Synthesis,crystallographic and spectroscopic characterization and magnetic properties of dimer and monomer ternary copper(II) complexes with sulfonamide derivatives and 1,10-phenanthroline. Nuclease activity by the oxidative mechanism

Three dinuclear and one mononuclear copper(II)-1,10-phenanthroline ternary complexes, [Cu(L1)(phen)(OH)]₂ (1), [Cu(L2)(phen)(OH)]₂·3H₂O (2), [Cu(L3)(phen)(OH)]₂ (3) and [Cu(L4)₂(phen)(H₂O)] (4), with thiadiazole sulfonamide derivative ligands: HL1 (N-(5-ethyl-1,3,4-thiadiazol-2-yl)naphthalene-1-sulfonamide), HL2 (N-(5-ethylthio)-1,3,4-thiadiazol-2-yl)-4-methylbenzenesulfonamide), HL3 (N-(5-ethyl-1,3,4-thiadiazol-2-yl)benzenesulfonamide) and HL4 (N-(5-ethyl-1,3,4-thiadiazol-2-yl)-4-methylbenzenesulfonamide) have been synthesized and characterized. In the four complexes each copper atom is five-coordinated. The structure of complexes 1, 2 and 3 consists of a dimeric unit with a C2 symmetry axis, where both coppers are bridged by two hydroxo anions. Magnetic measurements show that the dimer complexes are ferromagnetic according to the Cu–O–Cu angles. Cleavage experiments using pUC18 plasmid DNA in the presence of H₂O₂/ascorbic acid as an activating agent show that the title complexes are potent artificial chemical nucleases, the order of efficiency being 3 > 2 ∼ 1 > 4. Control cleavage experiments indicated that the dimer complexes are stronger artificial nucleases than the [Cu(phen)₂]²⁺ complex under the same experimental conditions, while the monomer 4 has a lower nuclease activity than the [Cu(phen)₂]²⁺ complex. The inhibition of the cleavage process in the presence of reactive oxygen intermediate scavengers suggests that the hydroxyl radical and the superoxide anion are reactive species for the breakage of the DNA strands.     

Polypyridyl-Based Copper Phenanthrene Complexes: A New Type of Stabilized Artificial Chemical Nuclease

The building of robust and versatile inorganic scaffolds with artificial metallo-nuclease (AMN) activity is an important goal for bioinorganic, biotechnology, and metallodrug research fields. Here, a new type of AMN combining a tris-(2-pyridylmethyl)amine (TPMA) scaffold with the copper(II) N,N′-phenanthrene chemical nuclease core is reported. In designing these complexes, the stabilization and flexibility of TPMA together with the prominent chemical nuclease activity of copper 1,10-phenanthroline (Phen) were targeted. A second aspect was the opportunity to introduce designer phenazine DNA intercalators (e.g., dipyridophenazine; DPPZ) for improved DNA recognition. Five compounds of formula [Cu(TPMA)(N,N′)]²⁺ (where N,N′ is 2,2-bipyridine (Bipy), Phen, 1,10-phenanthroline-5,6-dione (PD), dipyridoquinoxaline (DPQ), or dipyridophenazine (DPPZ)) were developed and characterized by X-ray crystallography. Solution stabilities were studied by continuous-wave EPR (cw-EPR), hyperfine sublevel correlation (HYSCORE), and Davies electron–nuclear double resonance (ENDOR) spectroscopies, which demonstrated preferred geometries in which phenanthrene ligands were coordinated to the copper(II) TPMA core. Complexes with Phen, DPQ, and DPPZ ligands possessed enhanced DNA binding activity, with DPQ and DPPZ compounds showing excellent intercalative effects. These complexes are effective AMNs and analysis with spin-trapping scavengers of reactive oxygen species and DNA repair enzymes with glycosylase/endonuclease activity demonstrated a distinctive DNA oxidation activity compared to classical Sigman- and Fenton-type reagents.     

