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A new diperoxovanadium compound, [NH4][VO(O2)2(pm-im)]⋅3H2O (1) (pm-im = 2-(1H-imidazol-2-yl)pyrimidine), has been prepared from aqueous solution and its crystal structure has been determined by single-crystal X-ray diffraction. It belongs to the monoclinic P21/n space group with a = 6.798(4) Å, b = 11.468(6) Å, c = 18.073(9) Å, β = 96.020(6)°, V = 1401.3(13) Å3, and Z = 4. The asymmetric unit of 1 consists of a diperoxovanadium [VO(O2)2(pm-im)]− anion, one free NH4+ counterion, and three lattice water molecules, which are further stacked to form a three-dimensional (3D) supramolecular structure through intra- and intermolecular hydrogen bond interactions. The solution stability of the ion ([VO(O2)2(pm-im)]−) was explored using a combination of multinuclear (1H, 13C, and 51V) magnetic resonance and variable temperature NMR in a 0.15 mol L−1 NaCl/D2O solution that mimics physiological conditions. Additionally, the compound exhibits significant DNA cleavage ability under light, and the electrophoretic result shows that the super helix DNA seems to be directly cleaved into single stranded DNA. [ABSTRACT FROM AUTHOR]

A complex containing two discrete molecules, [Cu2(bpy)2(4-Ab)2(NO3)(H2O)] and [Cu2(bpy)2(4-Ab)2(H2O)2] and the lattice including three NO3 anions, one 4-Ab, and three H2O molecules (bpy = 2,2′-bipyridine, 4-Ab = 4-aminobenzoate), was prepared and structurally determined using elemental analyses, IR, EPR, UV-visible, and single-crystal X-ray crystallography. X-ray single-crystal structural studies indicated that the [Cu2(bpy)2(4-Ab)2] unit was present in both the crystallographic units. The complex crystallized in an orthorhombic crystal system with space group Pna21, a = 35.004(3) Å, b = 18.4134(16) Å and c = 12.8659(12) Å. In both crystallographic units, the geometry of the Cu(II) ions is distorted square-pyramidal, where both nitrogen atoms from one bpy and two oxygen atoms from two different p-aminobenzoate ions constitute the square plane and the apical positions are occupied by solvent or nitrate oxygen atoms. The geometry optimization of both units of the binuclear complex was carried out by taking the coordinates of the respective X-ray structures using DFT. The binding studies of the copper(II) complex with calf thymus DNA (CT-DNA) were explored by UV-Vis absorption, fluorescence spectroscopic, and cyclic voltammetric techniques. Also, the cleavage of pBR322 DNA with the binuclear copper(II) complex was studied using the gel electrophoresis method. [ABSTRACT FROM AUTHOR]

Copper(II) complexes of sulfonamides have found importance in biological and pharmaceutical systems. This study focuses on copper(II) complexes that were synthesized by precipitation method. The spectroscopic characterization was done by different techniques like FT-IR, UV–Vis, and ESI-MS. Compound 6 [Cu(L2)]2·2DMSO [HL = 4-((naphthalene-1-sulfonamido)methyl)cyclohexanecarboxylic acid] was recrystallized from DMSO, and its structure was determined by single-crystal X-ray diffraction to confirm the results of the synthesis of series of compounds. The geometry around each Cu(II) is tetrahedral bipyramidal with monodentate DMSO at the apical and bidentate carboxylates in the equatorial positions and a Cu–Cu bond. The synthetic compounds were screened for their biological applications involving antibacterial (Escherichia coli [E.C], Staphylococcus aureus [S.A], Sheigella sonnei [S.S], Bacillus subtilis [B.S], Nesseria gonorrhoeae [N.G], and Chromohalobacter israelensis [C.I]), antifungal (Aspergillus niger [A.N] and Neurospora crassa [N.C]), enzyme inhibition (acetylcholinesterase [AChE] and butyrylcholinesterase [BChE]), and antioxidant study. Furthermore, molecular docking study of all compounds was performed against enzymes and DNA using AutoDock Tools version 1.5.6. After confirmation of DNA-interaction through docking studies, nuclease activity was performed using agarose gel electrophoresis method and all compounds have been found to cleave DNA. These results concluded that copper complexes of sulfonamide may be good induction in the future for medical purposes. [ABSTRACT FROM AUTHOR]

New mononuclear Cu(II), Co(II) and Ni(II) complexes of novel azo-dye ligand 4-[(4-hydroxy-7-methyl-1,3-benzothiazol-2-yl)diazenyl]-5-methyl-2-phenyl-2,4-dihydro-3-pyrazol-3-one (L) with O,N-donor site were synthesized and are characterized by various spectroscopic techniques. The quantum chemical parameters were evaluated for all the compounds by ZINDO/1 semi-empirical method and are compared with the experimental data. Spectral investigations suggested the octahedral geometry for Co(II) and Ni(II) complexes and distorted tetrahedral geometry for Cu(II) complex. The antibacterial activity of the compounds was screened against different microbial strains and the results indicated that all the metal complexes exhibited higher activity than the free ligand. The interaction of pUC18 DNA with the synthesized compounds was explored by gel electrophoresis technique. All metal complexes exhibited significant cleavage activity against supercoiled pUC18 DNA. The anticancer activity of the compounds was studied against K562, A549, and MDA-MB-231 by MTT assay and all the metal chelates exhibited good anticancer properties. [ABSTRACT FROM AUTHOR]

