Search

Six new Pd(II) and Ir(III) thiazole-based complexes were synthesized and characterized by EA, ICP, FTIR, TGA-MS and SEM-EDX. In order to evaluate the biological activity of the synthesized compounds CT-DNA binding was studied and moreover ligands, complexes were tested against cancer cell lines. [Display omitted] Thiazoles and their derivatives are one of the most active classes of compounds known for their wide spectrum of bioactivity. Metal complexes, based on them, show antitumor potential that is attractive for investigations. Herein, we report 6 new biologically active thiazole-based complexes have been synthesized. The iridium- and palladium-based coordination compounds obtained by the precipitation method were characterized using elemental analysis (EA), Fourier-transform infrared spectroscopy (FTIR), magnetic measurements, thermogravimetric analysis coupled with mass spectrometry (TGA-MS), and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). Spectroscopic data helped to propose the formulas of the complexes and indicated that all ligands acted in a monodentate manner. Water molecules were identified by thermal analysis and FTIR spectroscopy. Mathematical analysis and evaluation of thermodynamic parameters including entropy (ΔS), Gibbs free energy (ΔG), and activation energy (E) were performed using the Coats–Redfern method for all complexes. The biological potential (anticancer, antibacterial, and antifungal properties) of compounds was analyzed by biological evaluation studies. Investigated CT-DNA studies revealed that the prepared compounds were intercalatively bound to the DNA. Cytotoxicity analyses showed that complexation with Ir(III) increased the toxicity of L2 towards both tested cell lines (LN-229 and MDA-MB-231), while complexation of L3 with Pd(II) significantly increased cytotoxic activity against LN-229. Due to this, the further biological studies, such as apoptosis/necrosis detection, cell cycle analysis and JC-1 fluorescence measurements were performed on this pair of compounds. [ABSTRACT FROM AUTHOR]

Four novel zinc-gatifloxacin complexes exhibit noteworthy antimicrobial activity and bind tightly to albumins and to calf-thymus DNA. Four novel zinc coordination compounds of gatifloxacin (Hgati), a third-generation quinolone, with a N,N′-donor heterocyclic ligand, such as 2,2′-bipyridylamine, 1,10-phenanthroline or 2,2′-bipyridine, were characterized with physicochemical techniques and various spectroscopies. The antimicrobial activity of the compounds against the microorganisms Xanthomonas campestris , Escherichia coli , Bacillus subtilis and Staphylococcus aureus was similar or better than that of free Hgati. The complexes may bind to calf-thymus DNA via intercalation as concluded via a series of studies employing DNA-viscosity measurements, UV–Vis spectroscopy and competition with ethidium bromide. The complexes may bind to albumins in order to get transferred through the bloodstream. [ABSTRACT FROM AUTHOR]

Graphical abstract Copper(I) complexes with a phenanthroline-phosphine set of ligands were synthesized and characterized. The DNA-binding study of the complexes against ct-DNA showed binding constant values that correspond to the intercalation mode of binding, with notable variations in K b due to the different phosphine ligands. The anticancer activities of complexes show the influence of the different phosphine ligands. The data suggested potential anticancer activities against prostate and breast cancers. Molecular docking studies were conducted, highlighting some of the structural-DNA interactions. Abstract Copper(I) complexes with a phenanthroline-phosphine set of ligands were synthesized by refluxing methanolic solutions of CuBr 2 with at least a four fold molar excess of the phosphine ligands, followed by the treatment of the formed {CuBr(PR 3) 3 complexes [R = phenyl (1a), 4-fluorophenyl (1b), cyclohexyl (1c) or 4-methoxyphenyl (1d)]} with 1 molar equivalent of 1,10-phenanthroline in DCM. The tris(4-methoxyphenyl)phosphine ligand afforded the complex [Cu(P[C 6 H 4 -4-OMe] 3) 2 (phen)]Br (2d), while the other phosphines produced complexes with the general formula CuBr(PR 3)(phen) [R = phenyl (2a), 4-fluorophenyl (2b) or cyclohexyl (2c)]. The new complexes were characterized by elemental analysis, 31P NMR spectroscopy and mass spectrometry. Additional confirmation of the structures of 1b , 2b , 2c and 2d were determined by single crystal X-ray diffraction. A DNA-binding study of the complexes 2a – 2d against ct-DNA showed binding constant values that correspond to the intercalation mode of binding. The notable variations in the binding constants of the complexes suggest some contribution from the phosphine ligands. The lipophilicity of the complexes was evaluated theoretically and the calculated log P value of complex 2d is positive and high, being in the same range of relatively easy membrane penetrating drugs. The calculated log P values of complexes 2a – 2c are negative, indicating a low membrane permeability. Complexes 2a – 2d were examined against four different cancer cell lines. The choice of the phosphine ligand appears to influence the copper(I)-phosphine anticancer activities against the different cancer cell lines. The data suggested that complexes 2a and 2d show potential anticancer activity against prostate and breast cancers. The four copper complexes were docked against four different proteins associated with prostate or breast cancers activities, highlighting some of the structural-DNA interactions. [ABSTRACT FROM AUTHOR]

