN), the modification of PAN with melamine, and the in-situ magnetization of the PAN-Mel nanocomposite. During the fabrication of PAN-Mel@Fe3O4 nanocomposite, various analyses were used to investigate its physicochemical properties. The PAN-Mel@Fe3O4 nanoadsorbent was investigated to be able to efficiently adsorb cadmium (Cd) and lead (Pb) from aqueous media. Several experimental conditions were employed for evaluating adsorption performance, involving pH of medium, adsorbent dosage, contact time, and initial contaminant concentration. Therefore, the Cd (II) and Pb (II) maximum adsorption capacity (Qmax) in the optimized conditions reached 454.54 and 416.66 mg/g, respectively. The experimental adsorption data for both studied heavy metals was fitted well by the Freundlich isotherm model and adsorption kinetics for both heavy metals descriptions satisfactorily by the pseudo-second-order model. The PAN-Mel@Fe3O4 adsorbs mainly Cd (II) and Pb (II) by electrostatic interaction due to a great number of the nitrogen-rich bidentate chelating ligands. Regarding the adsorption–desorption of the PAN-Mel@Fe3O4 nanoadsorbent, after recycling it four times, no significant decrease in its efficiency was observed and it could be used for the four time as well.

Biological evaluation of nano-sized novel Schiff base ligand-based transition metal complexes

This study reports on the preparation, characterization, and biological evaluation of nano-sized novel Schiff base ligand (SBL) based transition metal complexes, which were synthesized by reacting metal chloride salts with SBL. The SBL and its complexes were characterized using different analytical and spectroscopic techniques including 1H - 13C NMR, UV–Vis, IR, CHN elemental analysis, TGA, DTA, SEM, TEM, XRD, ICP-MS, molar conductivity, and magnetic susceptibility. The characterization results showed that the complexes had formula [MLCl2 (H2O)2], where M = V3+ and Cr3+ or [M(L)2(H2O)2], where M = Mn2+, Ni2+, Zn2+ and Cd2+. The ligand behaved as a monobasic bidentate chelator bonding the metal via the deprotonated hydroxyl oxygen and azomethine nitrogen, adopting a distorted octahedral structure. XRD spectroscopy and SEM confirmed the complexes to be crystalline, with particle sizes ranging from 50 to 100 nm. The prepared nano-compounds were evaluated for their in vitro antimicrobial, antifungal, and anticancer activities, as well as in vivo oral toxicity tests. In-vitro antimicrobial activities demonstrated that the Zn2+ complex was the most active against bacteria, while the Cr3+ complex was the most active against fungi. The V3+ complex was shown to be the least active against all microorganisms tested. Moreover, the Zn2+ complexes showed the most effective anticancer activity against WI38 and MCF-7 cell lines with IC50 values of 39.82 and 7.31 µM, respectively, while, the Cr3+ complex was the most effective against the HEPG-2 cell line with an IC50 of 11.83 µM. In addition, in vivo, oral toxicity of (SBL) ligand and its metal complexes showed a safety limit of up to 2000 mg/kg of rat’s dose in the level of liver and kidney histology and hematology and biochemical analysis. We concluded that these novel nano-synthesized complexes can used in therapeutics to avoid microbial resistance problems.

Novel cobalt(II) complex of a new 24-membered macrocyclic bis-Schiff base bearing 3-mercapto-1,2,4-triazole: Synthesis, characterization, thermal and biological investigations

The synthesis of a new 24-membered macrocyclic bis-Schiff base, L1, and its corresponding binuclear cobalt(II) complex, [Co2(L1)2(Cl)4], 1, is reported. Compound L1 and complex 1 have been characterized by elemental analysis, FT-IR, 1H NMR, and UV-VIS spectroscopy as well as mass spectrometry. Furthermore, the molecular structures of the synthesized compounds were determined using single crystal X-ray diffraction analysis. The crystal structure of the binuclear cobalt(II) complex, 1, revealed that each ligand acts as a bidentate chelating one and links the metal ions through endocyclic nitrogen atoms of its 1,2,4-triazole moieties. The determined molecular structure as well as the UV-Vis studies indicated a tetrahedral geometry for complex 1. Moreover, the thermal stability of complex 1 has been investigated via thermogravimetric analysis (TGA). The product of pyrolysis of complex 1 was characterized as highly pure nano-scaled Co3O4 (mean crystallite size: 57 nm) by using a series of techniques including powder X-ray diffraction (P-XRD) and energy-dispersive X-ray spectroscopy (EDX). The biological activities of L1 and complex 1, including antibacterial and antifungal activities were evaluated. The antibacterial activity was tested against Gram-negative (Escherichia coli, E. coli ATCC 29232) and Gram-positive (Staphylococcus aureus, S. aureus ATCC 25922) organisms. Also, the pathogenic fungi Candida albicans (C. albicans, ATCC 10231) and Saccharomyces cerevisiae (S. cerevisiae, BY 4741) were used for antifungal tests. The synthesized cobalt(II) complex displayed moderate to good antifungal activity.

