New metal-organic precursors for MOCVD applications: Synthesis, characterization, crystal structure and thermal properties of mixed-ligand Mg(II) complexes

In an effort to develop new MOCVD precursors, mixed-ligand metal-organic complexes, bis (acetylacetonato-k(2)O,O') (2,2'-bipyridine-k(2)N,N') magnesium(II), and his (acetylacetonato-k(2)O,O') (1,10-phenanthroline-k(2)N,N') magnesium(II) were synthesized. Spectroscopic characterization and crystal structures confirmed them to be monomeric and stable complexes. Crystal structure analysis suggests in each of the magnesium(II) complexes, the metal center has a distorted octahedral coordination geometry. Thermo-gravimetric analysis (TGA/DTA) suggests that these complexes are volatile and thermally stable. The thermal characteristics of newly designed complexes make them attractive precursors for MOCVD applications. (c) 2012 Elsevier B.V. All rights reserved.

Palladium(II) complexes as biologically potent metallo-drugs: Synthesis, spectral characterization, DNA interaction studies and antibacterial activity

Four novel mononuclear Pd(II) complexes have been synthesized with the biologically active Schiff base ligands (L-1-L-4) derived from 3-amino-2-methyl-4(3H)-quinazolinone. The structure of the complexes has been proposed by elemental analysis, molar conductance, IR, H-1 NMR, mass, UV-Vis spectrometric and thermal studies. The investigation of interaction of the complexes with calf thymus DNA (CT-DNA) has been performed with absorption and fluorescence spectroscopic studies. The nuclease activity was done using pUC19 supercoiled DNA by gel-electrophoresis. All the ligands and their Pd(II) complexes have also been screened for their antibacterial activity by discolor diffusion technique. (C) 2013 Elsevier B.V. All rights reserved.

Photocytotoxic ferrocene-appended (L-tyrosine)copper(II) complexes of phenanthroline bases

Copper(II) complexes of ferrocene(Fc)-conjugated reduced Schiff base of L-tyrosine (Fc-TyrH), viz., Cu(Fc-Tyr)(L)](ClO4), where L is 1,10-phenanthroline (phen, 1), dipyrido3,2-d:2',3'-f]quinoxaline (dpq, 2), dipyrido3,2-a:2',3'-c]phenazine (dppz, 3) and 2-(naphthalen-1-yl)-1H-imidazo4,5-f]1,10]phenanthroline (nip, 4), were prepared and tested for their photocytotoxicity in cancer cells. Cu(Fc-Phe)(phen)](-ClO4) (5) of L-phenylalanine and Cu(Ph-Tyr)(L)(ClO4)] of the reduced Schiff base Ph-TyrH derived from benzaldehyde and L-tyrosine having phen (6) and dppz (7), and Cu(Ph-Phe)(phen)(ClO4)] (8) using L-phenylalanine were prepared and used as controls. Complexes 5 and 6 were structurally characterized by X-ray crystallography. A copper(II)-based d-d band near 600 nm and a ferrocenyl band at similar to 450 nm were observed in DMF-Tris-HCI buffer (1:4 v/v) in respective complexes. The complexes are photocleavers of pUC19 DNA in visible light forming (OH)-O-center dot radicals. They are cytotoxic in HeLa (human cervical cancer) and MCF-7 (human breast cancer) cells showing an enhancement of cytotoxicity in visible light. Fluorescence imaging shows nuclear localization of the complexes.

DNA and protein targeting 1,2,4-triazole based water soluble dinickel(II) complexes enhances antiproliferation and lactate dehydrogenase inhibition

Water soluble dinickel(II) complexes Ni-2(L)(2)(1-2)](NO3)(4) (1-2), where L1-2 are triazole based dinucleating ligands, were synthesized and characterized. The DNA binding, protein binding, DNA hydrolysis and anticancer properties were investigated. The interactions of complexes 1 and 2 with calf thymus DNA were studied by spectroscopic techniques, including absorption and fluorescence spectroscopy. The DNA binding constant values of the complexes 1 and 2 were found to be 2.36 x 10(5) and 4.87 x 10(5) M-1 and the binding affinities are in the following order: 2 > 1. Both the dinickel(II) complexes 1 and 2, promoted the hydrolytic cleavage of plasmid pBR322 DNA under both anaerobic and aerobic conditions. Kinetic data for DNA hydrolysis promoted by 1 and 2 under physiological conditions give the observed rate constants (k(obs)) of 5.05 +/- 0.2 and 5.65 +/- 0.1 h(-1), respectively, which shows 10(8)-fold rate acceleration over the uncatalyzed reaction of ds-DNA. Meanwhile, the interactions of the complex with BSA have also been studied by spectroscopy. Both the complexes 1 and 2 display strong binding propensity and the binding constant (K-b), number of binding sites (n) were obtained are 0.71 x 10(6) 1.47] and 5.62 x 10(6) 1.98] M-1, respectively. The complexes 1 and 2 also promoted the apoptosis against human carcinoma (HeLa, and BeWo) cancer cells. Cytotoxicity of the complexes was further confirmed by lactate dehydrogenase enzyme level in cancer cell lysate and content media. (c) 2013 Elsevier Ltd. All rights reserved.

