ESR Spectral Data Research Articles

Synthesis, characterization, and biological evaluation of Ni, Co, and Cu Metal Complexes with Heterocyclic Compounds

Two new clinically active Schiff bases and their transition metal complexes were synthesized and studied by different spectroscopic and physicochemical methods like NMR, IR, UV-Visible, ESR, TGA, XRD, mass, elemental analysis, molar conductivity and magnetic character. Synthesized complexes and Schiff bases were assessed for invitro antituberculosis activity for Mycobacterium tuberculosis (ATCC–27294) and for antimicrobial activity against drug resistant ESBL (Extended Spectrum β-lactamase) and MBL (Metallo β-lactamase) producing microbial strains. The biological activity of Schiff base was found to improve in presence of transition metal ions. Among the studied metal complexes, copper complexes displayed superior biological activity against all of the microbial strains. Binary complexes of Cu(II), Ni(II), and Co (II) ions have been synthesized by reacting metal salts with a Schiff base, 2-((E)-(5-methylisoxazol-3-ylimino)methyl)-4-methoxyphenol (MIIMMP) in an alcoholic medium. All the metal complexes and schiff base have been characterized by using elemental analysis, IR, UV-VIS, 1H-NMR, 13C-NMR, Mass, ESR spectral data, magnetic moments, TG, and DTA studies. Based on the analytical, spectral data and molecular modeling studies, Ni (II) and Co (II) metal complexes have octahedral geometry, whereas Cu(II) complex has tetragonal geometry. The antimicrobial and cytotoxic activities of the Schiff base and its metal complexes were studied on bacteria, fungi, and human cervical carcinoma cells (HeLa).

Synthesis and Biological Studies of Schiff Base Metal(II) Complexes Derived from Isatin

Potentially bioactive Schiff base metal complex is a kind of attractive reagents due to specific activities of pharmacology and physiology. Medical inorganic chemistry has exploited metal ions' unique properties to design new drugs. In this study a novel Cu(II), Ni(II), Mn(II) and Co(II) Schiff base complexes have been from p - nitroaniline, isatin and 2, 2′ bipyridyl. The elemental analyses of the complexes are confined to the stoichiometry of the type L1L2M [M = Cu(II), Ni(II), Mn(II) and Co(II)], respectively, where L is Schiff base ligand in the ratio of 1:1:1. Structures have been proposed from elemental analyses, IR, UV, 1H NMR, ESR spectral data and magnetic studies. The measured low molar conductance values in DMF indicate that the complexes are nonelectrolytes. The IR data tells us the association of C=N nitrogen atom in co - ordination to the metal ion. The UV spectral studies and magnetic measurements suggested the octahedral geometry around metal ion under investigation. The EPR spectral data shows additional proof for the octahedral geometry. In addition, the antioxidative activity was also determined. The ligand's antioxidative activity and its complexes demonstrate that, compared to the ligand, the complexes exhibit higher scavenging activity. The antibacterial activity of these compounds was studied in vitro by the disc diffusion assay against two Gram-positive bacteria like Staphylococcus aureus, Bacillus subtilis and two Gram-negative bacteria like Escherichia coli and Klebsilla pneumonia. The complexes show significant growth inhibitory activity than ligands.

Spectral, structural and cytotoxicity studies on the newly synthesized n'1,n'3-diisonicotinoylmalonohydrazide and some of its bivalent metal complexes

The reaction of diethyl malonate with isonicotinic hydrazide resulted in the formation of a new ligand, N'1,N'3-diisonicotinoylmalonohydrazide (H4INM), which was characterized by elemental and spectral studies. The existence of the free ligand in keto form was shown by its spectral data. The ligand reacted with Cu(II), Co(II), Ni(II) and Zn(II) acetates to produce bimetallic complexes. The ligand chelated to the metal ion in binegative tetradentate fashion via malonyl carbonyl oxygen and N2H atoms except in Zn(II) complex, where it acted as neutral tetradentate through the isonicotinyl carbonyl oxygen and N1H atoms. The various spectral measurements revealed that all complexes had an octahedral geometry except the Cu(II) complex which has square planar structure supported by the ESR spectral data. Moreover, the DFT quantum chemical calculations were performed and the HOMO-LUMO energy gap of the ligand and complexes were comparable to the optical band gap (Eg) estimated using Tauc's equation. Furthermore, isolated compounds’ in vitro cytotoxic activity against Hela (Epithelioid Carcinoma) and WISH (Human amnion) cell lines of was investigated. According to the results, the ligand exhibits moderate and weak effect against the Hela and WISH cell lines, respectively. While, the metal complexes exhibited more potent effect against WISH than against Hela, with IC50 ranging from 23.65 ± 1.7 to 46.28 ± 3.4 and 56.36 ± 3.5 to 83.88 ± 4.7 µM, respectively.

