Studies on preparation, characterization of cobalt(II) phenanthroline and 8-hydroxyquinoline complexes/Y zeolite, and catalytic hydroxylation of phenol

Cobalt(II) phenanthroline and 8-hydroxyquinoline complexes/Y zeolite, denoted as CoPhen/Y and CoOx/Y respectively, were prepared, The formation of the metal complexes mentioned above within the cages of Y zeolite and their crystal structures were determined by elementary analyses, TG-DTA, diffuse reflectance UV-Vis, SEM, BET and XRD methods. The influence of experimental parameters upon phenol conversion and product selectivities was investigated as well.

STUDIES ON OLEFIN-COORDINATING TRANSITION-METAL CARBENE COMPLEXES .20. SYNTHESIS OF 1,3-CYCLOHEXADIENE(DICARBONYL) [ETHOXY(ARYL)-CARBENE]IRON COMPLEXES AND THEIR PHOSPHINE ADDUCTS - CRYSTAL-STRUCTURE OF C6H8(CO)2FEC(OC2H5)C6H4CH3-O

Reaction of 1,3-cyclohexadiene(tricarbonyl)iron (1) with ortho-substituted aryllithium reagents ArLi (Ar=o-CH3C6H4, o-CH3OC6H4, o-CF3C6H4) in ether at low temperature, and subsequent alkylation of the acylmetalates formed with Et3OBF4 in aqueous solution at 0-degrees-C or in CH2Cl2 at -60-degrees-C gave the 1,3-cyclohexadiene(dicarbonyl)[ethoxy(aryl)carbene]iron complexes (eta4-C6H8)(CO)2FeC(OC2H5)Ar (3, Ar = o-CH3C6H4; 4, Ar = o-CH3OC6H4), and the isomerized product (eta3-C6H8)(CO)2FeC(OC2H5)C6H4CF3-o (5), respectively, among which the structure of 3 has been established by an X-ray diffraction study. Complex 3 is monoclinic, space group P2(1) with a = 8.118(4), b = 7.367(4), c = 14.002(6) angstrom, beta = 104.09(3)-degrees, V = 812.2(6) angstrom3, Z = 2, D(c) = 1.39 g cm-3, R = 0.056, and R(w) = 0.062 for 976 observed reflections. Complexes 3 and 5 were converted into the chelated allyliron phosphine adducts(eta3-C6H8)(CO)2(PR31)FeC(OC2H5)Ar (6, Ar = o-CH3C6H4, R1 = Ph; 7, Ar = o-CH3C6H4, R1 = OPh; 9, Ar = o-CF3C6H4, R1 = Ph), by reaction with phosphines in petroleum ether at low temperatures.

Synthesis of iminophosphine and phosphinoiminol cyclometallated Pt (II) and Pt (IV) chloro complexes and studies into their biological and photophysical properties

This thesis focuses on the synthesis and analysis of novel chloride based platinum complexes derived from iminophosphine and phosphinoamide ligands, along with studies on their reactivity towards substitution and oxidation reactions. Also explored here are the potential applications of these complexes for biological and luminescent purposes. Chapter one provides an extensive overview of platinum coordination chemistry with examples of various mixed donor ligands along with the history of platinum anticancer therapy. It also looks at metals in medicine, both for biological functions as well as for therapeutic purposes and gives a background to some other applications for platinum complexes. Chapter two outlines the design and synthetic strategies employed for the development of novel platinum (II) chloride complexes from iminophosphine and phosphinoamide ligands. Also reported is the cyclometallation of these complexes to form stable tridentate mixed donor platinum (II) compounds. In Chapter three the development of a direct method for displacing a chloride from a platinum metal centre with a desired phosphine is reported. Numerous methods for successful oxidation of the platinum (II) complexes will also be explored, leading to novel platinum (IV) complexes being reported here also. The importance of stabilisation of the displaced anion, chloride, by the solvent system will also be discussed in this chapter. Chapter four investigates the reactivity of the platinum (II) complexes towards two different biomolecules to form novel platinum bio-adducts. The potential application of the platinum (II) cyclometallates as chemotherapeutics will also be explored here using in-vitro cancer cell testing. Finally, luminescence studies are also reported here for the ligands and platinum complexes reported in chapter two and three to investigate potential applications in this field also. Chapter five provides a final conclusion and an overall summary of the entire project as well as identifying key areas for future work.

