DNA-binding and cleavage activity of polypyridyl ruthenium(II) complexes

Polypyridyl ruthenium(II) complexes [Ru^II(3-bptpy)(dmphen)Cl]ClO₄ (1), [Ru^II(3-cptpy)(dmphen)Cl]ClO₄ (2), [Ru^II(2-tptpy)(dmphen)Cl]ClO₄ (3), and [Ru^II(9-atpy)(dmphen)Cl]ClO₄ (4) {where 3-bptpy?=?4′-(3-bromophenyl)-2,2′:6′,2″-terpyridine, 3-cptpy?=?4′-(3-chlorophenyl)-2,2′:6′,2″-terpyridine, 2-tptpy?=?4′-(2-thiophenyl)-2,2′:6′,2″-terpyridine, 9-atpy?=?4′-(9-anthryl)-2,2′:6′,2″-terpyridine, dmphen?=?2,9-dimethyl-1,10-phenanthroline} have been synthesized and characterized. The DNA-binding properties of the complexes with Herring Sperm DNA have been investigated by absorption titration and viscosity measurements. The ability of complexes to break the pUC19 DNA has been checked by gel electrophoresis. The experimental results suggest that all the complexes bind DNA via partial intercalation. The results also show that the order of DNA-binding affinities of the complexes is 4?<?3?<?2?<?1, confirming that planarity of the ligand in a complex is very important for DNA-binding.     

A series of multidimensional MOFs incorporating a new N-heterocyclic building block: 5,5′-Di(pyridin-3-yl)-3,3′-bi(1,2,4-triazole)

Using the N-heterocyclic building block 5,5′-di(pyridin-3-yl)-3,3′-bi(1,2,4-triazole) (3,3′-H₂dbpt), four 3-D coordination polymers with diverse connectivity, [M(3,3′-dbpt)]_n, M=Co (1), M=Ni (2), M=Zn (3), and [Cd₂(3,3′-dbpt)Cl₂]_n (4), were constructed. By changing the central metal ions, 3,3′-H₂dbpt had three different coordination modes. Consequently, 1–3, which are isostructural, have a 3-D 4-connected topology with (4².8⁴) Schläfli symbol. 4 has a 3-D (4, 6)-topology, with (4³.6³)₂(4⁶.6⁶.8³) Schläfli symbol. Both 1 and 2 reveal weak antiferromagnetic behavior. In addition, 3 and 4 exhibit purple and blue emission bands, respectively. These results indicate that 3,3′-H₂dbpt is an excellent multi-connection linker to construct MOFs with interesting structures and properties.     

Solvothermal synthesis,structure, and luminescence of a 3-D Cd(II) complex assembled with biphenyl-2,5,2′,5′-tetracarboxylic acid involving in situ ligand reaction

A 3-D metal-organic framework [Cd₃(L)₂(DMF)₂]?·?2H₂O?·?2DMF (1) (H₃L?=?2-(dimethylcarbamoyl)biphenyl-5,2′,5′-tricarboxylic acid, DMF?=?N,N-dimethylformamide) with trinuclear Cd(II) units has been prepared. Complex 1 is a (3,?6)-connected (4²?·?6)₂(4⁴?·?6²?·?8⁸?·?10) coordination net, which results from the solvothermal in situ formation of a new asymmetric ligand, 2-(dimethylcarbamoyl)biphenyl-5,2′,5′-tricarboxylic acid (H₃L), through amidation of biphenyl-2,5,2′,5′-tetracarboxylic acid (H₄bptc). Additionally, the luminescence of 1 has been investigated.     

Indium(III) complexes containing bithiazole derivatives,chloride, methanol,and dimethyl sulfoxide: X‐ray studies,spectroscopic characterization,and thermal analyses

[In(dm4bt)Cl₃(MeOH)]?·?0.5dm4bt (1) (dm4bt is 2,2′‐dimethyl‐4,4′‐bithiazole) and [In(4bt)Cl₃(MeOH)] (2) (4bt is 4,4′‐bithiazole) were prepared from the reaction of 4,4′‐bithiazole and 2,2′‐dimethyl‐4,4′‐bithiazole with InCl₃?·?4H₂O in methanol, respectively. [In(4bt)Cl₃(DMSO)] (3) was also prepared from recrystallization of 2 in DMSO. These complexes were characterized by IR, UV‐Vis, ¹H NMR, ¹³C{¹H} NMR, and luminescence spectroscopy and their structures were studied by single‐crystal X‐ray crystallography. The thermal stabilities of 1 and 3 were studied by thermogravimetric and differential thermal analyses.     