SYNTHESIS, CHARACTERIZATION AND ANTIMICROBIAL ACTIVITY OF MIXED LIGAND COMPLEXES OF INNER TRANSITION METAL WITH L-ASCORBIC ACID, ITS DERIVATIVE AND ADENINE BASE

Complexes of La(III), Ce(III), Nd(III) and Gd(III) with mixed Ligand of 2-aminopurene and L-ascorbic acid derivative were prepared in aqueous ethanol. The two types of mixed ligand complexes [M(AA)(ADE)(H2O)2]+and [M(IPAA) (ADE)(H2O)2]+ have been synthesized. All complexes were characterized on the basis of elemental analysis, molar conductance, magnetic susceptibility measurements, IR, UV-VISSIBLE, NMR, ESR and Mass spectral studies. IR spectra of the complexes reveal that the complex formation occurred through both nitrogen and oxygen atoms. On the basis of electronic spectral data and magnetic susceptibility measurement octahedral geometry has been proposed for the complexes. The ESR spectral data of the M (III) complexes showed that the metal-ligand bonds have considerable covalent character. The electrochemical behaviour of mixed Ligand M(III) complexes was studied which showed that complexes of IPAA appear at more positive potential as compared to those for corresponding AA complexes. In addition, biological activity of the synthesised metal complexes against Salmonella typhi, Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae bacteria and Aspergillus niger, Aspergillus flavus, Fusarium oxisporium and Trichoderma viride fungi respectively were examined in-vitro. Some of the metal complex displayed pounced biological activity.

Spectroscopic studies, DFT calculations, thermal analysis, anti-cancer evaluation of new metal complexes of 2-hydroxy-N-(4-phenylthiazol-2-yl)benzamide

2-Hydroxy-N-(4-phenylthiazol-2-yl)benzamide was reacted with Cr(III), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Ag(I) metal ions to synthesize the corresponding coordination compounds. From the study, 2-hydroxy-N-(4-phenylthiazol-2-yl)benzamide was rearranged to 2-hydroxy-N-(4-phenyl-1,3-thiazole-2-yl)carboxymidic acid (HL) due to the keto-enol tautomeric forms, where the enol form is more dominant. The structures of the HL ligand and the newly synthesized coordination compounds have been characterized by elemental analysis, IR, UV-Visible, 1H NMR, ESR and mass spectral data, in addition to thermal gravimetric analysis (TGA) and magnetic and molar conductance measurements. The ligand behaves as a monobasic bidentate ON sites, where the bidentate binding of the ligand involving the phenolic oxygen and azomethine nitrogen. The binding modes of the coordination compounds were further confirmed using Gaussian 09 software. The complexes of Co(II), Cu(II), Zn(II), and Ag(I) were tested in vitro against human colon carcinoma cells (HCT-116). The IC50 values showed dramatic toxicity results for cobalt(II), copper(II) and zinc(II) complexes versus human colon carcinoma (HCT-116) cell line, compared to African green monkey kidney (VERO) normal cell line. According to the results of the IC50 values obtained for Co(II), Cu(II), Zn(II), and Ag(I) 1.5, 1.0, 1.8 and 7.3 μg/ml, respectively, compared to the reference drug (2.49 μg/ml), Co(II), Cu(II), Zn(II) compounds are considered strong antitumor agent while Ag(I) compound can be considered as a weak one. For both antifungal and antibacterial activities, HL and all its coordination compounds were evaluated. HL ligand has only high activity against B. subtilis and C. albicans while Co(II) and Zn(II) compounds have the highest activity against S. aureus, P. aeruginisa, B. subtilis and E. coli.