Synthesis and Thermal Studies of Some Metal azo Complexes Derived from Hydroxy coumarin

In the current study, of two azo dyes made from coumarin and procaine (T1) and coumarin and Sulfa guanidine (T2)were synthesized. The dyes were characterized by IR, CHN, 1H-NMR, 13C-NMR and MS spectroscopic techniques. . To make azo metal(II) complexes, these novel legands were combined with acetate salts of copper(II) and nickel(II) in a 1:2 molar ratio.The metal to ligand ratio [M:L] in all complexes, according to analytical data, is (1:2).This ligand behaves as a bidentate chelating, according to spectral and analytical data.Thermo gravimetric (TGA) analysis was used to study the thermal behavior of these substances. These chemicals' thermal breakdown is a multi-stage process

Understanding the coordination behavior of antibiotics: Take tetracycline as an example

Gaining insight into the occurrence states of residual antibiotics is crucial to demystify their environmental behavior. However, the complexation of heteroatoms functioned on antibiotic molecules to metal ions in the water environment is not fully understood. This study reports that a fluorescence response was unexpectedly triggered by tetracycline (TC) and Al3+, serving as solid evidence to visualize the Al3+-TC coordination reaction. Differential electron absorption spectroscopy shows a quantifiable signal of the redshifted n–π* transition with a coordination reaction, which is also proportional to the fluorescence. The occurrence of Al3+-complexed TC also caused a split in retention time in liquid chromatogram. The TC ligands were re-released in the presence of stronger ligands competing for central Al3+. The complex ratio of Al3+-TC is confirmed to be 1:1 using Job’s plot with a stability constant of 1.01 × 106. Quantum chemical computations coupled with Gibbs free energy analysis simulated the formation of octahedral Al3+-TC configuration through a spontaneous bidentate chelation. This study helps convey a broad consensus and opens a new door in the mechanistic study of metal-involved antibiotic transformation process, leading to a better understanding that can ultimately be essential to reach the final goal of alleviating the antibiotic crisis.

The coordination chemistry and supramolecular interactions of 2-(2′-Pyridyl)imidazole ligand: a comprehensive review with theoretical insight

Abstract This review explores the role of 2-(2′-Pyridyl)imidazole (PyimH) as a coordinating ligand and also its role as a supramolecular agent through hydrogen bonding and π⋯π interaction. Two N coordination sites make 2-(2′-Pyridyl)imidazole an analogous ligand to 2,2′-bipyridine. The syn orientation of imidazole and pyridine sp 2 nitrogen makes it a bidentate chelating ligand. PyimH mainly produces discrete coordination complexes (0D), but in a few cases, 1D coordination polymers are observed due to bridging co-ligands like oxalate, dicyanamide, tricyanomethanide, croconate, thiocyanate, and iso-thiocyanate. These discrete coordination units and co-ligand bridged 1D coordination polymers are further augmented to higher dimensional supramolecular systems having linear, zig-zag, ladder-shaped, ribbon-like, and helical geometry. These supramolecular structures are stabilized by intermolecular hydrogen bonding interaction (N–H⋯N, N–H⋯O, O–H⋯N, O–H⋯O, and C–H⋯O) and π⋯π interaction capability of PyimH ligand. PyimH generally acts as an excellent chelating ligand for a range of metal ions and is also a capable supramolecular glueing agent due to hydrogen bonding and π-stacking ability.

