Direct Electrocatalytic Oxidation and Simultaneous Determination of 5‐Methylcytosine and Cytosine at Electrochemically Reduced Graphene Modified Glassy Carbon Electrode

Direct electrocatalytic oxidation and simultaneous determination of 5‐methylcytosine (5‐mC) and cytosine(C) were realized in alkaline solutions by differential pulse voltammetry (DPV) based on an electrochemically reduced graphene oxide (er‐GO) modified glassy carbon electrode (er‐GO/GCE). The as‐prepared er‐GO/GCE exhibited good electrocatalytic activity towards the oxidation of 5‐mC and C. Under optimum conditions, the er‐GO/GCE was applied to the simultaneous determination of 5‐mC and C with a significantly improved peak potential resolution (about 150 mV), and a linear relationship can be obtained in the range of 6–200.0 µmol/L and 8–250.0 µmol/L, respectively. In addition, the proposed method was further successfully applied to the analysis of methylation status in short CpG oligonucleotides with satisfactory results.     

Sol—Gel Derived Carbon Ceramic Electrode Bulk—Modified with Tris（1,10—phenanthroline—5,6—dione） iron （Ⅱ）Hexafluorophosphate and Its Use as an Amperometric Iodate Sensor

A surface‐renewable tris(1, 10‐phenanthroline‐5, 6‐dione) iron (D) hexafluorophosphate (FePD) modified carbon ceramic electrode was constructed by dispersing FePD and graphite powder in methyltrimethoxysilane (MTMOS) based gels. The FePD‐modified electrode presented pH‐dependent voltammetric behavior, and its peak currents were diffusion‐controlled in 0.1 mol/L Na₂SO₄ + H₂SO₄ solution (pH = 0.4). In the presence of iodate, dear electrocatalytic reduction waves were observed and thus the chemically modified electrode was used as an amperometric sensor for iodate in common salt. The linear range, sensitivity, detection limit and response time of the iodate sensor were 5 × 10^?6–1 × 10^?2 mol/L, 7.448 μA·L/ mmol, 1.2 × 10^?6 mol/L and 5 s, respectively. A distinct advantage of this sensor is its good reproducibility of surface‐renewal by simple mechanical polishing.     

Cu(II) and Ni(II)‐1,10‐phenanthroline‐ 5,6‐dione‐amino acid ternary complexes exhibiting pH‐sensitive redox properties

Syntheses, and electrochemical properties of two novel complexes, [Cu(phendio)(L ‐Phe)(H₂O)](ClO₄) ·H₂O (1) and [Ni(phendio)(Gly)(H₂O)](ClO₄)·H₂O (2) (where phendio = 1,10‐phenanthroline‐5,6‐dione, L ‐Phe = L ‐phenylalanine, Gly = glycine), are reported. Single‐crystal X‐ray diffraction results of (1) suggest that this complex structure belongs to the orthorhombic crystal system. The electrochemical properties of free phendio and these complexes in phosphate buffer solutions in a pH range between 2 and 9 have been investigated using cyclic voltammetry. The redox potential of these compounds is strongly dependent on the proton concentration in the range of ? 0.3–0.4 V vs SCE (saturated calomel reference electrode). Phendiol reacts by the reduction of the quinone species to the semiquinone anion followed by reduction to the fully reduced dianion. At pH lower than 4 and higher than 4, reduction of phendio proceeds via 2e^?/3H⁺ and 2e^?/2H⁺ processes. For complexes (1) and (2), being modulated by the coordinated amino acid, the reduction of the phendio ligand proceeds via 2e^?/2H⁺ and 2e^?/H⁺ processes, respectively. Copyright © 2006 John Wiley & Sons, Ltd.     

