Bio-affinity of copper(II) complexes with nitrogen and oxygen donor ligands: Synthesis, structural studies and in vitro DNA and HSA interaction of copper(II) complexes.

Reported herein the binding affinity between Human Serum Albumin and the DNA binding and cleavage activity of three copper(II) complexes, [Cu(phen)(o-van)ClO4] (1), [Cu(phen)(gly)]ClO4 (2) and [Cu(L1)2(H2O)2] (3) wherein 1 and 2 are synthesized with 1,10-phenanthroline (phen) and co-ligands (o-van: o-vanillin; gly: glycine) and 3 with a ligand 2-hydroxy-3-methoxybenzylidene-4H-1,2,4-triazol-4-amine (H1L1). Complex 2 crystallizes in monoclinic (P21/n) space group shows square pyramidal geometry. The complex 3 crystallizes in monoclinic (P21/a) space group. All the three complexes exhibit binding affinity towards the transport protein Human Serum albumin (HSA). Quantitative evaluation of the thermodynamics of interaction and the results obtained from fluorescence spectroscopy suggest that metal coordinated glycynate, o-vanillin and perchlorate groups have a major role to play in the binding process, the latter two being stronger in the binding of complex 1. The coordinated water in complex 3 also plays an important role in the binding, which makes binding of complex 3 with HSA stronger than that of complex 2. Experimental results indicate that the binding affinity of the complexes towards CT-DNA is in the order 1>3>2 implying that complex 1 binds stronger than complex 3 and 2.The DNA cleaving activity of all the three complexes was explored in the presence of reactive oxygen compound, H2O2. All the three complexes have primarily shown the DNA cleaving activity.

Crystal structure of Zn(ZnCl4)2(Cho)2: the transformation of ions to neutral species in a deep eutectic system.

A neutral molecular complex, Zn(ZnCl4)2(Cho)2, has been isolated from the well-known choline chloride/ZnCl2 deep eutectic system (DES) and its crystal structure has been determined. The structure demonstrates the possibility of isolating unusual coordination complexes from DES which departs from the well-established observation of such systems being formed from large, ionic metal complexes or oligomers.

Versatile Reactivity and Theoretical Evaluation of Mono- and Dinuclear Oxidovanadium(V) Compounds of Aroylazines: Electrogeneration of Mixed-Valence Divanadium(IV,V) Complexes.

The substituted hydrazones H2L(1-4) (L(1-4) = dibasic tridentate ONO(2-) donor ligands) obtained by the condensation of 2-hydroxy-1-naphthaldehyde and 2-aminobenzoylhydrazine (H2hnal-abhz) (H2L(1)) , 2-hydroxy-1-naphthaldehyde and 2-hydroxybenzoylhydrazine (H2hnal-hbhz) (H2L(2)), 2-hydroxy-1-acetonaphthone and benzoylhydrazine (H2han-bhz) (H2L(3)), or 2-hydroxy-1-acetonaphthone and 2-aminobenzoylhydrazine (H2han-abhz) (H2L(4)) are prepared and characterized. Reaction of ammonium vanadate with the appropriate H2L(1-4) results in the formation of oxidoethoxidovanadium(V) [V(V)O(OEt)(L(1-4))] (1-4) complexes. All compounds are characterized in the solid state and in solution by spectroscopic techniques (IR, UV-vis, (1)H, (13)C, and (51)V NMR, and electrospray ionization mass spectrometry). Single-crystal X-ray diffraction analysis of 1, 3, and 4 confirms the coordination of the corresponding ligands in the dianionic (ONO(2-)) enolate tautomeric form. In solution, the structurally characterized [V(V)O(OEt)(L)] compounds transform into the monooxido-bridged divanadium(V,V) [(V(V)OL)2-µ-O] complexes, with the processes being studied by IR and (1)H, (13)C, and (51)V NMR. The density functional theory (DFT) calculated Gibbs free energy of reaction 2[V(V)O(OEt)(L(4))] + H2O ⇆ [(V(V)OL(4))2-µ-O] + 2EtOH is only 2-3 kcal mol(-1), indicating that the dinuclear complexes may form in a significant amount. The electrochemical behavior of the complexes is investigated by cyclic voltammetry, with the V(V)-V(IV) E1/2(red) values being in the range 0.27-0.44 V (vs SCE). Upon controlled potential electrolysis, the corresponding (L)(O)V(IV)-O-V(V)(O)(L) mixed-valence species are obtained upon partial reduction of the [(V(V)OL)2-µ-O] complexes formed in solution, and some spectroscopic characteristics of these dinuclear mixed-valence complexes are investigated using DFT calculations and by electron paramagnetic resonance (EPR), with the formation of V(IV)-O-V(V) species being confirmed by the observation of a 15-line pattern in the EPR spectra at room temperature.

