Electrochemical Studies of the Recognition Interaction of Rhodamine B with DNA

The recognition interaction of rhodamine B (RB) with DNA was studied in pH 7.5 Britton-Robinson (B-R) buffer solution by electrochemical techniques. An irreversible oxidation peak at glassy carbon electrode was obtained at 0.92V (vs. SCE). After the addition of DNA into the RB solution, the peak current of RB decreased apparently without the shift of peak potential. The electrochemical parameters such as the charge transfer coefficient α and the electrode reaction standard rate constant ks of RB in the absence and presence of DNA were determined, which did not change, indicating that a non-electroactive complex was formed, so the concentration of RB in the solution decreased and the peak current decreased correspondingly.     

Studies on the Interaction of Cobalt Mixed-Ligand Coordination Compound Containing Tetrapyrido [3,2-a:2′,3′-c:3″, 2″-h:2■,3■-j] phenazine with DNA

A new monometallic complex [Co(phen)_2tpphz]~(3+) (where tpphz is tetrapyrido [3,2-a:2′,3′-c:3″,2″-h:2′″,3′″-j] phenazine) was synthesized by the reaction of 5, 6-diamino-1,10-phenanthroline with [Co(phen)_2(phendione)]~(3+). It was characterized by elemental analysis, molar conductivity, IR, ~1H NMR, ultraviolet and fluorescence spectroscopy. The interaction of the complex with DNA was also investigated. The complex shows the absorption hypochromicity, fluorescence enhancement, the specific viscosity increased when bound to calf thymus DNA. The cyclic voltammetry (CV) measurement showed a change in peak current with the addition of DNA. All the results provide the support for the intercalative binding mode of the mononuclear complex.     

Crystal structure and DNA binding studies of a cobalt(Ⅱ) complex containing mixed-ligands of 1,10-phenathroline and glycollic acid

A cobalt（11） complex containing mixed-ligands of 1,10-phenathroline（phen） and glycollic acid（GA）.|Co（GA）₂（phen）| was synthesized and its structure was characterized by X-ray diffraction.The interaction of the complex with DNA was investigated by electronic absorption spectra and electrochemical methods.Electronic absorption spectrum experiments showed that after interaction with DNA.the characteristic absorption peaks of |Co（GA）₂（phen）| underwent hypochromic effect as well as redshift. Also,the binding strength of 3.8×10⁴L/mol was estimated by titration method.Electrochemical assays revealed that the redox peak currents of the complex decreased obviously accompanied by a positive shift of the formal potential after association with DNA.All these results revealed that the synthesized cobalt complex bound with DNA via an intercalation mode.     

Investigation of radionuclide 60Co(II) binding to TiO2 by batch technique, surface complexation model and DFT calculations

The interaction between radionuclides and solid/water interfaces is important to understand the physicochemical processes of radionuclides in the natural environment.Herein,the interaction of 60Co(Ⅱ) with TiO 2 in aqueous solution as a function of pH and ionic strength was studied by using batch technique combined with surface complexation model and density functional theory(DFT) calculations.The batch experimental results showed that the adsorption of 60Co(Ⅱ) was dependent on pH and independent of ionic strength,indicating the formation of inner-sphere surface complexes on TiO 2 surfaces.The results of surface complexation models and DFT calculations indicated that the surface species of 60Co(Ⅱ) adsorbed on TiO 2 followed the trend:B structure(i.e.,60Co(Ⅱ) was linked to one bridge oxygen site) was the dominant surface species at low pH,and TT structure(i.e.,60Co(Ⅱ) was linked to two terminal oxygen sites) became the important surface complex at neutral and alkaline pH values.These results demonstrated that a multi-technique approach could lead to definitive information on the structures of adsorbed 60Co(Ⅱ) at the molecular level at the TiO 2 /water interfaces,as well as realistic models to rationalize and accurately evaluate the macroscopic manifestations of radionuclide adsorption phenomena.     