Ruthenium(II) complexes of aroylhydrazones: structural,electrochemical and electrostatic interactions with DNA

Four Ru(II) complexes with tridentate ligands viz. (4-hydroxy-N′-(pyridin-2-yl-ethylene) benzohydrazide [Ru(L¹)(PPh₃)₂(Cl)] (1), N′-(pyridin-2-yl-methylene) nicotinohydrazide [Ru(L²)(PPh₃)₂(Cl)] (2), N′-(1H-imidazol-2-yl-methylene)-4-hydroxybenzohydrazide [Ru(L³)(PPh₃)₂(Cl)] (3), and N′-(1H-imidazol-2-yl-methylene) nicotinohydrazide [Ru(L⁴)(PPh₃)₂(Cl)] (4) have been synthesized and characterized. The methoxy-derivative of L³H (abbreviated as L³H*) exists in E configuration with torsional angle of 179.4° around C₇-N₈-N₉-C₁₀ linkage. Single crystal structures of acetonitrile coordinated ruthenium complexes of 1 and 3 having compositins as [Ru(L¹)(PPh₃)₂(CH₃CN)]Cl (1a) and [Ru(L³)(PPh₃)₂(CH₃CN)]Cl (3a) revealed coordination of tridentate ligands with significantly distorted octahedral geometry constructed by imine nitrogen, heterocyclic nitrogen, and enolate amide oxygen, forming a cis-planar ring with trans-placement of two PPh₃ groups and a coordinated acetonitrile. Ligands (L¹H-L⁴H) and their ruthenium complexes (1–4) are characterized by ¹H, ¹³C, ³¹P NMR, and IR spectral analysis. Ru(II) complexes have reversible to quasi-reversible redox behavior having Ru(II)/Ru(III) oxidation potentials in the range of 0.40–0.71 V. The DNA binding constants determined by absorption spectral titrations with Herring Sperm DNA (HS-DNA) reveal that L⁴H and 1 interact more strongly than other ligands and Ru(II) complexes. Complexes 1–3 exhibit DNA cleaving activity possibly due to strong electrostatic interactions while 4 displays intercalation.     

Two Zn(II) coordination polymers constructed by a new tricarboxylate and different N-containing ligands: synthesis,crystal structures,and selective luminescence sensing for Fe3+ in aqueous solution

Two Zn(II) coordination polymers, {[Zn₃(L)₂(bipy)₂(H₂O)₄}_n (1) and {[Zn(HL)(4,4′-bibp)}_n (2), were obtained from Zn(II) nitrate, a tricarboxylate ligand (H₃L) and different N-containing ligands with hydrothermal conditions, where H₃L = 4-((6-carboxynaphthalen-2-yl)oxy)phthalic acid, bipy = 4,4′-bipyridine, and 4,4′-bibp = 4,4′-di(1H-imidazol-1-yl)-1,1′-biphenyl. Single-crystal X-ray analysis reveals that 1 has a 2-D layer framework formed by L^3? and bipy and 2 has an infinite 1-D structure with Zn₂ units built by 4,4′-bibp ligands. The phase purity, IR spectra, thermal stabilities, and fluorescence properties in the solid state of 1 and 2 were investigated. Moreover, 1 and 2 were chosen as fluorescent probes to sense different metal ions, showing selective response to Fe³⁺ ion through luminescence quenching. The possible sensing mechanism to Fe³⁺ ion is also discussed.     

