Presence Of Complexes Research Articles

Influence of Li-N and Li-F co-doping on defect-induced intrinsic ferromagnetic and photoluminescence properties of arrays of ZnO nanowires

The role of N/F co-doping on the defect-driven room-temperature d0 ferromagnetism in group-I element Li doped ZnO nanowire arrays has been investigated. The ferromagnetic signature of pristine ZnO nanowires has enhanced significantly after Li doping but the Li-N co-doping has found to be more effective in the stabilization and enhancement in room-temperature ferromagnetism in ZnO nanowires. Saturation magnetization in Li-doped ZnO nanowires found to increase from 0.63 to 2.52 emu/g and the Curie temperature rises up to 648 K when 10 at. % N is co-doped with 6 at. % Li. On the other hand, Li-F co-doping leads to exhibit much poor room-temperature ferromagnetic as well as visible luminescence properties. The valance state of the different dopants is estimated by x-ray photoelectron spectroscopy while the photoluminescence spectra indicate the gradual stabilization of Zn vacancy defects or defect complexes in presence of No acceptor states, which is found to be responsible for the enhancement of intrinsic ferromagnetism in ZnO:Li matrix. Therefore, the Li-N co-doping can be an effective parameter to stabilize, enhance, and tune zinc vacancy-induced room-temperature d0 ferromagnetism in ZnO nanowires, which can be an exciting approach to prepare new class of spintronic materials.

The influence of local topography for wind direction on Mars: two examples of dune fields in crater basins

ABSTRACTIn this work, we perform an analysis of large dark dunes within Moreux Crater and Herschel Crater on Mars using High Resolution Imaging Science Experiment (HiRISE) and Context Camera (CTX) data sets. These data allow us to conduct a detailed analysis of dune morphology and slip faces, concluding that the studied dune fields are influenced by topographically‐controlled complex wind directions. Our morphological analysis reveals that inside Moreux Crater in particular, the topographic setting dominates the wind flow direction, leading to the development of a sand transport pathway encircling the central peak of the crater. The dune fields in Herschel Crater are also affected by winds controlled by variable topography as suggested by the presence of complex dunes and dune fields. Our analysis indicate that the studied dune systems is not the result of paleo‐wind regimes. Furthermore, we perform thermal inertia measurements using thermal emission spectrometer (TES) data, which indicate that the studied dune fields consist of medium sand 250–500 µm in diameter. Copyright © 2012 John Wiley & Sons, Ltd.

A Highly Efficient Turn-On Fluorescent Sensor for Determination of Water in Organic Solvents

2, 3 biphenyl quinoxaline 6-amine is a fluorescent compound in some organic solvents with an excitation wavelength at 435 nm and a fluorescence emission at 518 nm. The fluorescence intensity of 2, 3 biphenyl quinoxaline 6-amine is significantly reduced in the presence of bis-(2, 4, 6-trichlorophenyl) oxalate (TCPO) and Zn(2+) due to the nonfluorescent complex formation. The low stability of the complex in presence of trace amount of water results in decomposing complex, thereby recovering the photoluminescence of 2, 3 biphenyl quinoxaline 6-amine. Based on this fact, a turn-on fluorescence photoluminescence sensor for determination of water content in organic solvents was introduced for the first time.The fluorescence intensity of 2, 3 biphenyl quinoxaline 6-amine as a function of water concentration was used as a simple, sensitive and rapid method for determining trace amount of water in some organic solvents such as ethanol and methanol. The obtained results showed a good linear relationship between fluorescence intensity and the water content with a dynamic range of 0.0094 -1(v/v%), related coefficient of 0.9922 and limit of detection of 0.0026(v/v%). %).

Synthesis, characterization and application of enrofloxacin complexes as thermal stabilizers for rigid poly(vinyl chloride)