Photophysics of bifunctional Ru(II) complexes bearing an aminoquinoline organic unit. Potential new photoprobes and photoreagents of DNA

[Ru(BPY)2POQ-Nmet]2+ and [Ru(TAP)2POQ-Nmet]2+ (1 and 3) are bifunctional complexes composed of a metallic unit linked by a flexible chain to an organic unit. They have been prepared as photoprobes or photoreagents of DNA. In this work, the spectroscopic properties of these bifunctional complexes in the absence of DNA are compared with those of the monofunctional analogues [Ru(BPY)2Phen]2+, [Ru-(BPY)2acPhen]2+, [Ru(TAP)2Phen]2+, and [Ru(TAP)2acPhen]2+ (2 and 4). The electrospray mass spectrometry and absorption data show that the quinoline moiety exists in the protonated and nonprotonated form. Although the bifunctional complex containing 2,2′-bipyridine (BPY) ligands exhibits photophysical properties similar to those of the monofunctional compounds, the bifunctional complex with 1,4,5,8-tetraazaphenanthrene (TAP) ligands behaves quite differently. It has weaker relative emission quantum yields and shorter luminescence lifetimes than the monofunctional TAP analogue when the quinoline unit is nonprotonated. This indicates an efficient intramolecular quenching of the 3MLCT (metal to ligand charge transfer) excited state of the TAP metallic moiety. When the organic unit is protonated, there is no internal quenching. In organic solvent, the nonquenched excited metallic unit (bearing a protonated quinoline) and the quenched one (bearing a nonprotonated organic unit) are in slow equilibrium as compared to the lifetime of the two emitters. In aqueous solution this equilibrium is faster and is catalysed by the presence of phosphate buffer. Flash photolysis experiments suggest that the intramolecular quenching process originates from a photoinduced electron transfer from the nonprotonated quinoline to the excited Ru(TAP)2 2+ moiety.

Photophysics of Re(I) and Ru(II) diimine complexes covalently linked to pyrene: Contributions from intra-ligand charge transfer states

The photophysical properties of Ru(II) and Re(I) polypyridyl complexes including a bis-bipyridyl pyrene ligand are presented. The complexes ([(bpy)(2)Ru](2)bpb)(4+) and [(CO)(3)ReCl(bpb)] (bpy = 2,2'-bipyridine, bpb = 1,6-bis-(4-(2,2'-bipyrid-yl)-pyrene) were designed with the intent of examining intramolecular energy migration between MLCT states localized on the metal complexes and pyrene-localized (3)(pi-pi) states. Absorption spectroscopy of both complexes containing the bpb ligand reveals that in addition to the MLCT and the pyrene-centered (1)(pi-pi) transitions, a new absorption band is observed near 400 nm for both complexes. Absorption spectral data for the Re(I) complex strongly suggest the presence of a pyrene(pi) to bpy(pi) intraligand charge transfer (ILCT) transition. Emission spectra at room temperature and at 77 K are almost identical for the Ru(II) and Re(I) complexes containing the bpb ligand. The (3)MLCT emission of related bipyridyl compounds lacking the pyrene is observed at higher energy than for the pyrene-containing complexes, ([(bpy)(2)Ru](2)bpb)(4+) and [(CO(3)ReCl(bpb)]. The Ru(II) complex emits at room temperature with a remarkably long lifetime (130 micros in degassed DMSO). This emission is also strongly sensitive to oxygen and is almost entirely quenched in an aerated solution. In addition, excited-state absorption spectra exhibit features not consistent with (3)MLCT or (3)(pi-pi) states of the parent chromophores. The combined characteristics suggest the emission arises from either (3)(pi-pi) or (3)ILCT states or a state with mixed parentage.

