New heteroleptic palladium(II) dithiocarbamates: synthesis,characterization, packing and anticancer activity against five different cancer cell lines

Two new heteroleptic palladium(II) complexes have been synthesized by reacting equimolar quantities of palladium(II) chloride, sodium 4‐(2‐methoxyphenyl)piperazine‐1‐carbodithioate and diphenyl‐p‐tolylphosphine ( 1 ) or tri‐p‐tolylphosphine ( 2 ). Complexes 1 and 2 have been characterized using elemental analysis, Fourier transform infrared spectroscopy, multinuclear NMR (¹H, ¹³C and ³¹P) spectroscopy and single‐crystal X‐ray analysis. The latter technique confirms a pseudo square‐planar geometry in which two adjacent positions are occupied by bidentate dithiocarbamate while chloro and substituted triphenylphosphine are present at the remaining two positions. The anticancer activity of both complexes against five different cancer cell lines (LU – human lung carcinoma, established at UIC, Department of Surgical Oncology; MCF7 – human breast adenocarcinoma, ATCC number HTB‐22?; MDA‐MB‐231 – human breast adenocarcinoma, ATCC number HTB‐26?; Hepa‐1c1c7 – mouse liver hepatoma, ATCC number CRL‐2026?; PC‐3 – human prostate adenocarcinoma, ATCC number CRL‐1435?) was determined by MTT assay, revealing 2 has higher activity than 1 . A drug–calf thymus DNA binding study with UV–visible spectroscopy reveals a higher DNA binding affinity of 2 (3.511 × 10⁴ M^?1) than 1 (4.213 × 10³ M^?1). Density functional theory studies confirm the relatively more stable nature of 2 than 1 . Copyright © 2016 John Wiley & Sons, Ltd.     

DNA binding ad photocleavage properties of cationic porphyrin-polypyridyl ruthenium(II) hybrids

Three cationic porphyrin-polypyridyl ruthenium(II) hybrids, differing in the planar areas of the polypyridyl moieties, were synthesized and their interactions with DNA investigated using absorption and fluorescence titration, induced circular dichroism spectra, thermal DNA denaturation measurements, as well as surface-enhanced Raman spectroscopy. Ethidium bromide competition experiments determined the binding affinity constants (K_b) of these compounds for CT DNA. DNA photocleavage experiments indicated that these hybrids have a broader cleaving wavelength range than traditional drugs and ¹O₂ is the reactive species responsible for the cleavage. The proper planar area was proved to be responsible for the larger K_b and higher DNA photocleavage efficiency.     

Heteroleptic Pd(II) dithiocarbamates: synthesis,characterization, packing and in vitro anticancer activity against HeLa cell line

Two new heteroleptic Pd(II) dithiocarbamates (1 and 2) have been synthesized by reaction of equimolar quantities of palladium(II) chloride, sodium 4-(3-methoxyphenyl)piperazine-1-carbodithioate, and appropriate substituted triphenylphosphines. The synthesized complexes have been characterized by their physical, spectral (IR, ¹H, ¹³C, and ³¹P NMR), and X-ray crystallographic data. Complexes 1 and 2 showed square-planar geometry both in solution and solid states. The crystal packing of both complexes revealed similar 3-D-supramolecular networks comprised of 1-D chains. However, the nature and strength of various non-covalent interactions of these networks were slightly different. The DNA interaction studies of the complexes have been carried out by UV–visible spectroscopy to evaluate their anticancer potential. The study suggested intercalative interaction with 2.402 × 10⁴ and 2.713 × 10³ M^?1 binding constants, respectively. The complexes have also been evaluated for their anticancer activity against HeLa cell line. Both complexes showed higher activity with IC₅₀ values much lower (22.176 and 26.166 μM for 1 and 2, respectively) than the standard cisplatin (78.075 μM). Furthermore, the complexes induced stronger DNA fragmentation as investigated by DNA ladder assay for apoptosis. Our findings suggested that the anticancer action of these compounds stems from their interaction with DNA leading to DNA damage and apoptosis. The excellent activity of 1 and 2 deserves to be a focus for further research and in vivo studies.     