A Sensitive Fluorescence Quenching Method for the Determination of Iron( Ⅱ） with 1,10-Phenanthroline

A sensitive and selective fluorescence quenching method for the determination of Fe²⁺ with 1,10‐phenanthroline was developed. The fluorescence intensity of 1,10‐phenanthroline at λ_ex of 266 run and λ_em of 365 nm was constant in the range of pH 4.0 to 10.0 and decreased linearly upon addition of Fe²⁺ to its solution. This decrease was mainly due to a static quenching effect caused by the formation of a non‐fluorescent complex of Fe²⁺ with 1, 10‐phenanthroline. The total amount of iron was determined by using hydroxylamine hydrochloride to reduce Fe³⁺ to Fe²⁺. The linear range was from 5.0 × 10–⁷ to 2.0 × 10–⁵ mol/L with a detection limit of 2.4 × 10–⁸ mol/L at 3s?. The quenching constant of Fe²⁺ to 1,10‐phenanthroline was calculated to be (5.70 × 0.05) × 10⁴ L/mol at 25 °C. Effects of foreign ions on the determination of Fe²⁺ were investigated. The results of the new method for the determination of iron in tap water and natural water samples were in good agreement with those obtained by graphite atomic absorption spectrometry.     

Crystallographic report: Diaquabis(1,10‐phenanthroline)zinc(II) 4,5‐dihydroxy‐1,3‐benzenedisulfonate trihydrate

The zinc atom has a distorted octahedral geometry defined by two 1,10‐phenanthroline and two cis water molecules. A three‐dimensional network structure arises owing to extensive hydrogen bonds involving all the components of [Zn(phen)₂(H₂O)₂][C₆H₂(OH)₂(SO₃)₂]·3H₂O. Copyright © 2005 John Wiley & Sons, Ltd.     

Oxidative polymerization of 5 amino,1,10‐phenanthroline: A theoretical study

The molecular and electronic structures of 5‐amino‐1,10‐phenanthroline and its monoprotonated and diprotonated species were obtained from ab initio quantum mechanical calculations with unrestricted Hartree–Fock (HF) and Møller–Plesset perturbation theories. The analysis of the net atomic charges and the total spin densities show three possible sites for the monomeric coupling in the polymerization process. The minimal energy conformation for the different kinds of coupling in the formation of the dimers was obtained. The studies were extended to the HF/6‐311 + G(2d,p)//B3LYP (Becke's three‐parameter exchange functional and the gradient‐corrected functional of Lee, Yang, and Paar)/6‐31G(d) level of theory to obtain theoretical nuclear magnetic resonance spectra to study the number and kinds of species involved in the protonation mechanism. Theoretical and experimental nuclear magnetic resonance spectra are in excellent agreement. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004     

Application of the Fe3O4@1,10‐phenanthroline‐5,6‐diol@Mn nano‐catalyst for the green synthesis of tetrazoles and its biological performance

The Fe₃O₄ magnetic particles were modified with 1,10‐phenanthroline‐5,6‐diol (Phen) and the related Mn complex (Fe₃O₄@Phen@Mn) synthesized as a heterogeneous catalyst to be used for the one‐pot three‐component synthesis of various tetrazoles. The catalysts were characterized by several methods, such as the elemental analysis, FT‐IR, X‐ray powder diffraction, dispersive X‐ray spectroscopy, scanning electron microscopy, transmission electron microscopy, dynamic light scattering, thermogravimetric‐differential thermal analysis, vibrating sample magnetometer and X‐ray photoelectron spectroscopy. In addition, the antioxidant and antibacterial activities of the catalyst and its Phen ligand were in vitro screened with 2,2‐diphenyl‐1‐picrylhydrazyl by free radical scavenging methods. Results showed that the synthesized compounds possess strong antioxidant activity (IC50; 0.172  ±  0.005 mg ml^?1) as well as a good antibacterial potential in comparison to standards.     

Crystallographic report: Dibenzyl(dichloro)(1,10‐phenanthroline)tin (IV) chloroform solvate

The monomeric title compound features a distorted octahedral tin (IV) centre within a C₂Cl₂N₂ donor set with two cis Cl atoms and two trans benzyl groups. Copyright © 2005 John Wiley & Sons, Ltd.     

