Synthesis,characterization, and antitumor properties of ruthenium(II) anthraquinone complexes

Three new Ru(II) complexes, [Ru(dmb)₂(ipad)](ClO₄)₂ (dmb = 4,4′-dimethyl-2,2′-bipyridine, ipad = 2-(anthracene-9,10-dione-2-yl) imidazo[4,5-f][1,10]phenanthroline, 1), [Ru(dmp)₂(ipad)](ClO₄)₂ (dmp = 2,9-dimethyl-1,10-phenanthroline, 2), and [Ru(dip)₂(ipad)](ClO₄)₂ (dip = 4,7-diphenyl-1,10-phenanthroline, 3), have been synthesized and characterized. The three Ru(II) complexes intercalate with the base pairs of DNA. The in vitro antiproliferative activities and apoptosis-inducing characteristics of these complexes were investigated. The complexes exhibited cytotoxicity against various human cancer cell lines. BEL-7402 cells displayed the highest sensitivity to 1, accounted for by the greatest cellular uptake. Complex 1 was shown to accumulate preferentially in the nuclei of BEL-7402 cells and cause DNA damage and induce apoptosis, which involved cell cycle arrest and reactive oxygen species generation.     

Syntheses,crystal structures and solvatochromic properties of dinuclear oxalato-bridged copper(II) complexes

Three dinuclear copper(II) complexes, [Cu₂(L¹)₂(μ-ox)](ClO₄)₂?2(CH₃CN), [Cu₂(L²)₂(μ-ox)](ClO₄)₂?H₂O, and [Cu₂(L³)₂(μ-ox)](ClO₄)₂ where ox = oxalato; L = N,N-dimethyl,N′-benzylethane-1,2-diamine, L¹, N,N-diethyl,N′-benzylethane-1,2-diamine, L², N,N-diisoprophyl,N′-benzylethane-1,2-diamine, L³, were prepared and characterized by elemental analyses, spectral (IR, UV–Vis) data and molar conductance measurements. The crystal structures of [Cu₂(L¹)₂(μ-ox)](ClO₄)₂?2(CH₃CN) and [Cu₂(L³)₂(μ-ox)](ClO₄)₂ have been determined by single-crystal X-ray analysis. Solvatochromic behaviors were investigated in various solvents, showing positive solvatochromism. The effect of steric hindrance around the copper ion imposed by N-alkyl groups of the diamine chelates on the solvatochromism property of the complexes is discussed. Solvatochromism was also studied with different solvent parameter models using stepwise multiple linear regression method.     

Effects of substituent on the DNA-binding of ruthenium(II) complexes containing asymmetric tridentate intercalative ligands

Three novel unsymmetric tridentate ligands, namely, ptmi (ptmi = 3-(1,10-phenanthroline-2-yl)-as-triazino[5,6-f]-5-methoxyisatin), pti (pti = 3-(1,10-phenanthroline-2-yl)-as-triazino-[5,6-f]isatin), ptni (ptni = 3-(1,10-phenanthroline-2-yl)-as-triazino[5,6-f]-5-nitroisatin), and their complexes [Ru(tpy)(ptmi)](ClO₄)₂ (tpy = 2,2′:6′,2″-terpyridine) (1), [Ru(tpy)(pti)](ClO₄)₂ (2), and [Ru(tpy)(ptni)](ClO₄)₂ (3) were prepared and characterized by elemental analysis, ¹H NMR, ES–MS. The electrochemical behaviors were studied by cyclic voltammetry. The DNA-binding properties of these complexes were investigated by the spectroscopic method, viscosity measurements, and thermal denaturation. Theoretical studies on these complexes were also performed with the density functional theory (DFT) method. The experimental results showed that these complexes bind to calf thymus (CT-DNA) in an intercalative mode. The order of DNA-binding affinities (A) of these complexes is A(1) < A(2) < A(3). The trend in the DNA-binding affinities of this series of complexes can be reasonably explained by the DFT calculations.     