Rhenium(II) nitrosyl complexes: synthesis,characterization, DFT calculations and DNA nuclease activity

The rhenium(II) dinitrosyl and mononitrosyl complexes, i.e. [Re(NO)₂(CN)₄]·(Phen)₂·2H₂O (1) and PhenH[Re(NO)(CN)₄(H₂O)]·(Phen)·3H₂O (2) have been isolated and characterized. The X-ray crystal structure of 2 reveals that Re(II) is octahedrally coordinated with one nitrosyl, four cyanides, and one water, with one phenanthroline protonated to compensate the charge of the Re(II) center. The crystal structure shows chemically significant non-covalent interactions like hydrogen bonding involving the uncoordinated water and π–π interactions between phenanthrolinium and phen. The structures of both complexes have been optimized by DFT. Absorption and emission spectral studies and viscosity measurements indicate that both 1 and 2 interact with calf thymus DNA through partial intercalation of DNA bases. The intrinsic-binding constants, obtained from UV–vis spectroscopic studies, are 1.2?×?10⁴ and 7.2?×?10⁴?M^?1 for 1 and 2, respectively. Both 1 and 2 are capable of inducing cleavage of plasmid DNA in the presence of H₂O₂ to form the supercoiled form to nicked circular form. The spectroscopic results of DNA binding are supported by molecular docking studies.     

Oxovanadium(IV) and ruthenium(II) carbonyl complexes of ONS‐donor ligands derived from dehydroacetic acid and dithiocarbazate: Synthesis,characterization, antioxidant activity,DNA binding and in vitro cytotoxicity

A series of new complexes of oxovanadium(IV) [VO(L)(B)] and ruthenium(II) [Ru(CO)(PPh₃)₂(L)] ( 1.1- 1.3,  2.1–2.3 ) (H₂L = dehydroacetic acid Schiff base of S‐methyldithiocarbazate, H₂smdha ( 1 ) or S‐benzyldithiocarbazate, H₂sbdha ( 2 ); B = 2,2′‐bipyridine (bpy) or 1,10‐phenanthroline (phen)) have been synthesized. The structure of these complexes was authenticated using elemental analyses and spectroscopic techniques, and their magnetic properties and electrochemical behaviour were studied. The molecular structures of oxovanadium(IV) complexes [VO(smdha)(bpy)]?CH₂Cl₂ ( 1.1 ) and [VO(sbdha)(phen)]?2H₂O ( 2.2 ) were confirmed using single‐crystal X‐ray crystallography. Analytical data showed that the ligands 1 and 2 are chelated to the metal centres in a bi‐negative tridentate fashion through azomethine N, thiol S and deprotonated hydroxyl group. The antioxidant activity of the synthesized compounds was tested against 2,2‐diphenyl‐1‐picrylhydrazyl) radical, which showed that the complexes demonstrate a better scavenging activity than their corresponding ligands. The cupric ion reducing antioxidant capacity method was also employed and the total equivalent antioxidant capacity values were found to be higher for the oxovandium(IV) complexes. DNA binding affinity of the compounds was determined using UV–visible and fluorescence spectra, revealing an intercalation binding mode. Higher cytotoxicity for the complexes compared to their ligands was found against human liver hepatocellular carcinoma (HepG2) and breast adenocarcinoma (MCF7) cell lines using MTT assay.     