Three new binuclear copper(II) complexes with isonicotinic acid N-oxide: syntheses,crystal structures and properties

Three new copper(II) complexes with isonicotinic acid N-oxide (HL) and 1,10-phenanthroline (phen) as ligands, [Cu(L)(phen)(H₂O)]₂(NO₃)₂···2H₂O (1), [Cu(L)(phen)(H₂O)]₂(ClO₄)₂···2H₂O (2), and [Cu(L)(phen)Br]₂- [Cu(L)(phen)(H₂O)]₂Br₂···6H₂O (3) have been synthesized and structurally characterized. The structures of all three complexes feature a Cu₂ dimer formed by two Cu(II) ions interconnected by two bridging ligands. Each copper(II) ion has a distorted square pyramidal coordination geometry with elongated axial coordination by an aqua ligand or halogen anion. The isonicotinic acid N-oxide anion is bidentate, being coordinated to two Cu(II) ions through its N-O oxygen and one of its carboxylate oxygen atoms. Magnetic susceptibility measurements show a Curie–Weiss paramagnetic behavior characteristic of one unpaired electron for a copper(II) ion for all three complexes.     

New mononuclear copper(II) complexes from β-diketone and β-keto ester N-donor heterocyclic ligands: structure,bioactivity, and molecular simulation studies

Four new mononuclear copper(II) complexes with methyl acetoacetate and benzoylacetone in the presence of 1,10-phenanthroline and 2,2′-bipyridine were synthesized and characterized by elemental analyses, FT-IR, and UV–Vis spectroscopy. The molecular structures of complexes [Cu(MAA)(bpy)(ClO₄)] (1a), [Cu(bzac)(bpy)]ClO₄ (2a), [Cu(MAA)(phen)(ClO₄)] (1b) and [Cu(bzac)(phen)(ClO₄)] (2b) were determined by single crystal X-ray diffraction technique. 1a, 1b, and 2b are five coordinate with a distorted square pyramidal geometry and the structure of 2a consists of isolated [Cu(bzac)(bpy)]⁺ cations and perchlorate counter anions. The electrochemical studies of copper complexes in acetonitrile solution showed that Cu^II/Cu^I reduction processes are electrochemically irreversible. Cytotoxic activity of complexes was screened, including an MTT assay against gastric cancer cell line (MKN-45). The four Cu(II) complexes exhibited lethal effects against MKN-45 cell lines and the half maximal inhibitory concentration (IC₅₀) values obtained were much lower in comparison with 5-fluorouracil. In addition, MTT and migration studies revealed that benzoylacetone complexes are more active than complexes of methyl acetoacetate against the MKN-45 cancer cell lines. Docking simulations of Cu(II) complexes on DNA revealed that the most stable adducts with DNA bind in the minor groove. All complexes display a binding specificity to the A/T rich regions.     

Methyl substituent effect on one‐dimensional copper(II) coordination polymers containing biologically active ligands: Synthesis,characterization, DNA interactions and cytotoxicities

Three novel water‐soluble copper(II) complexes – {[Cu(phen)(trp)]ClO₄·3H₂O}_n ( 1 ), {[Cu(4‐mphen)(trp)]ClO₄·3H₂O}_n ( 2 ) and [[Cu(dmphen)(trp)(MeOH)][Cu(dmphen)(trp)(NO₃)]]NO₃ ( 3 ) (phen: 1,10‐phenanthroline; 4‐mphen: 4‐methyl‐1,10‐phenanthroline; dmphen: 4,7‐dimethyl‐1,10‐phenanthroline; trp: l ‐tryptophan) – have been synthesized and characterized using various techniques. Complexes 1 and 2 are isostructural, and exist as one‐dimensional coordination polymers. Complex 3 consists of two discrete copper(II) complexes containing [Cu(trp)(dmphen)(MeOH)]⁺, [Cu(trp)(dmphen)(NO₃)] and one nitrate anion. The binding interaction of the complexes with calf thymus DNA (CT‐DNA) was investigated using thermal denaturation, electronic absorption and emission spectroscopic methods, revealing that the complexes could interact with CT‐DNA via a moderate intercalation mode. The binding activity of the complexes to CT‐DNA follows the order: 3  >  2 > 1 . The pUC19 DNA cleavage activity of the complexes was investigated in the absence and presence of external agents using the agarose gel electrophoresis method. Especially, in the presence of H₂O₂ as an activator, the pUC19 DNA cleavage abilities of the complexes are clearly enhanced at low concentration. Addition of hydroxyl radical scavenger dimethylsulfoxide shows a marked inhibition of the pUC19 DNA cleavage activity of the complexes. In vitro cytotoxic effect of the complexes was examined on human tumor cell lines (Caco‐2, A549 and MCF‐7) and healthy cells (BEAS‐2B). The potent cytotoxic effect of complex 3 , with IC₅₀ values of 1.04, 1.16 and 1.72 μM, respectively, is greater relative to clinically used cisplatin (IC₅₀ = 22.70, 31.1 and 22.2 μM) against the Caco‐2, A549 and MCF‐7 cell lines.     