PMBP缩1-萘胺合钴(Ⅱ)配合物的合成和晶体结构

Using 4-[(1-naphthylamino)phenylmethylene]-5-methyl-2-phenyl-2H-pyrazol-3(4H) one (L), its Co(Ⅱ) complex was synthesized and characterized by IR and UV in which the ligand as a -1 valence bidentate with Co(Ⅱ) form 2∶1 complex. X-ray structure analysis indicates that the Co(Ⅱ) ion is coordinated with oxygen atoms of pyrazolinon, nitrogen atoms of imine and oxygen atoms of DMF molecules to form a distorted six-coordination octahedron. π-π reciprocity and aromatic stack interaction are observed. There are no intra- and inter- hydrogen bond in the crystal and the complexes are held together by electronic and Van der Waals forces.     

4-(2-QUINOLYLAZO)-1, 3-DIHYDROXY-NAPHTHALENE——A NEW SENSITIVE ANALYTICAL REAGENT FOR TRACE COPPER DETERMINATION

The azo compound 4-(2-quinolylazo)-1,3-dihydroxynaphthalene (2-QADNm) has been synthesized and used as a new sensitive spectrophotometric and electroanalytical reagent for determination of trace amounts of copper. In dilute alkaline solutions, 2-QADNm shows a single-sweep polarographic wave at -0.95 V (vs. SCE). In the presence of copper(Ⅱ) two new waves appear at -0.52 and -0.79 V. Using the wave at-0.79 V, a trace amount of copper down to 10~(-8) mol/L can be determined. The electroanalytical characteristics of 2-QADNm and the electrochemical reaction mechanism of the copper(Ⅱ)-2-QADNm complex have been studied in detail by the use of various electrochemical techniques. In alkaline solutions, 2-QADNm forms red complex with copper(Ⅱ) which has an absorption peak at 526 nm, the molar absorptivity being 6.4×10~4 1·mol~(-1)·cm~(-1). In the presence of a non-ionic surfactant the molar absorptivity of this complex is 1.6×10~5 1·mol~(-1)·cm~(-1).     

A new oxidovanadium(Ⅳ) Schiff base complex containing asymmetric tetradentate ONN0O0Schiff base ligand:Synthesis,characterization,crystal structure determination,thermal study and catalytic activity

After synthesis of an asymmetric tetradentate ONN0O0 Schiff base ligand(H2L) followed by reaction of the synthesized H2 L with an equimolar mixture of methanolic solutions of the VO(acac)2, a new oxidovanadium(IV) Schiff base complex(VOL) was synthesized. The Schiff base ligand and its complex were characterized by FT-IR and UV–vis spectra and C, H, N analysis. The crystal structure of VOL was also determined by single crystal X-ray analysis. The VOL complex crystallizes in monoclinic space group Cc. The Schiff base ligand acts as a tetradentate ligand through its two iminic nitrogens and two phenolic and acetylacetonate oxygens. Thermogravimetric analysis of the VOL showed that it decomposes in two steps and converts to mixed vanadium oxides at 477 8C. In addition, thermal decomposition of the VOL complex in air at 660 8C leads to formation of V2O5 nanoparticles with the average size estimated from XRD 49 nm. The catalytic activity of the VOL complex was investigated in the epoxidation reaction and different reaction parameters were optimized. The results showed that the cyclic alkenes were efficiently converted to the corresponding epoxides, whereas the VOL did not appreciably convert the linear alkenes.     

A mixed-valent high spin(μ-hydroxo)dicobalt(Ⅱ/Ⅲ) complex and its end-on type dioxygen adduct: synthesis,geometric and electronic structure studies