Supramolecular frameworks composed of copper(II), zinc(II), and ferrous(II) complexes having 3-bromo or 3,8-dibromo-1,10-phenanthroline ligand with different molar ratios of metal and ligand

Abstract  

Three copper(II), one zinc(II), and one ferrous(II) complexes having 3-bromo or 3,8-dibromo-1,10-phenanthroline ligand with different metal/ligand molar ratios, formulated as [Cu(3-bromo-phen)(ClO₄)(C₃H₇NO)₂(H₂O)](ClO₄) (1), [Cu(3,8-dibromo-phen)(ClO₄)(C₃H₇NO)₂(H₂O)](ClO₄) (2), [Cu(3,8-dibromo-phen)(ClO₄)(H₂O)₃](ClO₄)(H₂O)₃ (3), [Zn(3,8-dibromo-phen)₂(H₂O)₂](ClO₄)₂(H₂O)₂ (4), and [Fe(3,8-dibromo-phen)₃](ClO₄)₂(H₂O)(CH₄O)(C₃H₆O)₂ (5) (phen = 1,10-phenanthroline), have been synthesized and characterized in this paper. X-ray single-crystal diffraction studies reveal the different crystallographic symmetry and packing fashions between neighboring phen rings in 1:1 Cu(II) complexes 1–3 due to the alteration of bromo substituent 1,10-phenanthroline ligands and coordinated or free solvent molecules. Additionally, in 1:2 Zn(II) and 1:3 Fe(II) complexes 4 and 5, continuous π–π stacking and alternating π–π and dimeric p–π stacking are found.     

Synthesis,structures, and fluorescent properties of two oxalato-bridged dinuclear zinc(II) complexes with tridentate and tetradentate polybenzimidazole ligands

Two dinuclear oxalato-bridged zinc(II) complexes, [Zn₂(bbma)₂(μ₂-η⁴-ox)](ClO₄)₂ (1) and [Zn₂(ntb)₂(μ₂-η²-ox)](ClO₄)₂·4CH₃OH (2), containing tridentate and tetradentate polybenzimidazole ligands were synthesized, where bbma is bis(benzimidazol-2-yl-methyl)amine and ntb is tris(2-benzimidazolylmethyl)amine. They were characterized by single-crystal X-ray diffraction, elemental analysis, IR, and fluorescence spectroscopy. Zinc(II) complexes in 1 and 2 are five-coordinate in distorted trigonal bipyramidal geometry. Oxalate bridges two zinc(II) ions as a bis-bidentate chelate in 1, while bis-monodentate in 2. The Zn?Zn distances are 5.318(1)?Å for 1 and 7.1295(5)?Å for 2, respectively. 1-D chain structures are formed in 2 by intermolecular hydrogen bonds. The solid state fluorescence spectra have been studied for 1 and 2.     

OPTICAL ISOMERS OF 2,2′-DIAMINOBIPHENYLBIS(ETHYLENEDIAMINE) COBALT(III) CHLORIDE AND ITS RELATED COMPLEXES1

Abstract

Several cobalt(III) complexes incorporating 2,2′-diaminobiphenyl(dabp) and other 2(2N)- or 4N-type ligands were prepared and resolved by chemical and chromatographic methods: (1) [Co(en)₂(dabp)]Cl₂2H₂O, (2) [Co(l-pn)₂(dabp)] (ClO₄)₃4H₂O, (3) [Co(l-chxn)₂(dabp)](ClO₄)₃3H₂O, (4) α-[Co(trien)(dabp)](ClO₄)₃, (5) α-[Co(2S,9S-dimetrien)(dabp)] (ClO₄)₃ 2H₂O, (6) α-[Co(3S,8S-dimetrien)(dabp)] (ClO₄)₃3H₂O, (7 [Co(tren)(dabp)]Cl₃5H₂O, (8) [Co(bpy)₂(dabp)] Cl₃3H₂O. The complexes (1), (4) and (8) gave one pair of enantiomers, Δ(Λ) and Λ(δ), and the complexes (2) and (3) gave only one Δ-isomer. The absolute configuration of the complexes (5) and (6) was found to be Λ, and that of (7) was not determined because of unsuccessful resolution. The three geometric isomers of the complex (2) were separated and their structures assigned.     

