Synthesis and characterization of chiral ruthenium(II) complexes Λ/Δ-[Ru(bpy)2(H2iip)](ClO4)2 as stabilizers of c-myc G-quadruplex DNA

In this article, two chiral ruthenium(II) complexes, Λ/Δ-[Ru(bpy)₂(H₂iip)](ClO₄)₂ (Λ-1 and Δ-1, bpy = 2,2-bipyridine; H₂iip = 2-(indol-3-yl)-imidazo[4,5f][1, 10 G.L. Duveneck, C.V. Kumar, N.J. Turro, J.K. Barton. J. Phys. Chem., 92, 2028 (1988).10.1021/j100318a064 S.K. Singh, S. Joshi, A.R. Singh, J.K. Saxena, D.S. Pandey. Inorg. Chem., 46, 10869 (2007).10.1021/ic700885m ]phenanthroline), were synthesized and investigated as c-myc G4 DNA stabilizers. The interaction of both complexes with c-myc G4 DNA has been studied using UV–vis spectra, CD spectra, and ITC experiments, and the results show that both isomers strongly bind with c-myc G4 DNA. Furthermore, the FRET melting point experiments give a ΔT_m for Λ-1 and Δ-1, which is about 9.5 and 8.3 °C, respectively, indicating that both isomers can stabilize the G-quadruplex conformation of c-myc oncogene in vitro. As a result, the replication ability of c-myc DNA, as evaluated by using PCR-stop assay, by both isomers. Besides, the inhibitory activity evaluated by MTT assay showed that Λ-1 and Δ-1 can inhibit the growth of MDA-MB-231 cells, suggesting their potential utility as inhibitors targeting to c-myc G-quadruplexe in chemotherapy.     

Synthesis and structures of two uranyl β-diketonate complexes [UO2(DBM)2(DEDPU)] and [UO2(PMBP)2(DEDPU)]

Two new uranyl β-diketonate complexes [UO₂(DBM)₂(DEDPU)] (1) and [UO₂(PMBP)₂(DEDPU)](CH₃C₆H₅)_0.5 (2), (HDBM?=?dibenzoylmethane, HPMBP?=?1-phenyl-3-methyl-4-benzoyl-5-pyrazolone, DEDPU?=?N,N′-diethyl-N,N′-diphenylurea) were synthesized and characterized. The coordination geometries of the uranyl atoms in 1 and 2 are distorted pentagonal bipyramidal, coordinated by one oxygen atom of DBDPU molecule and four oxygen atoms of two chelating DBM molecules in 1 and PMBP molecules in 2.     

Synthesis, DNA-binding and photocleavage studies of ruthenium(Ⅱ) complexes [Ru(btz)_3]~(2+) and [Ru(btz)(dppz)_2]~(2+)

Two new ruthenium(Ⅱ) complexes, [Ru(btz)3](ClO4)2 (1) and [Ru(btz)(dppz)2](ClO4)2 (2) (btz = 4,4′-bithi-azole, dppz = dipyrido[3,2-a:2′,3′-c]phenazine), have been synthesized and characterized by elemental analysis, 1H NMR, ES-MS and X-ray crystallography. The DNA binding behaviors of two complexes have been studied by spectroscopic and viscosity measurements. The results suggest that complex 1 binds to CT-DNA via an electrostatic mode, while complex 2 via an intercalative mode. Under irradiation at 365 nm,...     

Kinetic and thermodynamic studies of aquation reactions in [RuL2(mac)]q+ complexes: [mac = 1,4,8,11-tetraazacyclotetradecane (cyclam) or 1,4,7,10-tetraazacyclododecane (cyclen); and L = Cl−, OH−, OH2]

Transition Metal Chemistry - We report here the synthesis, characterization and kinetic studies of [RuL2(mac)]n+ complexes [mac?=?1,4,8,11-tetraazacyclotetradecane (cyclam) or...     

Inhibiting the growth of tumor cells by ruthenium(II) complexes [Ru(phen)2L] (L = o-TFMPIP and p-CPIP) through DNA-binding

[Ru(phen)₂o-TFPIP]²⁺ (1) and [Ru(phen)₂p-CPIP]²⁺ (2) have been synthesized and demonstrated to inhibit the growth of tumor cells. The inhibitory activities (IC₅₀) of 1 against the growth of C6, MDA-MB-231 and HepG2 cells were about 24.5, 36.7, and 36.1 μM, respectively. Studies show that both complexes bind to CT-DNA, explained by using density functional theory calculations. The LogP calculated for 1 and 2 are ?0.4859 and ?1.279, respectively. These complexes, especially 1, can be used as promising inhibitors in chemotherapy, and their DNA-binding behaviors play a key role.     

