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.     

DNA-binding and photocleavage studies of metallofluorescein–porphyrin complexes of zinc(II) and copper(II)

The DNA-binding behaviors of the fluorescein?Cporphyrinatozinc(II) complex Zn(Fl-PPTPP) (Fl-PPTPP?=?5-(4-fluoresceinpropyloxy)phenyl-10,15,20-triphenylporphyrin) and fluorescein?Cporphyrinatocopper(II) complex Cu(Fl-PPTPP) with calf thymus DNA (CT-DNA) were investigated by UV?CVis absorption titrations, fluorescence spectra, viscosity measurements, thermal denaturation and circular dichroism. The results suggest that both complexes interact with CT-DNA by intercalation. In addition, their photocleavage reactions with pBR322 supercoiled plasmid DNA were investigated. Both complexes exhibit significant DNA cleavage activity, and singlet oxygen may play an important role in these reactions.     

Review: Synthesis,characterization, and DNA-binding properties of Ru(II) molecular “light switch” complexes

This article presents recent progress in our laboratory on the interactions of Ru(II) polypyridyl complexes with calf thymus DNA (CT-DNA). Mixed polypyridyl Ru(II) complexes [Ru(L)₄(AIP)]²⁺ and [Ru(L)₄PyIP]²⁺, where L is 4-amino pyridine and pyridine (AIP?=?2-(9-anthryl)-1H-imidazo[4,5-f][1,10]phenanthroline; PyIP?=?2-(1-pyrenyl)-1H-imidazo[4,5-f][1,10]phenanthroline), have been synthesized and characterized by elemental analysis, and physicochemical methods such as ESI-MS, UV-Vis, IR, and NMR spectroscopic techniques. Electronic absorption titrations, fluorescence spectroscopy, viscosity measurements, and salt-dependent studies of CT-DNA in the presence of incremental amounts of all four Ru(II) complexes clearly demonstrate that all four complexes bind to DNA by intercalation. The DNA-binding affinities of these complexes follow the order [Ru(4-APy)₄(PyIP)]^2+?>?[Ru(Py)₄PyIP]^2+?>?[Ru(4-APy)₄(AIP)]^2+?>?[Ru(Py)₄AIP]²⁺. Irradiation of pBR 322 DNA with these complexes results in nicking of the plasmid DNA. All four complexes were screened for antimicrobial activity. All complexes also exhibited DNA “light switch” properties. These results suggest that both ancillary ligand and intercalative ligand influence the binding of these complexes to DNA.     

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,characterization and redox properties of mono- and bis-β-diketonate ruthenium complexes

Complexes of the type [RuIII(L)Cl2(PPh3)2] and [RuII(L)2(PPh3)2] (HL=benzoylacetone or acetylacetone) have been synthesized by the reaction of [RuCl2(PPh3)3] with HL under various experimental conditions. The [RuIII(L)Cl2(PPh3)2] complexes are one-electron paramagnetic species and, in solution, they show intense LMCT transitions in the visible region together with weak ligand-field transitions at lower energies. The [RuII(L)2(PPh3)2] complexes are diamagnetic and their solutions show sharp 1H n.m.r. signals and also show intense MLCT transitions in the visible region. In MeCN solution, the [RuIII(L)Cl2(PPh3)2] complexes show a reversible RuIII-RuII reduction near –0.3V and an irreversible RuIII- RuIV oxidation near 1.2 V versus s.c.e. A reversible RuII-RuIII oxidation is displayed by the [RuII(L)2(PPh3)2] complexes in MeCN solution near 0.3 V versus s.c.e. followed by another reversible RuIII-RuIV oxidation near 1.1 V versus s.c.e. The [RuII(L)2(PPh3)2] complexes have been oxidized to the corresponding [RuIII(L)2(PPh3)2]+ analogues and isolated as ClO4– salts in the solid state. The oxidized complexes are one-electron paramagnetic. They are 1:1 electrolytes in solution and show intense LMCT transitions in the visible region along with weak ligand-field transitions at lower energies.     