Effect of melting condition on optical, FTIR and E.S.R properties of irradiated fluorophosphate glasses containing vanadium ions

Glasses from the system Na2O–CaF2–P2O5 with varying doping V2O5 (0.5, 0.75, 1%) were prepared under ordinary and reducing conditions. Multiple Characterizations including optical, FTIR and ESR spectral data were obtained for the prepared glasses before and after gamma irradiation (with a dose of 6 Mrad).Optical absorption spectrum of the undoped sample reveals strong and broad UV absorption with two peaks which are related to unavoidable traces of iron (Fe3+) ions contaminated within the chemicals used for the preparation of the glasses. The V2O5 doped glasses show two additional pronounced broad visible and near-IR bands which varied in intensity and position of their peaks with the V2O5 content and condition of melting. These distinct visible and near IR bands are assumed to be indicator for the presence for low valence trivalent and tetravalent vanadium ions with variable percents, in accordance with the included host fluoro-phosphate glass and different melting conditions. Gamma irradiation causes noticeable effect on the optical spectrum of the undoped glass but the spectra of V2O5-doped samples reveal pronounced shielding behavior. FTIR spectra of the prepared glasses show distinct vibrational bands due to asymmetric and symmetric vibrations of the phosphate groups of main (PO4) groups and together with the presence of some (PO3F) groups. The detailed FTIR spectra show minor variations with the V2O5 content or condition of melting. E.S.R results show distinct signals due to the presence of both trivalent and tetravalent vanadium ions which possess unpaired electrons in their outer electronic configurations. E.S.R data reveal limited variations in the intensity of the signals with varying V2O5 content or condition of melting and even upon gamma irradiation points out to the stability of V3+ and V4+ ions in the studied host fluorophosphate glass.

Polymer complexes. LVI. Supramolecular Architectures Consolidated byHydrogen Bonding and t-r Interaction (Dept.P)

In this study, amidation of aliphatic amine with acryloyl chloride in the dry benzene as solvent has been prepared. Moreover, the polymer complexes have been prepared. All compounds have been characterized by the analytical, spectroscopic ( IR, UV, NMR, ESR) and thermal methods. Addition, the magnetic susceptibility and molar conductance measurements have been made. Acryloylhydrazin (AH) has been shown to behave as a bidentate logand via its nitrogen (of the NH; of hydrazine group) and C-O/ C=0 (of the acryloyl group) in polymer complexes, all of which exhibit supramolecular architectures assembled through weak interaction including hydrogen bonding and 1- 1 stacking The magnetic and spectral data indicate a square planar geometry for Cu2+ complex and an octahedral geometry for Co(II) and UO2 (II). The ESR spectral data of the Cu(II) complexes showed that the metal-ligand bonds have considerable covalent character. The thermal stability was investigated using thermogravimetric analysis. The results showed that the polymer comp lexes are more stable than the homopolymer.

Synthesis, structural elucidation, pharmacological and molecular docking studies of terpolymer transition metal complexes

A novel monomer (terpolymer) was prepared by mixing of 2-amino-6-nitro-benzimidazole, 2,5-diaminophenol and formaldehyde. Based on the impressive material utilities and therapeutic potential, Cu2+, Ni2+, Co2+ and Zn2+ metal ions were mixed with terpolymer to form different metal chelates. UVVis., IR, 1H NMR, ESR spectral data analysis showed that the prepared metal chelates were of square planar geometry. The molecular mass of polymer was determined using gel permeation chromatography technique. Thermo gravimetric technique was utilized to measure the thermal withstanding ability of terpolymer chelates. The electron transfer mechanism of the metal complexes was investigated by the aid of cyclic voltammetry. The prepared compounds were also screened for antimicrobial efficiency against bacterial strains (B. subtilis, E. coli and S. aureus) and fungal strains (C. albicans, A. niger and A. flavus). The observed results indicated that the chelates showed greater antimicrobial efficiencies than terpolymer ligand. Furthermore, the SOD biomimetic activity of prepared metal chelates was accessed and copper complex was found to possess high antioxidant potential with IC50 value of 0.94 µM. Antituberculosis capacities of terpolymer and its metal chelates was assessed against M. tuberculosis H37Rv strain using MABA assay protocol. Copper complex was found to possess good antitubercular activity with MIC value of 6.20 mg/mL. Molecular docking study was conducted to assess the target for antitubercular activity. It was found that copper complex could be a potent inhibitor of pantothenate synthetase enzyme (a potential target for development of antitubercular drug) of M.tuberculosis with binding energy of -9.8 kcal/mol. Overall copper complex showed good antimicrobial, antioxidant and antitubercular activity when compared to other metal complexes and terpolymer ligand.