Synthesis, X-ray structure and in vitro cytotoxicity studies of Cu(I/II) complexes of thiosemicarbazone: special emphasis on their interactions with DNA.

4-(p-X-phenyl)thiosemicarbazone of napthaldehyde {where X = Cl (HL¹) and X = Br (HL²)}, thiosemicarbazone of quinoline-2-carbaldehyde (HL³) and 4-(p-fluorophenyl)thiosemicarbazone of salicylaldehyde (H2L4) and their copper(I) {[Cu(HL¹)(PPh3)2Br]·CH3CN (1) and [Cu(HL²)(PPh3)2Cl]·DMSO (2)} and copper(II) {[(Cu2L³2Cl)2(µ-Cl)2]·2H2O (3) and [Cu(L4)(Py)] (4)} complexes are reported herein. The synthesized ligands and their copper complexes were successfully characterized by elemental analysis, cyclic voltammetry, NMR, ESI-MS, IR and UV-Vis spectroscopy. Molecular structures of all the Cu(I) and Cu(II) complexes have been determined by X-ray crystallography. All the complexes (1-4) were tested for their ability to exhibit DNA-binding and -cleavage activity. The complexes effectively interact with CT-DNA possibly by groove binding mode, with binding constants ranging from 104 to 105 M⁻¹. Among the complexes, 3 shows the highest chemical (60%) as well as photo-induced (80%) DNA cleavage activity against pUC19 DNA. Finally, the in vitro antiproliferative activity of all the complexes was assayed against the HeLa cell line. Some of the complexes have proved to be as active as the clinical referred drugs, and the greater potency of 3 may be correlated with its aqueous solubility and the presence of the quinonoidal group in the thiosemicarbazone ligand coordinated to the metal.

Synthesis, characterization and reactivity studies of electrophilic ruthenium(II) complexes: a study of H2 activation and labilization.

Reaction of 2,2'-bipyridine (bpy) with dinuclear complexes [RuCl(dfppe)(µ-Cl)3Ru(dmso-S)3] (dfppe = 1,2-bis(dipentafluorophenyl phosphino)ethane (C6F5)2PCH2CH2P(C6F5)2; dmso = dimethyl sulfoxide) (1) or [RuCl(dfppe)(µ-Cl)3RuCl(dfppe)] (2) affords the mononuclear species trans-[RuCl2(bpy)(dfppe)] (3). Using this precursor complex (3), a series of new cationic Ru(II) electrophilic complexes [RuCl(L)(bpy)(dfppe)][Z] (L = P(OMe)3 (5), PMe3 (6), CH3CN (7), CO (8), H2O (9); Z = OTf (5, 6, 7, 8), BAr(F)4 (9) have been synthesized via abstraction of chloride by AgOTf or NaBAr(F)4 in the presence of L. Complexes 5 and 6 were converted into the corresponding isomeric hydride derivatives [RuH(PMe3)(bpy)(dfppe)][OTf] (10a, 10b) and [RuH(P(OMe)3)(bpy)(dfppe)][OTf] (11a, 11b) respectively, when treated with NaBH4. Protonation of the cationic monohydride complex (11a) with HOTf at low temperatures resulted in H2 evolution accompanied by the formation of either solvent or triflate bound six coordinated species [Ru(S)(P(OMe)3)(bpy)(dfppe)][OTf]n [(S = solvent (n = 2), triflate (n = 1)] (13a/13b); these species have not been isolated and could not be established with certainty. They (13a/13b) were not isolated, instead the six-coordinated isomeric aqua complexes cis-[Ru(bpy)(dfppe)(OH2)(P(OMe)3)][OTf]2 (14a/14b) were isolated. Reaction of the aqua complexes (14a/14b) with 1 atm of H2 at room temperature in acetone-d6 solvent resulted in heterolytic cleavage of the H-H bond. Results of the studies on H2 lability and heterolytic activation using these complexes are discussed. The complexes 3, 5, 11a, and 14a have been structurally characterized.