Synthesis,DNA binding and cleavage studies of the copper(Ⅱ) complexes of PNA-cyclen conjugates

Two dinucleotide PNA-cyclen copper(II) complexes with α-PNA (P1) and classical PNA (P2) backbones were synthesized and characterized.The interactions between title complexes and DNA were investigated under physiological conditions.Fluorescence studies indicate that the binding ability of complex P1 to CT-DNA is as twice as that of P2.DNA melting experiments were also carried out and the results show that ΔTm caused by P1 is higher than that caused by P2.Agarose gel electrophoresis experiments demonstrate th...     

Synthesis and spectral studies of some new dimeric [(μ-Cl)2M2(L)2 · xTHF] [M = Zn(II) and Hg(II)] complexes containing Schiff-base ligands

A series of binuclear Schiff-base complexes of zinc(II) and mercury(II) containing bidentate ligands (HL) [HL?=?salicylidene-2-methyl-1-aminobenzene (HL¹), salicylidene-2-aminopyridine (HL²), and salicylidene-3-nitro-1-aminobenzene (HL³)] with “N” and “O” donors have been synthesized by simple metathetic reactions of anhydrous metal chlorides with sodium salts of Schiff bases (in tetrahydrofuran (THF)/MeOH) in equimolar ratio to produce [(µ-Cl)₂M₂(L)₂?·?xTHF] [where M?=?Zn(II) and Hg(II); L?=?HL¹, HL², and HL³; x?=?0 for (1), (4), (6) and x?=?2 for (2), (3), (5)]. The main emphasis on the complexes [(µ-Cl)₂M₂(L)₂?·?2THF] (2), (3), and (5) is given due to their five-coordinate environment around metal ions. The complexes have been characterized by elemental analyses (M, Cl, C, H, N), melting point, and spectral (FT-IR, ¹H-NMR, and ¹³C-NMR) studies. The structural composition of the complexes has been determined by FAB-MS spectral studies. FAB-MS showed the isotopic molecular ion peak [M⁺] and fragments supporting the formulation. Powder X-ray diffraction study of 6 is also reported showing the crystallite size (404.5?Å) of the complex.     

Spectroscopic and electrochemical studies on (2-hydroxypicolinate)-bis(2,2′-bipyridine)ruthenium(II) and related complexes

Summary The synthesis, spectra and electrochemistry of [Ru(bipy)₂-(picOH)]⁺ and -picO-[Ru(bipy)₂]₂ ²⁺ (bipy = 2,2-bipyridine and picOH = 3-hydroxypicolinate ion) are described. The spectroscopic properties in the visible region are dominated by the intense Ru bipy chargetransfer transitions. In the binuclear complex, the two [Ru(bipy)₂L]²⁺ moieties are nonequivalent, exhibiting E _1/2 = 0.69 and 1.20 V versus s.h.e. The partially oxidized species exhibits a weak intervalence transfer band at 1085 nm, and is consistent with a Robin-Day class II mixed valence complex.     

[Ru（MeIm）4L]^2＋（L=iip，tip，2ntz）的电子结构、DNA-键合、构效关系及光谱特征

采用密度泛函的方法,结合导体极化连续模型研究了水溶性二价钌．甲基咪唑类配合物[Ru（MeIm）4iip]^2＋。（1）、[Ru（MeIm）4tip]^2＋0＋（2）和[Ru（MeIm）42ntz]^2＋（3）的电子结构、DNA的键合倾向及构效关系,在水溶液中几何优化的基础上分析了配合物的电子结构特征,并合理解释了配合物与DNA的键合倾向．计算结果表明,在主配体上用噻吩代替咪唑取代基可以有效提高配合物与DNA的键合力;同时,在主配体的骨架上引入强电负性的N原子及NO2基团可以明显降低配合物最低未占据分子轨道能量及前沿分子轨道能量差．基于以上计算结果,预测所设计的配合物3具有最大的DNA键合力常数．另外,详细分析了配合物1、2的构效关系及抗肿瘤作用机理,并预测了配合物3的抗肿瘤活性．最后,用含时密度泛函方法对配合物的电子吸收光谱进行了计算和模拟,并与实验结果进行了对比分析．     

Synthesis, and characterization of ruthenium(II) polypyridyl complexes containing α-amino acids and its DNA binding behavior