Synthesis, characterization, antitumor activity, molecular modeling and docking of new ligand, (2,5-pyrrole)-bis(5,6-diphenyl-[1,2,4]-triazin-3-yl)hydrazone and its complexes

Reactions of (2,5-pyrrole)-bis(5,6-diphenyl-[1,2,4]-triazin-3-ylhydrazone) ligand, (H2L; H2BisT) with VO(II), Co(II), Ni(II) and several copper(II) salts, including NO3−, AcO−, Cl− and SO42−, in presence of LiOH (in molar ratio 1:2:2, ligand:LiOH:metal) afforded mono- and bi-nuclear metal complexes. Characterization of H2BisT and its metal complexes was achieved by elemental analyses, conductance, magnetic moments, TG measurements, electronic, infrared and ESR spectral data. H2BisT acts as a neutral or dibasic tetradentate ligand, coordinating via two N-azomethine and two N-triazine atoms for all metal complexes. The morphological structure of H2BisT is determined using SEM, which changed by complexation to agglomerated spherical and sheet like shapes. The metal complexes have square pyramidal, square planar in addition to octahedral geometry. The theoretical parameters of H2BisT and its metal complexes have been calculated by Hyperchem program, PM3 method. Also, the best relations found from experimental (IR & UV–Vis spectra) and theoretical data. H2BisT and some complexes showed antitumor activity toward Hepatocellular carcinoma cells (Hep G-2). The molecular docking studies for H2BisT, chloro and acetato Cu(II) complexes were performed using MOE 2014.0901 software (PDB. I.D.3ce3). The docking data agreed with the antitumor activity results, where acetato Cu(II) complex had higher activity due to forming 5 H-bonds, while chloro Cu(II) complex had moderated activity as it could form only two hydrogen bonds. On the other hand, H2BisT had low activity with only Pi-cation bond formation.

Synthesis, characterization, DFT, In-vitro anti-microbial, cytotoxicity evaluation, and DNA binding interactions of transition metal complexes of quinoxaline Schiff base ligand

A series of Cr(III), Mn(II), Fe(III), Co(II), Cu(II) and Ni(II) transition metal complexes of the quinoxaline based Schiff base ligand were synthesized and characterized on the basis of analytical, conductance, magnetic moment, FT-IR, NMR, ESR, EDAX and electronic spectral data. The ligand behaves as bidentate OO donors through phenolic oxygen and carbonyl oxygen in the quinoxaline ring. The molecular structure of the quinoxaline Schiff base ligand and Cu(II) complex was investigated theoretically. The optimized molecular structure was obtained from Gaussian 09 program. The antimicrobial activity of the ligand and the complexes were screened for various bacterial and fungal strains and found to be good for Co(II) and Mn(II) complexes and moderate for the other synthesized complexes. The minimum inhibitory concentration of the Co(II) and Mn(II)complexes against S. aureus, S. paratyphi and A. niger were found to be 250 μg/ml, 125 μg/ml, 500 μg/ml and 250 μg/ml, 250 μg/ml , 500 μg/ml respectively. The anti-cancer activity of the ligand and the complexes were studied against the human breast cancer cell lines MCF-7 and found to be good for Cu(II), Co(II) and Mn(II) complexes. The in-vitro anti-oxidant activities of the complexes and found to be moderate for all complexes. The DNA binding ability of the complexes were checked and their binding constants were reported using absorption and emission spectral studies.