Synthesis,spectroscopic characterization,antineoplastic, in vitro-cytotoxic,and antibacterial activities of mononuclear ruthenium(II) complexes

The synthesis, antineoplastic, cytotoxic, and antibacterial activities of Ru(II) complexes derived from quinazoline and thiosemicarbazone ligands are reported. These complexes have been prepared and characterized by UV-Vis, IR, ¹H-NMR, FAB-mass spectroscopy, and elemental analysis. The ligands and resulting complexes were subjected to in vivo antineoplastic activity against a transplantable murine tumor cell line Ehrlich ascites carcinoma (EAC) and in vitro cytotoxic activity against human cancer cell line Molt 4/C₈, CEM, and murine tumor cell line L 1210. The ruthenium complexes show promising biological activity especially in decreasing tumor volume and viable ascitic cell counts. These complexes prolonged the life span of mice bearing EAC tumors by 10–52%. In vitro evaluation of these ruthenium complexes revealed cytotoxic activity from 0.29 to 2.9?µmol?L^?1 against Molt 4/C₈, 0.22 to 2.1?µmol?L^?1 against CEM and 0.42 to 4.7?µmol?L^?1 against L1210 cell proliferation, depending on the nature of the compound. The metal complexes are more active than the parent ligand and exhibit mild to moderate antibacterial activity.     

Synthesis,characterization, and reactivity of ruthenium(II) complexes containing η6-arene-η1-pyrazole ligands

New ruthenium(II) complexes containing η⁶-arene-η¹-pyrazole ligands were synthesized and characterized by elemental analysis and spectroscopic methods. In addition, the molecular structure of dichloro-3,5-dimethyl-1-(pentamethylbenzyl)-pyrazole–ruthenium(II), [Ru]L_3b, was determined by X-ray diffraction studies. These complexes were applied in the transfer hydrogenation of acetophenone by isopropanol in the presence of potassium hydroxide. The activities of the catalysts were monitored by NMR.     

Structural characterization and cytotoxicity studies of ruthenium(II)–dmso–chloro complexes of chalcone and flavone derivatives

A synthetic precursor cis-[Ru^IICl₂(dmso)₄] is complexed separately with 3-(4-benzyloxyphenyl)-1-(2-hydroxylphenyl)-prop-2-en-1-one (L¹H) and 2-(4-benzyloxyphenyl)-3hydroxy-chromen-4-one (L²H). The resulting complexes are assigned the composition fac-[RuCl(S-dmso)₃(L¹)] 1 and fac-[RuCl(S-dmso)₃(L²)] 2 using elemental analyses, FAB mass data and spectroscopic (IR, ¹H NMR, UV–Vis, emission) spectral properties. The X-ray diffraction analysis shows that complexes self-associate through non-covalent interactions and provide 1D and 2D supramolecular structures. These complexes are assayed for their cytotoxicity studies on Dalton Lymphoma cell lines.     

Synthesis,characterization and magnetic properties of supramolecular metal–organic complexes constructed from flexible–rigid mixed ligands

Two new supramolecular metal–organic complexes have been synthesized under hydrothermal conditions. Complex 1 exhibits a three-dimensional supramolecular network, constructed from [Co₂(H₃BPTC)₂(phen)₂] (H₄BPTC = 3,3′4,4′-benzophenone tetracarboxylate acid, phen = 1,10-phenanthroline) discrete units. Complex 2 similarly exhibits discrete [Cu₂(DPA)₂(bipy)₂(H₂O)₂] (DPA = 1,1′-biphenyl-2,2′-dicarboxylate acid, bipy = 2,2′-bipyridine) units, which are linked to form a three-dimensional supramolecular network through π–π interactions. It is interesting that during the synthesis of complex 1, the H₄BPTC ligands undergo partial decomposition to give 1,2,4-benzenetricarboxylate (H₃BTC) ligands, which react with Co to form [Co₃(BTC)₂]_n (3). Complex 3 shows a three-dimensional covalent network. The magnetic properties of complexes 1 and 2 have been studied.     

Synthesis,characterization and photophysical properties of homoleptic platinum(II) complexes with 2,2′-biimidazole-based ligands

Eight pairs of cis–trans isomeric homoleptic platinum(II) complexes based on N-alkyl- or aryl-substituted 2,2′-biimidazole ligands were synthesized, and their photophysical properties were investigated. The cis and trans isomers readily interconvert at slightly elevated temperature, implying that the activation barrier for this process is low. Single crystal X-ray diffraction analysis revealed that the complexes have an ideal square-planar geometry. Their UV–Vis spectra showed lower energy absorption bands in the range of 345–378 nm, which are assigned to the typical MLCT mixed with LC transitions. In frozen glass solution at 77 K and also in the powder state, these complexes exhibit green emission ranging from 440 to 540 nm with photoluminescence quantum yields of 3.3–24.4%. The emitting excited state is dominated by ³ππ* character with some contributions from ³MLCT according to the excitation spectra.     

