EPR Spectral Studies Research Articles

Theoretical, DNA/BSA Binding, Molecular Docking and In Vitro Cytotoxicity Studies of Homoleptic Metal(II) Complexes Derived from 2‐Formylpyridine‐Based Ligands

AbstractA new class of homoleptic metal(II) complexes of general formula [M(L1–4)2]2Cl in which L1=1‐([1,1′‐biphenyl]‐4‐yl)‐N‐(2‐((‐pyridin‐2‐ylmethylene)amino)ethyl)methanimine, L2=1‐([1,1′‐biphenyl]‐4‐yl)‐N‐(2‐((‐pyridin‐2‐ylmethylene)amino)phenyl)methanimine, L3=1‐([1,1′‐biphenyl]‐4‐yl)‐N‐(2‐((‐pyridin‐2‐ylmethylene)amino)‐4‐nitrophenyl)methanimine and L4=4‐(([1,1′‐biphenyl]‐4‐ylmethylene)amino)‐3‐((−pyridin‐2‐ylmethylene)amino)benzophenone, and M=Ni(II) (1–4), Cu(II) (5–8) and Zn(II) (9–12) have been synthesized and characterized. The IR spectra reveal the involvement of azomethine and 2‐formylpyridine ring nitrogen atoms in chelation. The UV‐Vis and EPR spectral studies envisage distorted octahedral geometry around metal(II) ion. All the complexes were stable for 72 h in biologically relevant solutions, and copper(II) complexes were reduced to Cu+ center in the presence of ascorbic acid solution. The binding studies of complexes with calf thymus DNA (CT‐DNA) indicate groove mode of binding, and the complexes 3, 7 and 11 containing the 4‐nitrophenyl substituent exhibit the highest binding affinity than the other complexes. Furthermore, the spectral studies also revealed the interaction of complexes with BSA through static mechanism. In vitro cytotoxicity activity of the complexes was screened against human lung adenocarcinoma (A549) and breast adenocarcinoma (MCF‐7) cancerous, and normal murine fibrosarcoma (L929) cell lines. The molecular docking studies of the homoleptic metal(II) complexes show hydrophobic, π–π, σ–π and hydrogen bonding interactions with EGFR/VEGFR2 kinase receptors.

Synthesis, Spectral Characterization, Antibacterial and Anticancer Evaluation of Novel Isoniazid based Schiff Base Ligand derived Transition Metal Complexes

A novel isoniazid based Schiff base ligand was synthesized by the condensation of 5-acetyl-N-(adamantan-2-yl)thiophene-2-carboxamide (1 mmol) and isoniazid (1 mmol). Metal complexes were prepared by reacting the Schiff base with metal(II) chloride (M = Ni2+, Cu2+ and Co2+), formed the novel metal coordination compound. The synthesized ligand and metal complexes were characterized by 1H NMR, mass spectral, UV-visible, IR & EPR spectral studies, themogravimetric analysis, cyclic voltametry and were screened with both Gram-positive and Gram-negative bacterias to evaluate the antibacterial activity by disc diffusion method. The zone of inhibition of the antibacterial assay demonstrated that all the three metal(II) complexes are active against the four bacterias, showed increased activity with increase in concentration and is more active against S. aureas at all concentrations. The systhesized complexes were also evaluated for its anticancer activities, only Ni(II) and Co(II) complexes showed the moderate levels of cytotoxicity activity.

In vitro cytotoxicity and antimicrobial evaluation of novel 24–28 membered Schiff base octaazamacrocyclic complexes of manganese(II): Synthesis, characterization, DFT and molecular docking studies