Synthesis and characterization of both binary Co(II)- (1), Ni(II)- (2) complexes with enrofloxacin drug (HL(1)) and ternary Co(II)- (3), Ni(II)- (4) complexes in presence of DL-alanine (H(2)L(2)) are reported using physico-chemical techniques. The antimicrobial activity of these complexes has been screened against two gram-positive and two gram-negative bacteria. Antifungal activity against two different fungi has been evaluated and compared with reference drug. All the binary and ternary complexes showed remarkable potential antimicrobial activity higher than the recommended standard agents. Ni(II)-complexes exhibited higher potency as compared to the parent drug against bacterial and fungal strain. In addition, it was of interest to investigate the reported complexes as thermal stabilizers and co-stabilizers for rigid PVC in air at 180 °C. Their high stabilizing efficiency is detected by their high induction period values (T(s)) compared with some of the common reference stabilizers used industrially, such as dibasic lead carbonate (DBLC) and calcium-zinc soap. Blending these complexes with some of the reference stabilizers in different ratios had a synergistic effect on both induction period as it gave better thermal stability and lower extent of discoloration. The stabilizing efficiency is attributed at least partially to the ability of the metal complex stabilizer to be incorporated in the polymeric chains, thus disrupting the chain degradation and replace the labile chlorine atoms on PVC chains by a relatively more s moiety of the inorganic stabilizer. Their amenability to use as a biomedical additives for PVC, has afforded them great potential for various medical applications.

Dimethylplatinum(II) Complexes: Computational Insights into Pt–C Bond Protonolysis

A detailed density functional theory (DFT) study of the protonation and subsequent methane elimination reactions of dimethylplatinum(II) complexes in presence of triflic acid in various solvents has been undertaken to contribute to the debate concerning the mechanism of the electrophilic cleavage of the Pt-C bond in Pt(II) complexes. Both mechanisms of direct one-step proton attack at the Pt-C bond (S(E)2) and stepwise oxidative-addition on the central metal followed by reductive elimination (S(E)(ox)) have been explored for a series of dimethylplatinum(II) complexes changing the nature of the ancillary ligands and the solvent. Theoretical calculations show that the most likely mechanism cannot be predicted on the basis of spectator ligands donating properties only. A one-step protonolysis pathway is characteristic for complexes containing P based ligands, whereas for complexes containing N based and, in general, hard poor-donor ligands a common behavior cannot be indicated. Solvent nucleophilicity can influence the rate of the S(E)(ox) rate mechanism, whereas its steric hindrance can induce a change of the preferred mechanism. The hypothesis that five-coordinate methyl hydrido platinum(IV) intermediates might be formed along the S(E)(ox) pathway is not supported. Only six-coordinate Pt(IV) hydride complexes are calculated to be stable intermediates generated by direct protonation at the platinum center. Formation and experimental detection of six-coordinate Pt(IV) hydrides, nevertheless, cannot be considered a definite evidence that a S(E)(ox) mechanism is operative because such intermediates can be also generated by a hydrogen migration to Pt from the carbon atom of the σ-complex methane molecule formed by a S(E)2 attack. For all the examined complexes methane loss occurs by an associative mechanism. Both solvent and anion of the acid can assist methane displacement. Calculations have been also carried out to probe whether the preference for a concerted or a stepwise mechanism should be predicted on the basis of two proposed criteria: metal-complex charge distribution as a consequence of the Pt-C bond polarization and the nature of the highest occupied molecular orbital (HOMO).

New copper(II), nickel(II) and zinc(II) complexes with 1,2,4-triazolo[1,5- a]pyrimidines and the chelating ligand 1,3-propanediamine: An unexpected coordination behavior for the 7-amine-derivative

Five new metal complexes with the metal ions Cu(II), Ni(II) and Zn(II) and containing 1,2,4-triazolo[1,5- a]pyrimidine derivatives and 1,3-propanediamine (tn) are described. The structural morphology of these coordination compounds depends on the triazolopyrimidine derivative used, being mononuclear for 5,7-dimethyl-1,2,4-triazolo[1,5- a]pyrimidine (dmtp) and 5-methyl-1,2,4-triazolo[1,5- a]pyrimidin-7(4 H)-one (HmtpO), and 1D-polymeric for 7-amine-1,2,4-triazolo[1,5- a]pyrimidine (7atp). In the 7atp case, this ligand does not coordinate through N3 atom, as expected, but through N1, N4 and N71 in a bridging fashion. This unexpected coordination mode seems to be induced by the stability of the polynuclear metal complex in presence of tn ligand. All isolated metal complexes have been characterized by single-crystal X-ray diffraction, IR and UV–Vis spectroscopies, and EPR measurements. Moreover, luminescence measurements have been carried out for 7atp ligand and its polynuclear complex with Zn(II).