Homobimetallic zinc(II) dithiocarbamates: synthesis,characterization and in vivo antihyperglycemic activity

This article presents structural characteristic and in vivo antihyperglycemic activities of three new homobimetallic Zn(II) dithiocarbamates (1–3) with general formula [ZnL₂]₂, where L is 4-(3-methoxyphenyl)piperazine-1-carbodithioate (1), 4-(4-methoxyphenyl)piperazine-1-carbodithioate (2) and 4-benzhydrylpiperazine-1-carbodithiaoate (3). These complexes have been characterized by elemental analysis, FT-IR, multinuclear NMR (¹H and ¹³C), and X-ray single crystal analysis. The latter technique has confirmed the homobimetallic nature of 1 and 2 in which Zn ions are linked via sulfurs to form a four-membered ring Zn₂S₂. Non-covalent intermolecular interactions give a supramolecular ladder-like zigzag chain (1) and layered structure (2). The antihyperglycemic activities revealed that the blood glucose lowering ability follows the trend: glibenclamide (83.0 mg dL^?1) > 3 (97.6 mg dL^?1) > 2 (100.4 mg dL^?1) > 1 (141.4 mg dL^?1).     

Copper(II) complexes of acylhydrazones: synthesis,characterization and DNA interaction

Two new acylhydrazone copper(II) complexes of 4‐hydroxy‐N′‐[(1E)‐1‐(4‐methylphenyl)ethylidene]benzohydrazide (HL¹) and 4 ethyl [4‐({(2E)‐2‐[1‐(4‐methylphenyl)ethylidene]hydrazinyl}carbonyl)phenoxy]acetate (HL²) have been synthesized and characterized. The structures of both acylhydrazone and copper(II) complexes were identified by elemental analysis, infrared spectra, UV–visible electronic absorption spectra, magnetic susceptibility measurements, TGA and powder X‐ray diffraction. DNA binding and DNA cleavage activities of the synthesized copper complexes were examined by using UV‐visible titration and agarose gel electrophoresis, respectively. The effect of complex concentration on the DNA cleavage reactions in the absence and presence of H₂O₂ was also investigated. The results indicate that all the complexes bind slightly to calf thymus DNA and cleavage pBR322 DNA. The mechanistic studies demonstrate that a hydrogen peroxide‐derived species and singlet oxygen (¹O₂) are the active oxidative species for DNA cleavage. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis,characterization and in vitro DNA binding studies of a new copper(II) complex containing an antiviral drug,valganciclovir

A new complex, [Cu(valcyte)₂(NO₃)₂], in which valcyte served as a valganciclovir drug, was synthesized and characterized by different physicochemical methods. Optimization of ligand structures and their complexes with Cu²⁺ were performed by semi-empirical and DFT methods. Binding interaction of this complex with calf-thymus DNA (ct-DNA) was explored by emission, absorption, circular dichroism and viscosity techniques. Additionally, cell line targeting was studied and cytotoxic effects of [Cu(valcyte)₂(NO₃)₂] (0.0–160 μg) on AGS and MCF-7 cell lines were reported. Percentage of Cell Viability and Apoptotic Index were assessed. The complex displayed significant binding properties to ct-DNA. Undertaking fluorometric studies, the binding mode of the complex with ct-DNA was explored utilizing Hoechst as a fluorescence probe, indicating the binding to be of groove mode. The DNA viscosity altered slightly in presence of the complex. Enthalpy and entropy changes during the interaction showed that the process is endothermic, with the complex mainly bound to ct-DNA by hydrophobic attraction. Values of ΔG revealed a spontaneous reaction between DNA and the complex. Optimized docked model of DNA–complex mixture confirmed the experimental results. The results of MMFF94 calculations indicated stability of [Cu(valcyte)₂(NO₃)₂] after docking with the modeled DNA profile, as compared to the DNA profile and valganciclovir results before the docking process. Cytotoxicity studies showed that an increase in [Cu(valcyte)₂(NO₃)₂] may result in a significant decrease in cell viability and increase apoptosis index in the treated cells, as compared to valganciclovir treated cells (p < 0.05). The findings further showed that [Cu(valcyte)₂(NO₃)₂] has potential for use in cancer therapy.     