Six tetradentate bis-thiosemicarbazone ligands formed by condensation of pyruvaldehyde with 4-(aryl) thiosmicarbazides and their Ru(II) complexes are reported. The complexes are of formula [Ru(PPh 3 ) 2 (L)], where L is the dianionic form of the bis-thiosemicarbazone ligands. X-ray crystal structures of two of the complexes suggest that the thiosmicarbazone ligands act in a tetradentate fashion occupying the basal plane of the Ru(II) coordination octahedron and each of the two thiosemicarbazone moiety forms five membered chelate ring involving deprotonated thiolato sulfur and the imine nitrogen atoms; the two triphenylphosphine ligands are trans to each other. The complexes undergo Ru(II)/Ru(III) oxidation at a relatively low potential of 0.05–0.12 V versus Ag/AgCl. One of the Ru(II) complex has been chemically oxidized to the corresponding Ru(III) complex [Ru(PPh 3 ) 2 (L)]PF 6 using ferrocenium hexafluorophosphate as an oxidizing agent. E.P.R. spectra of the Ru(III) complex and DFT calculations on the Ru(III) as well as two of the Ru(II) complexes suggest that there is extensive mixing between the ligand and metal valence orbitals. The DNA-binding properties of the Ru(II) complexes were studied by both UV–Vis spectroscopy and fluorescence quenching of ethidium bromide-DNA complex. The complexes showed strong DNA-binding ability with K app of the order of 10 6 M −1 . [ABSTRACT FROM AUTHOR]

The copper(II) complexes with the third-generation quinolone gatifloxacin (Hgati) were prepared in the absence or presence of the N,N′-donor heterocyclic ligands 2,2′-bipyridylamine (bipyam), 1,10-phenanthroline (phen) or 2,2′-bipyridine (bipy) and were characterized physicochemically and spectroscopically. The crystal structures of complexes [Cu(gati)(bipyam)Cl]·MeOH·H 2 O and [Cu(MOM-gati)(bipy)Cl]·MeOH·3H 2 O (MOM = methoxymethyl) were determined by X-ray crystallography. The antimicrobial activity of the compounds was tested against four different microorganisms (Escherichia coli , Xanthomonas campestris , Staphylococcus aureus and Bacillus subtilis ) and was found similar or higher than that of free Hgati. The interaction of the complexes with calf-thymus DNA was monitored by UV–vis spectroscopy and DNA-viscosity measurements and by competitive studies with ethidium bromide; intercalation is suggested as the most possible binding mode. The interaction of the complexes with human or bovine serum albumins was studied by fluorescence emission spectroscopy and the corresponding albumin-binding constants of the complexes were calculated. [ABSTRACT FROM AUTHOR]

Synthesis and cytotoxic property of Pt(II)–sulfur complexes are significant in biological aspect. In order to investigate their relevance, two sulfur chelated model complexes are considered for detailed study. In-vitro drug reservoir property of the complex [Pt(MAMP)(H 2 O) 2 ]X 2 2 (where, MAMP = 2-[(N-methylamino)methyl]pyridine and X = NO 3 − or ClO 4 − ) in model reactions with sulfur containing bio-molecules dl-methionine (dl-meth) and dl-penicillamine (dl-pen) are studied to explore the ‘drug reservoir’ mechanism. The complex [Pt(MAMP)(dl-meth)] 3 and [Pt(MAMP)(dl-pen)] 4 are synthesized from complex 2 , which is obtained from the hydrolysis of complex [Pt(MAMP)Cl 2 ] 1 and characterized by spectroscopic methods. Interaction mechanism between complex 2 with dl-meth and dl-pen has been established by kinetic study. Two step consecutive reaction rate constants ( k 1 and k 2 ) and corresponding activation parameters (Δ H ‡ and Δ S ‡ ) for both the steps are calculated and an associative mechanism is proposed. Theoretical investigations like structural optimization, HOMO–LUMO energy calculations, NBO analysis have been performed. The coordination mode of dl-meth and dl-pen via (S, O) are established by spectroscopic methods and confirmed by NBO analysis. DNA binding property of the complexes 2 – 4 has been investigated by UV–Vis spectra, competitive binding experiment, gel electrophoresis and their corresponding binding constants ( k b and k sv ) are calculated. The computational molecular docking study is carried out for the complexes with B-DNA to confirm their DNA binding mode. Cytotoxic property of the complexes 3 and 4 are investigated on HeLa and HepG2 cell lines and also been compared with complex 2 and well known anticancer drug cis platin and their corresponding IC 50 values are calculated. [ABSTRACT FROM AUTHOR]