Syntheses and structural investigation of some alkali metal ion-mediated LV(V)O2(-) (L(2-) = tridentate ONO ligands) species: DNA binding, photo-induced DNA cleavage and cytotoxic activities.

Eight alkali metal ion-mediated dioxidovanadium(v), [{V(V)O2L(1-6)}A(H2O)n]∝, complexes for A = Li(+), Na(+), K(+) and Cs(+), containing tridentate aroylhydrazonate ligands coordinating via ONO donor atoms, are described. All the synthesised ligands and the metal complexes were successfully characterised by elemental analysis, IR, UV-Vis and NMR spectroscopy. X-ray crystallographic investigation of 3, 5-7 shows the presence of distorted NO4 coordination geometries for LVO2(-) in each case, and varying µ-oxido and/or µ-aqua bridging with interesting variations correlated with the size of the alkali metal ions: with small Li(+), no bridging-O is found but four ion aggregates are found with Na(+), chains for K(+) and finally, layers for Cs(+). Two (5) or three-dimensional (3, 6 and 7) architectures are consolidated by hydrogen bonding. The dioxidovanadium(v) complexes were found to exhibit DNA binding activity due to their interaction with CT-DNA by the groove binding mode, with binding constants ranging from 10(3) to 10(4) M(-1). Complexes 1-8 were also tested for DNA nuclease activity against pUC19 plasmid DNA which showed that 6 and 7 had the best DNA binding and photonuclease activity; these results support their good protein binding and cleavage activity with binding constants ranging from 10(4) to 10(5) M(-1). Finally, the in vitro antiproliferative activity of all complexes was assayed against the HeLa cell line. Some of the complexes (2, 5, 6 and 7) show considerable activity compared to commonly used chemotherapeutic drugs. The variation in cytotoxicity of the complexes is influenced by the various functional groups attached to the aroylhydrazone derivative.

Dynamics of H-atom exchange in stable cis-dihydrogen/hydride complexes of ruthenium(II) bearing phosphine and N-N bidentate ligands.

Synthesis and characterization of cis,trans-[RuH(η(2)-H2)(PPh3)2(N-N)][OTf] (N-N = 2,2'-bipyridyl (bpy) 1a, 2,2'-bipyrimidine (bpm) 2a; OTf = trifluoromethane sulfonate (CF3SO3)) complexes are reported. The cis-H2/hydride ligands are involved in H-atom site exchange between the two moieties. This dynamics was investigated by variable temperature NMR spectral studies based on which the mechanism of the exchange process was deduced. The ΔG(≠) for the exchange of H-atoms between the η(2)-H2 and hydride ligands was determined to be around 8 and 13 kJ mol(-1), respectively, for 1a and 2a. The H-H distances (d(HH), Å) in complexes 1a and 2a have been calculated from the T1(minimum) and (1)J(H,D) and are found to be 1.07 Å (slow) and 0.95 Å for 1a and 1.04 Å (slow) and 0.94 Å for 2a, respectively. The molecular structure of 1a was determined by X-ray crystallography.

Highly stable hexacoordinated nonoxidovanadium(IV) complexes of sterically constrained ligands: syntheses, structure, and study of antiproliferative and insulin mimetic activity.