A series of novel binuclear Mn complexes, [Mn2(L1)2]·2DMF (1), [Mn2O(L2)2](ClO4)2·CH3OH (2), and [Mn2(L3)2Cl2]·2DMF (3), were synthesized and structurally characterized by single-crystal X-ray diffraction. Moreover, their DNA-binding and cleavage properties were investigated. Characterization of the complexes by electron absorption and fluorescence spectroscopy confirmed the binding to calf-thymus DNA (CT-DNA). The apparent binding constants (Kapp) for 1, 2, and 3 were determined as 7.06 × 105, 1.10 × 105, and 3.77 × 105 M−1, respectively, indicating intermediate-strength binding between the complexes and CT-DNA. Moreover, 2 exhibited static fluorescence quenching, while 1 and 3 displayed dynamic fluorescence quenching. Agarose gel electrophoresis studies of the complexes revealed that only 2 exhibits chemical nuclease activity in the absence of a redox agent. When H2O2 was added as the redox agent, 3 was still unable to cleave DNA; however, 1 showed chemical nuclease activity and the activity of 2 was enhanced. The cleavage mechanism exerted by the complexes on plasmid DNA is likely to involve oxidative cleavage processes with hydroxyl radicals (·OH) and singlet oxygen (1O2) as the active species. [ABSTRACT FROM AUTHOR]

The dinuclear copper(II) complex, [Cu2(phen)2(4-aminobenzoate)2(H2O)2](NO3)2·2(4-aminobenzoic acid)·3H2O (phen = 1,10-phenanthroline), has been synthesized and structurally characterized by elemental analyses, IR, EPR, UV-visible and single-crystal X-ray crystallography. The complex crystallized in a monoclinic system with space group C2/c, a = 26.0022(10) Å, b = 10.2524(4) Å, c = 20.9983(7) Å, α = 90°, β = 106.9550(10)° and γ = 90°. The Cu(II) ion adopts a distorted square-pyramidal geometry formed by two N atoms from the phen ligand and two O atoms of the two 4-aminobenzoic acid ligands and one water O atom. The Cu...Cu separation is 3.0570(5) Å. A twofold axis passes through the midpoint of the Cu-Cu vector. The complex has intraligand (π–π*) fluorescence properties. The binding of this dinuclear copper(II) complex with calf thymus DNA (CT-DNA) was investigated by UV-vis absorption, fluorescence spectroscopic, cyclic voltammetric and viscosity techniques. Also, the cleavage of pBR322 DNA with dinuclear copper(II) complex was studied using gel electrophoresis method. The exhibited potent cytotoxic effects against human cell line (HepG2) and it was found to have good antimicrobial activities. The primary coordination sphere of dinuclear copper(II) complex is optimized, structural parameters are calculated and energy gaps of frontier orbital (HOMO-LUMO) have been calculated with B3LYP/6-31G/LANL2DZ level of theory in the gaseous phase. The calculated geometric and spectral results reproduced the experimental data with well agreement. Theoretical calculated molecular orbitals (HOMO-LUMO) and their energies have been calculated that suggest charge transfer occurs within the complex. [ABSTRACT FROM AUTHOR]

We have developed complexes [Ni2(L)2(H2O)4]n (1), [Co2(L)2(H2O)4]n (2), [Cd2(L)2(H2O)2Cl2]n (3) and [Cd2(L)2(H2O)2]n (4), where HL = 5-(pyrazol-1-yl) nicotinic acid. All complexes were characterized by elemental analysis, IR spectroscopy and single crystal X-ray diffraction, showing monoclinic crystal lattice with space group P21/c (1), P21/c (2), P21/c (3), and triclinic crystal lattice with space group P-1 (4), separately. In vitro antitumor screening (MTT method) revealed that 3 exhibited better inhibitory activities than the commercial anticancer drug cisplatin against HeLa tumor cell lines, with IC50 values 9 ± 2. The bindings of these complexes with Fish Sperm DNA were measured by electronic absorption spectra and fluorescence spectroscopy, showing Ksq 0.1867 (1), 0.1589 (2), 0.2332 (3), and 0.1411 (4), with the binding affinities ranked 3 > 1 > 2 > 4. The experimental result showed that these complexes could bind DNA via intercalation. The ability of 1–4 to cleave the pBR322 plasmid DNA was demonstrated by gel electrophoresis assay. The experiment verified that these complexes could induce DNA damage. In addition, flow cytometric analysis showed that 1–4 induced apoptosis of HeLa tumor cell lines; as time increases, the apoptotic impact becomes increasingly significant. The potential of 1–4 as anticancer agents were examined using molecular docking of the complexes with DNA. [ABSTRACT FROM AUTHOR]

A new Schiff base ligand, H2L, and its Zn(II) complex were prepared and characterized by different analytical and spectroscopic techniques. The elemental analysis results suggest the stoichiometry of the complex to be 1:1. The molar conductance study shows the non-electrolytic nature of the complex. Infrared spectra reveal that the metal ion is coordinated in tetradentate fashion which was further confirmed by NMR study. The synthesized complex was found to interact with CT-DNA quite efficiently. The DNA binding study of the complex was explored by UV-vis and viscosity measurement. Fluorescence titration studies and the experimental results suggest that the complex might bind to DNA via an intercalative mode. The in silico target prediction and molecular docking experiments confirm that, apart from high interaction potentiality with nucleotides, the complex has possible implications in carcinogenesis, too. [ABSTRACT FROM AUTHOR]