Increasing complexity models for describing the generation of substrate radicals at the active site of ethanolamine ammonia-lyase/B 12

Ethanolamine ammonia-lyase ( EAL) is an adenosylcobalamin ( AdoCbl, a B 12 coenzyme) dependent enzyme expressed in enteric bacteria, which catalyzes conversion of ethanolamine in ammonia and acetaldehyde under anaerobic conditions. The most accepted reaction mechanism includes five steps: (a) 5-deoxyadenosyl radical ( Ado ) generation by homolytic cleavage of a Co–C bond in AdoCbl; (b) substrate activation by Ado H-abstraction from C 1; (c) 1,2-NH 2 migration in substrate’s radical; (d) Ado regeneration; (e) NH 3 elimination from substrate leaving acetaldehyde as final product. Steps a–c have been the subject of both empirical studies and computational modeling performed at the ab initio and DFT levels, with different representations of the protein environment, attempting to explain the observed kinetics by total/ partial protonation or by “ push– pull” catalysis assisted by two amino acid residues. In such models, a drastic reduction of the reactive system and of the influence of the enzyme environment was introduced, the latter mainly due to the lack of detailed data on the 3D structure of EAL (note elucidated until 2007) and the nature of the active site (for which a structure of the substrate- EAL complex in presence of adeninylpentylcobalamin has been very recently reported, shedding light on its structural features). Here we assess at the PCM//UB3LYP/6-31G(d,p) level how using a complete molecular description of both reactants in step b and introducing the polarizing effect of the protein/cofactor environment (mimicked through a continuum model with ε = 10) impacts on the nature and energetics of the intermediate complexes (ICs) and transition states (TSs) under three catalytic scenarios (total, partial, and no protonation). Our results show that a concerted asynchronous mechanism involving distonic radical species is at play, passing through quasi-linear early TSs displaying a C 1–H cleavage slightly more advanced than formation of the new H–C bond in Ado. Whereas the enzyme’s polarizing environment differentially stabilizes the TS lowering the barrier by ∼2.4–2.8 kcal/mol, a reduction of 1.4 kcal/mol in Δ G 298 ≠ is the outcome of substrate’s partial/total protonation, without a clear distinction among them, in opposition to what previously shown based upon more simplified models.

Oxidative DNA Damage Induced by a Copper(II)1,10‐PhenanthrolineL‐Serine Complex in the Presence of Rutin

The capacity of the ternary complex copper(II)-1,10-phenanthroline-L-serine ([Cu-Phen-Ser]) to induce double-strand scission of DNA was explored by agarose-gel electrophoresis. It was found that the complex exhibited remarkable activity to damage DNA in the presence of rutin. Analysis of the UV and fluorescence spectra clearly demonstrated that the complex was bound to DNA by intercalation. Further, the occurrence of 8-hydroxydeoxyguanosine (8-OHdG), a biomarker of oxidative DNA damage, after the treatment of DNA by the complex in presence of rutin was evidenced by an electrochemical method. Finally, the mechanism of oxidative damage to double-stranded DNA by the [Cu-Phen-Ser] complex in the presence of rutin was discussed.

Effect of silver nanoparticles with different shapes on luminescence of samarium complex at two different excitation wavelengths

The luminescence properties of Sm(TTFA)3 complex in presence of the silver (Ag) nanoparticles with size ranged from 80 nm to 120 nm and different shapes (nanorod, cube, tetrahedron, and nanowire) were investigated at two different excitation wavelengths of 397 nm and 350 nm, which was resonant and off-resonant excitation, respectively. The luminescence enhancement for the resonant excitation was much greater than that for the off-resonant excitation. The electric and magnetic dipole transitions were affected by the Ag nanoparticles and the results showed that their emission enhancement depended on the balance of the overlap between the emission wavelengths and the localized surface plasmon resonant of nanoparticles and their sensibility to the variation of local environments. The enhancement and quenching of the luminescence were both observed at the resonant excitation.

Photolysis of arene chromium tricarbonyl complexes in presence of amine–boranes: Observation of σ-borane complexes in solution

Activation of the B–H σ-bond of amine–boranes on the chromium(0) center of arene chromium tricarbonyl complexes ( η 6-arene)Cr(CO) 3 (arene = fluorobenzene, 1a; benzene, 1b and mesitylene, 1c) has been studied. Photolysis of 1b in presence of ammonia–borane (H 3N·BH 3, AB) and tert-butylamine–borane ( t BuH 2N·BH 3, TBAB) resulted in H 2 evolution and precipitation of a BNH x polymer. On the other hand, photolysis in the presence of trimethylamine–borane (Me 3N·BH 3, TMAB) resulted in the formation of a σ-borane complex ( 2) along with Cr(CO) 5( η 1-HBH 2·NMe 3) ( 3). The σ-borane complexes ( η 6-arene)Cr(CO) 2( η 1-HBH 2·NMe 3) (arene = fluorobenzene, 2a; benzene, 2b and mesitylene, 2c) were characterized in solution by 1H, 11B, and 13C NMR spectroscopy. Electron withdrawing substituents on the arene ring provide the more stable σ-borane moiety in this series of complexes.