The development of novel metal-based molecular antibiotics is an effective strategy to combat the rising threat of cancer and microbial diseases. In this view, novel Schiff base octaazamacrocyclic complexes of Mn(II) were synthesized using 2:2 molar ratio of macrocyclic ligands derived from Schiff base ligand [L] and dicarboxylic acids. The synthesized compounds were characterized by infra-red, 1H NMR, 13C NMR, ESI-mass, UV–visible, EPR, and powder X-ray diffraction spectral studies, together with elemental (CHN) analysis, molar conductance, and magnetic susceptibility measurements. Calculations based on density functional theory (DFT) help in determining the stability of synthesized macrocylic ligands. Electronic spectra led to the assignment of an octahedral geometry to the synthesized macrocyclic complexes. In vitro cytotoxicity of macrocyclic ligands and their Mn(II) complexes was examined against three distinct cancerous cell lines, including HeLa, A549, and MCF7 cells. The observed IC50 values for the tested compounds against cancerous cell lines demonstrate a relatively good level of cytotoxicity. Molecular docking of Schiff base macrocyclic ligands supported their cytotoxic potential against the tested cell lines. Moreover, the antimicrobial activity of the synthesized compounds was also evaluated against bacterial (E. coli, B. subtilis) and fungal strains (C. albicans, F. oxysporum). The results indicate that the macrocyclic Mn(II) complexes have more antimicrobial potential than macrocyclic ligands against tested pathogens.

Synthesis, spectral, biological, and computational studies of template engineered macrocyclic metal complexes

A series of macrocyclic Cu2+, Ni2+, and Co2+ complexes was synthesized using a template reaction between triethylenetetramine and dibenzoylmethane. These complexes may be represented by the general formula [M(C21H26N4)X2], where M = Cu2+, Ni2+, and Co2+ and X = NO3ˉ, Clˉ, and CH3COOˉ. Various techniques, including elemental analysis, molar conductance, magnetic moment, PXRD, thermal investigations, EPR, IR, UV-visible, and mass spectral studies, were used to characterize the synthesized complexes. Their results suggested the distorted octahedral geometry for copper complexes and octahedral geometry for nickel and cobalt complexes. All complexes showed molar conductance in the range of 8–20 ohm−1 cm2 mol−1 that indicated the non-electrolytic nature. The DFT studies of all complexes were also performed to analyze the stability of complexes. Antibacterial activities of all complexes were also examined, and it was observed that complexes [Ni(C21H26N4)(Cl)2] and [Co(C21H26N4)(Cl)2] exhibited remarkable antibacterial activity. Moreover, complex [Co(C21H26N4)(NO3)2] showed miraculous antioxidant activity, even better than that of ascorbic acid and other complexes. The docking studies of [Ni(C21H26N4)(Cl)2] and [Co(C21H26N4)(Cl)2] were also performed to enforce the results obtained from the antibacterial study of these complexes. Furthermore, the drug-likeness property of all complexes was also evaluated with the help of ADMET studies.

Syntheses, spectral, thermal and pH-metric studies on bivalent metal ion complexes of N,N’-bis(3-carboxy-1-oxo-z-prop-2-elenyl)ethylenediamine

A novel carboxyamide ligand has been synthesized using maleic anhydride and ethylenediamine. Co(II), Ni(II), Cu(II) and Pd(II) complexes of the ligand, i.e., N,N’-bis(3-carboxy-1-oxo-z-prop-2-elenyl)ethylenediamine [H2L] have been prepared and characterized by elemental analyses, IR, electronic, 1H NMR, EPR spectral and thermal studies. It is revealed by IR and 1H NMR spectral studies that the ligand coordinated to the metal ions through deprotonated carboxylate oxygen and non-deprotonated amide nitrogen in all the complexes. It is suggested by electronic spectral and magnetic moment studies that N2O2 coordination is around each metal center with a strong field square planar chromophore. All the complexes have been studied by TGA and DTA studies done simultaneously. The complex formation between ligand and metal ions [Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)] has also been studied pH metrically in 75% aqueous DMF solution at 298 K in 0.1 M NaClO4. The probable structures of the complexes have also been proposed.