Three oxovanadium complexes incorporating thiosemicarbazones and fluoro-phenanthroline derivatives [VO(hntdtsc)(CF 3 PIP)] ( 1 ) (hntdtsc = 2-hydroxyl-1-naphthaldehyde thiosemicarbazone, CF 3 PIP = 2-(2-trifluoromethyl phenyl)imidazole[4,5-f][1,10]phenanthroline [VO(hntdtsc)( m -CF 3 PIP)] ( 2 ) ( m -CF 3 PIP = 2-(3-trifluoromethyl phenyl)imidazole[4,5-f][1,10]phenanthroline), [VO(hntdtsc)( p -CF 3 PIP)] ( 3 ) ( p -CF 3 PIP = 2-(4-trifluoromethyl phenyl)imidazole[4,5-f][1,10]phenanthroline) were newly synthesized and characterized by elemental analysis and spectroscopic techniques. Their interactions with calf-thymus DNA (CT-DNA) and photocleavage properties with plasmid pBR322 DNA were investigated by a host of analytical methods. The results suggest that these three complexes interact with CT-DNA through an non-classical intercalative mode and can efficiently cleavage plasmid pBR322 DNA upon exposure to ultraviolet light. In addition, they all exhibited considerable anti-proliferative activity in vitro against human Hela, CaSki, SiHa, ECa9706, ECa109, MDA-MB-231 and MCF-7 tumor cell lines, to have an IC 50 values for cytotoxicity in the low micromole range 0.31–6.15 μM, which is very close to that of cisplatin (0.52–2.49 μM). Furthermore, their antitumor mechanism has been analyzed by the cell cycle arrest, and apoptosis analysis. The results showed that complexes 2 and 3 caused G0/G1 phase arrest in ECa9706 cells, but differentiatedly induced G0/G1 and S phase arrest in ECa109 cells. And significant apoptosis were observed in both the two tumor cell lines, which indicate these oxovanadium complexes induce proliferative suppression of ECa9706 and ECa109 cells via the induction of apoptosis. [ABSTRACT FROM AUTHOR]

The antiproliferative activity of mixed chelate copper complexes with general formulae [Cu(N–N)(α- l -amino acidato)]NO 3 and [Cu(N–N)(O–O)]NO 3 has been attributed to several possible targets: mitochondrial toxicity, ROS production and DNA interactions. The latter has been one of the principal targets studied through several techniques such as gel electrophoresis, atomic force microscopy, circular dichroism, and molecular dynamics calculations. In order to improve the understanding of the mode of molecular interaction with DNA, we studied DNA binding by fluorimetric methods employing two dyes: an intercalator (ethidium bromide) and a minor groove binder (Syber-Green I). The Stern–Volmer constant was calculated for every compound to provide quantitative information on fluorescence quenching. Results show that copper complexes interact with DNA by means of different binding modes; the mode of binding and intensity of these interactions are influenced by both ligands coordinated to copper. The analysis of the current information suggests that the steric hindrance of ligands, number of aromatic or pseudo-aromatic rings, unoccupied coordination positions at copper center, and stability play important roles in the interaction. The more extended aromatic ring of phenanthroline ligand seems to favor DNA interaction by any binding mode. The varied modes of interaction and the lack of correlation between affinity to DNA and biological activity reported in some trials lead to reconsider the hypothesis that attribute the antineoplastic activity to mainly intercalative DNA binding of intact complex as requirement or first step. [ABSTRACT FROM AUTHOR]

Abstract: DNA-binding and DNA-photocleavage properties of two Ru(II) complexes, [Ru(L1)(dppz)2](PF6)4 (1) and [Ru(L2)(dppz)2](PF6)4 (2) (L1 =5,5′-di(1-(triethylammonio)methyl)-2,2′-dipyridyl cation; L2 =5,5′-di(1-(tributylammonio)methyl)-2,2′-dipyridyl cation; dppz=dipyrido[3,2-a:2′,3′-c]phenazine, have been investigated. Experimental results show that the DNA-binding affinity of complex 1 is greater than that of 2, both complexes emit luminescence in aqueous solution, either alone or in the presence of DNA, complex 1 can bind to DNA in an intercalative mode while 2 most likely interacts with DNA in a partial intercalation fashion, and complex 2 serves as a better candidate for enantioselective binding to CT-DNA compared with 1. Moreover, complex 1 reveals higher efficient DNA cleavage activity than 2, during which supercoiled DNA is converted to nicked DNA with both complexes. Theoretical calculations for the two complexes have been carried out applying the density functional theory (DFT) method at the level of the B3LYP/LanL2DZ basis set. The calculated results can reasonably explain the obtained experimental trends in the DNA-binding affinities and binding constants (K b) of these complexes. [Copyright &y& Elsevier]