Synthesis and spectroscopic characterization of new heteroleptic ruthenium(II) complexes incorporating 2-(2′-pyridyl)quinoxaline and 4-carboxy-2-(2′-pyridyl)quinoline

Starting from cis-[Ru(dcbpyH₂)₂Cl₂] (1), two new heteroleptic ruthenium(II) complexes, [Ru(dcbpyH₂)₂(L¹)](NO₃)₂ (L^1?=?2-(2′-pyridyl)quinoxaline (2), and [Ru(dcbpyH₂)₂(L²)](NO₃)₂ (L^2?=?4-carboxy-2-(2′-pyridyl)quinoline (4); dcbpyH_2?=?2,2′-bipyridine-4,4′-dicarboxylic acid), were synthesized and spectroscopically characterized. During the preparation of 2 and 4, the homoleptic [Ru(dcbpyH₂)₃]Cl₂ complex (3) was isolated as a side product. Characterization includes IR and Raman spectroscopy, UV-Vis, multinuclear NMR spectroscopy, elemental, and ESI-mass spectrometric analyses.     

SYNTHESIS OF NEW 8-METHOXY-4-METHYL-3-(N-[2′-AMINO-(1′,3′,4′)THIA/OXA-DIAZOL-5′-YL]-SUBSTITUTED METHYL)-AMINO THIOCOUMARINS

8-Methoxy-4-methyl-3-(N-[2′-amino-(1′, 3′,4′)thia/oxa-diazol-5′-yl] substituted methyl)-amino thiocoumarins 6(a–f) and 7(a–f), were synthesized by using the unreported 8-methoxy-4-methyl-3-[N-(2′-oxo-2′-methoxy-1′-substituted ethan-1′-yl) amino thiocoumarins as key intermediates.     

Studies on the crystal structure and characterization of N-(4-acetylphenyl)-N’-(2-nitrobenzoyl)-thiourea

N-(4-acetylphenyl)-N′-(2-nitrobenzoyl)-thiourea has been synthesized in high yield under PEG-400 as the phase-transfer catalyst and its the compound structure was determined by single crystal X-ray diffraction. The compound is also a considerable plant-growth regulator. In addition, the compound L exhibited selective recognition for Hg²⁺ over other metals ions such as Ag⁺, Ca²⁺, Co²⁺, Ni²⁺, Cd²⁺, Pb²⁺, Zn²⁺, Cr³⁺, and Mg²⁺ in DMSO solutions.     

Effect of substituents on DNA-binding behaviors of ruthenium(II) complexes: [Ru(dmb)2(dtmi)]2+ and [Ru(dmb)2(dtni)]2+

Two Ru(II) complexes [Ru(dmb)₂(dtmi)](ClO₄)₂ (1) (dmb = 4, 4′-dimethyl-2, 2′-bipyridine, dtmi = 3-(pyrazin-2-yl)-as-triazino[5, 6-f]-5-methoxylisatin) and [Ru(dmb)₂(dtni)](ClO₄)₂ (2) (dtni = 3-(pyrazin-2-yl)-as-triazino[5, 6-f]-5-nitroisatin) have been synthesized and characterized by elemental analysis, ES-MS, and ¹H NMR. DNA-binding behaviors of these complexes have been investigated by spectroscopic titration, viscosity measurements, and thermal denaturation. The results indicate that the two complexes interact with calf thymus DNA by intercalation.     

Self-assembly and crystal structures of coordination polymers constructed by 4′-hydroxyisoflavone-3′-sulfonates with Cs(I) and Rb(I)

Four coordination polymers, [CsL1(H₂O)₂]·H₂O (1), [CsL2(H₂O)₂]·H₂O (2), [Rb₂(L2)₂(H₂O)₂]·2H₂O (3) and [RbL3(H₂O)] (4), were synthesized by Cs(I), Rb(I) and 4′-hydroxyisoflavone-3′-sulfonates L1–L3 [L1 = 7-methoxy-4′-hydroxyisoflavone-3′-sulfonate, L2 = 7-ethoxy-4′-hydroxyisoflavone-3′-sulfonate, L3 = 7-ethoxy-4′,5-dihydroxyisoflavone-3′-sulfonate]. The crystal structures of 1–4 were determined by single-crystal X-ray diffraction. The influences of 4′-hydroxyisoflavone-3′-sulfonate ligands and Cs⁺, Rb⁺ on their structural features and self-assembly were investigated. The sulfonates of L1–L3 not only coordinate with Cs⁺ or Rb⁺ directly, but also bridge the organic region and the inorganic region in 1–4. Non-covalent interactions such as coordination interaction, π–π stacking interaction and hydrogen bonding assembled 1–4 into 3-D networks together with the electrostatic interactions between Cs⁺, Rb⁺ and the sulfonate anions.     