In search of effective bioactive compounds, we have synthesized the new Co(II), Ni(II), and Cu(II) complexes of the Schiff base derived from 8-formyl-7-hydroxy-4-methylcoumarin and 2-hydrazino benzothiazole and characterized by analytical, spectroscopic (IR, NMR, UV-vis, Mass), magnetic, powder X-ray diffraction data (PXRD) and TGA studies. Elemental analysis suggests the stoichiometry of the synthesized complexes and the solution electronic spectral study revealed the octahedral geometry of the compounds. Thermal analysis shows the presence of water molecule outside the coordination sphere and powder-XRD patterns have been studied to test the degree of crystallinity of the complexes and unit cell calculations were made. All the synthesized compounds were tested against human ovarian cancer cell line (PA-1). The synthesized metal complexes exhibited enhanced activity against the tested bacterial (Staphylococcus aureus and Escherichia Coli) and fungal strains (Candida albicans and Aspergillus fumigatus) as compared to free ligand (LH). The results of the DNA-cleavage activity suggest that the ligand and its metal complexes can cleave CT-DNA at different degrees. Further, anti-tuberculosis activity was done using microplate almar blue assay. Among all these synthesized compounds, the Cu(II) complex exhibits good cleaving ability compared to other newly synthesized metal complexes. [ABSTRACT FROM AUTHOR]

New homoleptic zinc(II) complexes, [Zn(L)2], where L = methyl-3-hydroxy-(3-pyridyl)-2-propenedithioate L1 1, and methyl-3-hydroxy-(4-pyridyl)-2-propenedithioate L2 2, have been synthesized and characterized by elemental (C, H, and N) analysis, ESI-MS, and (IR, UV–vis, NMR) spectroscopy; the structure of 1 has been deduced by X-ray crystallography. The DNA binding and cleavage activity of the complexes have been studied. The cleavage potential of pBR322 DNA by 1 and 2 has been checked. Complex 1, which contains nitrogen of the pyridine group in the 3-position enhances DNA cleavage potential in the presence of ascorbic acid; however, the complex is protective against DNA cleavage in the presence of DMSO or H2O2. Also, 1 causes cytotoxicity against the MCF-7 breast cancer cell line. The efficient cytotoxic activity and DNA cleavage ability of 1 in the presence of ascorbic acid shows its potential anticancer properties and the need for further investigations of its potential as an anticancer drug. [ABSTRACT FROM AUTHOR]

Four Ru(II) complexes with tridentate ligandsviz. (4-hydroxy-N′-(pyridin-2-yl-ethylene) benzohydrazide [Ru(L1)(PPh3)2(Cl)] (1), N′-(pyridin-2-yl-methylene) nicotinohydrazide [Ru(L2)(PPh3)2(Cl)] (2), N′-(1H-imidazol-2-yl-methylene)-4-hydroxybenzohydrazide [Ru(L3)(PPh3)2(Cl)] (3), and N′-(1H-imidazol-2-yl-methylene) nicotinohydrazide [Ru(L4)(PPh3)2(Cl)] (4) have been synthesized and characterized. The methoxy-derivative of L3H (abbreviated asL3H*) exists inEconfiguration with torsional angle of 179.4° around C7-N8-N9-C10linkage. Single crystal structures of acetonitrile coordinated ruthenium complexes of1and3having compositins as [Ru(L1)(PPh3)2(CH3CN)]Cl (1a) and [Ru(L3)(PPh3)2(CH3CN)]Cl (3a) revealed coordination of tridentate ligands with significantly distorted octahedral geometry constructed by imine nitrogen, heterocyclic nitrogen, and enolate amide oxygen, forming acis-planar ring withtrans-placement of two PPh3groups and a coordinated acetonitrile. Ligands (L1H-L4H) and their ruthenium complexes (1–4) are characterized by1H,13C,31P NMR, and IR spectral analysis. Ru(II) complexes have reversible to quasi-reversible redox behavior having Ru(II)/Ru(III) oxidation potentials in the range of 0.40–0.71 V. The DNA binding constants determined by absorption spectral titrations with Herring Sperm DNA (HS-DNA) reveal thatL4Hand1interact more strongly than other ligands and Ru(II) complexes. Complexes1–3exhibit DNA cleaving activity possibly due to strong electrostatic interactions while4displays intercalation. [ABSTRACT FROM PUBLISHER]

Graphene quantum dots (GQDs), inheriting the superb property of graphene oxide, possess smaller lateral size and high biocompatibility, thus having potential in biomedical applications. We previously discovered that GQDs, combining with Cu2+ions, could cleave DNA primarily through an oxidative pathway; yet, oxidative DNA cleavage is not practically preferred in biology. In this work, we explore the DNA cleavage ability of GQDs with Zn2+and Ni2+. Zn2+and Ni2+alone are incapable of cleaving supercoiled DNA, but when combining with the GQDs, Zn2+and Ni2+exhibit DNA cleavage activity. However, the activity of these two systems is much lower than that of GQDs/Cu2+, and GQDs/Ni2+is less active than GQDs/Zn2+. The functional mechanism of GQDs/Ni2+and GQDs/Zn2+is different from that of GQDs/Cu2+. The GQDs play a key role in the two systems; the redox inactive Zn2+and Ni2+ions assist to generate the oxidative species that eventually lead to the DNA cleavage. The current results together with our previous result indicate that GQDs together with metal ions can cleave supercoiled DNA, and their cleavage activities depend on the properties of metal ions: for redox active metal ions, metal ions play key roles, for redox inactive metal ions, GQDs are dominant. [ABSTRACT FROM PUBLISHER]