SUMO-1 regulates the conformational dynamics of Thymine-DNA Glycosylase regulatory domain and competes with its DNA binding activity

BackgroundThe human thymine-DNA glycosylase (TDG) plays a dual role in base excision repair of G:U/T mismatches and in transcription. Regulation of TDG activity by SUMO-1 conjugation was shown to act on both functions. Furthermore, TDG can interact with SUMO-1 in a non-covalent manner.ResultsUsing NMR spectroscopy we have determined distinct conformational changes in TDG upon either covalent sumoylation on lysine 330 or intermolecular SUMO-1 binding through a unique SUMO-binding motif (SBM) localized in the C-terminal region of TDG. The non-covalent SUMO-1 binding induces a conformational change of the TDG amino-terminal regulatory domain (RD). Such conformational dynamics do not exist with covalent SUMO-1 attachment and could potentially play a broader role in the regulation of TDG functions for instance during transcription. Both covalent and non-covalent processes activate TDG G:U repair similarly. Surprisingly, despite a dissociation of the SBM/SUMO-1 complex in presence of a DNA substrate, SUMO-1 preserves its ability to stimulate TDG activity indicating that the non-covalent interactions are not directly involved in the regulation of TDG activity. SUMO-1 instead acts, as demonstrated here, indirectly by competing with the regulatory domain of TDG for DNA binding.ConclusionsSUMO-1 increases the enzymatic turnover of TDG by overcoming the product-inhibition of TDG on apurinic sites. The mechanism involves a competitive DNA binding activity of SUMO-1 towards the regulatory domain of TDG. This mechanism might be a general feature of SUMO-1 regulation of other DNA-bound factors such as transcription regulatory proteins.

Simultaneous Spectrophotometric Determination of Iron, Cobalt and Copper by Partial Least-Squares Calibration Method in Micellar Medium

Iron, cobalt and copper are metals, which appear together in many real samples, both natural and artificial. Recently a classical univariate micellar colorimetric method has been developed for determination of these metal ions. The organized molecular assemblies such as micelles are used in spectroscopic measurements due to their possible effects on the systems of interest. The ability of micellar systems to solublize slightly insoluble or even very insoluble complexes and/or ligands has been used to enhance the analytical merit of the given methods. The ability of micelles to solublize complexes in aqueous solutions can eliminate the need for non-aqueous extraction step in a given analysis. The simultaneous determination of Fe, Co and Cu was carried out as 1-nitroso-2-naphtol complexes in presence of aqueous solution of nonionic surfactant of Triton-X100. A partial least-squares multivariate calibration method for the analysis of ternary mixtures of Fe, Co and Cu was developed. For individual determinations, molar absorptivities and the limit of detection were obtained, respectively. The total relative standard error for applying the method on synthetic samples was 2.02%. The proposed method was also successfully when applied to the determination of Fe, Co and Cu in several synthetic alloy solutions

Synthesis, characterization and biological studies of some Co(II), Ni(II) and Cu(II) complexes derived from indole-3-carboxaldehyde and glycylglycine as Schiff base ligand

The Schiff base ligand derived from indole-3-carboxaldehyde(indal) and glycylglycine(glygly) were synthesized and characterized by elemental analysis, IR, electronic spectrum, 1H NMR and mass spectrum. Co(II), Ni(II) and Cu(II)–indal-glygly Schiff base complexes were synthesized and characterized by elemental analysis, molar conductance, IR, electronic spectra, magnetic measurements, ESR, electrochemical studies, TGA, DSC analysis, XRD and SEM. Conductance measurements indicate that the above complexes are 1:1 electrolytes. IR spectral data show that the ligand is tridentate and the binding sites are azomethine nitrogen, peptide nitrogen and carboxylato oxygen atoms. Electronic spectral measurements indicate tetrahedral geometry for Co(II) and Ni(II) complexes and square planar geometry for Cu(II) complex. Magnetic measurements show weak ferromagnetic behaviour for Co(II) and Ni(II) complexes and paramagnetic behaviour for Cu(II) complex. ESR spectral data shows the ionic link between metal and the Schiff base ligand. The metal complexes are found to be stabilized in the unusual oxidation states of the metal ion during electrolysis. Thermal analysis of the complex indicates that the decomposition takes place in three steps. IR and thermal studies indicate that the fourth position would be occupied by a water molecule in complexes. XRD shows that the complexes have the crystallite size of 31, 40 and 67nm, respectively. The surface morphology of the complexes was studied by SEM. The antimicrobial activity of the ligand and its complexes were screened by Kirby Bayer Disc Diffusion method. DNA cleavage studies were performed for metal–Schiff base complexes in presence of hydrogen peroxide as oxidant.