Novel hydridotris(pyrazolyl)borate ruthenium(II) complexes containing the water-soluble phosphane 1,3,5-triaza-7-phosphaadamantane: Synthesis and evaluation of DNA binding properties

A series of half-sandwich ruthenium(II) complexes containing κ³(N,N,N)-hydridotris(pyrazolyl)borate (κ³(N,N,N)-Tp) and the water-soluble phosphane 1,3,5-triaza-7-phosphaadamantane (PTA) [RuX{κ³(N,N,N)-Tp}(PPh₃)_2−n(PTA)_n] (n = 2, X = Cl (1), n = 1, X = Cl (2), I (3), NCS (4), H (5)) and [Ru{κ³(N,N,N)-Tp}(PPh₃)(PTA)L][PF₆] (L = NCMe (6), PTA (7)) have been synthesized. Complexes containing 1-methyl-3,5-diaza-1-azonia-7-phosphaadamantane(m-PTA) triflate [RuCl{κ³(N,N,N)-Tp}(m-PTA)₂][CF₃SO₃]₂ (8) and [RuX{κ³(N,N,N)-Tp}(PPh₃)(m-PTA)][CF₃SO₃] (X = Cl (9), H (10)) have been obtained by treatment, respectively, of complexes 1, 2 and 5 with methyl triflate. Single crystal X-ray diffraction analysis for complexes 1, 2 and 4 have been carried out. DNA binding properties by using a mobility shift assay and antimicrobial activity of selected complexes have been evaluated.     

多吡啶钌配合物作为DNA结构探针的研究

本文对多吡啶钌配合物作为DNA荧光或结构探针的研究背景、研究技术及其特点、钌配合物与DNA的键合模式及其结合力大小的影响因素、钌配合物与DNA键合的异构选择性及不同键合速率、非放射性核酸标记及DNA分子光开关等方面进行了简要述评     

Cellular uptake, cytotoxicity, apoptosis, antioxidant activity and DNA binding of polypyridyl ruthenium(II) complexes

Ruthenium(II) polypyridyl complexes [Ru(phen)₂(APIP)](ClO₄)₂1 and [Ru(phen)₂(HAPIP)](ClO₄)₂2 have been synthesized and characterized. The DNA-binding behaviors were investigated by electronic absorption titration, luminescence spectra, viscosity measurements, thermal denaturation and photoactivated cleavage. The DNA-binding constants K_b for complexes 1 and 2 were determined to be 3.38 (±0.42) × 10⁵ M⁻¹ (s = 1.48) and 3.93 (±0.60) × 10⁵ M⁻¹ (s = 3.14), respectively. The studies on the photocleavage demonstrated that the effects of cleavage are concentration-dependent. The results showed that complexes 1 and 2 interact with CT-DNA by intercalative mode. The cytotoxicity of complexes 1 and 2 has been evaluated by MTT method. The apoptosis assay was carried out with acridine orange/ethidium bromide (AO/EB) staining methods. The cellular uptake showed that complexes can enter into the cytoplasm and accumulate in the nuclei. The antioxidant activity studies suggested that the ligands and complexes may be potential drugs to eliminate the radical.     

Synthesis,characterization and arsenate binding events of new mononuclear copper(II) complexes

Two new mononuclear copper (II) complexes [Cu(L)(H₂O)Cl] (1) and [Cu(L)(H₂O)(SCN)] (2) (HL = 2-[1-(2-dimethylamino-ethylimino)-ethyl]-phenol) have been synthesized and characterized in order to investigate their binding interaction with arsenate ions. Complexes 1 and 2 were synthesized by performing reaction of CuCl₂·2H₂O or CuCl₂·2H₂O/NH₄SCN, respectively, with HL using Et₃N as mild base in MeOH solution at room temperature, and characterized by employing a number of analytical techniques, for example, elemental analysis, molar electrical conductivity, FTIR, UV–Vis and mass spectrometry. Their structures, optimized at DFT/B3LYP/6-311G level, show that the copper atom in 1 and 2 exhibits a distorted square pyramidal geometry. In H₂O/MeOH (3:1; v/v) solution, complexes 1 and 2 were examined for their binding affinity towards arsenate ions. The UV–Vis spectroscopic results specify that the arsenate group binds with 1 and 2 in 1:1 M ratio. The UV–Vis titration data were successfully utilized to calculate the binding constants of arsenate-bound Cu(II) complexes, and the values are found to be 1.723 × 10⁴ M^?1 and 2.161 × 10⁴ M^?1, corresponding to 1/AsO₄^3? and 2/AsO₄^3? assemblies, respectively.     