Electrocatalytic properties of guanine, adenine, guanosine-5'-monophosphate, and ssDNA by Fe(II) bis(2,2':6',2'-terpyridine), Fe(II) tris(1,10-phenanthroline), and poly-Fe(II) tris(5-amino-1,10-phenanthroline)

The electrocatalytic oxidations of guanine, adenine, guanosine-5'-monophosphate(GMP) and ssDNA were performed in the presence of Fe(II) bis(2,2':6',2'-terpyridine) and Fe(II) tris(1,10-phenanthroline) complexes as homogeneous catalysts by cyclic voltammetric methods. The Fe(II/III) redox couple of these compounds is responsible for their catalytic properties. The electrocatalytic oxidation current of above substrates were developed from the anodic peak currents of Fe(II) bis(2,2':6',2'-terpyridine) and Fe(II) tris(1,10-phenanthroline) complexes at about +0.93 V and 0.97 V, respectively. The electrocatalytic oxidative properties of guanine by Fe(II) bis(2,2':6',2'-terpyridine) complex was measured by amperometry method using the rotating disk electrodes. Electropolymerization of Fe(II) tris(5-amino-1,10-phenanthroline) complex produced thin polymer films on gold and glassy carbon electrodes. The electrochemical quartz crystal microbalance (EQCM) and cyclic voltammetry were used to study the in situ growth of the polymer. The poly(FeII(5-NH(2)-1,10-phen)(3)) exhibited a good electrocatalytic oxidation towards guanine and also for the mixture of guanine and adenine too.     

Crystallographic report: Cis‐[Zn(3,5‐dinitrobenzoato)2(1,10‐phenanthroline)2]·CH3CH2OH

Cis‐[Zn(3,5‐dinitrobenzoato)₂(1,10‐phenanthroline)₂]·CH₃CH₂OH features unidentate and cis‐disposed 3,5‐dinitrobenzoate ligands and chelating 1,10‐phenanthroline ligands so that a distorted octahedral N₄O₂ coordination geometry results. Copyright © 2005 John Wiley & Sons, Ltd.     

Syntheses and Crystal Structures of Copper(II) and Copper(I) dpp Complexes, [Cu(dpp)Br2] and [Cu(dpp)2][CuBr2] (dpp = 2,9‐diphenyl‐1,10‐phenanthroline)

The complexes [Cu(dpp)Br₂] ( 1 ) and [Cu(dpp)₂][CuBr₂] ( 2 ) (dpp = 2,9‐diphenyl‐1,10‐phenanthroline) were synthesized and characterized by single‐crystal X‐ray diffraction methods. Reaction of copper(II) bromide with the dpp ligand in dichloromethane at room temperature afforded 1 , which is a rare example of non‐square planar four‐coordinate copper(II) complexes. Complex 1 crystallizes in the monoclinic space group C2/c with a = 15.352(3), b = 13.192(3), c = 11.358(2) Å, β = 120.61(3)°, V = 1979.6(7) ų, Z = 4, D_calc = 1.865 g cm^?3. The coordination geometry about the copper center is distorted about halfway between square planar and tetrahedral. The Cu‐N distance is 2.032(2) Å and the Cu‐Br distance 2.3521(5) Å. Heating a CH₂Cl₂ or acetone solution of 1 resulted in complex 2 , which consists of a slightly distorted tetrahedral [Cu(dpp)₂]⁺ cation and a linear two‐coordinate [CuBr₂]^? anion. 2 crystallizes in the triclinic space group with a = 10.445(2), b = 11.009(2), c = 18.458(4) Å, α = 104.72(3), β = 94.71(3), γ = 103.50(3)°, V = 1973.3(7) ų, Z = 2, D_calc = 1.602 g cm^?3. The four Cu(1)‐N distances are between 2.042(3) and 2.067(3) Å, the distance of Cu(2)‐Br(1) 2.2268(8) Å, and the disordered Cu(3)‐Br(2) distances are 2.139(7) and 2.237(4) Å, respectively. Complex 2 could also be prepared by directly reacting CuBr with dpp in CH₂Cl₂.     