A series of albendazole-based copper(II) complexes with different counter anions, [Cu(Albz)(H2O)2](ClO4)2(1), [Cu(Albz)2(Cl)]Cl·2H2O (2), [Cu(Albz)2(NO3)](NO3) (3), and [Cu2(Albz)2(μ-SO4)2(H2O)2] (4) (Albz = albendazole), have been synthesized and characterized. Their structures and properties were characterized by elemental analysis, thermal analysis (TGA, DTG and DTA), IR, UV–vis and ESR spectroscopies, cyclic voltammetry, electrical molar conductivity, and magnetic moment measurements. A square-planar geometry is proposed for1, whereas the five-coordinate copper(II) complexes2,3, and4have a square pyramidal geometry. Theoretical calculations (DFT) using B3LYP/6–311 + G(d,p) level of theory corroborated the experimental results to investigate both the drug Albz and its copper(II) complex,1. The hepatoprotective and antioxidative efficacy of Albz and1–4were evaluated against carbon tetrachloride-induced acute hepatotoxicity in rats. Hepatotoxicity in experimental rats was evidenced by significant decrease in the antioxidant enzyme activities (SOD, GSH-S-transfers, and GSH-Rd levels). The results have strong impact for designing anticancer drugs, combined with their potential cytotoxic and antioxidant activities, which can be targeted selectively against cancer cells and increase their therapeutic index and advantages over other anticancer drugs. The DNA cleavage studies of Albz and its copper(II) complexes using genomic DNA indicated that Albz has no role in cleavage of DNA, and only1played a marked role in the DNA cleavage without any external additives. [ABSTRACT FROM AUTHOR]

A new copper(II) complex, [Cu(epoxy)(phen)(NO3)](NO3)·H2O (epoxy = 5,6-dihydro-5,6-epoxy-1,10-phenanthroline, phen = 1,10-phenanthroline), has been synthesized and characterized by elemental analysis, IR and UV–vis spectroscopy, and single crystal X-ray diffraction. The complex crystallized in a monoclinic system with space groupP21/n,a = 13.3199(8) Å,b = 11.2917(7) Å,c = 16.0832(9) Å,α = 90°,β = 107.827(4)°, andγ = 90°. The complex cation possesses a distorted octahedral geometry, with Jahn–Teller distortion occurring in the CuN4O2core. The binding interaction with calf thymus DNA (CT–DNA) was investigated by UV–vis and fluorescence spectroscopy, cyclic voltammetry, and viscometry. The results support a partially intercalative binding mode. Efficient cleavage of plasmid DNA by the complex was observed by gel electrophoresis. [ABSTRACT FROM AUTHOR]

Reaction of [RuIII(EDTA)(CyS)]2−(edta4− = ethylenediaminetetraacetate; CySH = cysteine) with molecular oxygen (O2) has been studied as a function of pH (4.0–8.0) and cysteine concentration (0.2–2.0 mM) at room temperature (25 °C). Biological activities of the [Ru(EDTA)]/CySH/O2system pertaining to cleavage of supercoiled plasmid DNA to its nicked open circular form has been explored in this work. Results are discussed in regard to the reaction of the ruthenium(III)-complex with molecular oxygen) and a working mechanism is proposed for the biological activities of the ruthenium(III)-complex in the presence of O2. [ABSTRACT FROM AUTHOR]

The DNA cleavage activities of two coordination polymers of Robson-type macrocycles, {[Cu4L1(4,4′-bipy)2](ClO4)4·H2O}∞(1) and {[Cu4L2(4,4′-bipy)4](ClO4)4·2CH3CN·2H2O}∞(2) (where H2L1and H2L2are the [2 + 2] condensation products of 1,3-diaminopropane with 2,6-diformyl-4-methylphenol and 2,6-diformyl-4-fluorophenol, respectively), have been studied. The interactions of the complexes with calf thymus-DNA were investigated by UV–vis spectroscopy, CD spectroscopy, and gel electrophoresis. The binding constants of1and2are 7.2 × 104and 2.1 × 105 M−1, respectively. The complexes exhibit DNA cleavage activity, with the cleavage process involving oxidative cleavage of DNA. The DNA cleavage activities of two new coordination polymers of Robson-type macrocycles, {[Cu2L1(bipy)]·(ClO4)2·CH3CN}∞(1) and {[Cu2L2(bipy)]·(ClO4)2·H2O}∞(2), have been studied. The interactions of the complexes with calf thymus-DNA were studied by UV–vis and CD spectroscopic techniques. The complexes exhibit good DNA cleavage activity. The results show that the substituent on the benzene ring plays an important role in DNA cleavage and the cleavage process occurs via oxidative cleavage. [ABSTRACT FROM AUTHOR]