Rapid ultrasound-assisted synthesis, characterization, DFT, molecular docking, and anticancer activity of palladium and zinc complexes with 2,6-dimethoxybenzoic acid: A comprehensive study

In this work, we present a thorough investigation encompassing various aspects of zinc and palladium complexes synthesized with 2, 6-dimethoxybenzoic acid. The complexes were prepared through an ultrasonic reaction, offering a rapid, cost-effective, and environmentally friendly method. Characterization of the complexes, prepared in a 1:2 metal-to-ligand ratio, was carried out using elemental analysis, infrared spectra, proton nuclear magnetic resonance, molar conductivity, and melting point measurements. The results revealed that the ligand exhibited chelating bidentate behavior, forming coordination bonds through both oxygen atoms of the carbonyl group. The prepared complexes were evaluated for their anticancer activity against breast cancer and colon cancer cell lines. Remarkably, the complexes exhibited significantly higher cancer cell-killing potential compared to the commonly used drug 5-fluorouracil, with cell death rates reaching 99% for both complexes. To gain insights into the underlying mechanisms of this enhanced anticancer activity, molecular docking studies were conducted, revealing a binding energy of no more than -9.14 kcal/mol between the complexes and the amino acids of the cancer cells. Furthermore, theoretical studies employing Density Functional Theory (DFT) were performed to provide additional diagnostic insights. These studies encompassed molecular structural analysis, computational vibrational properties, natural bond orbital analysis (NBO) and FMOs, electronic properties (UV–Vis spectra), average local ionization energy (ALIE), electrostatic potential (ESP), electron localization function (ELF), and reduced density gradient (RDG/NCI) analyses. The comprehensive investigation presented in this study sheds light on the synthesis, characterization, theoretical analysis, and remarkable anticancer potential of zinc and palladium complexes with 2,6-dimethoxybenzoic acid.

Synthesis and Crystal Structures of Bis(diallydithiocarbamato)zinc(II) and Silver(I) Complexes: Precursors for Zinc Sulfide and Silver Sulfide Nanophotocatalysts.

We report the preparation and crystal structures of bis(diallydithiocarbamato)zinc(II) and silver(I) complexes. The compounds were used as single-source precursors to prepare zinc sulfide and silver sulfide nanophotocatalysts. The molecular structure of bis(diallydithiocarbamato)zinc(II) consists of a dimeric complex in which each zinc(II) ion asymmetrically coordinates with two diallydithiocarbamato anions in a bidentate chelating mode, and the centrosymmetrically related molecule is bridged through the S-atom that is chelated to the adjacent zinc(II) ion to form a distorted trigonal bipyramidal geometry around the zinc(II) ions. The molecular structure of bis(diallydithiocarbamato)silver(I) formed a cluster complex consisting of a trimetric Ag3S3 molecule in which the diallydithiocarbamato ligand is coordinated to all the Ag(I) ions. The complexes were thermolyzed in dodecylamine, hexadecylamine, and octadecylamine (ODA) to prepare zinc sulfide and silver sulfide nanoparticles. The powder X-ray diffraction patterns of the zinc sulfide nanoparticles correspond to the hexagonal wurtzite while silver sulfide is in the acanthite crystalline phase. The high-resolution transmission electron microscopy images show that quantum dot zinc sulfide nanoparticles are obtained with particle sizes ranging between 1.98 and 5.49 nm, whereas slightly bigger silver sulfide nanoparticles are obtained with particle sizes of 2.70-13.69 nm. The surface morphologies of the ZnS and AgS nanoparticles capped with the same capping agent are very similar. Optical studies revealed that the absorption band edges of the as-prepared zinc sulfide and silver sulfide nanoparticles were blue-shifted with respect to their bulk materials with some surface defects. The zinc sulfide and silver sulfide nanoparticles were used as nanophotocatalysts for the degradation of bromothymol blue (BTB) and bromophenol blue (BPB). ODA-capped zinc sulfide is the most efficient photocatalyst and degraded 87% of BTB and 91% of BPB.