Synthesis and magnetism of 6-nitrobenzimidazolate and imidazolate-bridged copper(II) complexes

Summary Four new trinuclear copper(II) complexes, [Cu(phen)-(NBzIm)] (ClO₄) (1), [Cu(bpy)(NBzIm)](ClO₄) (2), [Cu-(Me₂-bpy)(NBzIm)](Ac)·1/2H₂O (3) and [Cu(Me₂-bpy)-(Im)](ClO₄)·1/2H₂O (4) (phen = 1, 10-phenanthroline, bpy = 2,2-bipyridine, NBzIm = 6-nitrobenzimidazolate ion, Im=imidazolate ion) have been prepared and characterized by variable temperature magnetic susceptibility measurements. A weak antiferromagnetic spin exchange interaction operates between copper(II) ions, exchange integrals evaluated as J =-23.82 cm^-1 for (1); and J=-21.91 cm^-1 for (2).     

Syntheses,structures and electrochemical properties of complexes of nickel(II) with triethylenetetramine and bidentate nitrogen donor co-ligands

Three new polyamine Ni(II) complexes, namely [Ni(trien)(phen)](BF₄)₂ 1, [Ni(trien)(bipy)](ClO₄)₂ 2 and [Ni(trien)(en)](ClO₄)₂ 3 [trine = triethylenetetramine, phen = 1,10-phenanthroline, bipy = 2,2′-bipyridyl, en = ethylenediamine] have been synthesized and characterized by physico-chemical and spectroscopic methods. Complexes 1 and 2 crystallize in monoclinic space group P21/c, and possess a distorted octahedral geometry. Significant hydrogen bonding interactions are found in both complexes.     

Phosphoester binding,DNA binding,DNA cleavage and in vitro cytotoxicity studies of simple heteroleptic copper(II) complexes with bidentate ligands

Abstract

Two mononuclear heteroleptic copper complexes, [Cu(±trans-dach)(bpy)](ClO₄)₂ 1a and [Cu(±trans-dach)(phen)](ClO₄)₂ 2a [dach?=?1,2-diaminocyclohexane, bpy?=?2,2′-bipyridine and phen?=?1,10-phenanthroline], were synthesized and analyzed by CHN analysis, electronic absorption, FT-IR spectroscopy, EPR, and SXRD. The molecular structures of 1a and 2a showed octahedral geometry around Cu(II). Both complexes interacted with phosphoesters and DNA. Their binding affinities with diphenylphosphate, di n-butylphosphate, trimethylphosphate, and triphenylphosphate were studied by UV–vis spectroscopy. For understanding the stereochemical role of dach ligand toward DNA interaction, enantiopure DACH complexes [Cu(R,R-trans-dach(bpy)](ClO₄)₂ 1b, [Cu(S,S-trans-dach)(bpy)](ClO₄)₂ 1c, [Cu(cis-dach)(bpy)](ClO₄)₂ 1d, [Cu(R,R-trans-dach)(phen)](ClO₄)₂ 2b, [Cu(S,S-trans-dach)(phen)](ClO₄)₂ 2c, and [Cu(cis-dach)(phen)](ClO₄)₂ 2d were synthesized and analyzed. All complexes interacted with calf thymus-DNA (CT-DNA) as studied by UV–vis spectroscopy. The nature of binding to CT-DNA was groove/electrostatic as supported by circular dichroism, cyclic voltammetry, and docking studies. Complexes were able to cleave plasmid DNA at 12.5 µM (1a–d) and 6 µM (2a–d), where 2d showed 64% Form II and 36% Form III. The in vitro cytotoxic studies of two different cancer cell lines showed inhibition with low IC₅₀ value in comparison to reference control (cisplatin). These complexes are efficient in inducing apoptosis in cancer cells, making them viable for potent anticancer activity.     