A mixed-valent high spin (μ-hydroxo)dicobalt(Ⅱ/Ⅲ) complex bearing N,N′-bis(5-tertbutylsalicylidene)-1,2-diaminobenzene(Salophen~(t Bu)) ligand was synthesized by reacting (Salophen~(t Bu))Co(Ⅱ)(Py) with O_2 at low temperature.This complex was isolated and structurally characterized by single crystal X-ray diffraction and infrared spectrum.Magnetic measurement showed a quartet ground state for this complex at room temperature,which was also supported by electron paramagnetic resonance (EPR)characterization.Computational investigations indicated the deviation of the equatorial N_2O_2 coordination geometry around the Co(Ⅱ) center from plane stabilized the quartet state.The end-on type O_2 adduct of this (μ-hydroxo)dicobalt(Ⅱ/Ⅲ) complex was isolated as dark-brown crystals and structurally and spectroscopically characterized.EPR measurement of this compound in solid state at room temperature presented an isotropic singlet at g～2,revealing the superoxide-like electronic feature of the coordinated O_2 and was in line with the calculation results.The reactivity of the Co(ⅡI)-O_2 complex with N-hydroxyphthalimide,which can act as hydrogen atom donor,was also examined.     

Synthesis of a New Cobalt (II) Complex and its Interaction with DNA

The interaction of metal complexes with DNA has been widely studied by differentmethods such as spectrophotometry, light scattering technique, fluorometry1-3. Manycomplexes such as Co(phen)2 ,Co(en)2 ,Fe(EDTA)2- etc.4,5 have been synthesized and 3+ 3+their effect on DNA has been studied in order to further explain the mechanism of genemutation, anti-cancer or cancer-induced reason and DNA targeted drugs. In this paper,a new cobalt complex was synth…     

多吡啶锌配合物键合与切割DNA研究

The complex of Zn[(phen)(dione)Cl]ClO_4·H_2O(where phen is 1,10-phenanthroline and dione is 1,10-phenan-throline-5,6-dione)has been synthesized and characterized.The interaction of the complex with DNA was investi-gated using UV absorption,fluorescence spectroscopy and electrophoresis measurements.The results show that thecomplex mainly binds to the double helix of DNA with intercalation mode and the binding constant K is 2.4×10~4mol~(-1)·L.Moreover,the complex can efficiently cleave plasmid DNA at physiological pH and temperature.Thecleavage occurs via a hydrolysis mechanism,which is showed by adding radical scavengers,rigorously anaerobicexperiments,analysis for malondialdehyde-like products,and the hydrolysis experiment of BDNPP with a rate con-stant k_(obs)of 5.3×10~(-6)s~(-1).     

A MODEL STUDY ON MODE OF BONDING OF CISPLATIN WITH DNA

The interaction of cis-[Pt(NK_3)_2Cl_2] with nucleosides, as constituents of DNA, was studled by spectrophotometric, ~(13)C NMR and CNDO/2 methods. The apparent stability constants of the complexes formed and the initial rate of formation were determined. The sites of binding of nucleoside (or nucleotide) with Cisplatin were ascertained and the electronic structure of the model coordination compounds of Cisplatin and guanine was calculated by MO approach. On the basis of the obtained results, the mechanism of the antitumour action of Cisplatin was discussed, and a new possible mode of bonding of Cisplatin with DNA was proposed.     

Studies on the Interaction of Beryllon Ⅲ with Proteins by Voltammetric Technique and its Application

A new quantitative determination method of proteins using beryllon Ⅲ by voltammetric technique was developed in this paper. In pH 3.5 Britton-Robinson (B-R) buffer solution, beryllon Ⅲ can bind with human serum albumin (HSA) to form an electro-inactive supermolecular complex. Beryllon Ⅲ has a well-defined voltammetric reduction peak at -0.38 V (vs. SCE) and the addition of protein in this solution can cause the decrease of the reductive peak current. Based on the decrease of the reduction peak current, a new electrochemical method for the determination of HSA was established with linear range of 1.0-40.0 mg/L and the detection limit of 1.0 mg/L. This method is further applied to the determination of real sample of healthy human serum.     