Abstract: The reaction of cis-[RuCl2(DMSO)4] with salicylaldehyde semicarbazone in ethanol resulted in the chemoselective cleavage of the C the Schiff base, forming a complex in which the semicarbazide remains coordinated to the metal, as observed previously with trans-[RuCl2(DMSO)4]. In another set of reactions of cis-[RuCl2(DMSO)4] with 4-aminoantipyrine derivatives of salicylaldehyde, 2-hydroxy-1-naphthaldehyde and o-vanillin, Ce was observed in all three cases yielding the same compound, [RuCl2(DMSO)2(4-aminoantipyrine)]. However, when the reactions, under the same experimental conditions, were extended to unsubstituted/N-substituted thiosemicarbazones of salicylaldehyde and 2-hydroxy-1-naphthaldehyde, no cleavage was observed. All the new complexes were characterized by analytical and spectroscopic techniques. The structures of two of the complexes, [RuCl2(DMSO)2(semicarbazide)]·2H2O and [RuCl2(DMSO)2(4-aminoantipyrine)], were determined by single crystal XRD and are in support of the cleavage. The electrochemistry of the complexes was studied by cyclic voltammetry. Further, the preliminary DNA-binding ability and antibacterial activity of the complexes were studied. [ABSTRACT FROM AUTHOR]

Abstract: The novel homodinuclear zinc(II) complexes with the quinolone antibacterial drugs ciprofloxacine and neutral bidentate ligands have been synthesized and characterized by elemental analysis, TG analyses and various spectroscopic techniques. The metal ion exhibits octahedral geometry with two water molecule in the inner sphere cavity environment. The interaction of complexes with DNA was determined using absorption titration, viscosity measurements and electrophoresis technique. The intrinsic binding constants (Kb ) of complexes were determined, which were ranging from 1.0 × 104 to 3.5×104 per mole. Suggesting that complexes bind more strongly to DNA. Effect on viscosity has also been checked to authenticate the binding of metal complexes with DNA. An antimicrobial activity of all the ligands and metal complexes has been examined by minimum inhibitory concentration method (MIC). [Copyright &y& Elsevier]

Abstract: The reaction of cis-[RuCl2(DMSO)4] with a family of aromatic and heterocyclic acid hydrazides yielded new complexes of the general formula trans-[RuCl2(DMSO)2(hydrazide)]· nH2O (n =0; 1–6; n =1; 7). The new complexes have been characterized by IR, UV–Vis and 1H NMR spectroscopic methods. In addition, the structure of one of the complexes, [RuCl2(DMSO)2(tcah)]·H2O (tcah = thiophene-2-carboxylic acid hydrazide), has been determined by single crystal X-ray diffraction. All the studies reveal the neutral bidentate coordination of the hydrazide ligands through the acyl oxygen and amine nitrogen atoms. The electron transfer properties of the complexes were studied by cyclic voltammetry and all the complexes except one show an irreversible/quasi-reversible reduction wave (RuII/RuI) and an uncoupled oxidation peak (RuIII/ RuII). The preliminary DNA-binding ability of the complexes, studied with herring sperm DNA, shows the binding of the complexes with DNA with a lesser affinity than classical intercalators. The complexes have also been screened for their antibacterial activity against five pathogenic bacteria. [Copyright &y& Elsevier]

Abstract: Two new Ru(II) complexes, [Ru(bpy)2(pmip)]2+ (1) and [Ru(phen)2(pmip)]2+ (2), have been synthesized and characterized by elemental analysis, ESI-MS and 1H NMR spectra. Their DNA-binding properties were studied by means of UV–VIS, emission and CD spectra, thermal denaturation and viscosity measurements as well as their DNA-photocleavage properties. The experimental results show that both 1 and 2 can bind to DNA in an intercalative mode; the DNA-binding affinity of 2 is greater than that of 1, which suggests that the ancillary ligands have a significant effect on the spectroscopic properties and DNA-binding behavior of the Ru(II) complexes. Under irradiation with UV light, the Ru(II) complexes show excellent efficiency of cleaving DNA. This research may provide valuable insight into the interactions of metal complexes with DNA, knowledge that is an excellent backdrop for the rational design of promising drugs. [Copyright &y& Elsevier]