IN VITRO ANTICANCER, ANTIOXIDANT AND MOLECULAR DOCKING STUDIES OF 4-AMINOBENZAMIDE METAL COMPLEXES

Objective: Mixed ligand complexes of Cu(II) and Cd(II) with 4-aminobenzamide(4-ABZ) have been synthesized under microwave irradiation and they were characterized by elemental analysis, estimation of metal ion, molar conductivity, magnetic study, FT-IR, Far-IR, electronic spectra, NMR (1H and 13C) and EPR spectral studies. Methods: The data of microanalysis and metal estimation showed that the complexes have the composition of [M(L1)2(L2)2] for Cu(II) and [M(L1)(L2)2] for Cd(II) complex respectively. The conductivity data confirmed the neutral nature of the complexes. The tetrahedral geometry of the Cd(II) complex was confirmed using UV-Visible spectra. The tetragonally distorted octahedral stereochemistry of Cu(II) complex was further confirmed by UV and EPR spectral studies. The diamagnetic nature and probable geometry of Cd(II) complex were also confirmed using NMR spectral studies, which are also compared with free 4-aminobenzamide. The in vitro bio-potential activities of 4-ABA and Cd(II) complex were screened for E. coli and C. Albicans microorganisms by Agar disc diffusion methods. Results: The cancer study of Cu(II) complex and antioxidant activity of DPPH free radical scavenging method of Cd(II) complex were measured and compared with 4-aminobenzamide and standard drugs. The breast cancer studies were also identified using the targeted proteins viz., BRCA1, PR and EGFR by molecular docking study. Conclusion: In the present study, we synthesized new metal complexes of Cu(II) and Cd(II) with 4-ABA and nitrite ion by microwave irradiation method. The analytical data show that the metal-ligand stoichiometry they are non-electrolytes in acetonitrile solution. The spectral data show that the synthesized ligand binds with metal ions through the nitrogen atom of the 4-ABA and oxygen atoms of the nitrite ion.

Controlled C–H bond activation leads to orthometalation and ring-hydroxylation in Ni(II) and Pd(II) complexes of a common tridentate azophenyl-salicylaldimine ligand

Using a common tridentate azophenyl-appended salicylaldimine ligand in its deprotonated form (L4)–, two classical coordination complexes [Ni(L4)2] (1) (NiIIO2N2N'2 coordination) and [Pd(L4)Cl]•CH2Cl2 (2) (PdIIONN'Cl coordination), two cyclometalated complexes [M(L4*)] (M = Ni 3 and Pd 4; MIIONN'C coordination), and two azophenyl ring-hydroxylated complexes [M(L4–O)] (M = Ni 5 and Pd 6; MIIONN'O' coordination), obtained due to selective oxidation of MII–C bond, have been synthesized. Complex 1 is paramagnetic (S = 1) but all other complexes are uniformly diamagnetic (S = 0). For 1–6, absorption spectral and redox properties have been investigated, along with single-crystal structural analysis. The regiospecific aryl ring-hydroxylation of M−C bonds in 3 and 4 are achieved due to H2O2 and m-CPBA oxidation, respectively, affording 5 and 6. Coulometically-generated one-electron oxidation and one-electron reduction have been done on 1–6, and the nature of the resulting species has been probed by EPR and absorption spectral studies. While oxidation of 1 and 3 generate Ni(III) species, it is a resonance hybrid between Ni(III) ⇔ Ni(II)-O(phenoxyl radical) species for 5. On the other hand, 2, 4, and 6 generate ligand radical species. Reduction of 1–6 generates ligand radical species uniformly. Density functional theory (DFT) calculations at the B3LYP level of theory have been done to extract information about the electronic structure of the complexes. Time-dependent (TD)-DFT calculations have been done to shed light on the origin of observed absorption spectra. Plausible mechanisms have been proposed for the observed orthometalation and ring-hydroxylation reactions.

Spectroscopic and antimicrobial studies of Cr(III), Mn(II) and Co(II) complexes with a tetradentate macrocyclic ligand

Complexes of Cr(III), Mn(II) and Co(II) with a tetradentate macrocyclic ligand i.e. 2,6,12,16,21,22-hexaaza;3,5,13,15-tetraphenyltricyclo[15,3,1,17–11]docosa;1(21),2,5, 7,9,11(22),12,15,17,19-decaene (L). These complexes were characterized by elemental analysis, molar conductance measurements, magnetic susceptibitity measurements, mass, 1H NMR, IR, electronic and EPR spectral studies. These spectral studies suggest an octahedral geometry for Cr(III), Mn(II) and Co(II) complexes. The ligand and its complexes have been screened in vitro against some species of bacteria and plant pathogenic fungi.