The new Ag(I) complexes (2–4) with proligand1were prepared and characterized as prospective antibacterial drug candidates. These compounds consist of a Ag(I) center linearly coordinated to two identicalN-heterocyclic carbenes (NHCs). Crystal structures were solved for complexes3and4, the resulting structural data being in good agreement with expectations. We wondered whether the presence of different counter ions in these compounds might lead to modulation of their biological properties. Notably, in spite of their similar structural pattern, Ag(I)–NHC complex2with Br−manifested better antibacterial actions than complexes3and4withand, respectively. Stability study over time in bacterial solutions revealed that these complexes have better stability than AgNO3. Their interaction with DNA and RNA was explored, cleavage activity indicates that all Ag(I)–NHC complexes exhibited interesting nuclease activity via non-oxidative pathway. [ABSTRACT FROM AUTHOR]

New metallointercalators (1a–1e) have been synthesized using the Schiff base,4-[phenyl(phenylimino)methyl]benzene-1,3-dioland metal(II) ions,viz. Mn(II), Co(II), Ni(II), Cu(II), and Zn(II). They are characterized by analytical and spectral methods. Elemental analyses and molar conductance values reveal that the Schiff base metal(II) complexes have 1?:?2 stoichiometry and are non-electrolytes. The Schiff base (HL) binds with M(II) ions through azomethine and deprotonated phenolic groups. Thermal studies reveal the presence of water in1a–1c. Powder X-ray diffraction and SEM studies show that all the complexes are microcrystalline with homogenous morphology.In vitrobiological activities of HL and1a–1ehave been screened against bacteria and fungi by well diffusion technique, revealing that these complexes are good antimicrobial agents against various pathogens. The complexes exhibit better biological activities than HL. Complex1dbinds with Calf thymus DNA through intercalation and weak covalent interactions. The oxidative cleavage of1a–1ewithpUC19 DNA has also been explored. The results indicate that they bind to DNA through intercalation and are efficient metallointercalators and cleaving agents. The4-[phenyl(phenylimino)methyl]benzene-1,3-diolSchiff base metallointercalators act as efficient DNA binding and cleaving agents. All the complexes arein vitrobiological and antioxidant activators. Cu(II) complex is found to be efficient intercalator than other chelates. [ABSTRACT FROM AUTHOR]

A series of new imidazolium salts (1–4) asN-heterocyclic carbene (NHC) precursors have been synthesized by successive N-alkylation method. Reactions of these salts with Ag2O by varying the metal to salt ratio forms a series of new Ag(I)–NHC complexes (5–8). All compounds were characterized by physico-chemical and spectroscopic techniques. The molecular structures of1and5were characterized by single-crystal X-ray diffraction analysis. A comparative investigation of the bacterial growth inhibition potential of the salts and respective complexes indicates that5–8displayed good antibacterial activities onStaphylococcus aureus(ATCC 12600) andEscherichia coli(ATCC 11303) compared with the salts. Furthermore, it was observed that with increase in chain length atN-positions, the antibacterial activities also increased. Nuclease activity of the reported salts and Ag(I)–NHC complexes with nucleic acids (DNA and RNA) were also studied using agarose gel electrophoresis; the results show that the compounds do not have any apparent interaction with nucleic acids in the absence of hydrogen peroxide (H2O2). However,5and8were efficient in promoting the cleavage of nucleic acids in the presence of H2O2. [ABSTRACT FROM AUTHOR]

Two new dinuclear macrocyclic complexes, [Ni2L1(OAc)]·ClO4(1) and [Co2L2(OAc)]·1.5(ClO4)·0.5Na·2(CH3OH) (2) (where H2L1and H2L2are the condensation products of N,N-bis(3-aminopropyl)-4-methoxybenzylamine with 2,6-diformyl-4-brominephenol and 2,6-diformyl-4-methylphenol in the presence of metal ions, respectively) have been synthesized and characterized by infrared spectra, elemental analysis, electrospray mass spectra, and X-ray single crystal diffraction. The interactions of the complexes with CT-DNA have been measured by UV-absorption titrations and fluorescence quenching experiments. Two new dinuclear macrocyclic polyamine complexes have been synthesized and characterized by infrared spectra, elemental analysis, ES-MS spectrum, and X-ray single crystal diffraction. The interactions of the complexes with CT-DNA have been measured by spectroscopy, viscosity, electrochemical measurements, and the agarose gel electrophoresis. [ABSTRACT FROM PUBLISHER]

Four dioxomolybdenum(VI) complexes were synthesized by reaction of [MoO2(acac)2] with thiosemicarbazones derived from 5-allyl-2-hydroxy-3-methoxybenzaldehyde (1), 2-hydroxynaphthaldehyde (2), 2,3-dihydroxybenzaldehyde (3), or 5-tert-butyl-2-hydroxybenzaldehyde (4). The ligands were coordinated to molybdenum as tridentate ONS donors. X-ray crystallography showed that the distorted octahedral coordination of molybdenum is completed by methanol (D) in1a,3a, and4aor H2O in2a. The molecular structures of1,3, and4, and the complexes were determined by single-crystal X-ray crystallography. Binding of the ligand and complexes with calf thymus DNA were investigated by UV, fluorescence titrations, and viscosity measurements. Gel electrophoresis revealed that all the complexes can cleave pBR322 plasmid DNA. The cytotoxic properties of the complexes against human colorectal (HCT 116) cell line showed strong antiproliferative activities in relative order4a > 3a > 1a > 2awith IC50values of 1.6, 4.0, 4.8, and 6.7 μM, respectively. The complexes exhibited more activity than the standard reference drug, 5-fluorouracil (IC507.3 μM). These studies show that dioxomolybdenum(VI) complexes have potential use in chemotherapy. [ABSTRACT FROM AUTHOR]