Manganese(II) complexes of hydrazone based NNO-donor ligands and their catalytic activity in the oxidation of olefins

The reaction between tridentate NNO donor hydrazone ligands, (E)-2-cyano-N′-(phenyl(pyridin-2-yl)methylene)acetohydrazide (HL¹) and (E)-2-cyano-N′-(1-(pyridin-2-yl)ethylidene)acetohydrazide (HL²), with MnCl₂·4H₂O in methanol resulted in [Mn(HL¹)Cl₂(CH₃OH)] (1) and [Mn(HL²)Cl₂(CH₃OH)] (2). Molecular structures of the complexes were determined by single-crystal X-ray diffraction. All of the investigated compounds were further characterized by elemental analysis, FT-IR, TGA, and UV–Vis spectroscopy. These complexes were used as catalysts for olefin oxidation in the presence of tert-butylhydroperoxide (TBHP) as an oxidant. Under similar experimental conditions with equal manganese loading, the presence of [Mn(HL²)Cl₂(CH₃OH)] (2) resulted in higher conversion than [Mn(HL¹)Cl₂(CH₃OH)] (1).     

Synthesis and characterization of tetra-armed-thiosemicarbazone and its salen/salophen capped transition metal complexes: Investigation of their thermal and magnetic properties

In this work, we aimed to synthesize and characterize a novel tetra-directional ligand, (2E,2′E)-2,2′-((((2-(1,3-bis(4-((E)-(2-carbamothioylhydrazono)methyl)phenoxy)propan-2-ylidene)propane-1,3-diyl)bis(oxy))bis(4,1-phenylene))bis(methanylylidene))bis(hydrazinecarbothioamide) (5), including thiosemicarbazone group and its novel tetra-directional-tetra-nuclear Schiff base complexes. For this purpose, we used 1,4-dibromo-2,3-bis(bromomethyl)but-2-ene (2) as starting material. 4,4′-((2-(1,3-Bis(4-formylphenoxy)propan-2-ylidene)propane-1,3-diyl) bis(oxy))dibenzaldehyde (3) was synthesized by the reaction of an equivalent 1,4-dibromo-2,3-bis(bromomethyl)but-2-ene (2) and 4 equivalents of 4-hydroxybenzaldehyde. Then, compound 5 was synthesized in high yield (86%) by a condensation reaction of compound 3 with thiosemicarbazide (4). Finally, four novel tetra-nuclear Cr(III) or Fe(III) complexes of compound 5 were synthesized. The synthesized compounds were characterized using elemental analyses, ¹H NMR, Fourier transform–infrared spectrometry, liquid chromatography–mass spectrometry (ESI⁺), and thermal analyses. The metal ratios of the prepared complexes were determined using an atomic absorption spectrophotometer. We also investigated their effects on the magnetic behaviors of [salen, salophen, Cr(III)/Fe(III)] capped complexes. The complexes were found to be low-spin distorted octahedral Fe(III) and distorted octahedral Cr(III), all bridged by thiosemicarbazone.     

Mononuclear manganese and tetranuclear copper compounds and their supramolecular networks constructed from hexafluoroglutaric acid and 2,2′-bipyridine

Mn(2,2′-bpy)₂(HFGA) (1) and [Cu₄(μ₃-OH)₂(μ₂-OH)₂(H₂O)₂(2,2′-bpy)₄]?·?2HFGA?·?4H₂O (2) (H₂HFGA?=?hexafluoroglutaric acid and 2,2′-bpy?=?2,2′-bipyridine) have been synthesized and characterized by X-ray structural analyses. 1 is a monomer with six-coordinate Mn²⁺ from two oxygens of HFGA and four nitrogens of two 2,2′-bpy. Complex 2 is tetranuclear with four Cu²⁺ ions bridged by triple-bridging μ₃-OH and double-bridging μ₂-OH. There are two crystallographically independent Cu²⁺ ions in different five-coordinate environments. Cu1 is coordinated by 2,2′-bpy and three OH ligands. Cu2 is coordinated by 2,2′-bpy, two μ₃-OH ligands, and one water molecule. The mononuclear and tetranuclear molecules as building blocks are connected to construct different 3-D supramolecular architectures via noncovalent interactions. Particularly, the lone pair (lp)–π (F···π) interaction in 1 is observed. A hybrid water-anionic tape by linkage of {[(H₂O)₄(HFGA)]₂ ^4?} _n fragments consisting of water dimers and HFGA anions in 2 is observed.     