Three highly stable, hexacoordinated nonoxidovanadium(IV), V(IV)(L)2, complexes (1-3) have been isolated and structurally characterized with tridentate aroylhydrazonates containing ONO donor atoms. All the complexes are stable in the open air in the solid state as well as in solution, a phenomenon rarely observed in nonoxidovanadium(IV) complexes. The complexes have good solubility in organic solvents, permitting electrochemical and various spectroscopic investigations. The existence of nonoxidovanadium(IV) complexes was confirmed by elemental analysis, ESI mass spectroscopy, cyclic voltammetry, EPR, and magnetic susceptibility measurements. X-ray crystallography showed the N3O3 donor set to define a trigonal prismatic geometry in each case. All the complexes show in vitro insulin mimetic activity against insulin responsive L6 myoblast cells, with complex 3 being the most potent, which is comparable to insulin at the complex concentration of 4 µM, while the others have moderate insulin mimetic activity. In addition, the in vitro antiproliferative activity of complexes 1-3 against the HeLa cell line was assayed. The cytotoxicity of the complexes is affected by the various functional groups attached to the bezoylhydrazone derivative and 2 showed considerable antiproliferative activity compared to the most commonly used chemotherapeutic drugs.

Self-assembly of an octanuclear platinum(II) tetragonal prism from a new Pt(II)4 organometallic star-shaped acceptor and its nitroaromatic sensing study.

[2 + 4] self-assembly of a pyrene-functionalized Pt(II)(8) tetragonal prism (2) is achieved using a newly designed star-shaped organometallic acceptor (1) in combination with an amide-based "clip" donor (L). The propensity of this prism (2) as a selective sensor for nitroaromatics (2,4-dinitrotoluene, 1,3,5-trinitrotoluene, and picric acid), which are the chemical constituents of many commercial explosives, has been examined.

Self-assembled Pd6 open cage with triimidazole walls and the use of its confined nanospace for catalytic Knoevenagel- and Diels-Alder reactions in aqueous medium.

The two-component self-assembly of a 90° Pd(II) acceptor and a triimidazole donor led to the formation of a water-soluble semi-cylindrical cage with a hydrophobic cavity, which was separately crystallized with hydrophilic- and hydrophobic guests. The parent cage was found to catalyze the Knoevenagel condensation reaction of a series of aromatic mono-aldehydes with active methylene compounds, such as Meldrum's acid or 1,3-dimethylbarbituric acid. The confined hydrophobic nanospace within this cage was also used in the catalytic Diels-Alder reactions of 9-hydroxymethylanthracene with N-phenylmaleimide or N-cyclohexylmaleimide.

Two novel heterometallic chains featuring Mn(II) and Na(I) ions in trigonal-prismatic geometries alternately linked to octahedral Mn(IV) ions: synthesis, structures, and magnetic behavior.

Two new one-dimensional heterometallic complexes, [Mn(3)Na(L)(4)(CH(3)CO(2))(MeOH)(2)](ClO(4))(2)·3H(2)O (1), [Mn(3)Na(L)(4)(CH(3)CH(2)CO(2))(MeOH)(2)](ClO(4))(2)·2MeOH·H(2)O (2) [LH(2) = 2-methyl-2-(2-pyridyl)propane-1,3-diol], have been synthesized and characterized by X-ray crystallography. Both complexes feature Mn(II) and Na(I) ions in trigonal-prismatic geometries that are linked to octahedral Mn(IV) ions by alkoxy bridges. Variable-temperature direct- and alternating-current magnetic susceptibility data indicated a spin ground state of S = 11/2 for both complexes. Density functional theory calculations performed on 1 supported this conclusion.

Pillar height dependent formation of unprecedented Pd8 molecular swing and Pd6 molecular boat via multicomponent self-assembly.

Three-component self-assembly of a cis-blocked 90° Pd(II) acceptor with a mixture of a tetraimidazole and a linear dipyridyl donor self-discriminated into unusual Pd(8) molecular swing (1) and Pd(6) molecular boat (2), which are characterized by single-crystal X-ray diffraction analysis; their ability to bind C(60) in solution is established by fluorescence titration.