Reactivity of the ruthenium complexes [Ru(κ³-tptz)(PPh₃)Cl₂] (1) and [Ru(κ³-tpy)(PPh₃)Cl₂] (2) [tptz = 2,4,6-tris(2-pyridyl)-1,3,5-triazine; tpy = 2,2′:6′,2″-terpyridine] with several α-amino acids [glycine (gly); leucine (leu); isoleucine (isoleu); valine (val); tyrosine (tyr); proline (pro) and phenylalanine (phe)] have been investigated. Cationic complexes with the general formulations [Ru(κ³-L)(κ²-L″)(PPh₃)]⁺ (L = tptz or tpy; L″ = gly, leu, isoleu, val, tyr, pro, and phe] have been isolated as tetrafluoroborate salts. The resulting complexes have been thoroughly characterized by analytical, spectral and electrochemical studies. Molecular structures of the representative complexes [Ru(κ³-tptz)(val)(PPh₃)]BF₄ (6)_, [Ru(κ³-tpy)(leu)(PPh₃)]BF₄ (10) and [Ru(κ³-tpy)(tyr)(PPh₃)]BF₄ (13) have been determined crystallographically. The complexes [Ru(κ³-tptz)(leu)(PPh₃)]BF₄ (4), [Ru(κ³-tptz)(val)(PPh₃)]BF₄ (6), [Ru(κ³-tpy)(leu)(PPh₃)]BF₄ (10) [Ru(κ³-tpy)(tyr)(PPh₃)] BF₄·3H₂O (13) exhibited DNA binding behavior and acted as mild Topo II inhibitors (10-40%). The complexes also inhibited heme polymerase activity of the malarial parasite Plasmodium yoelii lysate.     

A kinetic study on the iron(III)-promoted aquation of [Cr(C2O4)2(picolinato)]2− and [Cr(C2O4)2(2-pyridineacetato)]2− complexes

Two [Cr(C₂O₄)₂(AB)]^2– type complexes, obtained from the reaction of cis-[Cr(C₂O₄)₂(H₂O)₂]^– with the AB ligand, [AB = picolinic (pyac) or 2-pyridine-ethanoic acid (pyeac) anions], were converted into [Cr(C₂O₄)(pyac)(H₂O)₂]⁰ and [Cr(C₂O₄)(pyeac)(H₂O)₂]⁰ compounds, respectively via Fe^III-induced substitution of the oxalato ligand. The aquation products were separated chromatographically and their spectral characteristics and acid dissociation constants determined. The kinetics of the oxalato ligand substitution were studied with a 10–40 fold excess of Fe^III over [Cr^III] at [H⁺] = 0.2 M and at constant ionic strength 1.0 M (Na⁺, H⁺, Fe³⁺, ClO^– ₄). The reaction rate law is of the form: r = k _obs[Cr^III], where k _obs = kQ[Fe^III]/(1 + Q[Fe^III]). The first-order rate constants (k), preequilibria quotients (Q) and activation parameters derived from the k values have been determined. The reaction mechanism is discussed in terms of a Lewis acid catalyzed (induced) ligand substitution.     

Synthesis and structures of two cobalt complexes [NaCoII(NTA)(H2O)] n and NH4[CoIII(IDA)2] · 2H2O

Two cobalt complexes [NaCo^II(nta)(H₂O)] _n (H₃nta?=?nitrilotriacetic acid) (1) and NH₄[Co^III(ida)₂]?·?2H₂O (H₂ida?=?iminodiacetic acid) (2) have been synthesized and characterized by single-crystal X-ray diffraction analysis. Compound 1 crystallizes in the orthorhombic system, space group P2₁2₁2₁ with a?=?7.9770(12)?Å, b?=?9.7613(15)?Å, c?=?12.1945(18)?Å, V?=?949.5(2)?ų, Z?=?4, and R ₁?=?0.0705 for 1597 observed reflections. Compound 2 crystallizes in the monoclinic system, space group P2(1)/c with a?=?5.1801(3)?Å, b?=?11.2073(6)?Å, c?=?12.2891(7)?Å, V?=?707.09(7)?ų, Z?=?2, and R ₁?=?0.0349 for 1143 observed reflections. In compound 1, the Co is coordinated by a nitrogen and five oxygen atoms in a distorted octahedral geometry {CoNO₅}, and the Na is coordinated by one water molecule and four carboxyl oxygen atoms in slightly distorted square pyramidal geometry. The entire structure shows a three-dimensional network. In compound 2, Co atom is equatorially coordinated by two ida ligands in a distorted octahedral geometry {CoN₂O₄}. The discrete [Co(ida)₂]^2? anions are linked by hydrogen bonding to a three-dimensional supramolecular network.     