Stabilities and coordination modes of histidine in copper(II) mixed-ligand complexes with ethylenediamine,diethylenetriamine or N,N,N′,N″,N″-pentamethyldiethylenetriamine in aqueous solution

Solution equilibrium studies on the Cu(II)–polyamine–histidine ternary systems (polyamine: ethylenediamine (en), diethylenetriamine (dien), N,N,N′,N″,N″-pentamethyldiethylenetriamine (Me₅dien)) have been performed by pH-potentiometry, UV–Vis spectrophotometry and EPR methods. The obtained results suggest the formation of the mixed-ligand complexes with [Cu(A)(His)]⁺ stoichiometry in all studied systems. Additionally, in the systems with dien and Me₅dien protonated [Cu(A)(H–His)]²⁺ species also exists in acid solution. Our spectroscopic results indicate the tetragonal geometry for the [Cu(en)(His)]⁺, the geometry slightly deviated from square pyramidal for the [Cu(dien)(His)]⁺ and strongly deviated from square pyramidal towards trigonal bipyramidal for the [Cu(Me₅dien)(His)]⁺ species. The coordination modes in these mixed-ligand complexes are discussed.     

Copper complexes as chemical nucleases

Redox active mononuclear and binuclear copper(II) complexes have been prepared and structurally characterized. The complexes have planar N-donor heterocyclic bases like 1,10-phenanthroline (phen), dipyridoquinoxaline (dpq) and dipyridophenazine (dppz) ligands that are suitable for intercalation to B-DNA. Complexes studied for nuclease activity have the formulations [Cu(dpq)₂(H₂O)] (ClO₄)₂.H₂O (1), [CuL(H₂O)₂(μ-ox)](ClO₄)₂ (L = bpy,2; phen,3; dpq,4; and dppz,5) and [Cu(L)(salgly)] (L = bpy,6; phen,7; dpq,8; and dppz,9), where salgly is a tridentate Schiff base obtained from the condensation of glycine and salicylaldehyde. The dpq complexes are efficient DNA binding and cleavage active species. The dppz complexes show good binding ability but poor nuclease activity. The cleavage activity of thebis-dpq complex is significantly higher than thebis-phen complex of copper(II). The nuclease activity is found to be dependent on the intercalating nature of the complex and on the redox potential of the copper(II)/copper(I) couple. The ancillary ligand plays a significant role in binding and cleavage activity.     

In vitro biomolecular interaction studies and cytotoxic activities of copper(II) and zinc(II) complexes bearing ONS donor thiosemicarbazones

Among all the bio‐metals, zinc and copper derivatives of ONS donor thiosemicarbazone have aroused great interest because of their potential biological applications. Multisubstituted thiosemicarbazone ligand H₂dspt (3,5‐dichlorosalicylaldehyde‐N⁴‐phenylthiosemicarbazone) derived new ternary complexes like [Zn(dspt)(phen)]?DMF ( 1 ) and [Cu(dspt)(phen)]?DMF ( 2 ), and another thiosemicarbazone, H₂dsct (3,5‐dichlorosalicylaldehyde‐N⁴‐cyclohexylthiosemicarbazone), derived [Cu(dsct)(bipy)]?DMF ( 3 ). These complexes have been characterized by elemental analysis (CHNS), Fourier transform infrared (FT‐IR), ultraviolet–visible (UV–Vis) and proton nuclear magnetic resonance (¹H‐NMR) spectra. The structures of the complexes were obtained by single‐crystal X‐ray diffraction analysis. Compounds 1 and 2 got crystallized in the monoclinic P2₁/c space group. The complexes showed interesting supramolecular interaction, which in turn stabilizes the complexes. The ground state electronic configurations of the complexes were studied using the B3LYP/LANL2DZ basis set, and ESP plots of complexes were investigated. The interaction of the complexes with calf thymus DNA (CT‐DNA) was studied using absorption and fluorescence spectroscopic methods. A UV study of the interaction of the complexes with calf thymus DNA (CT‐DNA) has shown that the complexes can effectively bind to CT‐DNA, and [Cu(dspt)(phen)]·DMF ( 2 ) exhibited the highest binding constant to CT‐DNA (K_b = 3.7 × 10⁴). Fluorescence spectral studies also indicated that Complex 2 binds relatively stronger with CT DNA through intercalative mode, exhibiting higher binding constant (K_q = 4.7 × 10⁵). The DNA cleavage result showed that the complexes are capable of cleaving the DNA without the help of any external agent. Molecular docking studies were carried out to understand the binding of complexes with the molecular target DNA. Complex 2 exhibited the highest cytotoxicity against human breast cancer cell line MD‐MBA‐231 (IC₅₀ = 23.93 μg/mL) as compared to Complex 1 (IC₅₀ = 44.40 μg/mL) .     