Abstract: New Ru(II) complexes with dicationic ligand, [Ru(phen)2L1]4+ (1) and [Ru(phen)2L2]4+ (2) (phen=1,10-phenanthroline; L: L1 =5,5′-di(1-(triethylammonio)methyl)-2,2′-dipyridyl cation; L2 =5,5′-di(1-(tributylammonio)methyl)-2,2′-dipyridyl cation) have been synthesized and structurally characterized. The interaction of these complexes with calf thymus DNA (CT-DNA) has been investigated. The intrinsic binding constants (K b: 1, 7.73×104 M−1; 2, 2.50×104 M−1) determined by absorption spectral titrations of these complexes with CT-DNA indicate the DNA-binding affinity of 1 is stronger than that of 2. Both complexes can display luminescence either alone in aqueous solution or in the presence of DNA. Equilibrium dialysis experiments monitored by CD spectroscopy reveal the preferential binding of the Δ-enantiomer to the right-handed CT-DNA. DNA-viscosity studies suggest that the binding modes are different, 1 may partially intercalate between DNA base-pairs while 2 most likely interact with DNA in an electrostatic binding mode. [Copyright &y& Elsevier]

Abstract: The synthesis and characterization of ruthenium(II) complexes, [RuCl2(dmso)2(bfmh)] (1; dmso=dimethyl sulfoxide, bfmh=benzoic acid furan-2-ylmethylene-hydrazide), [RuCl2(dmso)2(btmh)](2; btmh=benzoic acid thiophen-2-ylmethylene-hydrazide), [RuCl2(dmso)2(bfeh)](3; bfeh=benzoic acid (1-furan-2-yl-ethylidene)-hydrazide) and [RuCl2(dmso)2(bpeh)](4; bpeh=benzoic acid (1-pyridin-2-yl-ethylidene)-hydrazide) are described. The ligands, when treated with either cis-[RuCl2(dmso)4] or trans(Cl)–[RuCl2(dmso)2(bpy)], resulted in the same products. This has been confirmed by IR spectra and single crystal X-ray diffraction studies. The redox behaviors of the complexes have been found to be strongly dependent on the electronic nature of the moieties present in the hydrazone ligands. The binding of the complexes to Herring sperm DNA has been studied by absorption titration and cyclic voltammetry. But, due to the random change in the absorption on the addition of DNA, only a qualitative result rather than a quantitative result has been obtained. All the complexes have been found to bind DNA through different modes to different extents. The antibacterial properties of the ligands and the complexes have been studied against five pathogenic bacteria and also the minimum inhibitory concentrations (MIC) of all the ligands and complexes 2 and 4 have been evaluated. [Copyright &y& Elsevier]

Abstract: A series of Ru(II) and Ru(III) complexes of the types [RuX(CO)(EPh3)2L] (X=H, E=P; X=Cl, E=P or As) and [RuX2(EPh3)2L] (X=Cl, E=P or As; X=Br, E=As, L=monoanion of dehydroacetic acid) have been synthesized in order to explore their biological activities, such as DNA-binding and antibacterial activity. The complexes were characterized by analytical and spectroscopic techniques. The crystal and molecular structure of [RuCl2(AsPh3)2(L)] has been determined by single crystal XRD. The cyclic voltammograms of the complexes in acetonitrile displayed either quasi-reversible or irreversible redox couples based on the metal centre. The ligand, dehydroacetic acid (DHA) and its metal complexes were tested against five pathogenic bacteria. Absorption titration and cyclic voltammetric studies revealed that the complexes interact with Herring Sperm ds DNA through different binding modes to different extents. [Copyright &y& Elsevier]

Abstract: The new polypyridyl ligand MIP {MIP=2-(2,3-methylenedioxyphenyl)imidazo[4,5-f]1,10-phenanthroline} and its ruthenium(II) complexes [Ru(phen)2(MIP)]2+ (1) (phen=1,10-phenanthroline) and [Ru(dmp)2(MIP)]2+ (2) (dmp=2,9-dimethyl-1,10-phenanthroline) were synthesized and characterized by elemental analysis, MS and 1H NMR spectroscopy. The DNA-binding properties of the two complexes to calf-thymus DNA (CT-DNA) were investigated by different spectrophotometric methods and viscosity measurements, as well as equilibrium dialysis and circular dichroism spectroscopy. The results suggest that complex 1 binds to CT-DNA through intercalation, and complex 2 binds to CT-DNA via a partial intercalative mode. This difference in binding mode probably is caused by the different ancillary ligands. Also, when irradiated at 400nm, complex 1 was found to be a more-effective DNA-cleaving agent than complex 2. [Copyright &y& Elsevier]