Investigation of the Stability and Insulating Properties of Mineral Oil-Based Surface Modified Silicon Nanofluid

The requirement for high voltage is growing extensively, which has obligated to enhance the dielectric and thermal properties of the insulators. Nanofluids are a new insulating material class that exhibits exceptional thermal and electrical characteristics. The relative permittivity and conductivity of Si nanoparticles (nSi) of diameter 10-30 nm synthesized from the p-type wafer are ideal values for free charge trapping; hence the mixture of mineral oil and nSi has the potential to replace the standard insulating oil. During the pre-breakdown phenomena of the insulator, the nSi in the base fluid act as a charge trap, capable of capturing about 45 electrons with a significantly shorter relaxation time of 1.42 × 10-14 s relative to the streamer propagation time. Oleic acid, an oil-soluble dispersant, improved the dispersion and stability of the nanofluids. The FTIR analysis determined the type of interaction as chelating bidentate between the oleic acid and the nSi surface. The impulse breakdown voltage of the nanofluids revealed the effect of trapping the free charges generated by the molecular ionization on enhancing the impulse breakdown strength. The relative permittivity measurement of the nanofluid followed the Clausius-Mossotti polarization model of a mixed dielectric. Due to increased nanosized pores (with the number of nanoparticles), partial discharge inception voltage and the AC breakdown voltage were reduced with concentration.

Synthesis, structure, properties and theoretical studies of novel tetranuclear nickel(II) bis(salamo)-like complex

Novel tetranuclear Ni(II) complex [Ni4(L)(acac)4(EtOH)2]⋅4CH2Cl2 was synthesized by a rigid bis(salamo)-like ligand H4L and Ni(acac)2 in ethanol/dichloromethane mixed solvents, and characterized by different physicochemical methods. The X-ray diffraction result showed that all Ni(II) atoms are hexa-coordinated with slightly distorted octahedral geometries, and four Ni(II) atoms are correlated with each other through inversion. Acetylacetone anions acted as auxiliary ligands for bidentate chelation, and the monodentate ethanol molecules of solvent participated in the coordination. The properties of the ligand H4L and its Ni(II) complex were studied, including molecular electrostatic potential surface (MEPs), Hirshfeld surface and interaction region indicator (IRI) analysis. Through the above study, the reaction active sites were visualized, and the intermolecular interactions of the Ni(II) complex were clarified, which is consistent with the crystal structure of the Ni(II) complex. In addition, fluorescence spectra of the ligand H4L and its Ni(II) complex were investigated.

New Palladium(II) Complexes Containing Methyl Gallate and Octyl Gallate: Effect against Mycobacterium tuberculosis and Campylobacter jejuni.

This work describes the preparation, characterization and antimicrobial activity of four palladium(II) complexes, namely, [Pd(meg)(1,10-phen)] 1, [Pd(meg)(PPh3)2] 2, [Pd(og)(1,10-phen)] 3 and [Pd(og)(PPh3)2] 4, where meg = methyl gallate, og = octyl gallate, 1,10-phen = 1,10-phenanthroline and PPh3 = triphenylphosphine. As to the chemical structures, spectral and physicochemical studies of 1-4 indicated that methyl or octyl gallate coordinates a palladium(II) ion through two oxygen atoms upon deprotonation. A chelating bidentate phenanthroline or two triphenylphosphine molecules complete the coordination sphere of palladium(II) ion, depending on the complex. The metal complexes were tested against the Mycobacterium tuberculosis H37Rv strain and 2 exhibited high activity (MIC = 3.28 μg/mL). As to the tests with Campylobacter jejuni, complex 1 showed a significant effect in reducing bacterial population (greater than 7 log CFU) in planktonic forms, as well as in the biomass intensity (IBF: 0.87) when compared to peracetic acid (IBF: 1.11) at a concentration of 400 μg/mL. The effect provided by these complexes has specificity according to the target microorganism and represent a promising alternative for the control of microorganisms of public health importance.

Co(III) Intermediates in Cobalt-Catalyzed, Bidentate Chelation Assisted C(sp2)-H Functionalizations

The C-H bond activation and functionalization is a powerful tool that provides efficient access to various organic molecules. The cobalt-catalyzed oxidative C-H bond activation and functionalization has earned enormous interest over the past two decades. Since then, a wide diversity of synthetic protocols have been published for C-C, C-Het, and C-Hal bond formation reactions. To gain some insights into the reaction mechanism, the authors performed a series of experiments and collected evidence. Several groups have successfully isolated reactive Co(III) intermediates to elucidate the reaction mechanism. In this review, we will summarize information concerning the isolated and synthesized Co(III) intermediates in cobalt-catalyzed, bidentate chelation assisted C-H bond functionalization and their reactivity based on the current knowledge about the general reaction mechanism.