Synthesis and Characterization of Copper(I) Complexes Containing Tri(2‐Pyridylmethyl)Amine Ligand

Reaction of copper halides CuX (X=Cl, Br, I) with tri(2‐pyridylmethyl)amine) (TPMA) in THF under N₂ affords a series of monomeric copper(I) complexes CuX(TPMA) (X=Cl ( 1 ), Br ( 2 ) and I ( 3 )). Treatment of [CuCl(TPMA)] ( 1 ) with 0.5 equivalent of 1,4‐diisocyanobenzene following by equimolar amount of NaBF₄ affords a novel binuclear complex [(TPMA)Cu(μ‐1,4‐CNC₆H₄NC)Cu(TPMA)](BF₄)₂ ( 4 ). The copper(I) halide TPMA complexes show interesting fluxional behaviors in temperature dependence in the ¹H NMR spectrum that can be explained by the dissociation and reassociation of the pyridyl group and alkylamine nitrogen of TPMA ligand. The crystal structures of 1 , 3 and 4 are determined by an X‐ray diffractometer. Complexes 1 and 3 are distorted tetrahedral coordinates with strong bonding between three pyridyl N atoms and the corresponding halide donor. Crystallographic results of 4 clearly indicates two Cu(I) ions are bridged by 1,4‐diisocyanobenzene, forming a centro‐symmetrical homobinuclear complex with a “dangling” uncoordinated pyridyl group.     

Novel metal-based antimicrobial agents of copper(II) complexes: Synthesis,spectral characterization and DNA interaction study

Few novel mixed ligand copper(II) complexes of the type [Cu(L)(Cl)₂(H₂O)], [Cu(L)₂]Cl₂, [Cu(L)L¹] and [Cu(L)(phen)H₂O]Cl₂ (where L is the ligand obtained from the condensation of N-(2-aminoethyl)-1,3-propanediamine with m-nitrobenzaldehyde (L_a)/o-chlorobenzaldehyde (L_b)/benzaldehyde (L_c)/p-methoxybenzaldehyde (L_d)/p-hydroxybenzaldehyde (L_e)/furfuraldehyde (L_f)/pyrrole-2-carboxaldehyde (L_g); L¹ is another ligand obtained from the condensation of anthranilic acid with salicyaldehyde; phen = 1,10-phenanthroline) have been synthesized and characterized by the spectral and analytical techniques. From these data, it is found that the ligands adopt distorted octahedral geometry on metalation with Cu(II) ion. The XRD data indicate that the complexes are polycrystalline with nanosized grains. The SEM images of [Cu(L_a)phen(H₂O)]Cl₂ and [Cu(L_f)₂]Cl₂ complexes show that they have leaf and cauliflower like morphology. The in vitro biological screening effects of the investigated compounds have been tested against the bacteria such as Escherichia coli, Klebsiella pneumoniae, Salmonella typhi, Pseudomonas aeruginosa and Staphylococcus aureus and fungi such as Aspergillus niger, Rhizopus stolonifer, Aspergillus flavus, Rhizoctonia bataicola and Candida albicans by the well diffusion method. A comparative study of MIC values of the Schiff base ligands and their complexes indicates that the complexes exhibit higher antimicrobial activity than the free ligands. An electrochemical study of the copper complexes containing electron withdrawing substituted ligands reveals that they prefer to bind to DNA in Cu(II) rather than Cu(I) oxidation state.     