Photocytotoxicity of copper(II) complexes of curcumin and N-ferrocenylmethyl-L-amino acids

Copper(II) complexes Cu(Fc-aa)(cur)] (1-3) of curcumin (Hcur) and N-ferrocenylmethyl-L-amino acids (Fc-aa), viz., ferrocenylmethyl-L-tyrosine (Fc-TyrH), ferrocenylmethyl-L-tryptophan (Fc-TrpH) and ferrocenylmethyl-L-methionine (Fc-MetH), were prepared and characterized. The DNA photocleavage activity, photocytotoxicity and cellular localization in HeLa and MCF-7 cancer cells of these complexes were studied. Acetylacetonate (acac) complexes Cu(Fc-aa)(acac)] (4-6) were prepared and used as controls. The chemical nuclease inactive complexes showed efficient pUC19 DNA cleavage activity in visible light. Complexes 1-3 showed high photocytotoxicity with low dark toxicity thus giving remarkable photodynamic effect. FACScan analysis showed apoptosis of the cancer cells. Fluorescence microscopic studies revealed primarily cytosolic localization of the complexes. (C) 2013 Elsevier Masson SAS. All rights reserved.

C-H center dot center dot center dot O-nitrate synthon assisted molecular assembly of hydrogen bonded Ni(II) and Cu(II) complexes

Two Schiff base metal complexes Cu-SPETNNO3 (1) and Ni-SPETNNO3 (2) SPETN=2,2-propane,1,3-diylbis(nitrilomethyldyne)pyridyl,phenolate] ] with hydrogen bonding groups have been synthesized and characterized by single-crystal X-ray diffraction. In both of the compounds nitrates occupy a crystallographic general position. In 1 the lattice nitrates are on the 2(1) screw axis while in 2 they are at the crystallographic inversion center. C-HOnitrate synthons (formed by the nitrate anions and peripheral hydrogen bonding groups of the metal complexes) are non-covalent building blocks in molecular-assembly and packing of the cationic Schiff base metal complexes (M=Ni2+, Cu2+), resulting in 2-D hydrogen bonded networks. The CuCu non-bonding contact in 1 is 3.268 angstrom while the Ni-Ni bonding distance in 2 is 3.437 angstrom.

Remarkable anticancer activity of ferrocenylterpyridine platinum(II) complexes in visible light with low dark toxicity

Ferrocenyl platinum(II) complexes (1-3), viz. Pt(Fc-tpy)Cl]Cl (1), Pt(Fc-tpy)(NPC)]Cl (2, HNPC = N-propargyl carbazole) and Pt(Fc-bpa)Cl]Cl (3), were prepared, characterized and their anti-proliferative properties in visible light in human keratinocyte (HaCaT) cell lines have been studied. Pt(Ph-tpy)Cl]Cl (4) was prepared and used as a control. Complexes 1 and 3, structurally characterized by X-ray crystallography, show distorted square-planar geometry for the platinum(II) centre. Complexes 1 and 2 having the Fc-tpy ligand showed an intense absorption band at similar to 590 nm. The ferrocenyl complexes are redox active showing the Fc(+)-Fc couple near 0.6 V vs. SCE in DMF-0.1 M tetrabutylammonium perchlorate (TBAP). Complexes 1-3 showed external binding to calf thymus DNA. Both 1 and 2 showed remarkable photocytotoxicity in HaCaT cell lines giving respective IC50 values of 9.8 and 12.0 mu M in visible light of 400-700 nm with low dark toxicity (IC50 > 60 mu M). Fluorescent imaging studies showed the spread of the complexes throughout the cell localising both in cytoplasm and the nucleus. The ferrocenyl complexes triggered apoptosis on light exposure as evidenced from the Annexin V-FITC/PI and DNA ladder formation assays. Spectral studies revealed the formation of ferrocenium ions upon photo-irradiation generating cytotoxic hydroxyl radicals via a Fenton type mechanism. The results are rationalized from a TDDFT study that shows involvement of ferrocene and the platinum coordinated terpyridine moiety as respective HOMO and LUMO.