The Unexpected Preference for the fac-Isomer with the Tris(5-ester-substituted-2,2′-bipyridine) Complexes of Ruthenium(II)

The synthesis of a number of new 2,2'-bipyridine ligands, functionalized with bulky ester side groups is reported (L2 - L8). Their reaction with [Ru(DMSO)4Cl2] gives rise to tris-chelate ruthenium(II) metal complexes which show an unusually high proportion of the fac-isomer, as judged by 1H NMR following conversion to the ruthenium(II) complex of 2,2'-bipyridine-5-carboxylic acid methyl ester (L1). The initial reaction appears to have thermodynamic control with the steric bulk of the ligands causing the third ligand to be labile under the reaction conditions used, giving rise to disappointing yields and allowing rearrangement to the more stable facial form. DFT studies indicate that this does not appear to be as a consequence of a metal centered electronic effect. The two isomers of [Ru(L1)3](PF6)2 were separated into the two individual forms using silica preparative plate chromatographic procedures, and the photophysical characteristics of the two forms compared. The results appear to indicate that there is no significant difference in both their room temperature electronic absorption and emission spectra or their excited state lifetimes at 77K.

Inert benzothiazole functionalised ruthenium(II) complexes; potential DNA hairpin binding agents

The two enantiomers of [Ru(bpy)2(bbtb)]2+ {bpy = 2,2'-bipyridine; bbtb = 4,4'-bis(benzothiazol-2-yl)-2,2'-bipyridine} have been isolated and fully characterised. Both enantiomers have been shown to have a strong association with calf thymus DNA by UV/visible absorption, emission and CD spectroscopy, with the lambda enantiomer having the greater affinity. The binding of both enantiomeric forms of [Ru(bpy)2(Me2bpy)]2+ and [Ru(bpy)2(bbtb)]2+ {Me2bpy = 4,4'-dimethyl-2,2'-bipyridine} to a range of oligonucleotides, including an octadecanucleotide and an icosanucleotide which contain hairpin-sequences, have been studied using a fluorescent intercalator displacement (FID) assay. The complex [Ru(bpy)2(bbtb)]2+ exhibited an interesting association to hairpin oligonucleotides, again with the lambda enantiomer binding more strongly. A 1H NMR spectroscopic study of the binding of both enantiomers of [Ru(bpy)2(bbtb)]2+ to the icosanucleotide d(CACTGGTCTCTCTACCAGTG) was conducted. This sequence contains a seven-base-pair duplex stem and a six-base hairpin-loop. The investigation gave an indication of the relative binding of the complexes between the two different regions (duplex and secondary structure) of the oligonucleotide. The results suggest that both enantiomers bind at the hairpin, with the ruthenium centre located at the stem-loop interface. NOE studies indicate that one of the two benzothiazole substituents of the bbtb ligand projects into the loop-region. A simple model of the metal complex/oligonucleotide adduct was obtained by means of molecular modelling simulations. The results from this study suggest that benzothiazole complexes derived from inert polypyridine ruthenium(II) complexes could lead to the development of new fluorescent DNA hairpin binding agents.

A modular approach to luminescent dinuclear ruthenium(II) and rhenium(I) complexes

A series of dinuclear (bipyridine)tricarbonylrhenium(I) and tris(bipyridine)ruthenium(II) complexes have been isolated and characterised, bridged by a flexible diamido ethylene glycol chain. A new stepwise synthetic pathway has been investigated to heterometallic complexes, with the rhenium(I) complexes exhibiting an unusual configuration and inequivalence of the metal centres potentially arising from a surprising hydrogen-bonding interaction between an Re–CO group and an amide proton in low-polarity solvents. This interaction appears to be broken by competing hydrogen-bonding species such as dihydrogen phosphate. This effect was not observed in the corresponding ruthenium(II) complexes, which showed very little interaction with anions. The photophysical characterisation shows that the inclusion of two ester/amide groups to the rhenium centre effectively quenches the fluorescence at room temperature. The ruthenium(II) complexes have considerably stronger fluorescence than the rhenium species, and are less affected by theinclusion of ester and amide groups to the 2,2'-bipyridine chelating group.