Microwave-Assisted Synthesis, Spectral and Biopotential Characterization of Cr(III), Cu(II) and Zn(II) Complexes with 4-Aminothiophenol and Benzoate Ion

Bioactive metal complexes of Cr(III), Cu(II), and Zn(II) were synthesized with 4-aminothiophenol and benzoate ion under microwave irradiation. The synthesized metal chelates were characterized by physical, spectral, biological studies. The geometry and magnetism of all the complexes were monitored by electronic spectra and magnetic studies. The metal complexes possess the metal-ligand ratios is in the order of 1:3:3 metal:ligand1:ligand2 for Cr(III), 1:2:2 metal: ligand1:ligand2 for Cu(II) and Zn(II) complexes were predicted based on the elemental analysis and metal estimation. The synthesized metal chelates are monomeric and neutral in nature and they show well redox properties based on the results of conductivity and electrochemical studies. Octahedral geometry of Cr(III), tetragonal geometry of Cu(II) and square planar geometry of Zn(II) complexes confirmed by IR, far-IR, NMR and EPR spectral studies. The crystalline nature and lattice parameters of Zn(II) complex were predicted by using the X-ray diffraction powder method. Biopotential activities of 4-aminothiophenol compared with metal chelates and standard drug namely chloramphenicol for bacterial and fluconazole for fungal strain by Agar disc diffusion method using Streptococci, Shigella and C. albicans. The results of DNA cleavage of pBR322 DNA and binding nature of ct-DNA to Cr(III) complex possess the binding and cleavage nature of them by predicting the binding constant of the metal complex.

Reversible photochromism and photoresponsive luminescence in naphthalene diimide-based framework with Lindqvist-type polyoxometalate template

Metal-organic frameworks that contain photoactive organic ligands or photoactive inorganic components are an emerging class of multifunctional hybrid materials that in recent years has gradually become an ideal platform for building photochromic complexes. In this paper, a metal-organic framework based on naphthalene diimide (NDI) ligand with Lindqvist-type W6O192– polyanions, [Ce2(BINDI) (DMF)8]·[W6O19] (1), (H4BINDI = N, N'-bis(5-isophthalic acid)-1,4,5,8-naphthalene diimide) was synthesized and systematically characterized. It displays a cationic two-dimensional grid coordination network, featuring anion–π interactions between W6O192– and expanded π–electron deficient naphthalene diimide (NDI) moieties. Moreover, because of the presence of electron-deficient NDI moieties and photoactive W6O192–, this complex exhibits fast responsive reversible photochromism and photoresponsive tunable luminescence. UV–Vis, IR, PXRD, EPR, and XPS spectral studies indicate that the obviously photochromic phenomenon of complex 1 is derived from photoinduced electron-transfer form NDI radicals and W5+ species.

Mass, FTIR, EPR and XRD Spectral Studies of the Complex of CuSO4 with Trithio Thiazyl Trichloride

Mass, FTIR, EPR and XRD Spectral Studies of the Complex of CuSO4 with Trithio Thiazyl Trichloride

Synthesis and Spectral Characterization of Mn(II) and Co(II) Complexes with Tetradentate Macrocyclic Ligand

Manganese(II) and cobalt(II) complexes were synthesized with [N4] tetradentate macrocyclic ligand using different metal salts i.e. MnCl2, Mn(NO3)2, CoCl2 and Co(NCS)2. The ligand was prepared by condensation of glyoxal and carbahydrazide. All these were characterized by elemental analysis, molar conductance measurements, magnetic moment, IR, mass, electronic and EPR spectral studies. Elemental analysis indicates that the complexes have composition MLX2 where (X = Cl–, NO3 –,NCS–). All the complexes were found to be non-electrolytic in nature so can be formulated as [MLX2]. Infrared spectra of metal complexes suggest that the ligand behaves as tetradentate. On the basis of magnetic moment, electronic and EPR spectral data, all the metal complexes were found to be high spin with octahedral geometry.