Abstract: New ligand 2-(4′-biphenyl)imidazo[4,5-f][1,10]phenanthroline (BPIP) and its complexes [Ru(bpy)2(BPIP)]2+ (1) (bpy=2,2′-bipyridine) and [Ru(phen)2(BPIP)]2+ (2) (phen=1,10-phenanthroline) have been synthesized and characterized by mass spectroscopy, 1H NMR and cyclic voltammetry. The interaction of two Ru(II) complexes with calf thymus DNA (CT-DNA) was investigated by spectroscopic and viscosity measurements. Results indicate that both complexes bind to DNA via an intercalative mode and the DNA-binding affinity of complex 2 is much greater than that of complex 1. Furthermore, when irradiated at 365nm, both complexes have also been found to promote the photocleavage of plasmid pBR 322 DNA. [Copyright &y& Elsevier]

Abstract: Two complexes of the type [Co(en)2IP]3+ (IP=imidazo[4,5-f][1,10]-phenanthroline) and [Co(en)2PIP]3+ (PIP=2-phenylimidazo[4,5-f][1,10]-phenanthroline) have been synthesized and characterized by UV–VIS, IR and1H NMR spectral methods. Absorption spectroscopy, emission spectroscopy, viscosity measurements and DNA melting techniques have been used to investigate the binding of these two complexes with calf thymus DNA and photocleavage studies have been used to investigate the binding of these complexes with plasmid DNA. The spectroscopic studies together with viscosity measurements and DNA melting studies support that complexes 1 and 2 bind to CT DNA(=calf thymus DNA) by an intercalation mode via IP or PIP into the base pairs of DNA. Complex 2 binds more avidly to CT DNA than 1, which is consistent with the extended planar ring π system of PIP. Noticeably, the two complexes have been found to be efficient photosensitisers for strand scissions in plasmid DNA. [Copyright &y& Elsevier]

Two Cu(II) complexes of pyridoxal-aminoguanidine Schiff base are reported. Both the complexes bind to calf-thymus DNA via intercalative mode. In addition, both the complexes selectively recognize l -histidine amino acid via ligand displacement approach. [Display omitted] • Two Cu(II) complexes of pyridoxal-aminoguanidine Schiff base ligand are reported. • The complexes bind DNA strongly by intercalation. • The complexes can also selectively sense histidine in octamolar concentration. Two Cu(II) complexes of pyridoxal-aminoguanidine Schiff base ligand with formula [Cu(HL)Cl] 2 (OAc) 2 ·4H 2 O (1) and [Cu(HL)Cl(N CS)].H 2 O (2) are reported. The ligand and the complexes were characterized by their elemental analyses, ESI-MS, Uv–Vis, IR spectroscopy and cyclic voltammetric measurements. Single crystal structures of complex 1 and 2 were solved by X-ray diffraction. In both the Cu(II) complexes Cu(II) ions are in a square pyramidal geometry having geometry index (τ) value of 0.11 for complex 1 and 0.15 for complex 2. Both the complexes bind to calf-thymus DNA with binding constant comparable to ethidium bromide. Circular dichroism studies revealed an intercalative mode of binding for both the complexes. In addition, the complexes also show promising cleavage of pUC19 supercoiled plasmid DNA with 1 showing the highest cleavage activity of ∼ 99%. In addition, both the complexes selectively recognize l -histidine amino acid. The low detection limit values (0.085 μM and 0.19 μM for complexes 1 and 2 , respectively) ascertain the making of an efficient l -histidine biosensor. The absorption, emission and mass spectral results establish the formation of Cu(His) 2 complex, with liberation of the fluorescent free ligand as the mechanism of sensing. [ABSTRACT FROM AUTHOR]