Two new zinc(ii) coordination complexes constructed by phenanthroline derivate: Synthesis and structure

Abstract Two new Zn(ii) coordination complexes [Zn(L)(dna)(H2O)] (1) and [Zn(L)(glu)]2·H2O (2) (L = 2-(4-fluorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline, H2dna = 3,5-dinitrosalicylic acid, H2glu = glutaric acid) have been hydrothermally synthesized and characterized by single crystal X-ray diffraction, elemental analysis, fluorescence spectrum, and infrared spectroscopy. For complex 1, the dna2− anion adopts μ 1 -η 1 :η 1 chelating bidentate mode to coordinate with one Zn(ii) atom and π–π stacking interactions are formed between the L ligands. For complex 2, glu2− anions connect Zn(ii) atoms to form a wavy two-dimensional layer, and the L ligands are attached on two sides of the two-dimensional layer.

Photophysical study on DNA & BSA binding and cytotoxic behaviour of piperidine-Pt(II) complexes: Their kinetics & mechanism and molecular docking

For the development of Pt(II) based anticancer drug candidates, carrier ligand 2-(Piperidine-1-yl)ethylamine (PIEAM) was used as a bidentate chelator to synthesize dichloro complex [Pt(PIEAM)Cl2] C-1 and its diaqua [Pt(PIEAM)(OH2)2](X)2 (C-2). The diaqua complex C-2 was further used to synthesize thiol substituted Pt(II)-sulfur complexes with l-cysteine (LC) and N-acetyl-l-cysteine (NAC). The Pt(II) complexes were characterized by multi spectroscopic methods and thermal analysis. The role of electronic and steric factors of carrier ligand PIEAM on substitution reactions of C-2 with LC and NAC was studied in aqueous medium at pH 4.0 under pseudo first-order kinetics and rate constant, equilibrium constant and thermodynamic parameters were calculated. The DNA binding activity and binding mode were confirmed by gel electrophoresis and viscosity measurement. The binding activity of Pt(II) complexes with DNA and BSA was explored by absorption and fluorometric titration methods. In vitro MTT assay of Pt(II) complexes were tested on different cancer cell lines like; MCF 7, A549, HCT 116 and also on normal human embryonic kidney cell HEK 293. The cell cycle arrest of MCF 7 cell growth and also the oxidative stress level (ROS) after treating with Pt(II) complexes were analysed. The structural optimization for molecular docking of Pt(II) complexes at B3LYP functional level were performed to correlate the experimental findings. The antineoplastic activity and drug likeness behaviour of Pt(II) complexes were further supported by PASS prediction and in silico ADME analysis.

Synthesis of Bivalent Ni(II), Cu(II) and Zn(II) Complexes of Azodicarbonamide in Mixture of Methanol and Aqueous Solvents: Spectral Characterizations and Anti-Microbial Studies

Three new transition-metal complexes were produced by refluxing azodicarbonamide (ADCA) with nickel(II), copper(II), and zinc(II) solutions in a mixture of 50% (v/v) methanol and water. The magnitude of chelation between metal ions and ligand molecules was assessed by FT-IR, UV, elemental analysis, TGA, conductivity, mass, and magnetic susceptibility measurements. FT-IR analysis suggested a bi-dentate chelation in all complexes, which takes place through the N-azo and O-carbonyl groups. Based on the measurement of magnetic moments and spectral analysis, a distorted octahedral geometry was proposed for Ni(II) and Cu(II) complexes, whereas zinc complex showed a hexa-coordinated geometry. The optical band gaps of the nickel(II), copper(II) and zinc(II) complexes were found to be 1.91, 2.50, and 1.96 eV, respectively, which means that they can be employed as semiconductors and that they are in the same range as highly effective photovoltaic materials. The Urbach energy parameters were also estimated from other optical parameters. The biological activity of azodicarbonamide and its synthesized complexes has been screened against the selected gram bacteria (+ve) and fungi.