Adducts of ruthenium(IV) thiolates with substituted pyridines. Syntheses and structures of [Ru(SMes)4(R-py)] (R = 4-Et, 4-tBu,and 3,5-Me2) and [{Ru(SMes)4}2(μ-4,4’-bipy)] (Mes = 2,4,6-trimethylphenyl)

Treatment of the trigonal-bipyramidal ruthenium(IV)–thiolate complex, [Ru(SMes)₄(MeCN)] (Mes = 2,4,6-trimethylphenyl, 1), with an anhydrous diethyl ether solution of hydrogen chloride in THF afforded [Ru(SMes)₃Cl(MeCN)] (2), whereas interaction of 1 with [Et₄N]Cl in THF gave an anionic ruthenium(IV)–thiolate complex, [Et₄N][Ru(SMes)₄Cl] (3). Reaction of 1 with one equivalent of substituted pyridines in dichloromethane gave the corresponding pyridine-coordinated ruthenium(IV)–thiolate complexes, [Ru(SMes)₄(R-py)] (R = 4-Et, 4; 4-^tBu, 5; 3,5-Me₂, 6), while reaction of 1 with 0.5 equiv. of 4,4’-bipy (4,4’-bipy = 4,4’-bipyridine) in dichloromethane resulted in the formation of a dinuclear ruthenium(IV)–thiolate complex [{Ru(SMes)₄}₂(μ-4,4’-bipy)] (7). Complexes 2–7 have been spectroscopically characterized along with their electrochemical analyses, and their structures have been determined by single-crystal X-ray diffraction.     

Catalytic and antimicrobial studies of binuclear ruthenium(III) complexes containing bis-β-diketones

A series of new binuclear Ru(III) complexes of the type {[RuX₃(EPh₃)]₂(bis- β-dk)} [X = Cl/Br; E = P/As bis- β-dk = bis(β-diketone)] have been prepared by reacting [RuCl₃(PPh₃)₃], [RuCl₃(AsPh₃)₃], [RuBr₃(PPh₃)₃], [RuBr₃(AsPh₃)₃] with bis(β-diketones) in a 2:1 molar ratio in benzene. These complexes have been characterized by physico-chemical and spectroscopic methods. The redox property of the complexes were studied by cyclic voltammetric technique. The complexes were found to be effective catalysts for the aryl–aryl coupling and oxidation of benzyl alcohol, cyclohexanol, propan-1-ol and 2-methylpropanol to benzaldehyde, cyclohexanone, propionaldehyde and 2-methylpropionaldehyde, respectively, using molecular oxygen as primary oxidant. All the complexes have been screened for their antibacterial and antifungal activities.     

Synthesis, characterization and cyclic voltammetric studies of β-ketooximato ruthenium(II) complexes

Summary -Ketooxime [RC(O)C(NOH)R] (R = Me or Ph) ligands (HL) react with [Ru(PPh₃)₃Cl₂] in refluxing EtOH to yield [Ru(PPh₃)₂(L)₂] complexes. For R = Me, one isomer was obtained, while two isomers were isolated when R = Ph, due to a bulk effect. The complexes are diamagnetic and absorb intensely in the vis. region due to MLCT transitions. In MeCN and CH₂Cl₂ solution, Ru^II-Ru^III oxidation occurs in the 0.69–0.92 V versus s.c.e. range. The oxidation potential depends on both the electronic nature of R and the stereochemistry of the complexes.     

Synthesis, spectroscopic, powder X-ray diffraction and DNA binding studies on copper(II) complexes of 4,4′-diaminodiphenyl sulfone

Four new Cu(II) complexes of 4,4??-diaminodiphenyl sulfone (DDS) with different anions (chloride, sulfate, nitrate or acetate) were synthesized and characterized by elemental analysis, electronic absorption, IR, magnetic moment, thermal analysis and powder X-ray diffraction studies. It was found that the pure DDS and complex [Cu₂(DDS)₂(NO₃)₂].(NO₃)₂ (3) crystallize in orthorhombic system while the complexes [Cu₂(DDS)₂].Cl₄ (1), [Cu₂(DDS)₂].(SO₄)₂ (2), and [Cu₂(DDS)₂].(CH₃COO)₄ (4) crystallize in monoclinic system. The crystallite sizes of complexes have smaller values as compared to pure DDS. Infrared studies suggest that the coordination of NH₂ of DDS with Cu(II) ion. The binding of the complexes with calf thymus (CT) DNA was investigated by electronic absorption titration, fluorescence measurements and DNA thermal denaturation. The spectroscopic studies together with the DNA melting studies indicated that the complexes may bind to CT-DNA in a non-intercalative mode.     