One-pot synthesis,characterization, DNA binding and enzymatic studies of 4-methyl trans-cinnamate zinc(II)-mixed ligand complexes

Four new zinc(II) complexes formulated as [Zn(L)₂] (1), [Zn(L)₂(phen)] (2), [Zn(L)₂(bipy)H₂O] (3), and [Zn(en)₂(H₂O)₂](L)₂(H₂O)₂ (4), where HL = 4-methyl trans-cinnamic acid, bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline, and en = ethylenediamine, have been synthesized and characterized by FT-IR and NMR spectroscopy. Single-crystal XRD revealed distorted square-pyramidal structure for 3 and octahedral for 4. The complexes were screened for DNA interaction via viscommetry and UV–visible spectroscopy. The apparent binding constants were calculated to be 1.18 × 10⁴, 1.26 × 10⁵, 4.64 × 10⁴_, and 1.89 × 10⁴ for 1–4, respectively. The binding propensity to salmon sperm DNA was in the order: K₂ > K₃ > K₄ > K₁. Furthermore, these complexes demonstrated efficient inhibition of alkaline phosphatase, which was attributed to the binding of zinc(II) to the enzyme’s active site.     

New mixed ligand complexes of ruthenium(II) that incorporate a modified phenanthroline ligand: Synthesis, spectral characterization and DNA binding

The hexafluorophosphate and chloride salts of two ruthenium(II) complexes, viz. [Ru(phen)(ptzo)₂]² and [Ru(ptzo)₃]²⁺, where ptzo = 1,10-phenanthrolino[5,6-e]1,2,4-triazine-3-one (ptzo) — a new modified phenanthroline (phen) ligand, have been synthesised. These complexes have been characterised by infrared, UV-Vis, steady-state emission and¹H NMR spectroscopic methods. Results of absorption and fluorescence titration as well as thermal denaturation studies reveal that both thebis- and tris-complexes of ptzo show moderately strong affinity for binding with calf thymus (CT) DNA with the binding constants being close to 10⁵M^-1 in each case. An intercalative mode of DNA binding has been suggested for both the complexes. Emission studies carried out in non-aqueous solvents and in aqueous media without DNA reveal that both [Ru(phen)(ptzo)₂]²⁺ and [Ru(ptzo)₃]²⁺ are weakly luminescent under these solution conditions. Successive addition of CT DNA to buffered aqueous solutions containing [Ru(phen)(ptzo)₂]²⁺results in an enhancement of the emission. These results have been discussed in the light of the dependence of the structure-specific deactivation processes of the MLCT state of the metallo-intercalator with the characteristic features of its DNA interaction. In doing so, attempts have been made to compare and contrast its properties with those of the analogous phenanthroline-based complexes including the ones reported by us previously.     

p‐Toluate‐bridged dinuclear Cu(II) complexes in combination with tridentate chelating ligand: Crystal structure,density functional theory calculation,DNA/protein binding and catecholase activity