Synthesis,Characterization, and Luminescent Properties of Silver(I) Complexes based on Diphosphine Ligands and 2,9‐Dimethyl‐1,10‐phenanthroline

Five mono‐nuclear silver(I) complexes with the ligand 2,9‐dimethyl‐1,10‐phenanthroline, namely [Ag(DPEphos)(dmp)]BF₄ ( 1 ), [Ag(DPEphos)(dmp)]CF₃SO₃ ( 2 ), [Ag(DPEphos)(dmp)]ClO₄ ( 3 ), [Ag(DPEphos)(dmp)]NO₃ ( 4 ), and [Ag(dppb)(dmp)]NO₃ · CH₃OH ( 5 ) {DPEphos = bis[2‐(diphenylphosphanyl)phenyl]ether, dppb = 1,2‐bis(diphenylphosphanyl)benzene, dmp = 2,9‐dimethyl‐1,10‐phenanthroline} were characterized by X‐ray diffraction, IR, ¹H NMR, ³¹P NMR and fluorescence spectroscopy. Their terahertz (THz) time‐domain spectra were also studied. In these complexes the silver(I), which is coordinated by two kinds of chelating ligands, adopts four‐coordinate modes to generate mono‐nuclear structures. In complexes 1 , 3 – 5 , offset π ··· π weak interactions exist between the neighboring benzene rings. In the ³¹P NMR spectra, there exist splitting signals (dd), which can be attributed to the coupling of the ^107,109Ag–³¹P. All the emission peaks of these complexes are attributed to ligand‐centered excited states.     

Synthesis,characterization and 1,3‐butadiene polymerization behaviors of cobalt complexes bearing 2‐pyrazolyl‐substituted 1,10‐phenanthroline ligands

A series of cobalt(II) complexes containing tridentate 2‐pyrazolyl‐substituted 1,10‐phenanthroline ligands (L) with the general formula [LCoCl₂] have been successfully synthesized and fully identified by IR spectroscopy, elemental analysis and mass spectroscopy. Cobalt complexes Co4–Co8 were further confirmed by X‐ray crystallographic analysis, and all the complexes adopted distorted trigonal pyramid geometries around the cobalt center. In combination with methylaluminoxane, the complexes exhibit high cis‐1,4‐selectivity for 1,3‐butadiene polymerization. The catalytic activities of the complexes mainly depend on the nature of the substituent and its position at the pyrazolyl ring of the ligand. Complexes having a bulkier substituent on the pyrazolyl ring of the ligand show lower catalytic activity and the incorporation of electron‐withdrawing substituent enhances the activity. Polymerization behaviors were almost not affected with varying [Al]/[Co] ratio, but both activity and the cis‐1,4 content decrease slightly as polymerization temperature increasing. Copyright © 2013 John Wiley & Sons, Ltd.     

La(OH)_3纳米片修饰玻碳电极对鸟嘌呤和腺嘌呤的电催化氧化

以La(OH)3纳米片为修饰剂,制备了基于La(OH)3纳米片修饰玻碳电极(LNP/GCE)。采用循环伏安(CV)法研究了鸟嘌呤(G)和腺嘌呤(A)在该修饰电极上的电化学行为。实验结果表明,在HAc-NaAc缓冲溶液中,该修饰电极对G和A都表现出了良好的电催化性能。在最佳条件下,用差分脉冲伏安(DPV)法对G和A进行了测定,其氧化峰电流与G和A的浓度在0.1~10μmol/L范围内呈良好的线性关系,检测限(S/N=3)分别为0.01μmol/L和0.03μmol/L。将该修饰电极用于DNA中A和G的同时测定,获得较好结果。     

In‐house and synchrotron X‐ray diffraction studies of 2‐phenyl‐1,10‐phenanthroline,protonated salts,complexes with gold(III) and copper(II), and an orthometallation product with palladium(II)