铜(Ⅱ)邻菲咯啉蛋氨酸配合物与DNA相互作用的研究

在pH=6．86磷酸盐缓冲溶液中，采用电化学(循环伏安法、微分脉冲伏安法和 交流阻抗及数据拟合技术)、粘度测定、电子吸收光谱和溴化乙锭(EB)荧光分析法 研究了[Cu(phen)(H2O)(L—Met)]^+(phen＝1，10-邻菲咯琳，L—Met=L-蛋氨酸)与 小牛胸腺DNA的相互作用。结果发现中心铜离子在循环伏安图上呈现1对明显的准可 逆氧化还原波。当加入一定量的DNA时，配合物的氧化还原峰电流明显降低，扩散 系数减小，电化学反应电阻增大，电子光谱的最大吸收峰明显红移，产生明显的减 色效应，同时，配合物也能较大程度地猝灭EB-DNA体系的荧光，说明[Cu(phen) (H2O)(L—Met)]^+与DNA的作用较强，作用模式为部分插入作用。     

Synthesis,structure and in vitro antiproliferative activities of oxamido‐bridged dicopper(II) complexes: A comparative study of experimental evidence and molecular docking of DNA/protein binding

Two μ‐oxamido‐bridged dicopper(II) complexes, namely [Cu₂(hmpoxd)(H₂O)(phen)](ClO₄) ( 1 ) and [Cu₂(papo)(H₂O)(phen)](ClO₄)·2H₂O ( 2 ), where H₃hmpoxd and H₃papo represent N‐(2‐hydroxy‐5‐methylphenyl)‐N′‐[3‐(dimethylamino)propyl]oxamide and N‐(2‐hydroxylphenyl)‐N′‐(3‐aminopropyl)oxamide, respectively, and phen represents 1,10‐phenanthroline, were synthesized. Single‐crystal X‐ray crystallography and other methods revealed that the two copper(II) ions in complex 1 are bridged by the cis‐hmpoxd^3? with Cu···Cu separation of 5.1896(7) Å, in which the inner (Cu1) and outer (Cu2) copper(II) atoms are located in square‐planar and square‐pyramidal geometries, respectively. To evaluate the effects of bridging ligand hydrophobicity on DNA/protein binding and potential anticancer activities, comparative studies of the reactivity towards herring sperm DNA and protein bovine serum albumin (BSA) as well as cytotoxicity of complex 1 with our previously reported complex 2 were conducted theoretically and experimentally. The results indicate that the two complexes can interact interactively with DNA, and bind to BSA via the binding sites Trp213 for 1 and Trp134 for 2 . Interestingly, the in vitro anticancer activities and DNA/protein binding affinities consistently follow the order of 1 > 2 .     

Complex Formation Reactions of (2,2′-dipyridylamine)copper(II) with Various Biologically Relevant Ligands. The Kinetics of Hydrolysis of Amino Acid Esters

Binary and ternary copper(II) complexes involving 2,2′-dipyridylamine (DPA) and various biologically relevant ligands containing different functional groups are investigated. The ligands used are dicarboxylic acids, amino acids, peptides and DNA unit constituents. The ternary complexes of amino acids, dicarboxylic acids or peptides are formed by simultaneous reactions. The results showed the formation of 1:1 complexes with amino acids and dicarboxylic acids. The effect of chelate ring size of the dicarboxylic acid complexes on their stability constants was examined. Peptides form both 1:1 complexes and the corresponding deprotonated amide species. The ternary complexes of copper(II) with DPA and DNA are formed in a stepwise process, whereby binding of copper(II) to DPA is followed by ligation of the DNA components. DNA constituents form both 1:1 and 1:2 complexes with Cu(DPA)²⁺. The concentration distribution of the complexes in solution was evaluated. [Cu(DPA)(CBDCA)], [Cu(DPA)(malonate)] and [Cu(DPA)(oxalate)] were isolated and characterized by elemental analysis, i.r. and magnetic measurements. Spectroscopic studies of [Cu(DPA)(malonate)] revealed that the complex exhibits square planner coordination with copper(II). The hydrolysis of glycine methyl ester (MeGly) is catalyzed by the Cu(DPA)²⁺ complex. The reaction has been studied by a pH-state technique over the pH range 5.8–6.8 at 25 °C and I=0.1 mol dm⁻¹. The kinetic data fits assuming that the hydrolysis proceeds in two steps. The first step, involving coordination of the amino acid ester by the amino and carboxylic group, is followed by the rate-determining attack by the OH⁻ ion. The second step involves equilibrium formation of the hydroxo-complex, Cu(DPA)(MeGly)(OH), followed by intramolecular attack.     