Binuclear metal complexes of a symmetric polydentate donor hydrazone: synthesis, spectral characterization, DNP DFT computational and biological studies

Co(II), Ni(II)and Cu(II) complexes of a new chelate namely 2,2'-((9S,10S,11R,12R)-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarbonyl)bis(N-phenylhydrazine-1-carboxamide) (H6EPH) were synthesized and were characterized by using analytical and spectral techniques suggesting tetrahedral geometry for Ni(II) and Cu(II) complexes and an octahedral for Co(II) complex. The ESR spectral data showed one broad band with g|| > 2.0036 indicating the axial symmetry with the unpaired electron residing in the dx2-y2 orbital with appreciable covalent character of the metal-ligand bond. The molecular modeling a using DFT method was drawn and the bond lengths, bond angles, chemical reactivity and energy components (kcal/mol) for all the title compounds were evaluated. Also, all compounds were examined for DNA cleavage ability and antioxidant using superoxide dismutase like- activity.

Cu(II), Co(II), Ni(II), Mn(II) and Zn(II) Schiff base complexes of 3-hydroxy-4-[N-(2-hydroxynaphthylidene)-amino]-naphthalene-1-sulfonic acid: Synthesis, Spectroscopic, thermal, and antimicrobial studies

Abstract Five divalent transition metals Cu(II), Co(II), Ni(II), Mn(II) and Zn(II) complexes have been synthesized using 3-hydroxy-4-[N-(2-hydroxynaphthylidene)-amino]-naphthalene-1-sulfonic acid (H3L) Schiff base as a ligand derived from the condensation reaction between 4-amino-3-hydroxynaphthalene-1-sulfonic acid and 2-hydroxy-1-naphthalde-hyde. The synthesized complexes were characterized using microanalytical, conductivity, FTIR, electronic, magnetic, ESR, thermal, and SEM studies. The microanalytical values revealed that the metal-to-ligand stoichiometry is 1:1 with molecular formula [M2+(NaL)(H2O)x].nH2O (where x = 3 for all metal ions except of Zn(II) equal x = 1; n = 4, 10, 7, 4, and 6 for Cu(II), Co(II), Ni(II), Mn(II) and Zn(II), respectively). The molar conductivity result indicates that all these complexes are neutral in nature with non-electrolytic behavior. Dependently on the magnetic, electronic, and ESR spectral data, octahedral geometry is proposed for all the complexes except to zinc(II) complex is tetrahedral. Thermal assignments of the synthesized complexes indicates the coordinated and lattice water molecules are present in the complexes. SEM micrographs of the synthesized complexes have a different surface morphologies. The antimicrobial activity data show that metal complexes are more potent than the parent ligand.

Synthesis, Spectral Characterization and Antibacterial Activity of Copper(II) Complexes of Functionalized Hydrazones

Copper(II) complexes having the formula CuL2 {where, L = 2-acetylthiophene acetoylhydrazone (ATAH), 2-acetylthiophene benzoylhydrazone (ATBH)} have been investigated on the basis of elemental analysis, molar conductivity measurements, magnetic susceptibility, UV-visible, IR and ESR spectral data. Non-electrolytic nature of the complexes are revealed by molar conductance data. IR spectral data suggested that hydrazones act as tridentate ligands. The spin Hamiltonian, orbital reduction and bonding parameters of complexes are calculated using ESR spectra of complexes. The compounds are screened for their antibacterial activities against Pseudomonas aureoginos and Bacillus cereus. Acetoylhydrazones show more antibacterial activity than the corresponding benzoyl hydrazones. Some of the Cu(II) complexes show more activity than hydrazone ligands.

Synthesis for novel VO(II)- triazole complexes; spectral, analytical characterization and catalytic usage for biodiesel synthesis from waste oil

Novel mono-nuclear VO(II)-traizoles complexes have been synthesized and fully characterized by all possible tools(analytical, spectral and conformational). The neutral tri-dentate mode, was the suggested bonding feature based on comparative IR spectra. The octahedral geometry, was suggested for all complexes except for [VO(CATP)(H2O)] (SO4)(H2O)2 complex. ESR spectral data clarify, the ionic feature of in plane σ-bonding as well as in plane π - bonding. XRD patterns display the amorphous feature, as the main characteristic for most tested compounds. Two crystalline complexes, showed crystallite-sizes located excellently in nanometer range. SEM images displayed rocky-shape surfaces for all tested compounds, except for the two crystallite complexes. TGA curves displayed discriminated thermal stability, among investigated complexes, which most of them appeared with high thermal stability. Conformational indexes calculated predict the superiority features of [VOSO4(CATB)]H2O complex. This study was strengthen by docking process, which orients to the negligible inhibition role of most VO(II)-complexes against DNA (2hio). Another application pathway was interested to synthesize biodiesel from waste oils. A chosen complex (VO(II)-CATB) was utilized in heterogeneous-catalytic process. Moreover, its V2O5 oxide has been prepared from deliberate calcinations process. The complex and its oxide have been used separately to prepare economic compound (biodiesel) from waste oil. The two catalysts succeeded in isolating biodiesel, in particular the complex which produced a perfect product in record time. Some physical characteristics were estimated for synthesized biodiesel, which highly compatible with that reported in literature for other undesirable biodiesel-synthesis processes.

