Thesis (Ph. D.)--University of Hong Kong, 2005.

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xii, 286 p.; also includes graphics (some col.). Includes bibliographical references (p. 273-286). Available online via OhioLINK's ETD Center

Thesis (Ph.D.)--Baylor University, 2009. / Includes bibliographical references (p. 233-237).

The chapter one introduces the reported examples of rare earth metal (RE) complexes with different oxidation states. It also reviews the synthesis and reactivity study of N-heterocyclic carbene (NHC) supported transition metal and RE metal complexes. Chapter two focusses on the synthesis and characterisation of a series of tetraaryloxide Ce and Pr complexes. With the reaction of bulky tetraphenol proligand H4LR(R = P, PT, M) with four equivalents of KN"(N" = N(SiMe3)2), a dimerised complex of [K4LP]2(thf)11 was synthesised and characterised. The salt metathesis reactions of this complex with RECl3(thf)2 afford bimetallic aryloxide complexes of K2L2RE2(thf)11 (RE = Ce, Pr), which display divergent structures under different conditions. Reactions of the CeIII complex of K2L2Ce2(thf)11 with a variety of oxidants(I2, CuCl2 and O2, etc.) lead to the oxidation of CeIII to CeIV, affording purple ceric dimer of L2Ce2. The reaction of the PrIII complexes with I2 under 60 °C affords a mixture from which PrIII iodide (LPr2I2) has been isolated and characterised. This chapter also discusses the reactivity of the bimetallic aryloxide complexes towards different substrates, such as MeLi, KC8 and KBn (Bn = benzyl). Bimetallic complexes of L(REX)2(py)8 (RE = Ce, Pr; X = Cl, BH4) are synthesised and characterised. The preliminary study on the copolymerization of cyclohexene oxide (CHO) and CO2 is conducted for CeIII and PrIII complexes. Chapter three details the work on two different types of NHC ligand. The first ligand is the β-ketoimidazolinium salts H2LBr {L = RC(O)CH2{CH[NCH2CH2NMes], R = tBu, naphth} which reacts with MHBEt3 (M = Na, K) to form carbene-borane adducts RC(O)CH2{C(BEt3[NCH2CH2NMes]}. This type of reactivity differs from the previous work on imidazole derivatives. The possible mechanism of these reactions is provided and discussed. The other ligand is p-aryloxy-tethered imidazolinium salt H2LX (L = N-3,5-di-tert-butyl-4-hydrooxyphenyl-N’-mesityl-imidazolinium, X = Cl, Br, PF6 ), which have been synthesised and characterised. The reactions of these salts with MN"(M = Na, K) enabled the characterisation of polymerised complexes of [NaL]n and [KL(thf)2]n. The yttrium complex YL3 is synthesised and its reactivity towards small molecules such as boranes, CO2 and CS2 is discussed. Chapter four presents the primary results on the study of macrocyclic NHC based cyclophane ligand H6LPF6 (L = calix[4]imidazolylidene[2]pyrazolato). Investigations on the reactivity of the ligand towards different bases (NaN", KN", KBn etc.) are examined and subsequent metathesis reactions with RE complexes are explored. Chapter five concludes the work presented in this thesis. Chapter six contains all experimental and characterisation details.

Luminescent transition metal complexes have attracted tremendous interest in the analytical field. Most luminescent metal complexes possess long emission lifetimes in the visible region, and their phosphorescence can be readily distinguished from short-lived background auto-fluorescence. Moreover, their large Stokes shift can prevent self-quenching, while their modular synthesis allows their properties to be readily tuned without labor-intensive synthetic protocols. These properties render transition metal complexes as promising candidates for the development of biosensors. In this study, I aimed to explore different kinds of Ir(III) complexes that can be used as biosensors to monitor DNA secondary structures or protein conformations. Chapter 1 gives a brief introduction regarding the luminescence mechanism of transition metal complexes, and the properties, structures and preparations of Ir(III) complexes are also introduced. Chapters 24 report the syntheses and screening of Ir(III) complexes, and the use of these Ir(III) complexes to monitor the secondary structure of DNA, such as G-quadruplex, G-triplex and i-motif DNA. Chapter 2 reports the G-quadruplex-selective properties of two luminescent Ir(III) complexes 2.1 and 2.9 for the detection of ochratoxin A (OTA) and nicking endonuclease in aqueous solution, respectively; Chapter 3 explores a novel Ir(III) complex 3.8 which is highly specific for G-triplex DNA, and was thus employed for Mung Bean nuclease activity detection; Chapter 4 introduces the Ir(III) complex 4.1 that exhibited a high signal enhancement to i-motif DNA, and was therefore used for terminal deoxynucleotidyl transferase (TdT) activity detection. Chapter 5 describes the two novel cyclometalated Ir(III) complexes 5.1 and 5.21 that were used to monitor two kinds of proteins, human serum albumin (HSA) and beta-amyloid(140) (Aβ140), respectively.