[Cu2L(phen)(H2O)3(ClO4)](ClO4)3{phen = 1,10-phenanthroline,L = 4-((bis(pyridine2-ylmethyl)amino)methyl)-N,N-bis(pyridin-2-ylmethyl)aniline} was prepared and characterized by physical chemical techniques. The X-ray single-crystal structure analysis shows an unsymmetrical dinuclear species. The interaction of the complex with calfthymus DNA (CT-DNA) was studied by various spectroscopic and viscosity measurements, which indicate that the complex can interact with CT-DNA through intercalation. In the presence of H2O2, the complex can cleave pBR322 DNA more efficiently and hydroxyl radicals (HO.) may serve as the major cleavage active species. Interactions of the compound with bovine serum albumin (BSA) were also investigated using UV−Vis and fluorescence spectroscopic methods. The results show that the complex quenches the intrinsic fluorescence of BSA by a static quenching mechanism. The X-ray single-crystal structure analysis shows that the complex is an unsymmetrical dinuclear species. [ABSTRACT FROM PUBLISHER]

Ruthenium(II) complexes with 2-acetylpyridine-thiosemicarbazones (L1–L4) were synthesized and characterized by analytical and spectral (FT-IR, UV–vis, NMR [1H,13C and31P], and ESI-Mass) methods. Systematic biological investigations, free radical scavenging, anticancer activities, and DNA cleavage studies, were carried out for the complexes. Antioxidant studies showed that the complexes have significant antioxidant activity against DPPH, hydroxyl, nitric oxide radicals and hydrogen peroxide assay. Thein vitrocytotoxicity of complexes against breast cancer (MCF-7) cell line was assayed showing high cytotoxicity with low IC50values indicating their efficiency in destroying the cancer cells even at very low concentrations. The DNA cleavage studies showed that the complexes efficiently cleaved DNA. [ABSTRACT FROM PUBLISHER]

Two transition metal complexes, [Cu2(bpdc)2H2O]·2H2O (1) and Zn(bpdc)(H2O)2(2) (H2bpdc = 2,2′-bipyridine-6,6′-dicarboxylic acid), were synthesized and characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Complex1is dinuclear with two five-coordinate cupric ions and2is mononuclear with one six-coordinate zinc. Interactions of1and2with DNA have been investigated using UV–Vis absorption spectra. The cleavage reaction on DNA has been monitored by agarose gel electrophoresis. [ABSTRACT FROM AUTHOR]

[Ni(QTS)2] · Cl · CH3OH, where QST = quinoline-2-carboxaldehyde thiosemicarbazone, has been synthesized and characterized. The complex crystallized in a monoclinic system with space group P2(1)/n. Nickel(II) is situated in a distorted octahedral geometry with two tridentate ligands and one ligand is mono-deprotonated to coordinate to nickel(II). Interaction of the nickel(II) complex with calf thymus DNA was investigated by electronic absorption, CD, and fluorescence spectra. The results suggest that nickel(II) complex binds to DNA through a groove binding mode. The nickel(II) complex exhibited efficient DNA cleavage at micromolar concentration in the presence of ascorbate with hydroxyl radicals as the active species. In vitro cytotoxicity assay showed that the nickel(II) complex was more potent against MCF-7 cell line but less active against A-549 cell line than cisplatin at the concentrations tested. [ABSTRACT FROM AUTHOR]

Four mononuclear complexes of Cu(II) and Zn(II) having a Schiff-base ligand and 1,10-phenanthroline/2,2′-bipyridine have been synthesized and characterized. From electronic spectral and magnetic susceptibility data, octahedral geometry has been proposed for the complexes. DNA-binding behaviors of these complexes are studied by absorption titration, electrochemical, and viscosity methods. The results indicate that the complexes bind to calf thymus DNA in an intercalative mode. The gel electrophoresis results reveal that 1 cleaves pBR322 DNA effectively. The ligand and its complexes have been screened for their antimicrobial activities against a few microorganisms. The data exhibit that they are better antimicrobial agents than the ligand. [ABSTRACT FROM PUBLISHER]

A new water-soluble copper(II) complex, Cu(TACNA)Br · 0.375H2O (1) [TACNA = 1,4,7-triazacyclononane-N-acetate], has been synthesized to serve as artificial nucleases. The X-ray crystal structure of 1 indicates that one bromide and an oxygen from acetate pendant coordinate to copper(II) in addition to the nitrogen atoms in the TACN macrocycle, resulting in a five-coordinate complex with square-pyramidal geometry. The interaction of 1 with calf thymus DNA (ct-DNA) has been investigated by UV absorption and fluorescence spectroscopies, and the mode of ct-DNA binding for 1 has been proposed. In the absence of external agents, supercoiled plasmid DNA cleavage by 1 was performed under aerobic condition; the influences on DNA cleavage of different complex concentrations and reaction times were also studied. The cleavage of plasmid DNA likely involves oxidative mechanism. [ABSTRACT FROM AUTHOR]