Stabilities of the Ternary Complexes of Copper(II) with Substituted 1,10-Phenanthrolines and Some Amino Acids in Aqueous Solution

In this study the binary and ternary complexes of copper(II) with substituted 1,10-phenanthrolines [s-phen: 1,10-phenanthroline (phen), 4,7-dimethyl-1,10-phenanthroline (dmphen) and 5-nitro-1,10-phenanthroline (nphen)] and l-amino acids [aa: l-phenylalanine (phe), l-tyrosine (tyr) and l-tryptophan (trp)] have been investigated using potentiometric methods in 0.1 mol·L^?1 KCl aqueous ionic media at 298.2 K. The protonation constants of the ligands and the stability constants of the binary and ternary complexes of Cu(II) with the ligands were calculated from the potentiometric data using the “BEST” software package. It was inferred that the aromatic 1,10-phenanthrolines act as a primary ligand in the ternary complexes, while the oxygen and nitrogen donor-containing amino acids are secondary ligands. The observed values of Δlog₁₀ K indicate that the ternary complexes are more stable than the binary ones, suggesting no interaction takes place between the ligands in the ternary complexes. The magnitudes of the measured stability constants of all of the ternary complexes are in the order [Cu(s-phen)(trp)]⁺ > [Cu(s-phen)(tyr)]⁺ > [Cu(s-phen)(phe)]⁺, which is identical to the sequence found for the binary complexes of Cu(II) with the amino acids. When the substituted 1,10-phenanthroline is changed, the stability constants of the ternary complexes decrease in the following order: [Cu(dmphen)(aa)]⁺ > [Cu(phen)(aa)]⁺ > [Cu(nphen)(aa)]⁺.     

Synthesis and application of a new copper(II) complex containing oflx and leof

Two new copper(II) complexes of [Cu(Ofloxacin)(phen)(H₂O)] · (NO₃) · 2H₂O and [Cu(Levofloxacin)(phen)(H₂O)] · (NO₃) · 2H₂O were obtained and their structures were studies. Both ligands and complexes were assayed against gram-positive and gram-negative bacteria by the in vitro doubling dilutions method. The inhibitory effect of the ligands and complexes on the leukemia HL-60 cell line were measured with the MTT assay method and the liver cancer HePG-2 cell line measured by the SRB method. The results indicated that the complexes have stronger inhibitory effect on HL-60 than on HePG-2. The complex [Cu(Levofloxacin)(phen)(H₂O)] · (NO₃) · 2H₂O (I) has stronger effect on HL-60 than the complex (Cu(Ofloxacin)(phen)(H₂O)] · (NO₃) · 2H₂O (II). The text was submitted by the authors in English.     

Voltammetric detection of damage to DNA caused by nitro derivatives of fluorene using an electrochemical DNA biosensor

An electrochemical DNA biosensor based on the screen printed carbon paste electrode (SPCPE) with an immobilized layer of calf thymus double-stranded DNA has been used for in vitro investigation of the interaction between genotoxic nitro derivatives of fluorene (namely 2-nitrofluorene and 2,7-dinitrofluorene) and DNA. Two types of DNA damage have been detected at the DNA/SPCPE biosensor: first, that caused by direct association of the nitrofluorenes, for which an intercalation association has been found using the known DNA intercalators [Cu(phen)₂]²⁺ and [Co(phen)₃]³⁺ as competing agents, and, second, that caused by short-lived radicals generated by electrochemical reduction of the nitro group (observable under specific conditions only).     