Cu(II)-azide polymers with various molar equivalents of blocking diamine ligands: synthesis, structures, magnetic properties with DFT studies.

Four new neutral copper-azido polymers [Cu(4)(N(3))(8)(Me-hmpz)(2)](n) (1), [Cu(4)(N(3))(8)(men)(2)](n) (2), [Cu(5)(N(3))(10)(N,N-dmen)(2)](n) (3) and [Cu(5)(N(3))(10)(N,N'-dmen)(5)](n) (4) [Me-hmpz = 1-methylhomopiperazine; men = N-methylethylenediamine; N,N-dmen = N,N-dimethylethylenediamine and N,N'-dmen = N,N'-dimethylethylenediamine] have been synthesized by using various molar equivalents of the chelating diamine ligands with Cu(NO(3))(2)·3H(2)O and an excess of NaN(3). Single-crystal X-ray structures show that the basic asymmetric units of 1 and 2 are very similar, but the overall 1D structures were found to be quite different. Complex 3 with a different composition was found to be 2D in nature, while the 1D complex 4 with 1 : 1 metal to diamine ratio presented several new structural features. Cryomagnetic susceptibility measurements over a wide range of temperature were corroborated with density functional theory calculations (B3LYP functional) performed on the complexes 1-3 to provide a qualitative theoretical interpretation of their overall magnetic behavior.

Improved activity and stability of Rhizopus oryzae lipase via immobilization for citronellol ester synthesis in supercritical carbon dioxide.

In present work, Rhizopus oryzae lipase immobilized on a film prepared using blend of hydroxylpropyl methyl cellulose (HPMC) and polyvinyl alcohol (PVA) was investigated for synthesis of citronellol esters with supercritical carbon dioxide (Sc-CO(2)) as a reaction medium. The transesterification reaction was optimized for various reaction parameters like effect of molar ratio, acyl donor, time, temperature, enzyme concentration, effect of pressure and co-solvent to achieve the maximum yield of desired product. The results obtained signify remarkable increment (about eightfold) in the yield of citronellol acetate (91%) as compared to that of free lipase (11%) in Sc-CO(2). The developed biocatalytic methodology provides a substantial advantage of low biocatalyst loading (1.5%, w/v), lower reaction temperature (45°C) and lower pressure (8 MPa) as compared to previous reports. The immobilization method has significantly enhanced the operational stability of lipase for ester synthesis under Sc-CO(2) conditions. The developed methodology was successfully applied for synthesis of three different industrially important citronellol esters namely citronellol acetate (91%), citronellol butyrate (98%), citronellol laurate (99%) with excellent yields using vinyl esters as acyl donor under Sc-CO(2) conditions. In addition, the immobilized biocatalyst was effectively recycled for three consecutive recycles.

A homobimetallic complex of chromium(0) with a σ-borane component.

The synthesis, characterization, and reactivity of a chromium(0) complex bearing an amine-borane moiety (η(6)-C(6)H(5)CH(2)NMe(2)·BH(3))Cr(CO)(3) (2) is reported. Photolysis of complex 2 results in the elimination of a CO ligand followed by the formation of an intramolecular σ-borane complex (η(1)-(η(6)-C(6)H(5)CH(2)NMe(2)·BH(2)-H))Cr(CO)(2) (3). This species was characterized in solution by NMR spectroscopy. Reaction of complex 2 with photochemically generated (OC)(5)Cr(THF) affords a novel homobimetallic σ-borane complex (OC)(3)Cr(η(6)-C(6)H(5)CH(2)NMe(2)·BH(2)-H-Cr(CO)(5)) (4), wherein one of the BH moieties is bound to the chromium center in an η(1)-fashion. The σ-borane complex 4 was isolated in moderate to good yield (72%). The BH(3) fragment in the complexes 3 and 4 are highly dynamic involving exchange of the BH hydrogen bound to the metal with the terminal BH hydrogen atoms. The dynamics has been studied using variable-temperature NMR spectroscopy. Complexes 2 and 4 have been characterized by X-ray crystallography.