A Schiff base, obtained by the condensation of isatin monohydrazone with 2,3,5-trichlorobenzaldehyde, and its Co(II), Ni(II), Cu(II), and Zn(II) complexes have been synthesized and characterized. The interaction of these complexes with DNA is investigated using viscosity, absorption titration, and electrochemical techniques. The results indicate that the complexes bind to Calf thymus DNA through intercalation. Oxidative cleavage activities of the complexes are studied using supercoiled pBR322 DNA by gel electrophoresis. Antimicrobial study reveals that copper and zinc complexes are better antimicrobial agents than the Schiff base and its other complexes. [ABSTRACT FROM AUTHOR]

Four water-soluble dinuclear Zn(II) complexes (1–4) of compartmental ligand L = 2,6-bis(R-iminomethyl)-4-R′-phenolate (where R = N-ethylpiperidine or R = N-ethylpyrrolidine, R′ = methyl or tert-butyl) have been synthesized, characterized, and their DNA cleavage activity and cytotoxicity toward HepG2 cancerous cells are evaluated. The dinuclear complexes are formed by a pentadentate-substituted phenolate ligand chelating the metal ions separated by ca 3.27 Å. Each metal is a distorted trigonal bipyramid, completing the coordination sphere through acetate. The X-ray structural determination of 2 shows that the complex is counterbalanced by half (formulation [Zn2L2(CH3CO2)2][(Zn(SCN)4]0.5), while in 1 and 3 two crystallographically-independent complexes are present in the unit cell with a . Among the four complexes only the 4-tert-butyl-phenolato derivatives (3 and 4) show DNA cleavage activity in in-vivo conditions and appear to be promising toward metal complexes to be used as anticancer agents. The cytotoxicity of the complexes, investigated through MTT assay, suggests that 4 is a better choice as artificial nuclease. [ABSTRACT FROM AUTHOR]

Two complexes, [Zn2L(µ-OAc)](ClO4) (1) and [Mn2L(OAc)2] · 4H2O (2), were synthesized by [2 + 2] cyclo-condensation between 2,6-diformyl-4-fluorophenol and 1,3-propyldiamine in the presence of metal ions M(II) (M = Zn and Mn), and were characterized by chemical analyses, IR spectra, electrospray mass spectra, and X-ray determinations. The results show that 1 forms dimers through hydrogen bonding. In 2, lattice waters, forming a 1-D water chain, function as glue to form a 3-D supramolecular network through extended hydrogen bonding. pBR322 plasmid DNA can be transformed to nicked form in air by 1 or nicked and linear forms in air by 2. Moreover, their antibacterial activities against S. aureus were investigated using penicillin as reference system. [ABSTRACT FROM AUTHOR]

Reaction of [RuII(tpy)(pic)(H2O)]+ (1) with KHSO5 resulting in the formation of [RuIV(tpy)(pic)(O)]+ (2) was studied kinetically as a function of [KHSO5], temperature (15-35°C), and pressure (10-30 MPa) at a fixed pH of 5.1 using spectrophotometric techniques. A suggested mechanism that is in agreement with the observed rate and activation parameters is presented. Complex 1 was found to induce DNA (pBluescript) cleavage in the presence of KHSO5, which proceeds via oxygen transfer from 2. [ABSTRACT FROM AUTHOR]

The structure of 1 consists of [Cu(HCp)(phen)(H2O)]2+ (HCp is ciprofloxacin and phen is 1,10-phenanthroline), two acetates, and four free water molecules. In each cation, copper displays a distorted square pyramid, coordinated to ring 3-carboxylate and 4-oxo oxygen from HCp, two nitrogens from phen, and one water molecule. There are five water molecules in each discrete complex with one coordinated to Cu center, and the other four linked to each other by intermolecular hydrogen bonds. Two uncoordinated acetates make the compound neutral. The complex exhibits higher DNA binding compared to HCp at the same conditions by fluorescence and viscosity measurements. Combining its structure with the DNA-binding result, the binding mechanism may be explained by intercalation. Moreover, 1 shows significant cleavage of DNA in the presence of a reducing agent, such as ascorbate by gel electrophoresis using supercoiled pBR322 DNA in Tris-HCl buffer (pH 7.4). The complex also has a higher activity against Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Klebsiella pneumoniae than HCp. [ABSTRACT FROM AUTHOR]

Co(II), Ni(II), Cu(II), Zn(II), and VO(IV) complexes containing a versatile β-diketone Schiff-base ligand (obtained by the condensation of 3-furan-2-ylmethylene-2,4-dione and 2-aminophenol) have been synthesized and characterized. Microanalytical, magnetic, and spectroscopic data reveal that the central metal is coordinated to two oxygens of phenolate and two nitrogens of imine of the ligand. Binding of synthesized complexes with calf thymus DNA has been investigated by spectroscopic and electrochemical methods and viscosity measurements. The complexes are able to form adducts with DNA and to distort the double helix by changing the base stacking. Electrostatic binding of vanadyl complex is observed from the weak hypochromism in electronic absorption spectra and no change in the viscosity with DNA. Oxidative DNA cleavage activities of the complexes are studied with supercoiled pUC19 DNA using gel electrophoresis. The hydroxyl radical (OH•) is likely to be the species responsible for the cleavage of pUC19 DNA by the synthesized complexes. Under our experimental conditions, the vanadyl complex has no significant cleavage of DNA. The compounds have been screened for activity against several bacterial and fungal strains and the results are compared with the activity of standard drugs. [ABSTRACT FROM AUTHOR]