Versatile binding properties of di-pyridyl ligands with Cu(II) complexes: The syntheses,structural characterization and thermal analysis of six new species

A novel series of 4,4′-bipyridine- and 1,2-bis(4-pyridyl)ethane-Cu(II) complexes were synthesized using a variety of amine ligands (DPA = di(2-pyridylmethyl)amine, Medpt = 3,3′-diamino-N-methyldipropylamine, Hbpca = bis(2-pyridylcarbonyl)amine, TPA = tris(2-pyridylmethyl)amine) and cyclen = 1,4,7,10-tetraazacyclododecane). Different complexes were obtained including mononuclear [Cu(cyclen)(4,4′-bipy)](ClO₄)₂ (1), dinuclear {[Cu(μ₂-bpca)(4,4′-bipy)(H₂O)]ClO₄}₂ (2), [Cu₂(DPA)₂(μ₂-4,4′-bipy)(ClO₄)₄)]·H₂O (3), [Cu₂(cyclen)₂(μ₂-bpe)](ClO₄)₄ (4) and [Cu₂(TPA)₂(μ₂-bpe)](ClO₄)₄ (5) and the 1-D polymer, {[Cu(Medpt)(μ₂-4,4′-bipy)](ClO₄)₂}_n (6). In the 1–6 samples, cooling up to 100 K produces only the expected, minor, changes in cell constants given no space group changes. Therefore, data for the 100 K structures are reported only. Single-crystal X-ray crystallography reveals the monodentate coordination of the 4,4′-bipy in 1 and 2, and the bridged nature of the di-pyridyl ligands in the dinuclear complexes 2–5 and in the polymeric complex 6. In this series, structures 3–6 consist of the 4,4′-bipy or bpe bridging the two Cu(II) centers, the coordination by the tri- or the tetra-N donors of the amine, and the ClO₄^? groups as counter ions in 4–6 complexes. In the complexes 3–6, the Cu···Cu distances across the bridged di-pyridyl ligands were found to be greater than 11 Å. The magnetic properties of complex 3 reveal no evidence for magnetic coupling between the two Cu(II) centers (J = ?0.58 cm^?1).     

Zinc(II) Complexes with 1H‐Imidazol‐4‐yl‐Containing Polyamine Ligand

The protonation and Zn^II/Cu^II complexation constants of tripodal polyamine ligand N¹‐(2‐aminoethyl)‐N¹‐(1H‐imidazol‐4‐ylmethyl)‐ethane‐1,2‐diamine (HL) were determined by potentiometric titration. Three new compounds, i.e. [H₃(HL)](ClO₄)₃ ( 5 ), [Zn(HL)Cl](ClO₄) ( 6 ) and {[Zn(L)](ClO₄)}_n ( 7 ) were obtained by reactions of HL · 4HCl with Zn(ClO₄)₂ · 6H₂O under different reaction pH, and they were compared with the corresponding Cu^II complexes reported previously. The results indicate that the reaction pH and metal ions have remarkable influence on the formation and structure of the complexes.     

Structural characterisation of mononuclear zinc(ii) complexes of 4-methyl-3,5-di(2-pyridyl)-4H-1,2,4-triazole with three-atom co-ligands: [ZnII(medpt)2X]ClO4 (X?=?NCS?, N3?, NO2?)

The reaction of 4-methyl-3,5-di(2-pyridyl)-4H-1,2,4-triazole (medpt) with Zn(ClO₄)₂·6H₂O and NaSCN, NaN₃ or NaNO₂ in a 2:1:1 molar ratio in MeOH/H₂O (9:1) affords the mononuclear complexes [Zn^II(medpt)₂(NCS)]ClO₄, [Zn^II(medpt)₂(N₃)]ClO₄ and [Zn^II(medpt)₂(NO₂)]ClO₄, respectively. All three complexes have been structurally characterised and found to feature unusual coordination polyhedra for 3,5-di(2-pyridyl)-4H-1,2,4-triazole complexes. In [Zn^II(medpt)₂(NCS)]ClO₄ and [Zn^II(medpt)₂(N₃)]ClO₄, the zinc atom resides within a distorted square-pyramidal N₅ coordination sphere [τ = 0.22 and 0.04, respectively] with two bidentate medpt ligands bound equatorially and the pseudohalide ion coordinating as a unidentate co-ligand in the apical position. In contrast, the NO₂ ⁻ ion in [Zn^II(medpt)₂(NO₂)]ClO₄ acts as a bidentate ligand, which leads to a strongly distorted N₄O₂ coordination environment about the metal centre.     