The dinuclear Cu(II) complexes [Cu₂(L¹)₂(mb)]?ClO₄ ( 1 ) and [Cu₂(L²)₂(mb)]?ClO₄ ( 2 ) (HL¹ = 2‐[(2‐diethylaminoethylimino)methyl]phenol; HL² = 2‐[1‐(2‐diethylaminoethylimino)propyl]phenol; mb = 4‐methylbenzoate) were synthesized and characterized using X‐ray crystal structure analysis and spectroscopic methods. Complexes 1 and 2 are dinuclear with distorted square pyramidal Cu (II) geometries, where Schiff base coordinates with tridentate (N,N,O) chelating mode and mb bridges two metal centres. Optimized structures and photophysical properties of ligands and complexes were calculated using density functional theory and time‐dependent density functional theory methods using B3LYP functional with 6‐31G (d,p) and LanL2MB basis sets. Interactions of the complexes with bovine serum albumin (BSA) and human serum albumin (HSA) were studied using UV–visible absorption and fluorescence spectroscopies and the calculated values of association constants (M^?1) are 1.7 × 10⁵ ( 1 –BSA), 5.7 × 10⁵ ( 2 –BSA), 1.6 × 10⁵ ( 1 –HSA) and 6.9 × 10⁵ ( 2 –HSA). Interactions of the complexes with calf thymus DNA were also investigated and the binding affinities are 1.4 × 10⁵ and 1.6 × 10⁵ M^?1 for 1 and 2 , respectively. Both complexes catalytically oxidize 3,5‐di‐tert‐butylcatechol to 3,5‐di‐tert‐butylbenzoquinone in the presence of molecular oxygen.     

Synthesis,characterization and in vitro DNA binding studies of a new copper(II) complex containing antioxidant ferulic acid

A mononuclear Cu(II) complex, [Cu(FA)₂(NO₃)₂], in which FA is ferulic acid ((E)-3-(4-hydroxy-3-methoxy-phenyl)prop-2-enoic acid), was synthesized and characterized by spectroscopic methods. The main structures of the ligand and its complexes with Cu²⁺ were optimized by QM calculations. The calculations on the structures of the [Cu(FA)₂(NO₃)₂] complexes forms and the intercalating with DNA profile were undertaken by UHF/PM6 and MMFF94 methods, respectively. In vitro studies (UV-vis spectroscopy, emission titration, circular dichroism techniques, and viscometry) under physiological conditions (Tris-HCl buffer solutions, pH 7.4) showed that the complex interacts with calf-thymus DNA (ct-DNA) via an intercalative binding mode. The thermodynamic parameters, enthalpy change (ΔH), and entropy change (ΔS) showed that the acting forces between Cu(II) complex and ct-DNA mainly included van der Waals interactions and hydrogen bonds. Methylene blue (MB) displacement studies revealed that Cu(II) complex can substitute MB probe in the MB-DNA complex which was indicative of intercalative binding. The theoretical data confirm the experimental results with respect to the mechanism of binding.     

Coordination behavior of 3,4-bis(2-pyridylmethylthio)toluene with copper(II) ions: Synthesis,structural characterization and reactivity,and DNA binding study of the dinuclear copper(II) complex

On reaction of different copper(II) salts with 3,4-bis(2-pyridylmethylthio)toluene (L) having neutral tetradentate NSSN donor set in different chemical environments, two mononuclear copper(II), one dinuclear copper(I) and one dinuclear copper(II) complexes, formulated as [Cu^II(L)(H₂O)₂](NO₃)₂ (1), [Cu^II(pic)₂] (2), [Cu^I₂(L)₂](ClO₄)₂ (3) and [Cu^II₂(L)₂Cl₂](ClO₄)₂ (4), respectively, were isolated in pure form [where pic = picolinate]. All the complexes were characterized by physicochemical and spectroscopic methods. The product of the reactions are dependent on the counter anion of copper(II) salts used as reactant and on the reaction medium. Complexes 1 and 4 were obtained with nitrate and perchlorate copper(II) salts, respectively. On the other hand, C–S bond cleavage was observed in the reaction of L with copper(II) chloride to form in situ picolinic acid and complex 2. Dinuclear complexes 3 and 4 were separated out when copper(II) perchlorate was allowed to react with L in methanol and in acetonitrile, respectively, under aerobic condition. The X-ray diffraction analysis of the dinuclear complex 3 shows a highly distorted tetrahedral geometry about each copper ion. Complex 4 is converted to 3 in acetonitrile in presence of catechol. The spectral study of complex 4 with calf thymus DNA is indicative of a groove binding mode interaction.     