Two copper(II) complexes with naphthalene ring [Cu(L1)(H2O)](ClO4)2 · H2O (1) or [Cu2(L2)(ClO4)(H2O)3](ClO4)3 · H2O (2) (L1 = 1-[bis(pyridine-2-ylmethyl)aminomethyl]naphthalene and L2 = 1,4-di[bis(pyridine-2-ylmethyl)aminomethyl]naphthalene) were synthesized. Structural characterization of complex 2 by X-ray crystallography showed that the cations form a double-forficiform structure and each Cu(II) ion is bound by an in-plane N3Ow-coordination. Thermal melting curves and fluorescence spectroscopes of complex-DNA binding indicate that both complexes can efficiently interact with calf thymus DNA and that the binding ability of complex 2 is greater than that of complex 1. Viscosity measurements suggest that complex 2 partially intercalates between DNA base pairs via the naphthalene ring, whereas complex 1 most likely interacts with DNA through the electrostatic binding. In the presence of H2O2 and ascorbic acid, dinuclear complex 2 was more efficient than mononuclear complex 1 in cleaving double-stranded circular DNA into linear DNA. The interaction modes between the complexes and DNA were also discussed. [ABSTRACT FROM AUTHOR]

RuIII-edta (edta, ethylenediaminetetraacetate) induced cleavage of pBluescript SK+ plasmid DNA in the presence of air with primary oxidant, PO (PO = H2O2, KHSO5) or reductant (L-ascorbic acid) has been studied at pH 7.2. The studies revealed that the RuIII-edta complex induces DNA cleavage in different ways. A mechanism suggesting the involvement of [RuV(edta)O]- in the oxidative cleavage of DNA is proposed for H2O2 and KHSO5. Generation of active oxygen radical species ( [image omitted]/OH•) is proposed for cleavage of DNA with RuIII-edta/ascorbate system. Results are discussed in reference to the data reported for the reaction of Ru-edta with DNA constituents, H2O2, KHSO5, and L-ascorbic acid. [ABSTRACT FROM AUTHOR]

A μ-oxo-di-μ-carboxylato-bridged iron(III) complex containing two tridentate nitrogen ligands, {[Fe2(bpma)(bpea)(μ-CH3COO)2 μ-O)] · (ClO4)2 · 0.5CH3OH} (1) (bpma = N, N-bis(2-pyridylmethyl)methyl-amine, bpea = N,N-bis(2-pyridylmethyl)ethylamine), has been synthesized and determined by X-ray diffraction. Complex 1 crystallizes in the monoclinic space group P21/c with a = 10.9434(12) Å, b = 23.118(3) Å, c = 15.8721(18) Å, β = 92.736(2)° and Z = 4. In 1, each Fe(III) has a distorted octahedral geometry with a N3O3 donor set. The Fe(III) atoms are bridged by two carboxyl groups and one μ-oxo oxygen with Fe1-Fe2 separation of 3.064 Å. Susceptibility data of 1 indicate strong intramolecular antiferromagnetic coupling of the high-spin Fe(III) atoms with J = -121.0 cm-1 and g = 2.04. The interaction with calf thymus DNA was investigated by UV absorption and fluorescent spectroscopy. Results show that the complex binds to ct-DNA with a moderate intercalative mode. The interaction between 1 and pBR322 DNA has also been investigated by submarine gel electrophoresis; the complex exhibits effective DNA cleavage activity in the absence of activating agents under similar physiological conditions. [ABSTRACT FROM AUTHOR]

A ternary copper(II) complex, [Cu(phen)(L-Gly)(H2O)] · NO3 · 1.5H2O (phen = 1,10-phenanthroline, L-Gly = L-glycine), has been synthesized and structurally characterized. The complex crystallized in a monoclinic system with space group C2/c, a = 20.572(3) Å, b = 6.9987(10) Å, c = 23.561(3) Å, β = 98.776(5)°. The five-coordinate copper(II) center is a distorted square pyramid. Absorption spectra, fluorescence spectra and viscosity measurements showed interaction between the copper complex and DNA through an intercalative mode. The complex exhibited efficient DNA cleavage activity at micromolar concentration in the presence of ascorbate with hydroxyl radicals as the active species. [ABSTRACT FROM AUTHOR]

Aquabis( N , N -dimethylglycinato)copper(II) dihydrate, [Cu(dmg) 2 (H 2 O)]·2H 2 O, has been synthesized and characterized by elemental analysis, FT-IR, magnetic data, thermal analysis, solution UV-visible spectroscopy, X-ray crystal structure analysis and electrospray ionization mass spectroscopy. The square pyramidal copper(II) complex crystallizes in the orthorhombic space group P 2 1 2 1 2 1 . The complex cleaves circular plasmid DNA (pBR322) in the presence of H 2 O 2 . The extent of cleavage varies with the concentration range of the complex, the type of buffer used, pH of buffer and the concentration of H 2 O 2 . Hydroxyl radical scavenger can inhibit the nucleolytic ability of this complex. [ABSTRACT FROM AUTHOR]