Synthesis and crystal structures of terephthalato-bridged macrocyclic nickel(II) complexes with <Emphasis Type="Italic">cis</Emphasis> configurations

Three dinuclear terephthalato-bridged nickel(II) complexes [Ni(rac-L)]₂(μ-TPA)(ClO₄)₂ (1), [Ni(RR-L)]₂(μ-TPA)(ClO₄)₂ (2), and [Ni(SS-L)]₂(μ-TPA)(ClO₄)₂ (3) (L = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane, TPA = terephthalic acid) have been synthesized and characterized. Single-crystal X-ray diffraction analyses revealed that the Ni(II) atoms have six-coordinated distorted octahedral environments, and the terephthalato ligand bridges two Ni(II) centres in a bis bidentate fashion to form dimers in all three complexes. The monomers of {[Ni(RR-L)]₂(μ-TPA)}²⁺ and {[Ni(SS-L)]₂(μ-TPA)}²⁺ are connected through intermolecular hydrogen bonds to generate 1D right-handed and left-handed helical chains, respectively. The racemic character of 1 and the homochiral natures of 2 and 3 are confirmed by the results of CD spectroscopy.     

Tetranuclear Zn(II) complexes with compartmental and dicyanamido ligands: synthesis,structure, and luminescent properties

New tetranuclear compounds have been obtained by reacting binuclear complexes, [Zn₂L ⁿ (μ-OH)(H₂O)₂](ClO₄)₂, with sodium dicyanamide (HL ⁿ are end-off bicompartmental ligands resulting from condensation between 2,6-diformyl-p-cresol with N,N-dimethyl-ethylenediamine or 2-aminomethyl-pyridine). The complexes, [{L¹(μ-OH)Zn₂}(μ _1,5-dca)₂{Zn₂(μ-OH)L¹}](ClO₄)₂ (1) and [{Zn₂L²(μ ₃-OH)(dca)}₂](ClO₄)₂?·?2H₂O (2), have been characterized by single-crystal X-ray diffraction. The angular nature of the bridging dicyanamido induces the “M” shape of the tetranuclear cationic unit in 1. The tetranuclear cation, because of its particular shape, acts as a receptor toward one perchlorate ion, which is hydrogen bonded to the hydroxo groups. This tetranuclear unit in 2 has a defective heterocubane structure. The luminescence properties of the new tetranuclear complexes have been investigated.     

Ruthenium(II) complexes containing 2,9-dimethyl-1,10-phenanthroline and 4,4′-dimethyl-2,2′-bipyridine as ancillary ligands: synthesis,characterization and DNA-binding

Two new Ruthenium (II) polypyridyl complexes [Ru(dmp)₂(ipbp)](ClO₄)₂ (1) (dmp = 2,9-dimethyl-1,10-phenanthroline, ipbp = 3-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)-4H-1-banzopyran-2-one) and [Ru(dmb)₂(ipbp)](ClO₄)₂ (2) (dmb = 4,4′-dimethyl-2,2′-bipyridine) have been synthesized and characterized by elemental analysis, FAB-MS, ES-MS and ¹H NMR and cyclic voltammetric methods. The DNA-binding behaviors of these complexes were investigated by spectroscopic titration, viscosity measurements, and thermal denaturation. Absorption titration and thermal denaturation studies reveal that these complexes are moderately strong binders of calf thymus DNA (CT-DNA). Viscosity measurements show that the complexes 1 and 2 interact with CT-DNA by intercalative mode. The DNA-binding affinity of the complex 2 is larger than that of complex 1.     