Benzothiazole bipyridine complexes of ruthenium(II) with cytotoxic activity

A series of benzothiazole-substituted trisbipyridine ruthenium(II) analogues {[Ru(bpy)(2)(4,5'-bbtb)](2+), [Ru(bpy)(2)(5,5'-bbtb)](2+) and [Ru(bpy)(2)(5-mbtb)](2+) [bpy is 2,2'-bipyridine, bbtb is bis(benzothiazol-2-yl)-2,2'-bipyridine, 5-mbtb is 5-(benzothiazol-2-yl),5'-methyl-2,2'-bipyridine]} have been prepared and compared with the complex [Ru(bpy)(2)(4,4'-bbtb)](2+) reported previously. From the UV-vis spectral studies, substitution at the 5-position of the bpy causes the ligand-centred transitions to occur at considerably lower energy than for those with the functionality at the 4-position, while at the same time causing the emission to be effectively quenched. However, substitution at the 4-position causes the metal-to-ligand charge transfer to occur at lower energies. Fluorescent intercalator displacement studies indicate that the doubly substituted complexes displace ethidium bromide from a range of oligonucleotides, with the greater preference shown for bulge and hairpin sequences by the Lambda enantiomer. Since the complexes only show small variation in the UV-vis spectra on the introduction of calf thymus DNA and a small increase in fluorescence they do not appear to be intercalators, but appear to associate within one of the grooves. All of the reported bisbenzothiazole complexes show reasonable cytotoxicity against a range of human cancer cell lines.

Polynuclear metal complexes obtained from the task-specific ionic liquid betainium bistriflimide

The task-specific ionic liquid betainium bis(trifluoromethylsulfonyl)imide, [Hbet][Tf2N], was used to dissolve metal oxides and hydroxides. The crystal structures of the resulting metal betaine bistriflimide complexes exhibit a rich structural variety. A trimeric structure was found for the cobalt(II) compound, [Co-3(bet)(8)(Hbet)(2)(H2O)(2)][Tf2N](9)[Hbet], a tetrameric structure for the manganese(II) and zinc(II) compound, [Mn-4(bet)(10)(H2O)(4)][Tf2N](8) and [Zn-4(bet)(10)(H2O)(2)][Tf2N](8), respectively, a pentameric structure for the nickel(II) compound, [Ni-5(bet)(12)(H2O)(6)][Tf2N](10), an oxo-hydroxo-cluster formation for the lead(II) compound, [(Pb4O)Pb(OH)(bet)(8)(Tf2N)3] [Tf2N](4)center dot MeOH, and a polymeric structure for the silver(I) compound, [Ag-2(bet)(2)(Tf2N)Ag-2(bet)(2)][Tf2N](3). The zwitterionic nature of the betaine ligand and the weakly coordinating ability of the bis(trifluoromethylsulfonyl)imide [Tf2N]- anion facilitates the incorporation of metal ions into oligonuclear and polynuclear metal complexes.

Mandelohydroxamic acid as ligand for copper(II) 15-metallacrown-5 lanthanide(III) and copper(II) 15-metallacrown-5 uranyl complexes

The formation of pentanuclear copper(ii) complexes with the mandelohydroxamic ligand was studied in solution by electrospray ionization mass spectrometry (ESI-MS), absorption spectrophotometry, circular dichroism and H-1 NMR spectroscopy. The presence of lanthanide(iii) or uranyl ions is essential for the self-assembly of the 15-metallacrown-5 compounds. The negative mode ESI-MS spectra of solutions containing copper(II), mandelohydroxamic acid and lanthanide(iii) ions (Ln = La, Ce, Nd, Eu, Gd, Dy, Er, Tm, Lu, Y) or uranyl in the ratio 5:5:1 showed only the peaks that could be unambiguously assigned to the following intact molecular ions: {Ln(NO3)(2)[15-MCuIIN(MHA)-5](2-)}(-) and {Ln(NO3)[15-MCCuIIN(MHA)-5](3-)}(-), where MHA represents doubly deprotonated mandelohydroxamic acid. The NMR spectra of the pentanuclear species revealed only one set of peaks indicating a fivefold symmetry of the complex. The pentanuclear complexes synthesized with the enantiomerically pure R- or S-forms of mandelohydroxamic acid ligand, showed circular dichroism spectra which were mirror images of each other. The pentanuclear complex made from the racemic form of the ligand showed no signals in the CD spectrum. The UV/ Vis titration experiments revealed that the order in which the metal salts are added to the solution of the mandelohydroxamic acid ligand is crucial for the formation of metallacrown complexes. The addition of copper(ii) to the solutions containing mandelohydroxamic acid and neodymium(iii) in a 5:1 ratio lead to the formation of a pentanuclear complex in solution. In contrary, titration of lanthanide(iii) salt to the solution containing copper(ii) and mandelohydroxamic acid did not show any evidence for the formation of pentanuclear species. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Bis(trifluoromethyl)mercury(II) complexes with purine and 3,5-dimethyl-4 '-amino-triazole as ligands, [Hg(CF3)(2)(Pur)](4) and [Hg(CF3)(2)(Dat)](2)