Structural studies and biological evaluation of Co (II), Ni (II) and Cu (II) complexes of carbohydrazone derived from ethyl acetoacetate in addition to crystallographic description of La (III) or Sm (III) catalytic activity abnormal product

New carbohydrazone ligand derived from the condensation of carbohydrazide and ethyl acetoacetate, diethyl 3,3′‐(carbonylbis (hydrazin‐2‐yl‐1‐ylidene))(3E,3′E)‐dibutyrate (H4EBC), and its divalent Co, Ni and Cu chelates have been isolated and characterized utilizing convenient methods. 1H‐NMR spectrum of H4EBC revealed the abundance of the enol isomer in solution, which was the opposite to what was shown by the solid IR. This was supported by comparing the theoretical IR of both keto and enol forms. In [Ni(H4EBC)Cl2(H2O)]·2H2O, H4EBC acts as a neutral NON tridentate ligand via the (C=O)carbonyl oxygen atom besides the two (C=N)azomethine nitrogen atoms, while in [Co(H4EBC)Cl2(2H2O)]·2H2O, H4EBC behaves as a neutral NN bidentate ligand through the two azomethine groups. Magnetic measurements inherent to their electronic spectra show that both Ni (II) and Co (II) chelates have octahedron coordination frameworks. On the other hand, the ligand behaves as a binegative tetradentate in [Cu2(H4EBC)Cl2]·H2O via the deprotonated (C=O)carbonyl groups of the ethyl acetoacetate framework and the two (C=N)azomethine groups. In the latter complex, the carbonyl group of the carbohydrazide moiety is converted to hydroxyl group. Cu (II) complex has a tetrahedral geometry according to ESR and electronic spectral data. The reaction of H4EBC with SmCl3·6H2O or LnCl3·7H2O gave single crystals of abnormal product (C16H16N4O4). The packing diagram of this crystal has a chain structure. The photoluminescence spectra of [Cu2(H4EBC)Cl2]·H2O, [Co(H4EBC)Cl2(H2O)2]·2H2O and [Ni(H4EBC)Cl2(H2O)]·2H2O display emission broad‐bands at 342, 321 and 337 nm, respectively. The microbial behavior of the synthesized moieties was investigated against various bacterial and fungal strains. [Cu2(H4EBC)Cl2]·H2O complex shows the same activity as ampicillin towards Escherichia coli and Staphylococcus aureus with inhibition zones of 26 and 22 mm, respectively. Antioxidant activity is determined using bleomycin‐dependent DNA damage assay besides erythrocyte hemolysis. Finally, in vitro cytotoxic activities against two different cell lines have been examined.

Synthesis and Biological Evaluation of some 3d Metal Complexes with a Novel Heterocyclic Schiff Base

A heterocyclic Schiff base was prepared by condensing 3‐acetylcoumarin with 2‐amino‐3‐carboxyethyl‐4,5,6,7‐tetrahydrobenzo[b]thiophene. Such Schiff bases derived from two different heterocyclic moieties are rare and expected to have properties surpassing those of either of the parent compounds in effectiveness of complex formation and biological activities. This ligand formed a series of complexes with manganese(II), cobalt(II), nickel(II), copper(II), and zinc(II) ions. The ligand and the metal complexes were characterized by various physicochemical and spectral studies. These included elemental analysis, molar conductance, magnetic susceptibility, as well as UV–vis, IR, 1H NMR, 13C NMR, and ESR spectral studies. The ESR spectral data adequately supported the covalent nature of the metal–ligand bonds. The ligand possessed a hexagonal crystal structure, but on complexation the crystallinity was lost. The fluorescence spectra of the ligand and its metal complexes in DMSO were also recorded. The ligand and the metal complexes were screened for their antimicrobial activities, and it was observed that the metal complexes are more active than the ligand. The α‐amylase inhibitory activity and the DNA cleavage activity of the ligand and the metal complexes were also examined. in vitro antitumor activity of the copper(II) complex was assayed against human cervical carcinoma cells (HeLa cell line), showing that the complex exhibited promising antitumor activity on the HeLa cell line.