Synthesis,characterization, X-ray structure and DFT calculation of two Mo(VI) and Ni(II) Schiff-base complexes

In this study, the syntheses of two new Mo(VI) and Ni(II) complexes with H₂L tridentate (ONO) Schiff-base ligand have been described and fully characterized by means of elemental analysis, FT–IR, electronic, ¹H-NMR spectroscopy and single-crystal X-ray diffraction. In both complexes, the Schiff-base completely deprotonates and coordinates to the metal ion as a dianionic tridentate ligand via the donor oxygens and nitrogen atoms. The coordination numbers of Mo(VI) and Ni(II) are six and four, respectively. The DFT-B3LYP/6–31 + G (d,p) and PBEPBE/6–31 + G (d,p) calculations are carried out for the determination of the optimized structures. Frequency calculations and NBO analysis are also performed for characterization. According to the theoretical analysis of the complexes, ligand-to-metal donation is greater than back donation. NBO data revealed that the main contribution of the frontier orbitals belongs to L⁻².     

Fluorescent UO2(II) and ZrO(II) complexes: Synthesis,structural characterization,fluorescence, DNA binding studies and biological applications in cell probing

A new series of UO2(II) and ZrO(II) azo‐complexes based on 5‐nitro‐8‐hydroxyquinoline; [UO₂(H₂L¹)(NO₃)EtOH] (1), [ZrO(H₂L¹)(NO₃)H₂O] (2), [UO₂(HL²)(NO₃)EtOH]3H₂O (3), [ZrO(HL²)(NO₃)EtOH] (4), [UO₂(HL³)(NO₃)(H₂O)₃]2H₂O (5) and [ZrO(HL³)(NO₃)EtOH] (6); have been synthesized. The structure of these complexes has been characterized using elemental analysis, thermal analysis, molar conductance, UV–vis, IR, electron impact mass, X‐ray powder diffraction and NMR spectra. The results revealed the formation of non‐electrolyte mononuclear complexes via the N atom of the azo group or of the quinoline ring and the oxygen atom of the deprotonated OH. Fluorescence properties of the synthesized complexes have been examined and the fluorescence quantum yield (Φ_f) has been determined. The complexes have been tested as cell staining and imaging under the fluorescent microscope. The data showed that complexes 1 and 2 efficiently stain the nuclei in addition to some focal cytoplasmic areas. Other than complexes 3 and 4 exclusively stained the nuclei. On the other hand, complexes 5 and 6 stained the cytoplasm exclusively. It has been demonstrated that complex 4 was the most effective in cell staining. The binding constant (Kb) with DNA was calculated using UV–vis absorption titration and fluorescence spectral methods. It was concluded that complex 4 can be used effectively as fluorescent probes in studying cell biology.     

Synthesis, characterization, DNA binding and cleavage studies of chiral Ru(II) salen complexes

Interaction of chiral Ru(II) salen complexes (S)-1 and (R)-1 with Calf Thymus DNA (CT-DNA) was studied by absorption spectroscopy, competitive binding study, viscosity measurements, CD measurements, thermal denaturation study and cleavage studies by agarose gel electrophoresis. The DNA binding affinity of (S)-1 (6.25 × 10³ M⁻¹) was found to be greater than (R)-1 (3.0 × 10³ M⁻¹). The antimicrobial studies of these complexes on five different gram (+)/(−) bacteria and three different fungal organisms showed selective inhibition of the growth of gram (+) bacteria and were not affective against gram (−) and fungal organisms. Further, the (S)-1 enantiomer inhibited the growth of organisms to a greater extent as compared to (R)-1 enantiomer.