Colourless single crystals of [Hg(CF3)(2)(Pur)](4) and [Hg(CF3)(2)(Dat)](2) were obtained from aqueous and etheric solutions of the respective components Purine, (imidazo[4,5-d]pyrimidine, Pur), 3,5-dimethyl-4 '-amino-triazole (Dat) and bis(trifluoromethyl)mercury(II), Hg(CF3)(2). [Hg(CF3)(2)(Pur)](4) crystallizes with the tetragonal system (P-4, Z = 8, a = 1486.8(2), c = 1026.2(l) pm, R-all = 0.0657) with tetrameric molecules consisting of four purine molecules bridged by slightly bent Hg(CF3)2 molecules forming a cage with the CF3 ligands surrounding this cage. The two modifications of [Hg(Dat)(CF3)2]2 (1: 170 K, triclinic, P-1, Z = 2, a 814.9(2), b = 845.4(2), c = 968.4(3) pm, alpha = 106.55(2)degrees, beta= 103.41(2)degrees, gamma = 110.79(2)degrees, R-all = 0.1189; II: monoclinic, P2(1)/c, Z = 8, a = 879.8(2), b = 1731.0(3), c = 1593.9(3) pm, beta = 106.89(2)degrees, R-all = 0.1199) both contain dimeric molecules that are stacked parallel to one crystal axis to strands which are arranged in a parallel fashion in I and rotated against each other in 11 by 110 degrees. In both, the tetrameric [Hg(CF3)(2)(Pur)](4) and the dimeric [Hg(CF3)(2)(Dat)](2) the Hg(CF3)(2) molecules are slightly bent (around 167 and 170 degrees) and rather weakly attached to the N-donor ligands Pur and Dat with Hg-N distances around 272 pm, although in both cases the Hg atoms bridge between two ligand molecules.

Cobalt(II) Complexes of Nitrile-Functionalized Ionic Liquids

A series of nitrile-functionalized ionic liquids were found to exhibit temperature-dependent miscibility (thermomorphism) with the lower alcohols. Their coordinating abilities toward cobalt(II) ions were investigated through the dissolution process of cobalt(II) bis(trifluoromethylsulfonyl)imide and were found to depend on the donor abilities of the nitrile group. The crystal structures of the cobalt(II) solvates [Co(C1C1CNPyr)2(Tf2N)4] and [Co(C1C2CNPyr)6][Tf2N]8, which were isolated from ionic-liquid solutions, gave an insight into the coordination chemistry of functionalized ionic liquids. Smooth layers of cobalt metal could be obtained by electrodeposition of the cobalt-containing ionic liquids.

Sequential C-H and C-Ru bond formation and cleavage during the thermally induced rearrangement of aryl ruthenium(II) complexes with [C6H3(CH2NMe2)(2)-2,6](-) as a bidentate eta(2)-C,N coordinated ligand. The crystal structures of the isomeric pairs [RuCl{eta(6)-C10H14}{eta(2)-C,N-C6H3(CH2NMe2)(2)-2,n}] (n = 4 or 6) and [Ru(eta(5)-C5H5){(eta(2)-C,N-C6H3(CH2NMe2)(2)-2,n} (PPH3)] (n = 4 or 6)