Different salts of the 2‐phenyl‐1,10‐phenanthrolin‐1‐ium cation, (pnpH)⁺, are obtained by reacting 2‐phenyl‐1,10‐phenanthroline (pnp), C₁₈H₁₂N₂, (I), with a variety of anions, such as hexafluoridophosphate, C₁₈H₁₃N₂⁺·PF₆⁻, (II), trifluoromethanesulfonate, C₁₈H₁₃N₂⁺·CF₃SO₃⁻, (III), tetrachloridoaurate, (C₁₈H₁₃N₂)[AuCl₄], (IV), and bromide (as the dihydrate), C₁₈H₁₃N₂⁺·Br⁻·2H₂O, (V). Compound (I) crystallizes with Z′ = 2, with both independent molecules adopting a coplanar conformation. In (II)–(IV), a hydrogen bond exists between the cation and anion, while one of the lattice water molecules serves as a hydrogen‐bonded bridge between the cation and anion in (V). Reaction of (I) with HAuCl₄ gives the salt complex (IV); however, reaction with KAuCl₄ produces the monodentate complex trichlorido(2‐phenyl‐1,10‐phenanthroline‐κN¹⁰)gold(III), [AuCl₃(C₁₈H₁₂N₂)], (VI). Dichlorido(2‐phenyl‐1,10‐phenanthroline‐κ²N,N′)copper(II), [CuCl₂(C₁₈H₁₂N₂)], (VII), results from the reaction of CuCl₂·2H₂O and (I), in which the Cu^II center adopts a tetrahedrally distorted square‐planar geometry. The pendent phenyl ring twists to a bisecting position relative to the phenanthroline plane. The square‐planar Pd^II complex, bromido[2‐(phenanthrolin‐2‐yl)phenyl‐κ³C¹,N,N′]palladium(II), [PdBr(C₁₈H₁₁N₂)], (VIII), is obtained from the reaction of (I) with [PdCl₂(cycloocta‐1,5‐diene)], followed by addition of bromine. A coplanar geometry for the pendent ring is adopted as a result of the tridentate bonding motif.     

Hydrothermal Synthesis and Characterization of a One—Dimen—sional Copper（Ⅰ） Halide Cluster with 1,10—Phenanthroline

The title compound Cu₂Cl₂phen (phen = 1,10‐phenanthroline, C₁₂H₈N₂) 1 was synthesized from CuCl₂·2H₂O, CuCl and phen by hydrothermal method and its structure was determined by single crystal X‐ray analysis. With phen, CuG forms one‐dimensional chains, which comprise two zigzag chains based on fused Cu‐X units and connected via covalent bonds. The compound contains two crystallographically unique monovalent copper ions, Cu(1) and Cu(2). The Cu(1) atom in the tetrahedral site, is coordinated to two bridging Cl^? and two N atoms in phen. The Cu(2) atom with a slightly distorted triangular planar geometry, is coordinated to three Cl^?. The compound 1 was crystallized in monoclinic, space group P2₁/n with a = 0.37338(4), b = 1.9510(2), c = 1.68008(19) nm, β = 95.605 (3)°, R = 0.0458, and was characterized by elemental analysis, IR spectrum and TGA analysis.     

Experimental and Theoretical Studies on DNA‐Binding and Spectral Properties of ‘Light Switch’ Complexes [Ru(L)2(ppn)]2+ (L=2,2′‐Bipyridine and 1,10‐Phenanthroline; ppn=Pteridino[6,7‐f] [1,10]phenanthroline‐11,13‐diamine)

The ligand pteridino[6,7‐f] [1,10]phenanthroline‐11,13‐diamine (ppn) and its Ru^II complexes [Ru(bpy)₂(ppn)]²⁺ ( 1 ; bpy=2,2′‐bipyridine) and [Ru(phen)₂(ppn)]²⁺ ( 2 ; phen=1,10‐phenanthroline) were synthesized and characterized by elemental analysis, electrospray MS, ¹H‐NMR, and cyclic voltammetry. The DNA‐binding behaviors of 1 and 2 were studied by spectroscopic and viscosity measurements. The results indicate that both complexes strongly bind to calf‐thymus DNA in an intercalative mode, with DNA‐binding constants K_b of (1.7±0.4)?10⁶ M ^?1 and (2.6±0.2)?10⁶ M ^?1, respectively. The complexes 1 and 2 exhibit excellent DNA‐‘light switch’ performances, i.e., they do not (or extremely weakly) show luminescence in aqueous solution at room temperature but are strongly luminescent in the presence of DNA. In particular, the experimental results suggest that the ancillary ligands bpy and phen not only have a significant effect on the DNA‐binding affinities of 1 and 2 but also have a certain effect on their spectral properties. [Ru(phen)₂(ppn)]²⁺( 2 ) might be developed into a very prospective DNA‐‘light switch’ complex. To explain the DNA‐binding and spectral properties of 1 and 2 , theoretical calculations were also carried out applying the DFT/TDDFT method.     