Octahedral iron(II) complexes with pyridyl triazine and bipyridine ligands – synthesis,computational studies,mechanisms and kinetics with 1,10-phenanthroline and 2,2′,6,2″-terpyridine

[Bis(3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine)(2,2′-bipyridine)iron(II)], [Fe(PDT)₂(bpy)]²⁺ (1), [bis(3-(4-phenyl-2-pyridyl)-5,6-diphenyl-1,2,4-triazine)(2,2′-bipyridine)iron(II)], [Fe(PPDT)₂(bpy)]²⁺ (2), [bis(2,2′-bipyridine)(3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine)iron(II)], [Fe(PDT)(bpy)₂]²⁺ (3), and [bis(2,2′-bipyridine)(3-(4-phenyl-2-pyridyl)-5,6-diphenyl-1,2,4-triazine)iron(II)], [Fe(PPDT)(bpy)₂]²⁺ (4) have been synthesized and characterized. Substitution of the triazine and bipyridine ligands from the complexes by nucleophiles (nu), namely 1,10-phenanthroline (phen) and 2,2′,6,2″-terpyridine (terpy) was studied in a sodium acetate-acetic acid buffer over the pH range 3–6 at 25, 35, and 45°C under pseudo-first order conditions. Reactions are first order in the concentration of complexes 1–4. The reaction rates increase with increasing [nu] and pH whereas ionic strength has no effect on the rate. Straight-line plots with positive slopes are observed when the k_obs values are plotted against [nu] or 1/[H⁺]. The substitution reactions proceed by dissociative as well as associative paths and the latter path is predominant. Observed low E_a values and negative ΔS^# values support the dominance of the associative path. Phenyl groups on the triazine ring modulate the reactivity of the complexes. The π-electron cloud on the phenyl rings stabilizes the charge on metal center by inductive donation of electrons toward the metal center, resulting in a decrease in reactivity of the complex and the order is 1 < 2 < 3 < 4. Density functional theory (DFT) calculations also support the interpretations drawn from the kinetic data.     

Syntheses,structures of Mn(II), Ni(II), Cu(II) and Zn(II) coordination complexes based on 3,4,5-trifluorobenzeneseleninic acid and N-donor ligands

Abstract

Five new coordination complexes [Mn^II (L₁)₂(4,4′-bpy)]_n (1), [Ni^II (L₁)₂(4,4′-bpy)]_n (2), [Zn^II (L₁)₂(4,4′-bpy)]_n (3), [Cu^II (L₁)₂(phen)₂]Cl₂ (4) and [Cu^II ₂(L₁)₂(2,2′-bpy)₂]Cl₂ (5) (HL₁?=?3,4,5-trifluorobenzeneseleninic acid, 4,4′-bpy = 4,4′-bipyridine, 2,2′-bpy = 2,2′-bipyridine and phen = 1,10-phenanthroline), have been synthesized and characterized by single-crystal X-ray diffraction, powder X-ray diffraction (PXRD), elemental analysis and IR spectroscopy. Complexes 1–3 display similar layers structures. In 1–3, the adjacent layers are further connected through π···π interactions to form three-dimensional supramolecular structures. Complexes 4 and 5 show a dimer containing an eight-membered ring. The dimer extends into three-dimensional supramolecular structures through π···π interactions, C–H···F and C–H···Cl interactions.     

Synthesis and DFT calculations of new ruthenium(II) nitrosyl complexes using cis-fac-dichlorotetrakis(dimethylsulfoxide)ruthenium(II) precursor and different oximes as sources of nitrosyl ligand