Synthesis, Characterization, Antimicrobial and Anticancer Activity of New Bidentate Schiff Base Ligand and their Transition Metal(II) Complexes

The metal(II) complexes were synthesized by addition of corresponding MCl2 (M = Mn2+, Ni2+, Cu2+ and Zn2+) with 1,2-bis(1H-pyrrol-2-ylmethylene)diazane in methanol. The ligand acts as a bidentate as confirmed from the mass, IR, UV, NMR and EPR spectral studies. The Schiff base ligand forms hexa-coordinated complexes having octahedral geometry for Mn(II), Ni(II), Zn(II) and Cu(II) complexes. The metal complexes showed an excellent antimicrobial activity spectrum in vitro against both Gram-negative (Klebsiella pneumoniae and Acinetobacter baumannii), Gram-positive (Staphylococcus aureus and Enterococcus faecalis) and human pathogenic bacteria isolates. To find the binding affinity with protein BSA kinase, for that molecular docking studies were also carried for all the four synthesized metal(II) complexes. The anticancer activity of the synthesized metal(II) complexes was also screened against the three human tumor cell lines MCF7 human breast adenocarcinoma cell line, CaSki human caucasian cervical epidermoid carcinoma and HCT116 human colon cancer cell lines. The present study showed that Zn(II) complex showed potent inhibition by the ratio of 80% as compared to the inhibition in the normal cells (L-6).

Synthesis, characterization, ADMET, in vitro and in vivo studies of mixed ligand metal complexes from a curcumin Schiff base and lawsone

Complexes are currently synthesized from plant origin because of their therapeutic effect against certain diseases with toxicity. Hence, in this work, four new transition metal(II) mixed ligand complexes have been synthesized using a curcumin Schiff base (primary ligand) and lawsone (as co-ligand). The geometry of these complexes was explored by elemental analyses, molar conductance, thermal analysis, magnetic moment values, IR, NMR, Mass, electronic and EPR spectral studies. Electronic absorption titrations, viscosity measurements and molecular docking studies reveal that all the metal complexes interact with the CT DNA by groove binding. Among all the complexes, the copper(II) complex (complex 1) exhibits a higher Kb value (3.5 × 10−4 M) which reveals that it has a strong binding efficiency toward the CT DNA. The complexes also possess strong DNA cleavage efficiency. Cytotoxicity investigations on Artemia salina show that all the complexes possess higher cytotoxic effect than the ligand. Moreover, all the metal complexes have better antimicrobial efficacy than the ligand. Swiss ADME, PASS and pkCSM online softwares are helpful to predict the pharmacokinetic and biological actions of the curcumin Schiff base. Theoretical results obtained from the in silico study are experimentally corroborated by in vivo anti-inflammatory screening study. All the above studies demonstrate that the copper complex possesses biological activity similar to that of the drug like molecules. Research Highlights Synthesis and characterization of four novel transition mixed ligand complexes using plant moieties Promising in vivo anti-inflammatory agents and in vitro DNA metallonucleases Cytotoxicity investigation on Artemia salina Higher cytotoxic effect for the complexes than the ligand Identification of copper(II) complex as lead like molecule among all

Structural and spectral characterization of Cu(II) complexes of N(4)-substituted thiosemicarbazones derived from 2-hydroxyacetophenone: Crystal structure of a dinuclear Cu(II) complex

Copper(II) complexes of 2-hydroxyacetophenone-N(4)-cyclohexylthiosemicarbazone (H2L1) and 2-hydroxyacetophenone-N(4)-phenylthiosemicarbazone (H2L2) have been synthesized and characterized by different physicochemical techniques like magnetic studies and electronic, infrared and EPR spectral studies. [(CuL1)2] (1) is a dinuclear complex having four coordination around copper(II) with distorted square planar geometry. The two individual dinuclear complexes are interconnected through two bifurcated classical hydrogen bond interactions producing a sheet-like structure along b axis. [(CuL2)2]·1/2H2O (2) also has a dimeric structure. The thiosemicarbazones bind to the metal as dianionic ONS donor ligand in all the complexes, except in the complexes [Cu(HL1)Cl]·2H2O (3), [Cu(HL1)Br]·4H2O (4) and [Cu(HL1)NO3]·C2H5OH(H2O) (5), where the ligand moieties are coordinated as monoanionic (HL¯) ones. Complexes [CuL1dmbipy] (6), [CuL2dmbipy]·3H2O (7), [CuL2bipy]·H2O (8) and [CuL2phen]·2C2H5OH (9) are heterocyclic base adducts. The synthesis and characterization of monomeric and dimeric Cu(II) complexes with 2-hydroxyacetophenone-N(4)-cyclohexyl/phenyl substituted ONS donor ligands is described. It also reports the crystal structure of a novel binuclear Cu(II) complex with oxygen bridging and its interesting coordination. This compound [CuL1]2 is a rare example of copper(II)-thiosemicarbazone complex with oxygen bridging structure.