Amplified ultraviolet detection of natural DNA based on Mo6S9-xIx nanowires

We demonstrate that Mo_6S_(9_x)I_x nanowires(MoSI NWs) can serve as an excellent signal-intensifying nanomaterial for highly sensitive and label-free detection of DNA by ultraviolet(UV) spectrophotometry.The DNA extinction at 260 nm was greatly enhanced after addition of MoSI NWs solute,and the extinction value was linear with DNA concentration in the range of 0.0289-11.68 μg/mL with the real determination limit of 28.9 ng/mL.The association of DNA with the nanowires was characterized by transmission electronmicroscopy and circular dichroic spectroscopy.The results illustrate that the UV response amplification of DNA in the presence of MoSI NWs is attributed to the greater DNA coverage on the MoSI NW surface and the conformational transformation of DNA due to interaction of DNA with MoSI NWs.MoSI NWs are a promising nano-structured material for developing ultrasensitive sensors for detection of DNA.     

Synthesis, Crystal Structure and DNA Binding Studies of a Nickel（II） Complex with 2-Aminomethylbenzimidazole and Demethylcantharate

A new mixed-ligand nickel(Ⅱ) complex, [Ni(L)(DCA)(H2O)]·2H2O (L = C8H9N3, 2-aminomethyl-benzimidazole, DCA2- = 7-oxabicyclo[2,2,1]heptane-2,3-dicarboxylate, demethylcantharate, C8H8O5), has been synthesized and characterized. The structure of the complex was determined by single-crystal X-ray diffraction. It is of monoclinic system, space group P21/c with a = 7.7211(7), b = 12.0799(12), c = 19.7867(19), β = 100.390(6)°, V = 1815.2(3) nm3, Dc = 1.625 g·cm-3, Ζ = 4, F(000) = 928, R = 0.0314 and wR = 0.0822. In addition, the interaction between the complex and DNA was studied by means of fluorescence spectra and viscosity. The results indicate that the complex binds to DNA by the mode of partial intercalation with the Stern-Volmer constants Ksv of 3.81 × 104 mol·L-1.     

Celestine blue as a new indicator in electrochemical DNA biosensors

Celestine blue(CB)was introduced as a new electroactive indicator in DNA biosensors.The interaction of CB with DNA was investigated by electrochemical and spectroscopic methods.The effect of buffer kind and p H on the electrochemical behavior of CB was studied.The peak currents of CB were linearly related to DNA concentration in the range of 5.0×10~(-9) to 1.0×10~(-7)mol/L.The detection limit of this approach was 4.76×10~(-10) mol/L.Based on spectrometry data a hypochromic effect was observed in UV-Vis spectra of CB with increasing DNA concentration.The results illustrate the possible interaction mode between CB and DNA is electrostatic binding.     

Iodide analysis by ion chromatography on a new stationary phase of polystyrene-divinylbenzene agglomerated with polymerized-epichlorohydrin-dimethylamine

A new stationary phase for iodide ion analysis has been developed. The cationic polymerepichlorohydrin-dimethylamine(PEPI-DMA) was served as modifier in synthesizing polyelectrolyte sorbents and the macroporous polystyrene-divinylbenzene(PS-DVB) resin was used as support. The positively charged polymer(PEPI-DMA) was electrostatically bonded to a negatively charged particle(PS-DVB sulfonated). The new stationary phase was characterized by scanning electron microscopy(SEM), Fourier transform infrared(FTIR), elemental analysis, chemical adsorption and desorption measurements. The chromatographic evaluation of the new stationary phase was performed using various anions with a conductivity detector. The new stationary phase was also applied to the determination of iodide directly with a DC amperometric detector using a platinum working electrode and an Ag/Ag Cl reference electrode. The chromatographic conditions were optimized and the eluent solution contained 5 mmol/L HNO3 and 15 mmol/L Na NO3 at a flow rate of 1.0 m L/min and column temperature of 30 8C. The applied voltage of the DC amperometric detector was 0.9 V. Under the optimum conditions, the linear range of the method was 0.2–50 mg/L for iodide ion with a correlation coefficient of 0.9990. The detection limit was 0.05 mg/L(calculated at S/N = 3) and the relative standard deviations(RSD, n = 6) were all less than 1% for retention time, peak area and peak height. This method was also utilized for the determination of iodide ions in samples of povidone iodine solution and kelp samples with satisfactory results.     