Synthesis,characterization, photocleavage,cytotoxicity in vitro,apoptosis, and cell cycle arrest of ruthenium(II) complexes

Two new ruthenium(II) complexes, [Ru(dmp)₂(BHIP)]²⁺ (1) and [Ru(dmb)₂(BHIP)]²⁺ (2), were synthesized and characterized by elemental analysis, ESI-MS, and ¹H NMR. DNA-binding constants of these complexes with calf-thymus DNA (ct-DNA) were determined to be 2.09 (±0.18)?×?10⁴ (mol?L^?1)^?1 (s?=?2.58) and 1.48 (±0.17)?×?10⁵ (mol?L^?1)^?1 (s?=?1.57), respectively. Viscosity measurements show that 1 and 2 interact with ct-DNA by intercalation. Upon irradiation at 365?nm, 1 and 2 induce cleavage of pBR322 DNA. The cytotoxicity of these complexes was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The apoptosis induced by the complexes was studied by flow cytometry. The results of the cell cycle arrest show that 2 can inhibit the proliferation of BEL-7402 cells in the G0/G1 phase.     

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.     

Synthesis,crystal structure and spectroscopic characterization of new neutral and cationic (η-p-cymene)–ruthenium(II) complexes with phosphine–amide ligands

The dimeric starting material [Ru(η⁶-p-cymene)(μ-Cl)Cl]₂ reacts with the phosphino-amides o-Ph₂P–C₆H₄CO–NH–R [R = ⁱPr (a), Ph (b), 4-MeC₆H₄ (c), 4-FC₆H₄ (d)] to give the mononuclear compounds 1a–d [RuCl(η⁶-p-cymene)(o-Ph₂P–C₆H₄–CO–NH–R)]Cl. The subsequent reaction of these complexes with KPF₆ produced the cationic species 2a–d [RuCl(η⁶-p-cymene)(o-Ph₂P–C₆H₄–CO–NH–R)][PF₆] in which phosphino-amides also act as rigid P,O-chelating ligands. The molecular structures of 2b–d were determined crystallographically. Amide deprotonation is achieved when complexes 2a–d were made react with 1 M aqueous solution of KOH, affording the corresponding neutral species 3a–d [RuCl(η⁶-p-cymene)(o-Ph₂P–C₆H₄–CO–N–R)] in which a P,N-coordination mode is suggested.     

Synthesis and characterization of sterically encumbered β-ketoiminate complexes of iron(II) and zinc(II)

The synthesis, structure, and spectroscopic signatures of a series of four-coordinate iron(II) complexes of β-ketoiminates and their zinc(II) analogues are presented. An unusual five-coordinate iron(II) triflate with three oxygen bound protonated β-ketoimines is also synthesized and structurally characterized. Single-crystal X-ray crystallographic analysis reveals that the deprotonated bis(chelate)metal complexes are four-coordinate with various degrees of distortion depending on the degree of steric bulk and the electronics of the metal center. Each of the high-spin iron(II) centers exhibits multiple electronic transitions including ligand π to π*, metal-to-ligand charge transfer, and spin-forbidden d-d bands. The (1)H NMR spectra of the paramagnetic high-spin iron(II) centers are assigned on the basis of chemical shifts, longitudinal relaxation times (T(1)), relative integrations, and substitution of the ligands. The electrochemical studies support variations in the ligand strength. Parallel mode EPR measurements for the isopropyl substituted ligand complex of iron(II) show low-field resonances (g > 9.5) indicative of complex aggregation or crystallite formation. No suitable solvent system or glassing mixture was found to remedy this phenomenon. However, the bulkier diisopropylphenyl substituted ligand exhibits an integer spin signal consistent with an isolated iron(ii) center [S = 2; D = -7.1 ± 0.8 cm(-1); E/D = 0.1]. A tentative molecular orbital diagram is assembled.     