Tetra-(benzo-24-crown-8)-phthalocyanines as a platform for supramolecular ensembles: Synthesis and interaction with viologen

The synthesis of a series of novel tetra-(benzo-24-crown-8)-phthalocyanines (Mg(II), Ni(II) and Co(II)) as well as a modified procedure for the free-base ligand and its Zn(II) and Cu(II) complexes are reported. The tendency of these phthalocyanines to undergo supramolecular cofacial dimerization induced by interaction with a viologen ([Formula: see text]-di(but-3-ynyl)-4,4[Formula: see text]-bipyridinium) was investigated by UV-vis absorption and EPR spectral studies in solution. The nature of the metal cation in phthalocyanine, the concentration, as well as the solvent all influenced the assembly processes.

Spectroscopic, SOD, anticancer, antimicrobial, molecular docking and DNA binding properties of bioactive VO(IV), Cu(II), Zn(II), Co(II), Mn(II) and Ni(II) complexes obtained from 3-(2-hydroxy-3-methoxybenzylidene)pentane-2,4-dione

Novel macrocyclic Schiff base complexes [[ML]X; where M = Cu(II), Co(II), Ni(II), Zn(II), Mn(II) and VO(IV); L = macrocyclic ligand; X = Cl2 and SO4 2−] have been synthesized and characterized by microanalytical, 1H, 13C NMR, IR, Mass, UV–Vis, EPR spectral studies, as well as conductivity data. All the complexes exhibit square-planar geometry except vanadium complex. Magnetic susceptibility measurements and high conductance data reveal the monomeric and electrolytic nature of the complexes. Electronic absorption, cyclic voltammetry, viscosity measurements have been carried out on the interaction of the complexes with DNA. The results suggest that the complexes bind to DNA by intercalation via the aromatic ring of the macrocycle into the base pairs of DNA. Using gel electrophoresis experiment in the presence and absence of oxidant (H2O2) the nuclease cleavage activity of the complexes has been performed on plasmid DNA. The results demonstrate that most of the complexes have promising superoxide dismutase (SOD)-mimetic activity. The in vitro cytotoxicity of ligand and its complexes has also been evaluated against human breast and colon carcinoma cells. Binding interactions and energies of ligand and its metal complexes [ML]2+ (M = VO(IV), Mn(II), Co(II), Ni(II), Cu(II), Zn(II)) against the receptors EGFR and HER2 are performed using the Auto dock module. Consequently, it is found that the ligand is strong inhibitor for EGFR and HER2 while [VOL]SO4 is good inhibitor for EGFR and [ZnL]Cl2 is moderate inhibitor for HER2. The antimicrobial activity of the ligand and its complexes against bacteria Salmonella typhi, Staphylococcus aureus, Escherichia coli and Bacillus subtilis and fungi Aspergillus niger, Aspergillus flavus, Candida Albicans and Rhizoctonia bataicola. The complexes have higher activities than the macrocyclic free Schiff base. Communicated by Ramaswamy H. Sarma

A combined experimental and theoretical study to explore the catecholase-like activity of a hepta coordinated dinuclear Zn(II) complex