Cover Picture: Substituent‐Free Gallium by Hydrogenolysis of Coordinated GaCp*: Synthesis and Structure of Highly Fluxional [Ru2(Ga)(GaCp*)7(H)3] (Angew. Chem. Int. Ed. 21/2009)

AbstractSoft skin, hard core …︁ is the basic principle for the formation of a nano‐alloy from molecular precursors. The co‐hydrogenolysis of ruthenium complexes in presence of GaCp* gives the isolable key intermediate [Ru2(Ga)(GaCp*)7(H)3] featuring a substituent‐free bridging gallium atom. From this “embryonic” species Ru/Ga phases are formed by complete cleavage of the protective Cp* shell (depicted as an eggshell in the Cover picture), as described by R. A. Fischer et al. in their Communication on page 3872 ff.magnified image

High-dimensional mixed-valence copper cyanide complexes: Syntheses, structural characterizations and magnetism

Reactions of CuCl 2 with different CN complexes in presence of a neutral ancillary ligand lead to two novel mixed-valence Cu complexes [Cu II(bpy)Cu I(CN) 3] n , 1 (bpy = 2,2′-bipyridine) and {[Cu II(tn) 2][Cu I 4(CN) 6]} n 2 (tn = 1,3-diaminopropane). For compound 1, the asymmetric unit involves two Cu ions Cu1 and Cu2 (Cu I and Cu II centres, respectively) which strongly differ in their environments. The Cu1 ion presents a CuC 4 pseudo-tetrahedral geometry, while the Cu2 ion presents a CuN 5 slightly distorted square-pyramidal geometry. The extended structure of 1 is generated by three cyano ligands which differ in their coordination modes. One CN group has a μ 3 coordination mode and bridges two Cu I and one Cu II ion, while the two other CN groups act as μ 2 bridges leading to a sophisticated 3-D structure. As for 1, the asymmetric unit of 2 involves three crystallographically different Cu ions (Cu1A and Cu1B, presumably Cu I centres, and Cu2 presumably Cu II centres). The Cu2 ion presents centrosymmetric CuN 4 coordination environments involving four nitrogen atoms from two bidentate tn ligands; while the Cu1A and Cu1B ions are three coordinated to cyano groups. The structure can be described as formed by 18-membered “[Cu I(CN)] 6” planar metallocycles that are connected to their six neighbors to generate 2-D sheets; these sheets stack forming infinite hexagonal channels in which the [Cu(tn) 2] 2+ units are located. Magnetic measurements show an unexpected weak ferromagnetic coupling ( θ = 0.239(1) K) of the Cu II ions through the long and “a priori diamagnetic” –NC–Cu I–CN– bridges in compound 1 and an essentially paramagnetic behavior in compound 2.

Preparation and bioevaluation of a 99mTc-labeled chlorambucil analog as a tumor targeting agent

Chlorambucil belongs to a group of nitrogen mustards which are used for the treatment of variety of cancers. Hence, a chlorambucil derivative has been radiolabeled with [99mTc(CO)3(H2O)3]+ core and its efficacy as a tumor targeting agent has been evaluated. Radiochemical yield of the complex was >98% as observed by HPLC. The in vitro studies in MCF-7 breast cancer cells showed about 30% inhibition of the radiolabeled complex in presence of the cold chlorambucil derivative. Biodistribution studies in Swiss mice bearing fibrosarcoma tumor showed an uptake of 3.2±0.3%ID/g at 3h.p.i.