Abstract

Three NO⁺-ruthenium(II) complexes were prepared by using cis-[RuCl₂(DMSO)₄] as precursor, P, and the compounds benzohydroxamic acid (BHA), 1′, anti-diphenylglyoxime (H₂dpg), 2′, and dimethylglyoxime (H₂dmg), 3′, as sources of NO moiety. The three complexes [RuCl₂(DMSO)₃(NO)]⁺(BA)^?, 1, [RuCl₂(DMSO)₃(NO)]⁺(Hdpg)^?, 2, and [RuCl₂(DMSO)₃(NO)]⁺(Hdmg)^?, 3, were characterized by (FT-IR, NMR, UV-Vis) spectroscopy, thermogravimetry, and microanalysis. From FT-IR spectral data, two modes of coordination of DMSO to Ru atom through both S and O atoms were detected for 1 and 2. For 3, only S coordination was reported. Computational studies on the [RuCl₂(DMSO)₃(NO)]⁺ cationic parts, 1″, 2″ and 3″, of the investigated complexes 1, 2 and 3 were carried out by DFT. The molecular geometry and mode of attachment of Ru(II) with DMSO were performed with the B3LYP/LANL2DZ level of theory and basis set. Theoretical to the experimental agreement was achieved for analysis of IR data of the investigated complexes. Additional information about binding between the ruthenium atom and the DMSO ligand has been obtained by NBO analysis.     

Two copper(II) metal–organic networks derived from bis-pyridyl-bis-amide ligands and aromatic polycarboxylates: a 2-D layered structure and a 4-connected trinodal 3-D topology

Two metal–organic coordination polymers, [Cu₃(4-bpcb)₂(1,2,4-btc)₂(H₂O)₂] (1) and [Cu₃(3-bpcb)₃(btec)_1.5] (2), have been synthesized from hydrothermal reaction of copper chloride with mixed ligands [4-bpcb?=?N,N′-bis(4-pyridinecarboxamide)-1,4-benzene, 3-bpcb?=?N,N′-bis(3-pyridinecarboxamide)-1,4-benzene, 1,2,4-H₃btc?=?1,2,4-benzenetricarboxylic acid, and H₄btec?=?1,2,4,5-benzenetetracarboxylic acid]. X-ray diffraction analysis reveals that 1 exhibits a 2-D layer structure and 2 possesses a three-dimensional (3-D) network. In 1 and 2, Cu^II ions are connected by bridging 1,2,4-btc or btec to form 2-D polymeric layers. Cu-1,2,4-btc layer does not propagate into a 3-D coordination framework in 1 due to 4-bpcb showing monodentate coordination (via ligation of only one pyridyl nitrogen). In 2, Cu-btec 2-D layers are further extended into a 3-D network with (6⁴.8²)₃ topology by 3-bpcb ligand in μ ₂-bridging coordination (via ligation of two pyridyl nitrogens). The different structures of the two complexes illustrate the influence of different polycarboxylates and N-donor positions of organic ligands on the formation of such coordination architectures. Moreover, the thermal properties and electrochemical properties of the copper complexes bulk-modified carbon paste electrodes have been studied.     

1,3,2-Δ5[sgrave]5-DIAZAPHOSPHOLENES: VERSATILE REACTANTS

Abstract

In an oxidative addition reaction O,O′-bis(trimethylsilyl)diacetyldioxime 2 and triethylphosphite give 1,3,2-Δ⁵[sgrave]⁵-diazaphospholene 3a which hydrolyzes to form (Z)-2,3-bis(hydroxylamino)-2-butene 4. Benzaldehyde and 4 condensate to furnish 1,3-dihydroxy-4,5-dimethyl-2-dimethyl-4-imidazoline 5. Tris(trimethylsilyl)phosphite and 2 react to give the first tris(trimethylsiloxy)phosphorane 3b.     

Regiocontrolled Incorporation and Annulation of Glucose into Spirothiazole and Spirothiazoloxazole Derivatives

ABSTRACT

Cyclic ketones 1a-f reacted with mercaptoacetic acid in benzene and/or toluene in the presence of p-toluenesulfonic acid afforded the corresponding spiro-1,3-oxathialanone derivatives (2a-f). Compounds 2a-f reacted with glucosamine hydrochloride in a mixture of pyridine and ethanol to yield 3-(2′-glucosyl)-2-spiro[1′-cycloalkyl]thiazolidin-4-one derivatives 4a-f. Reaction of 4a-f with fused sodium acetate in a mixture of acetic anhydride and acetic acid gave annulated spirothiazoloxazologlucose derivatives 6a-f. All the synthesized spiro derivatives were identified by conventional methods (IR, ¹H NMR spectroscopy and elemental analyses).