[Display omitted] The synthesis, structural characterization and biological relevance of three paddlewheel binuclear carboxylate copper(II) complexes with the formulae [Cu 2 (2-nitrophenylacetate) 4 (H 2 O) 2 ]C 2 H 5 OH (1), [Cu 2 (diclofenate) 4 (acetone) 2 ] (2) and [Cu 2 (4-bromophenylacetate) 4 (pyridine) 2 ] (3) have been presented here. These complexes have been characterized using melting point, FTIR, absorption spectroscopy, electron spin resonance, cyclic voltammetry (CV) and single crystal XRD techniques, while their biological relevance was ascertained using molecular docking and DNA-binding studies. The FTIR spectra indicated all the important functionalities and the typical bridging bidentate coordination mode of the carboxylate moieties to the copper ion. Absorption spectroscopy yielded broad spectra corresponding to the 2 B 1g ground state and the singly occupied d x 2– y 2 orbital, typical of the copper(II) ion. This finding was confirmed by the ESR signals of complexes 1 – 3 , with g values of 1.44353, 1.44317 and 1.44324, respectively. CV yielded redox couples typical of complexes with Cu2+ metal centers. XRD showed that the copper(II) ions in all three complexes are coordinated by four carboxylate ligands, constituting the square base of the square pyramid around each copper ion. The apical position is occupied by water (1), acetone (2) or pyridine (3) molecules. Owing to the structural differences, 1 and 3 have inter-molecular interactions and growth along all three axes, while 2 has such interactions only along the a-axis, leading to preferential growth along this axis. The structural parameters of the structures are different from each other and have been correlated mutually as well as with their literature analogues. Their supra-molecular synthons have been presented and explained. A computational study by molecular docking using MOE (molecular operating environment) software has yielded docking scores of −8.4098, −8.0453 and −9.4098, respectively for 1 – 3. The DNA-binding activity, explored via spectrophotometry and cyclic voltammetry, yielded intrinsic binding constant values of the order of 104 M−1 for all the complexes, showing excellent binding potency with DNA. The structural as well as biological importance of the complexes has been manifested. [ABSTRACT FROM AUTHOR]

Preparation, characterization and some applications of novel Cu(II) and Zn(II) compounds with halogenated bis-N,O-bidentate Schiff base ligands is reported. The structural elucidations of the synthesized compounds were confirmed by various spectroscopic and physicochemical methods. DNA binding experiments and molecular docking simulations illustrated that the ligands bound in minor grooves of DNA. The oxygen of the ethoxy group has played an important role in DNA binding investigations. • New metal complexes bearing halogenated bidentate N,O-donor Schiff base were synthesized and characterized. • Single crystal X-ray analysis was used to structure determination. • Computational calculations were carried out by DFT and TD-DFT. • The interactions of ligands and complexes with DNA were studied by spectroscopic and computational methods. • The results obtained from theoretical calculations support our experimental studies. A novel series of transition metal complexes of Cu(II) and Zn(II), including: [Cu(L1) 2 ]: C1 , [Cu(L2) 2 ]: C 2, [Cu(L3) 2 ]: C3 , [Cu(L4) 2 ]: C4 , [Zn(L1) 2 ]: Z1 , [Zn (L2) 2 ]: Z2 , [Zn (L3) 2 ]: Z3 , and [Zn (L4) 2 ]: Z4 , with four halogenated bis-N,O-bidentate Schiff base ligands (H L1 : 2-ethoxy-6-[(4-fluorophenyl)iminomethyl]phenol; H L2 : 2-ethoxy-6-[(4-chlorophenylimino)methyl]phenol; H L3 : 2-ethoxy-6-[(4-bromophenyl)iminomethyl]phenol; H L4 : 2-ethoxy-6-[(4-iodophenylimino)methyl]phenol have been synthesized and characterized by elemental analyses, FT-IR, UV–Vis and 1H NMR spectroscopic techniques. Furthermore, the crystal structures of H L2 , H L4 , Z1 and Z2 were determined by single crystal X-ray analysis. These bidentate ligands coordinated to the metal(II) ions through the deprotonated phenolic oxygens and the azomethine nitrogens. The X-ray diffraction analysis revealed that Z1 and Z2 adapted distorted tetrahedral geometries. Theoretical calculation of the synthesized compounds, carried out by DFT as well as TD-DFT using B3LYP method with employing the Def2-TZVP basis set, indicated that the calculated results are in accordance with the experimental findings. NBO analysis has been used to elucidate charge transfer information of the H L2 , H L4 , Z1 and Z2. Moreover, binding ability of the Schiff base ligands and their metal complexes with FS-DNA was studied by spectroscopic and computational methods. The results of both methods showed that the ligands bound in minor grooves of DNA. The oxygen of the ethoxy group has played an important role in DNA binding investigations. [ABSTRACT FROM AUTHOR]