Synthesis,DNA-binding,and antitumor activity of polypyridyl-ruthenium(II) complexes [Ru(L)2(DClPIP)] (L = bpy,phen; DClPIP = 2-(2,4-dichlorophenyl)-1H-imidazo[4,5-f][1, 10]phenanthroline)

Abstract

Two new ruthenium(II) complexes, [Ru(bpy)₂(DClPIP)](ClO₄)₂ (1) and [Ru(phen)₂(DClPIP)](ClO₄)₂ (2) (bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline, and DClPIP = 2-(2,4-dichlorophenyl)-1H-imidazo[4,5-f][1, 10]phenanthroline), have been prepared in high yield by using microwave-assisted synthesis technology. The anticancer activity of the two ruthenium(II) complexes against A549, C6, CNE-1 and MDA-MB-231 cell lines has been evaluated by MTT assay and results showed that 2 exhibited higher antitumor activity than 1 toward all the selected tumor cell lines. Besides, A549 cell line was sensitive to both ruthenium(II) complexes, especially to 2 (IC₅₀ = 8.01?±?0.36?μM). Meanwhile, 2 showed low toxicity against MCF-10A human normal cells. Furthermore, the DNA-binding properties of the two new ruthenium(II) complexes with CT-DNA have been investigated by electronic absorption titration, luminescence spectra, circular dichroism spectra and viscosity measurements. The results suggested that 1 and 2 were able to interact with CT-DNA via intercalative mode with a strong binding affinity in the order 2?>?1. All of these results suggested that anticancer activity of both ruthenium(II) complexes could be closely related to their interaction with DNA.     

Synthesis,characterization, crystal structure,and DNA binding of two copper(II)–hydrazone complexes

Two new Cu(II)–hydrazone complexes, [Cu(L)(Hbpe)ClO₄]·ClO₄·[Cu(L)Cl] (1) and [Cu(HL)₂]·1.5ClO₄·0.5OH (2) (where HL?=?(E)-N′-(1-(pyridine-2-yl)ethylidene)benzohydrazide and bpe = trans-1-(2-pyridyl)-2-(4-pyridyl)ethylene), have been synthesized and characterized by physicochemical methods. The structures of the complexes have been established by single-crystal X-ray diffraction direct methods, which reveal that the metal ions have distorted square-pyramidal and square-planar geometries in 1, and a distorted octahedral geometry in 2. DNA binding of HL, 1, and 2, performed by UV–vis titration in tris-buffer medium, yielded binding constants, which are 9.5 × 10³, 1.88 × 10⁴, and 4.66 × 10⁴ M^?1, respectively. Viscosity measurements suggest a surface or groove-binding mode of interaction between CT-DNA with HL, 1, and 2.     

Effect of intraligand π-delocalization on the photophysical properties of two new Ru(II) complexes

Two new Ru(II) complexes, [Ru(bpy)₂(1-COO-iqu)]⁺ (2; bpy = 2,2′-bipyridine, 1-COO-iqu^? = isoquinoline-1-carboxylate) and [Ru(bpy)₂(3-COO-iqu)]⁺ (3; 3-COO-iqu^? = isoquinoline-3-carboxylate), were prepared and their crystal structures solved. The ground and excited state properties of 2 and 3 were characterized and compared to those of [Ru(bpy)₃]²⁺ (1). The presence of the oxygen atom in the Ru(II) coordination sphere makes 2 and 3 easier to oxidize than 1. The Ru → bpy MLCT absorption and emission of 2 and 3 are red-shifted relative to that of 1 in CH₂Cl₂, and the E₀₀ energies were estimated to be 1.89 eV and 1.95 eV from the low temperature emission of 2 and 3, resulting in excited state oxidation potentials of ?1.03 V and ?1.10 V vs SCE, respectively. In addition to the short-lived emissive ³MLCT state, a long-lived species is observed in the transient absorption of 3 in DMSO (τ = 49 μs) and pyridine (τ = 44 μs), assigned to a solvent-coordinated complex. This intermediate is not observed for 3 in non-polar solvents or for 2. The absence of the solvent coordinated intermediate in 2 is explained by the stronger Ru–O bond afforded by the lower conjugation in that extends onto the carboxylic acid in the 1-COO-iquo^?ligand, compared to that in the 3-COO-iqu^?ligand in 3. Transient absorption experiments also show that the ³MLCT excited state of 3 is able to reduce methyl viologen.