Investigation of Antimicrobial, Antioxidant, and DNA Binding Studies of Bioactive Cu(II), Zn(II), Co(II), and Ni(II) Complexes of Pyrimidine Derivative Schiff Base Ligand

A new pyrimidine based Schiff base ligand (HL) and its four complexes of type [MLOAc]·nH2O (Cu(II), 1; Zn(II), 2; Co(II), 3; and Ni(II), 4) have been synthesized and characterized by elemental analysis, MS, 1H-NMR, FT-IR, UV-visible, and ESR techniques. The electronic and ESR spectral data suggested that complexes 1–4 possess square planar geometry. Antimicrobial activities of HL and complexes 1–4 were tested against four bacteria (Staphylococcus aureus, Staphylococcus pneumonia, Salmonella enterica typhi, and Haemophilus influenzae) and two fungal strains (Aspergillus flavus and Aspergillus niger). These results show that complexes 1–4 have good antimicrobial activity compared to HL. The DNA cleavage activity of HL and complexes 1–4 was monitored by the agarose gel electrophoresis method. The antioxidant property of the prepared compounds was assessed by using 2,2′-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging method. DNA binding properties of HL and complexes 1–4 have been investigated by electronic absorption technique and viscometric measurements.

Antimicrobial, antioxidant and SOD activities of copper(II) complexes derived from 2-aminobenzothiazole derivatives

A series of Cu(II) complexes have been synthesized from bidentate Schiff base ligands (by condensation of Knoevenagel condensate of acetoacetanilide (obtained from substituted benzaldehydes and acetoacetanilide) and 2-aminobenzothiazole). They were characterized by elemental analysis, IR, 1H NMR, 13C NMR, UV–vis., molar conductance, magnetic moment, ESR spectra and electrochemical studies. Based on the magnetic moment, ESR, and electronic spectral data, a distorted square planar geometry has been suggested for the complexes. Antibacterial and antifungal screening of the ligands and their complexes reveal that all the complexes show higher activities than the ligands. The antioxidant activities of the ligands and complexes were determined by superoxide and hydroxyl radical scavenging methods in vitro, indicating that the complexes exhibit more effective antioxidant activity than the ligands alone. The results show that the Cu(II) complexes also have similar superoxide dismutase activity to that of native Cu, Zn-SOD. All complexes exhibit suitable Cu(II)/Cu(I) redox potential (E1/2) to act as synthetic antioxidant enzyme mimics.

ChemInform Abstract: Polymeric Complexes ‐ LXII. Coordination Chemistry of Supramolecular Schiff Base Polymer Complexes ‐ A Review

AbstractReview: 30 refs.

Influence of Bi3+ ions on low temperature D.C. conductivity of Na2SiCuO4 glasses

Sodium silicate glasses doped with CuO and mixed with different contents of Bi2O3 (ranging from 4 to 16 mol%) were prepared. D.C. conductivity studies over a range of temperature from 225 to 325 K have been carried out. The conductivity is observed to decrease linearly with increase of Bi2O3 concentration. The results are analyzed using optical absorption, ESR, and IR spectral data. The spectroscopic studies have indicated that there is a gradual reduction divalent copper ions to monovalent ions with increase of Bi2O3 concentration. These studies have also indicated that such Cu+ ions participate in the glasses network forming and increase the polymerization of the glass network. The analysis of the results of D.C. conductivity indicated that in temperature region T > θ D/2, the small polaron hoping model is valid, and the conduction is predicted to be adiabatic type. The analysis of the results has further revealed that there is a gradual change over of conduction mechanism from ionic to electronic with increase of Bi2O3 concentration. The low temperature part of D.C. conductivity is explained using variable range hopping (VRH) model.