A set of copper(I) complexes with the general formula [CuBr(PPh 3)(N^N)] (N^N = 2,2′-bipyridine (1), 1,10-phenanthroline (2), 4,4′-dimethyl-2,2′-bipyridine (3), 4,4′-dimethoxy-2,2′-bipyridine (4), 3-(2-pyridyl)-4,5-diphenyl-1,2,4-triaine (5), 4,7-diphenyl-1,10-phenanthroline (6), 5-nitro-1,10-phenanthroline (7), dipyrido[3,2- a :2′,3′- c ]phenazine(8)) have been synthesized and characterized by elemental analysis, 31P NMR spectroscopy and mass spectrometry. The structure of complexes 5 and 7 were confirmed by X-ray crystallography. Complex 5 is the second example to be reported with an unusual 4 N -triazine-ligated coordination mode of the 3-(2-pyridyl)-4,5-diphenyl-1,2,4-triazine. Calculated energies of the two possible bidentate modes of the ligand (2 N - and 4 N -triazine) at the copper center showed no significant difference, rationalizing that with the absence of the steric hindrance effect around the metal center. Preliminary biological studies were conducted, highlighting the effect of the diimine ligands. Complexes 5 and 8 exhibited good cytotoxicity against prostate (PC-3), leukemia (MOLT-4) and breast (MCF-7) cancer cell lines, consistent with the presence of nitrogen heteroatoms and extended delocalized systems correlating with strong cytotoxic performance. Binding affinity studies against ct-DNA and docking studies with B-DNA and MDM2 protein highlighted the strong π interactions of 5 and 8 , with the planarity of the diimine ligand of the latter contributing to its better binding and cytotoxicity. The current results afford structural requirements for the design of new copper(I) complexes with enhanced biological/physiochemical properties. • A set of complexes with [CuBr(PPh 3)(N^N)] formulation was synthesized. • The 2nd example of 4 N -triazine-ligated coordination mode of 3-(2-pyridyl)-4,5-diphenyl-1,2,4-triazine is reported. • Anticancer studies was conducted, highlighting the effect of the diimine ligands. • Good anticancer activities were associated with ligands with nitrogen heteroatoms and extended delocalized. • Docking studies were conducted to rationalize the results. The copper(I) coordination compounds of general formula [CuBr(PPh 3)(N^N)] (N^N = 2,2′-bipyridine (1), 1,10-phenanthroline (2), 4,4′-dimethyl-2,2′-bipyridine (3), 4,4′-dimethoxy-2,2′-bipyridine (4), 3-(2-pyridyl)-4,5-diphenyl-1,2,4-triazine (5), 4,7-diphenyl-1,10-phenanthroline (6), 5-nitro-1,10-phenanthroline (7), dipyrido[3,2- a :2′,3′- c ]phenazine(8)) have been synthesized and characterized by elemental analysis, 31P NMR spectroscopy and mass spectrometry. The structure of 5 and 7 were confirmed by X-ray crystallography. 5 is the second example to be reported with an unusual 4 N -triazine-ligated coordination mode of the 3-(2-pyridyl)-4,5-diphenyl-1,2,4-triazine. Calculated energies of the two possible bidentate modes of the ligand (2 N - and 4 N -triazine) at the copper center showed no significant difference, consistent with the absence of the steric hindrance at the metal center. Preliminary biological studies were conducted, highlighting the effect of the diimine ligands. 5 and 8 exhibited good cytotoxicity against prostate (PC-3), leukemia (MOLT-4) and breast (MCF-7) cancer cell lines, consistent with the presence of nitrogen heteroatoms and extended delocalized systems correlating with strong cytotoxic performance. Binding affinity studies against ct-DNA and docking studies with B-DNA and MDM2 protein highlighted the strong π interactions of 5 and 8 , with the planarity of the diimine ligand of the latter contributing to its better binding and cytotoxicity. The present results afford structural design requirements for new copper(I) coordination compounds with enhanced biological/physiochemical properties. [ABSTRACT FROM AUTHOR]

Yb(III), Sm(III) and La(III) complexes of a tetradentate Schiff base ligand, bis(pyridoxylidene) ethyelenediamine are reported. The complexes bind ct-DNA very strongly by intercalation mode. The low toxicity and bright fluorescence of the complexes can be used for bio-imaging. Yb(III), Sm(III) and La(III) complexes of a tetradentate Schiff base ligand, bis(pyridoxylidene)ethyelenediamine, are reported. Single crystal X-ray structures of the complexes reveal that in all the three complexes the Ln(III) ions are in a distorted dodecahedral geometry with N 4 O 4 -coordination environment provided by two coordinated ligands. Fluorescence spectroscopy shows that in the Yb(III) and Sm(III) complexes energy transfer from ligand centered excited state leads to population of an emissive f-f excited state. The complexes bind to ct-DNA, with high binding constant (K b) comparable to those compounds (like ethydium bromide) which bind by intercalative mode. Cytotoxicity study shows that the complexes have quite low cytotoxicity towards HeLa cells. Further, they exhibited fast response, bright fluorescence and stability at physiological pH, making them suitable for use in fluorescence bio-imaging. [ABSTRACT FROM AUTHOR]