Electrochemical Studies on the Interactions of Dipyridophenazine Complex of Ruthenium and Herring Sperm DNA

Cyclic voltammetry (CV) and single-step chronocoulometry were used to study the interaction of [Ru(phen)2dppz]2 (phen=l,10-phenanthroline; dppz=dipyrido[3,2-a:2‘,3‘-c]phen-azine) with herring sperm DNA. The addition of DNA caused a diminution in the peak current and a positive shift in the peak potential of the complex of [Ru(phen)2dppz]2 . The 12 mV positive shift in the peak potential of [Ru(phen)2dppz]^2 indicates that [Ru(phen)2dppz]^2 binds 2.6 times more strongly to DNA than its reductive form. In addition, by using fluorimetric and UV-spectrophotometric methods and studies of denatured DNA and the effect of NaC1 solution, it was also found that the binding mode was intercalation. The decrease of peak current is proportional to the concentration of DNA, which can be applied to estimate DNA concentration.     

Effect of Cr and Co Promoters Addition on Vanadium Phosphate Catalysts for Mild Oxidation of n-Butane

In this study, Cr and Co promoted, as well as unpromoted vanadium phosphate (VPO) catalysts were synthesized by the reaction of V2O5 and o-H3PO4 in organic medium followed by calcination in n-butane/air environment at 673 K. The physico-chemical properties and the catalytic behavior were affected by the addition of Cr and Co dopants. H2-TPR was used to investigate the nature of oxidants in the unpromoted and promoted catalysts. The results showed that both the Cr and Co promoters remarkably lowered the temperature of the reduction peak associated with V5 . The amount of oxygen species originated from the active phase, V4 , removed was significantly increased for Co and Cr-promoted catalysts. Both Cr and Co dopants improve strongly the n-butane conversion without sacrificing the MA selectivity. A good correlation was observed between the amount of oxygen species removed from V4 phase and the activity for n-butane oxidation to maleic anhydride. This suggested that V4 -O was the center for the activation of n-butane.     

三元配合物钯（Ⅱ）-2,2''-联吡啶-L-天冬氨酸与DNA作用研究

The ternary complex Pd(Ⅱ)-2,2‘-bipyridine-L-asparagic acid was synthesized and characterized by elemental analysis, IR-spectra and molar conductance. The formula of the complex is Pd(bipy)(L-asp). The interaction of the complex with DNA has been studied by UV-spectra, fluorescence spectra, CD-spectra and gel electrophoresis. The results showed that the interaction of the complex with DNA performed mainly in intercalative mode and the extent of interaction was dependent on the concentration of the complex.     

Synthesis and Characterization of a New Ligand 2-（4, 5-Dihydro-2-thiazolyl）-6-methoxylbenzothiazole and Its Dinuclear Co（II） Complex

A new ligand 2-(4,5-dihydro-2-thiazolyl)-6-methoxyl benzothiazole and its new dinuclear Co(II) coordination complex [Co(C11H10N2OS2)Cl2]2·2CHCl3 (1) have been synthesized and characterized. Complex 1 was synthesized by the reaction of Co(II) salt with 2-(4,5-dihydro- 2-thiazolyl)-6-methoxyl benzothiazole under room-temperature evaporation condition and struc- turally characterized by single-crystal X-ray diffraction analysis and IR spectroscopy. The supramolecular network of complex 1 is stabilized by the presence of intermolecular interaction, such as C–H···Cl hydrogen bonding and π-π stacking. The complex crystallizes in triclinic, space group P1 with a = 8.3288(12), b = 10.5273(15), c = 10.822(2), α = 93.416(3), β = 90.864(3), γ = 94.890(3)o, V = 943.60(2)3, Z = 2, Dc = 1.758 g/cm3, F(000) = 498 and μ = 1.840 mm-1. The final complex [Co(C11H10N2OS2)Cl2]2·2CHCl3 is a diplex bridged dinuclear complex consisting of two Co(II) ions, two ligands, two bridging Cl- anions and two terminal Cl- anions.