Thermochemistry of rare earth complexes [Ln(Ala)2(Im)(H2O)](ClO4)3 (Ln=Pr, Gd)

The two complexes, [Ln(Ala)₂(Im)(H₂O)](ClO₄)₃ (Ln=Pr, Gd), were synthesized and characterized. Using a solution-reaction isoperibol calorimeter, standard enthalpies of reaction of two reactions: LnCl₃⋅6H₂O(s)+2Ala(s)+Im(s)+3NaClO₄(s)=[Ln(Ala)₂(Im)(H₂O)](ClO₄)₃(s)+3NaCl(s)+5H₂O(l) (Ln=Pr, Gd), at T=298.15 K, were determined to be (39.26±0.10) and (5.33±0.12) kJ mol^–1 , respectively. Standard enthalpies of formation of the two complexes at T=298.15 K, Δ_fH^Θ_m {[Ln(Ala)₂(Im)(H₂O)](ClO₄)₃(s)} (Ln=Pr, Gd), were calculated as –(2424.2±3.3) and –(2443.4±3.3) kJ mol^–1 , respectively.     

Construction of zinc–organic frameworks by flexible aliphatic dicarboxylates plus 2-(1H-imidazolyl-1-methyl)-1H-benzimidazole ligand

Three new Zn(II) complexes, [Zn(ox)(imb)] (1), [Zn₂(mal)₂(imb)₂] (2), and [Zn(suc)(imb)]·H₂O (3) (imb = 2-(1H-imidazolyl-1-methyl)-1H-benzimidazole, H₂ox = oxalic acid, H₂mal = malonic acid, H₂suc = succinic acid), have been synthesized and structurally characterized. Complex 1 is a 3-D framework with a 4-connected diamond topology with the topological notation of 6⁶. Complex 2 exhibits 2-D layers with (6,3) networks. Complex 3 displays a 3-D framework constructed through unusual 2-D → 3-D parallel interpenetration of corrugated 2-D (6,3) networks. IR spectra, PXRD patterns, thermogravimetric curves, and photoluminescence spectra are addressed.     

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.     

Three polynuclear complexes with bridging triazole ligand: crystal structures

Three polynuclear clusters, [Cu₄L₈](ClO₄)₄·4H₂O (1), [Zn₃L₆(H₂O)₆](ClO₄)₆·6H₂O (2), and [Mn₃L₆(CH₃OH)₆](ClO₄)₆·4.5H₂O (3) (L?=?4-(4-hydroxyphenyl)-1,2,4-triazole), obtained by the reactions of M(ClO₄)₂·6H₂O with L have been isolated and structurally characterized. Complex 1 featured a tetranuclear Cu(I) structure. Both 2 and 3 are linear hexapositive trimers linked by three N1,N2–1,2,4-triazole ligands to the divalent central and terminal metal ions. Furthermore, the luminescence properties of 2 were investigated at room temperature in the solid state.     

Hydrogen-bonded supramolecular structures constructed from trinuclear copper units

Four copper complexes with similar trinuclear copper units, [Cu₆(Bmshp)₂(SO₄)₂(H₂O)₇]·2H₂O (1), [Cu₃(Bmshp)(ClO₄)₂(H₂O)₄]·5H₂O (2), [Cu₃(Bmshp)(DMF)₄(H₂O)₂]·H₂O·2DMF·2ClO₄ (3) and [Cu₃(H₂Bcshp)(ClO₄)₂(H₂O)₄]·3H₂O (4) (H₄Bmshp = 2,6-bis[(3-methoxysalicylidene)hydrazinocarbonyl]pyridine, H₆Bcshp = 2,6-bis[(3-carboxylsalicylidene)hydrazinocarbonyl]pyridine), were synthesized and characterized by elemental analysis, IR and single crystal X-ray diffraction analysis. Due to the different anions, solvents and ligands used in the syntheses, complexes 1–4 exhibit diverse supramolecular structures constructed from the corresponding trinuclear copper units via H-bonds.