A heptadentate N4O3 coordinating dinuclear zinc complex was synthesized and characterized by 1H NMR spectroscopy, IR spectroscopy and ESI MS spectroscopy studies. X-ray single crystal structure of the dinuclear complex revealed that both zinc atoms have pentacoordinated environment realized by the N2O2 donor set of ligand and one water molecule. The theoretical optimized structure of the dinuclear complex in solution phase was indicated a larger elongation take place in the bond distance between zinc and oxygen atom of coordinated water molecule which leads to come closer of two zinc atoms in solution phase in comparison of crystalline structure. This proximity of two zinc atoms fulfilled my aim for investigating the catalytic catecholase activity. The catecholase activity of the complex has been investigated under completely aerobic conditions in MeOH water medium at pH 8.0 against the model substrate 3,5-di-tert-butylcatechol (3,5-DTBC). Saturation kinetic studies have shown the order of conversion of substrate to product quinone. The mechanistic path of the oxidation process has been confirmed by UV–vis, CV and EPR spectral studies are made-up to be responsible for the oxidation of 3,5-DTBC. EPR experiment suggested generation of radical in the presence of 3,5-DTBC and that finding has been strengthened by cyclic voltammetric study. Thus, it proposed that the radical pathway is responsible for conversion of 3,5-DTBC to 3,5-DTBQ promoted by complex of redox-innocent ZnII ion. The ligand-centered radical generation has been further verified by density functional theory calculation.

Molecular docking, photocatalytic activity and biomedical investigations of some metal complexes

Metal(II)–(furfural-L-his) complexes with a potentially bidentate furfural-L-his have been synthesized. Furfural-L-his and its Co/Ni/Cu/Zn(II)–(furfural-L-his) complexes have been optimized by DFT. The structural features were determined from their elemental analyses, molar conductance, magnetic, UV–Vis, IR, mass, 1H NMR and EPR spectral studies. On the basis of electronic spectral data and magnetic measurements, suitable geometry has been proposed for each complex. The redox behaviour of Cu(II)–(furfural-L-his) complex has been studied by cyclic voltammetry. Thermal decomposition profiles are consistent with the proposed formulation of Co/Ni/Cu/Zn(II)–(furfural-L-his) complexes. PXRD studies reveal that furfural-L-his and Zn(II)–(furfural-L-his) complex are of nanomeric structure. SEM images of furfural-L-his exhibit flake-like morphology. Photodegradation of methylene blue dye indicates that they are photocatalyticaly efficient. NBO and NPA shown considerable reduction in the formal charge on metal ions. Docking analysis with EGFR and cyclooxygenase-2 receptor has been performed to find the best binding energy. Antimicrobial, antioxidant and anti-inflammatory activity against standard at variable concentrations revealed that the Co/Ni/Cu/Zn(II)–(furfural-L-his) complexes show enhanced antimicrobial, free radical scavenging and anti-inflammatory activities as compared to furfural-L-his. Furfural-L-his and Cu(II)–(furfural-L-his) complex have been tested against human ovarian cancer cells, which showed that Cu(II)–(furfural-L-his) complex exhibited promising anticancer activity. Communicated by Ramaswamy H. Sarma

Ru(III)-pseudohalide complexes with alkynyl functionalized salicylaldimine ligand and heterocyclic coligand: Synthesis, characterization, electrochemical and luminescence properties

A new series of hexa-coordinated Ru(III) complexes of the type [Ru(L)(phen)X2] (1a-3a) and [Ru(L)(bipy)X2](1b-3b) [where, X = NCS, N3, CN] have been prepared by the reaction of RuCl3·H2O with 2-((E)-(4-(2-(4-methoxyphenyl)ethynyl)phenylimino)methyl)-4-(2-(4-methoxy phenyl)ethynyl)phenol (L) in presence of 1,10-phenanthroline (phen) or 2,2′-bipyridine (bipy) as a ligand. The molecular structure of ligand L was confirmed by single crystal X-ray diffraction. All complexes were characterized on the basis of elemental analysis, magnetic moment, TGA, IR, UV–Vis, EPR and mass spectral studies. The EPR spectral data and magnetic susceptibility measurement showed octahedral geometry around Ru(III). The electrochemical properties of all complexes indicate quasireversible redox behaviour corresponding to Ru(III)/Ru(IV) and Ru(III)/Ru(II) couple and are variable to π-acidic character of phen and bipy. All complexes exhibit strong emissions from lowest energy ILCT state with some LMCT character in DMF (10-4 M) at room temperature indicating that alkynyl functionality on salicylaldimine ligand enhances the emission property of the complexes and varies considerably with quenching ability of pseudohalides.