mu-Oxamido binuclear copper (II) complexes: Synthesis, crystal structure, DNA interaction and antibacterial studies

Four binuclear copper (II) complexes Cu(oxpn)Cu(B)](2+) (2-5) bridged by N, N'-bis3-(methylamino) propyl] oxamide (oxpn), where, B is N, N-donor heterocyclic bases (viz. 2,2'-bipyridine (bpy, 2), 1,10-phenathroline (phen, 3), dipyrido3,2-d:2',3'-f]quinoxaline (dpq, 4) and dipyrido3,2-a:2',3'-c]phenazine (dppz, 5) are synthesized, characterized by different spectroscopic and single crystal X-ray data technique. The phen (3) and dpq (4) complexes were structurally characterized by X-ray data analysis. Their DNA binding, oxidative cleavage and antibactirial activities were studied. The dpq (4) and dppz (5) complexes are avid binders to the Calf thymus DNA (CT-DNA). The phen (3), dpq (4) and dppz (5) complexes show efficient oxidative cleavage of supercoiled DNA (SC DNA) through hydroxyl radical ((OH)-O-center dot) pathway in the presence of Mercaptopropionic acid (MPA). (C) 2013 Elsevier Ltd. All rights reserved.

Synthesis, crystal structure, DNA interaction and cleavage activities of mononuclear and trinuclear copper(II) complexes

Mono- and trinuclear copper(II) complexes with 2-1-(2-dimethylamino-ethylamino)-ethyl]-phenol (HL) have been synthesized and structurally characterized. The mononuclear complex Cu(L)(H2O)(ONO2)] (1) crystallizes in monoclinic space group P2(1) /n with a square pyramidal Cu(II) center coordinated by the tridentate Schiff base (L) and a water ligand in the equatorial plane and an oxygen atom from nitrate in the axial position. The trinuclear complex (CuL)(3)(mu(3)-OH)](ClO4)(2)center dot H2O (2) crystallizes in hexagonal space group P6(3); all three copper atoms are five-coordinate with square pyramidal geometries. The interactions of these complexes with calf-thymus DNA have been investigated using absorption spectrophotometry. The mononuclear complex binds more strongly than the trinuclear complex. The DNA cleavage activity of these complexes has been studied on double-stranded pBR 322 plasmid DNA by gel electrophoresis experiments in the absence and in the presence of added oxidant (H2O2). The trinuclear complex cleaves DNA more efficiently than the mononuclear complex in the presence of H2O2.

Approaches toward (eta(2)-HX) (X = H, SiR (R = Me-3 or Me2Ph), CH3) sigma-complexes of ruthenium

Two new Ru(II)-complexes RuH(Tpms)(PPh3)(2)] 1 (Tpms - (C3H3N2)(3)CSO3, tris-(pyrazolyl) methane sulfonate) and Ru(OTf)(Tpms)(PPh3)(2)] 2 (OTf = CF3SO3) have been synthesized and characterized wherein Ru-H and Ru-OTf are the key reactive centers. Reaction of 1 with HOTf results in the Ru(eta(2)-H-2)(Tpms)(PPh3)(2)]OTf] complex 3, whereas reaction of 1 with Me3SiOTf affords the dihydrogen complex 3 and complex 1 through an unobserved sigma-silane intermediate. In addition, an attempt to characterize the sigma methane complex via reaction of complex 1 with CH3OTf yields complex 2 and free methane. On the other hand, reaction of Ru(OTf)(Tpms)(PPh3)(2)] 2 with H-2 and PhMe2SiH at low temperature resulted in sigma-H-2, 3 and a probable sigma-silane complexes, respectively. However, no sigma-methane complex was observed for the reaction of complex 2 with methane even at low temperature. (C) 2014 Elsevier B. V. All rights reserved.

Mitigating UVA light induced reactivity of 6-thioguanine through formation of a Ru(II) half-sandwich complex

The organometallic complex of (eta(6)-cymene)Ru(II)Br with 6-thioguanine (6-TG) shows better photostability than the biologically active 6-thioguanine which is used as an immunosuppressant and as an anticancer agent.