Spectral,thermal, biological and multi‐heating rate kinetic properties of Cu(II) complexes containing N2O2 donor ligands: 1,10‐phenanthroline and acyl coumarins

A series of newly synthesized coumarin‐based mixed‐ligand copper complexes with 1,10‐phenanthroline (Ph) were investigated by means of thermogravimetry, differential thermogravimetry, differential scanning calorimetry (DSC), electronic spectra and magnetic measurements. Structural and spectroscopic properties of neutral bidentate ligands as well as all complexes were studied on the basis of mass spectra, NMR (¹H and ¹³C) spectra, FT‐IR spectrophotometry and elemental analyses. IR spectral data suggest tetra‐coordinated N₂O₂ bonding of ligand toward metal ion. Dynamic scan of DSC experiments for copper complexes were obtained at different heating rates (2.5–20°C min^?1). Isoconversion methods of Kissinger and Ozawa were used for the determination of the pre‐exponential factor (A), activation energy (E_a) and order of reaction (n). Kinetic parameters for second‐step degradation obtained by Kissinger's and Ozawa's methods are in good agreement. The results indicate that complexes are much stronger free radical scavenger and antioxidant compounds than ligands. Antimycobacterial screening of ligand and its copper compound against Mycobacterium tuberculosis shows clear enhancement in antitubercular activity upon copper complexation. Also good antimicrobial activities of the complexes against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Salmonella typhus, Aspergillus niger, Candida albicans and Aspergillus clavatus have been found compared to its free ligands. Copyright © 2012 John Wiley & Sons, Ltd.     

Syntheses,Crystal Structures and Cytotoxities of Silver (I) Complexes of 2,2′‐Bipyridines and 1,10‐Phenanthroline

The syntheses, characterizations and in vitro cytotoxities of seven soluble silver (I) compounds (1–7) with 2,2′‐bipyridine (bpy), 5,5′‐dimethyl‐2,2′‐bipyridine (dmbpy) and 1, 10‐phenanthroline (phen) are described. Two of the complexes, [Ag(dmbpy)(NO₃)] (1) and [Ag(dmbpy)]ClO₄(2), have been structurally established by single‐crystal X‐ray diffraction, which reveals the silver(I) atom in compound 1 is in a Y‐shape coordination geometry with two N atoms (av. Ag? N = 227.8 pm) from a chelate dmbpy ligand and an O atom (Ag? O=221.8(4) pm) from a monodentate nitrate. The Ag(I) atom in compound 2 is three‐coordinated by three N atoms, two of which are from a chelate dmbpy, and one from an acetonitrile ligand. The seven compounds showed strong cytotoxities in vitro to both normal and carcinoma cells.     

Synthesis and Structures of Bis(alkene) Complexes of Tungsten and Molybdenum, [M(CO)2(dpphen)(dbf)2] (M = W or Mo; dpphen = 4,7‐diphenyl‐1,10‐phenanthroline; dbf = dibutylfumarate)

Tungsten and molybdenum complexes [M(CO)₂(dpphen)(dbf)₂] (M = W 1 or Mo 2 ; dpphen = 4,7‐diphenyl‐1,10‐phenanthroline; dbf = dibutylfumarate) have been synthesized and structurally characterized by X‐ray diffraction analysis. In both complexes which have similar structure, the metal atom co‐ordination is distorted octahedral with dpphen and two CO groups in the equatorial plane and the metal atom binds in an η²‐fashion to the C–C bonds of two dbf ligands. The two C–C bonds are almost mutually orthogonal. The two complexes are different in conformation which result from face selection of the two dbf ligands for coordination to the metal atom.