Nucleic Acid Biosensor for Detection of Human Immunodeficiency Virus Using Aquabis(1,10‐phenanthroline)copper(II) Perchlorate as Electrochemical Indicator

The electrochemical behavior of aquabis(1,10‐phenanthroline)copper(II) perchlorate [Cu(H₂O)(phen)₂]·2ClO₄, where phen=1,10‐phenanthroline, on binding to DNA at a glassy carbon electrode (GCE) and in solution, was described. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) results showed that [Cu(H₂O)(phen)₂]²⁺ had excellent electrochemical activity on the GCE with a couple of quasi‐reversible redox peaks. The interaction mode between [Cu(H₂O)(phen)₂]²⁺ and double‐strand DNA (dsDNA) was identified to be intercalative binding. An electrochemical DNA biosensor was developed with covalent immobilization of human immunodeficiency virus (HIV) probe for single‐strand DNA (ssDNA) on the modified GCE. Numerous factors affecting the probe immobilization, target hybridization, and indicator binding reactions were optimized to maximize the sensitivity and speed of the assay. With this approach, a sequence of the HIV could be quantified over the range from 7.8×10^?9 to 3.1×10^?7 mol·L^?1 with a linear correlation of γ=0.9987 and a detection limit of 1.3×10^?9 mol·L^?1.     

L-argininato copper(II) complexes in solution exert significant selective anticancer and antimicrobial activities

A search for new drugs that overcome the multidrug resistance of microorganisms or are effective against cancer cells prompted us to investigate the binary and ternary Cu(II) complexes containing L-arginine, [CuCl(L-Arg)(phen)]Cl·2H₂O (phen = 1,10-phenanthroline) ( 1 ) and [Cu(L-Arg)₂(H₂O)]C₂O₄·6H₂O ( 2 ), for which crystal and molecular structures were characterized previously. In order to discuss the biological function, the complexes have been screened for their antitumor activity against A549 (human lung cancer cells), HepG2 (human liver hepatocellular carcinoma cells) and antimicrobial activity. To identify the complexes forms existing in the solutions of 1 and 2 crystals, the results obtained from EPR, NIR–Vis–UV and MS (mass spectrometry) measurements were correlated with those from analysis of potentiometric titration of Cu(II)―L-Arg and Cu(II)―L-Arg―phen systems. This comprehensive study indicated that the [Cu(L-Arg)(phen)]²⁺ and [Cu(L-Arg)₂]²⁺ species are dominant in the solution. Complexes 1 and 2 were found to present specific ligand-dependent cytotoxic and antiproliferative potential against cancer cells. They also show antibacterial activity against Gram-positive and Gram-negative bacteria as well as display antifungal properties.     

Synthesis,structure, DNA binding and cleavage ability of a new copper ciprofloxacin complex

The structure of 1 consists of [Cu(HCp)(phen)(H₂O)]²⁺ (HCp is ciprofloxacin and phen is 1,10-phenanthroline), two acetates, and four free water molecules. In each cation, copper displays a distorted square pyramid, coordinated to ring 3-carboxylate and 4-oxo oxygen from HCp, two nitrogens from phen, and one water molecule. There are five water molecules in each discrete complex with one coordinated to Cu center, and the other four linked to each other by intermolecular hydrogen bonds. Two uncoordinated acetates make the compound neutral. The complex exhibits higher DNA binding compared to HCp at the same conditions by fluorescence and viscosity measurements. Combining its structure with the DNA-binding result, the binding mechanism may be explained by intercalation. Moreover, 1 shows significant cleavage of DNA in the presence of a reducing agent, such as ascorbate by gel electrophoresis using supercoiled pBR322 DNA in Tris-HCl buffer (pH 7.4). The complex also has a higher activity against Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Klebsiella pneumoniae than HCp.     

Interaction of cobalt(III) polypyridyl complexes containing asymmetric ligands with DNA

Four asymmetric cobalt(III) complexes, [Co(bpy)₂(aip)]³⁺, [Co(bpy)₂(pyip)]³⁺, [Co(phen)₂(aip)]³⁺, and [Co(phen)₂(pyip)]³⁺ (bpy = 2,2,bipyridine, phen = 1,10-phenathroline), (pyip = 2-(1-pyrenyl)-1H-imidazo[4,5-f][phen], (aip = 2-(9-anthryl)-1H-imidazo[4,5,-f][phen], have been synthesized and characterized. Their interaction with calf thymus DNA (CT-DNA) was investigated by physico-chemical methods and photocleavage. The size and shape of the ligands have a marked effect on the DNA-binding affinity of the complexes. Irradiation of pBR322 DNA with these novel cobalt(III) complexes results in nicking of the plasmid DNA. Toxicity and induced cell death investigations revealed that the complexes of pyip had higher toxicity than those of aip. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.