Ferrocenyl-L-amino acid copper(II) complexes showing remarkable photo-induced anticancer activity in visible light

Ferrocene-conjugated copper(II) complexes Cu(Fc-aa)(aip)](ClO4) (1-3) and (Cu(Fc-aa)(pyip)](ClO4) (4-6) of L-amino acid reduced Schiff bases (Fc-aa), 2-(9-anthryl)-1H-imidazo4,5-f]1,10]phenanthroline (aip) and 2-(1-pyrenyl)-1H-imidazo4,5-f] 1,10]phenanthroline (pyip), where Fc-aa is ferrocenylmethyl-L-tyrosine (Fc-Tyr in 1, 4), ferrocenylmethyl-L-tryptophan (Fc-Trp in 2, 5) and ferrocenylmethyl-L-methionine (Fc-Met in 3, 6), were prepared and characterized, and their photocytotoxicity was studied (Fc = ferrocenyl moiety). Phenyl analogues, viz. (Cu(Ph-Met)(aip)](ClO4) (7) and (Cu(Ph-Met)(pyip)](ClO4) (8), were prepared and used as control compounds. The bis-imidazophenanthroline copper(II) complexes, viz. (Cu(aip)(2)(NO3)](NO3) (9) and Cu(pyip)(2)(NO3)](NO3) (10), were also prepared and used as controls. Complexes 1-6 having a redox inactive cooper(II) center showed the Fc(+)-Fc redox couple at similar to 0.5 V vs. SCE in DMF-0.1 mol (Bu4N)-N-n](ClO4). The copper(II)-based d-d band was observed near 600 nm in DMF-Tris-HCl buffer (1 :1 v/v). The ferrocenyl complexes showed low dark toxicity, but remarkably high photocytotoxicity in human cervical HeLa and human breast adenocarcinoma MCF-7 cancer cells giving an excellent photo-dynamic effect while their phenyl analogues were inactive. The photo-exposure caused significant morphological changes in the cancer cells when compared to the non-irradiated ones. The photophysical processes were rationalized from the theoretical studies. Fluorescence microscopic images showed 3 and 6 localizing predominantly in the endoplasmic reticulum (ER) of the cancer cells, thus minimizing any undesirable effects involving nuclear DNA.

Substitution-Modulated Anticancer Activity of Half-Sandwich Ruthenium(II) Complexes with Heterocyclic Ancillary Ligands

Ten new organometallic half-sandwich ruthenium complexes with heterocyclic ligands have been synthesized (H1-H10). The substituents on the ancillary heterocyclic ligands were varied to understand the effect of substitution on anticancer activity. The crystallographic characterization of five complexes confirms that they adopt three-legged piano-stool structures and are stabilized by intramolecular hydrogen bonding. Complexes H2 and H3 also exhibit halogen bonding in the solid state. In aqueous media, the complexes form dinuclear ruthenium species. Complex H1 with a noncytotoxic heterocycle, 6-fluoro-2-mercaptobenzothiazole, and complex H11 with the unsubstituted 2-mercaptobenzothiazole are the most active against A2780 and KB cell lines. The substitution of the H atoms on the ancillary ligand with Cl or Br atoms leads to a decrease in the anticancer activity. With the exception of fluorine-substituted H5, the complexes with mercaptobenzoxazole (H6-H9) are inactive against all of the tested cell lines. Ruthenium complexes with mercaptonaphthimidazole (H10) and mercaptobenzimidazole (H13) do not show any anticancer activity. The active complexes show a biphasic melting curve when incubated with calf thymus (CT) DNA. These complexes only inhibit thioredoxin reductase (TrxR) enzyme activity to a small extent. The substitution of hydrogen atoms with fluorine atoms in the aromatic heterocyclic ligands on organometallic half-sandwich ruthenium complexes has the most beneficial effect on their anticancer activity.

Single-ion magnet behaviour of heptacoordinated Fe(II) complexes: on the importance of supramolecular organization

Supramolecular organization of a metal complex may significantly contribute to the magnetization dynamics of mononuclear SMMs. This is illustrated for a heptacoordinated Fe(II) complex with rather moderate Ising-type anisotropy for which a slow magnetization relaxation with significant energy barrier was reached when this complex was properly organized in the crystal lattice. Incidentally, it is the first example of single-ion magnet behaviour of Fe(II) in a pentagonal bipyramid surrounding.