Synthesis, characterization, and biological properties of N-phenolato-N′-(3-dimethylaminopropyl)oxamide and its binuclear copper(II) complexes

A new asymmetric N,N′-bis(substituent)oxamide ligand, N-phenolato-N′-(3-dimethylaminopropyl)oxamide (H₃pdmapo), and two of its binuclear Cu(II) complexes with different terminal ligands, namely [Cu₂(pdmapo)(phen)(H₂O)](ClO₄) (1) and [Cu₂(pdmapo)(bpy)(CH₃OH)](ClO₄) (2), where phen = 1,10-phenanthroline and bpy = 2,2′-bipyridine, have been synthesized and characterized. The crystal structures of both complexes have been determined by single-crystal X-ray diffraction. Both structures contain binuclear Cu(II) cationic complexes with pdmapo^3? ligands. The asymmetric pdmapo^3? ligands bridge two Cu(II) atoms in the cis conformation and the Cu···Cu separations through the oxamide bridge are 5.2046(18) and 5.207(2) Å for complexes 1 and 2, respectively. The coordination environments of the two Cu(II) atoms in each binuclear complex are different. The copper occupying the inner site of the pdmapo^3? ligand is four-coordinated in a CuN₃O distorted square-planar environment, while the other is five-coordinated in a square pyramid geometry. In complex 1, O–H···O and C–H···O hydrogen bonds link the complex into a one-dimensional chain. In complex 2, O–H···O hydrogen bonds link the molecules to form a dimer, together with two types of strong π–π interactions, giving a two-dimensional network structure. The cytotoxicities and DNA-binding properties of H₃pdmapo and the two complexes were studied. The experimental evidence suggests that the ligand binds to DNA via a groove binding mode, while the binuclear complexes bind intercalatively to DNA.     

Novel dithiocarbamate–Hg(II) complexes containing mixed ligands: Synthesis,spectroscopic characterization,and H2 storage capacity

A tetrahedral Hg(II) diethyl dithiocarbamate (Et₂Dt) complex containing triphenylphosphine (PPh₃) of the composition [HgCl(κ²-Et₂Dt)₂(PPh₃)] ( 1 ) is prepared. Furthermore, complex ( 1 ) is used as a synthone to prepare a novel series of complexes of the following composition [Hg(Et₂Dt)L(PPh₃)] {L = saccharinate ( 2 ), thiosaccharinate ( 3 ), benzisothiazolinate ( 4 ), benzothiozole-2-thiolate ( 5 ), and benzooxazole-2-thiolate ( 6 ) anions}. The resulted complexes ( 1 )–( 6 ) are characterized by elemental analysis, molar conductivity, powder X-ray diffraction, fourier transform Infrared, and NMR (¹H and ³¹P) spectroscopic techniques. The Et₂Dt ligand is coordinated as bidentate chelate through the sulfur atoms, whereas the L ligands are bonded as monodentate ligands to afford a tetrahedral geometry around the Hg(II) ion. Nitrogen adsorption–desorption isotherm for two of as-prepared complexes ( 2 ) and ( 3 ) are measured first to get their Brunauer–Emmett–Teller surface area. Moreover, the mentioned two complexes are evaluated for their ability to store hydrogen gas at 77 K. However, the results of the hydrogen storage tests proved that the selected complexes are all capable of storing hydrogen, but in varying degrees, where complex ( 2 ) exhibited a storage capacity of 4.22 wt% under 88 bar.     

Synthesis, characterization and magnetic properties of μ-iodanilato dinuclear oxovanadium (Ⅳ) complexes

Five oxovanadium(Ⅳ) dinuclear complexes described by the overall formula [(VO)2(IA)L2]-SO4, where IA represents the dianion of iodanilic acid and L denotes 2,2'-bipyridine (bpy) ; 4,4'-dimethyl-2,2'-bipyridine (Me2-bpy); 1,10-phenanthroline (phen); 4,7-diphenyl-1, 10-phenanthroline (Ph2-phen) and 5-nitro-l, 10-phenanthroline (NO2-phen) , have been synthesized and characterized by elemental analyses, molar conductivity and room-temperature magnetic moment measurements, IR and electronic spectral studies. It is proposed that these complexes have IA-bridged structures and consist of two oxovanadium(Ⅳ) ions each in a square- pyramidal environment. The complexes [ ( VO)2 (IA) (bpy )2 ] SO4 (1) and [ ( VO )2 ( IA) ( phen)2 ] -SO4 (2) were further characterized by variable temperature (4.2-300 K) magnetic susceptibility measurements and the observed data were fitted to the modified Bleaney-Bowers equation by the least-squares method, giving the exchange integral J = -2.15 cm-1 for 1 and J = - 9.88 cm-1 for 2     

Synthesis,characterization, and investigation of catalytic activity of copper(II) porphyrin graphene oxide for azide–alkyne cycloaddition

Research on Chemical Intermediates - A covalently cross-linked graphene oxide (GO) catalyst was prepared by a cross-linking process using nucleophilic reaction of copper(II)‐coordinated...