Effect of particle size and alloying with different metals on 57Fe Mössbauer spectra

Iron nanoparticles of various sizes have been synthesized using the chemical route which involves the preparation of iron bipyridine complexes in presence of different capping agents followed by thermal decomposition at 450°C in inert atmosphere. The bimetallic nanoalloys of Fe with Mg and Pd have also been prepared by following the same route. The resulting nanoparticles have been characterized by EDX-RF, XRD, AFM and 57Fe Mossbauer spectroscopy. The appearance of quadrupole doublets in the Mossbauer spectra of Fe nanoparticles indicates the absence of magnetic interaction and variation in parameters is due to the varying particle size. The Mossbauer spectrum of Fe–Mg2 bimetallic nanoalloy shows two doublets indicating the presence of superparamagnetism. The two doublets can be attributed to change in s-electron density of iron resulting from its two neighboring magnesium atoms. Fe–Pd nanoalloy Mossbauer spectrum is characterized by having a superparamagnetic doublet and a ferromagnetic sextet.

Synthesis of new piperazine derived Cu(II)/Zn(II) metal complexes, their DNA binding studies, electrochemistry and anti-microbial activity: Validation for specific recognition of Zn(II) complex to DNA helix by interaction with thymine base

New 3,4:9,10-dibenzo-2,11-dihydroxy-1,12-bispiperazine-5,8-dioxododecane complexes [C 24H 36N 4O 6Cu] ( 1), [C 24H 32N 4O 4Zn] ( 2) have been synthesized and characterized by elemental analysis, IR, NMR, Mass, EPR, UV–vis spectroscopy and molar conductance measurements. The complexes are non-ionic in nature and possess octahedral geometry around Cu 2+, Zn 2+ central metal ions. The binding studies of 1 and 2 with calf thymus DNA (CT-DNA) were investigated by UV–vis, fluorescence, cyclic voltammetery and viscosity measurements. The calculated binding constant K b for 1 and 2 obtained from UV–vis absorption studies was 7.6 × 10 3 M −1, 80.8 × 10 4 M −1, respectively. The intrinsic binding constants were also estimated to be 7.0 × 10 4 M −1 and 7.53 × 10 5 M −1 for 1 and 2, respectively by using emission titrations. These experimental results suggest that complexes are groove binders and interact to CT-DNA with different affinities. Both the complexes in presence and absence of CT-DNA show quasireversible wave corresponding to Cu II/Cu I and Zn II/Zn I redox couple. The changes in E 1/2, Δ E, I pa/ I pc ascertain the interaction of 1 and 2 with CT-DNA. Further, decrease in viscosity of CT-DNA with increasing concentration of complexes was observed. In vitro, antimicrobial activity against fungi A. brassicicola, A. niger and bacteria E. coli, P. aeruginosa of complexes were carried out, which indicate that complex 2 is more active against both fungal and bacterial strains as shown by % inhibition data.

Synthesis and Kinetic Study of Hydroxy/Fluoroapatite Solid Solution Formation by Decomposition of a Ca‐EDTA Complex

AbstractFluoroapatite/hydroxyapatite (FA/HA) solid solutions were synthesized through the decomposition of a Ca(EDTA) complex in presence of phosphate and fluoride ions. Fluorine content and morphology depend on initial pH value. Phase identification, fluorine content, crystallinity and morphology of the obtained products were studied via chemical analysis, FTIR, SEM, XRD, and EDS. The kinetic study shows a catalytic dependence on pH value. The values of k0, kH+ and kOH are reported.

Dimethyl sulfoxide ruthenium(II) complexes of thiosemicarbazones and semicarbazone: Synthesis, characterization and biological studies

In an attempt to synthesize Ru(II)-dmso-thiosemicarbazone complexes, a series of carbonyl compounds were selected to condense with thiosemicarbazide in ethanol in order to get the respective thiosemicarbazone ligand as the first step. All the selected carbonyl compounds yielded the expected thiosemicarbazone ligand, but the product obtained by the reaction of benzaldehyde with thiosemicarbazide in ethanol was found to show sharp IR peak characteristic of C O group and thought to be benzaldehyde semicarbazone. When the ligands were treated with cis-[RuCl 2(dmso) 4)] in ethanol, all the ligands yielded thiosemicarbazone complexes, while the suspected semicarbazone ligand resulted in orange-yellow crystalline product which has been found to be a semicarbazone complex by XRD studies. A mechanism has been proposed for the conversion of C S to C O during ligand preparation, which involves the role of adventitious water in ethanol. All the complexes were characterized by analytical and spectroscopic (IR, UV–Vis and 1H NMR) methods. The redox behaviors of the complexes were studied by cyclic voltammetry. The preliminary DNA-binding ability of the complexes was studied by recording electronic absorption spectra of the complexes in presence of herring sperm DNA. Antibacterial activities of the complexes were also been evaluated against five pathogenic bacteria.