New air-stable ruthenium(II) complexes that contain the aryldiamine ligand [C6H3(CH2-NMe2)(2)-2,6](-) (NCN) are described. These complexes are [RuCl{eta(2)-C,N-C6H3(CH2NMe2)(2)-2,6}(eta(6)-C10H14)] (2; C10H14 = p-cymene = C6H4Me-Pr-i-4), [Ru{eta(2)-C,N-C6H3(CH2NMe2)(2)-2,6}(eta(5)-C5H5)(PPh3)] (5), and their isomeric forms [RuCl{eta(2)-C,N-C6H3(CH2NMe2)(2)-2,4}(eta(6)-C10H14)] (3) and [Ru{eta(2)-C,N-C6H3(CH2NMe2)(2)-2,4}(eta(5)-C5H5)(PPh3)] (6), respectively. Complex 2 has been prepared from the reaction of [Li(NCN)](2) with [RuCl2(eta(6)-C10H14)](2), whereas complex 5 has been prepared by the treatment of [RuCl{eta(3)-N,C,N-C6H3(CH2NMe2)(2)-2,6}(PPh3)] (4) with [Na(C5H5)](n). Both 2 and 5 are formally 18-electron ruthenium(II) complexes in which the monoanionic potentially tridentate coordinating ligand NCN is eta(2)-C,N-bonded, In solution (halocarbon solvent at room temperature or in aromatic solvents at elevated temperature), the intramolecular rearrangements of 2 and 5 afford complexes 3 and 6, respectively. This is a result of a shift of the metal-C-aryl bond from position-1 to position-3 on the aromatic ring of the NCN ligand. The mechanism of the isomerization is proposed to involve a sequence of intramolecular oxidative addition and reductive elimination reactions of both aromatic and aliphatic C-H bonds. This is based on results from deuterium labeling, spectroscopic studies, and some kinetic experiments. The mechanism is proposed to contain fully reversible steps in the case of 5, but a nonreversible step involving oxidative addition of a methyl NCH2-H bond in the case of 2. The solid-state structures of complexes 2, 3, 5, and 6 have been determined by single-crystal X-ray diffraction. A new dinuclear 1,4-phenylene-bridged bisruthenium(II) complex, [1,4-{RuCl(eta(6)-C10H14)}(2){C-6(CH2NMe2)(4)-2,3,5,6-C,N,C',N'}] (9) has also been prepared from the dianionic ligand [C-6(CH2NMe2)(4)-2,3,5,6](2-) (C2N4). The C2N4 ligand is in an eta(2)-C,N-eta(2)-C',N'-bis(bidentate) bonding mode. Compound 9 does not isomerize in solution (halocarbon solvent), presumably because of the absence of an accessible C-aryl-H bond. Complex 9 could not be isolated in an analytically pure form, probably because of its high sensitivity to air and very low solubility, which precludes recrystallization.

New ruthenium(II) complexes of functionalized monoanionic aryldiamine N,C,N'-terdentate ligands: Syntheses of [Ru-II{2,6-(Me(2)NCH(2))(2)-4-R-C6H2}(terpy)]Cl+(-); X-ray structure of a dimeric organolithium compound,[Li{2,6-(Me(2)NCH(2))(2)-4-Ph-C6H2}](2)

The new anionic functionalized aryldiamine ligands [2,6-(Me(2)NCH(2))(2)-4-R-C6H2](-) (R = Me(3)SiC=C, C6H5, Me(3)Si), formally derived from [2,6-(Me(2)NCH(2))(2)C6H3](-), have been prepared as their lithium compounds. The compound [Li{2,6-(Me(2)NCH(2))(2)-4-Ph-C6H2}](2) crystallizes in the monoclinic space group C2/c (no. 15) with a = 13.1225(5), b = 13.5844(7), c = 15.9859(12) Angstrom, beta = 105.329(5)degrees, V = 3264.0(3)Angstrom(3), Z = 4. The structure refinement converged to R(1) = 0.0374 for 2037 observed reflections [F-o>4 sigma(F-o)] and wR(2) = 0.0922 for 2560 unique data. The organolithium compounds have been used in transmetalation reactions to give the corresponding functionalized organoruthenium(II) complexes [Ru-II{2,6-(Me(2)NCH(2))(2)-4-R-C6H2}(terpy)]Cl-+(-) (terpy = 2,2';6',2 ''-terpyridine). The Ru-II species with R = HC = C has also been synthesized.