No description available.

The use of two different chelating redox active ligands, 2,6-bis(6-methyl-1,2,4,5-3-yl) pyridine (BTZP) and 2,6-bis-(5,6-dialkyl-1,2,4-triazin-3-yl)-pyridine (BTP) in heterometallic first row and second row transition metal chemistry has yielded two new families of redox active metal complexes. These complexes were found to exhibit interesting electrochemical and magnetic properties. In this thesis, Chapter 1 lays the foundation for the research presented within. This section covers the fundamentals of the ligand design, ligand synthesis and related coordination chemistry literature review. Chapters 2 and 3 report the results of the current thesis. In Chapter 2, the synthesis and characterization of a family of discrete molecules and supramolecular arrangements, employing the ligand BTZP, is presented. All of the complexes presented in Chapter 2 are successfully synthesized and characterized with electrochemical and magnetic studies. According to the electrochemical data, it is found that the classic “terpy-like” complexes with [Co(BTZP) 2]2+ formula fosters more stability in the redox process. In Chapter 3, a family of transition metal complexes with [M(BTP) 2]2+ (M=Fe or Co) inorganic cores were obtained through the employment of the ligand BTP with various anions. In addition, dimeric molecules with [CoX4(BTP)2] formula were also obtained by solvothermal synthesis. The complexes were also electrochemically characterized, with all the complexes capable of being reduced, while only [CoII(BTP)2] (ClO4)2 showed reversible redox process. Similar with BTZP, the series of BTP based complexes are also characterized through magnetic measurement. Only cobalt-based BTP complexes are paramagnetic, with [CoII(BTP)2]2+ being spin crossover active when BF4- and ClO4- are present. However, the presence of NCS- and halides lead to either antiferromagnetic interactions and ferromagnetic interactions dominating at different temperature regimes.

Submitted by Marlene Santos (marlene.bc.ufg@gmail.com) on 2017-09-04T17:43:49Z No. of bitstreams: 2 Dissertação Tracy Martina Marques Martins - 2017.pdf: 2276783 bytes, checksum: 1db8548b9383656806b83fc1c22de5d7 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-09-15T13:58:00Z (GMT) No. of bitstreams: 2 Dissertação Tracy Martina Marques Martins - 2017.pdf: 2276783 bytes, checksum: 1db8548b9383656806b83fc1c22de5d7 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-09-15T13:58:00Z (GMT). No. of bitstreams: 2 Dissertação Tracy Martina Marques Martins - 2017.pdf: 2276783 bytes, checksum: 1db8548b9383656806b83fc1c22de5d7 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-08-05 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / Bacterial multidrug resistance is to global public health a serious problem. With the emergence of multidrug-resistant bacteria pharmaceutical industry focuses on developing new drugs that are effective in antimicrobial therapy, which presents low cost, high efficiency and has reduced side effects. That is why new research and investments are needed. Several studies have shown that the Schiff Bases are potential compounds with pharmacological effect, some examples of these compounds being semicarbazide, thiosemicarbazides and hydrazines. Condensation reactions of these compounds with aldehyde or ketone, and metals allow the generation of new structural modifications that can produce relevant biological effects against fungi and pathogenic bacteria. The objective of this work was to evaluate the biological potential of organic binders based on thiosemicarbazones, semicarbazones, hydrazones and their metal complexes on fungi and bacteria. Organic binders of the class of the semicarbazones, thiosemicarbazones and hydrazones were obtained by a condensation reaction of a semicarbazide, thiosemicarbazide or hydrazine with an aldehyde or ketone and sequentially with a transition metal. Three binders and two metal complexes were obtained: NMHC, NMHC+ Sn, MTHC, NMH, NMH+Sn. The biological activity was verified by means of microbiological tests to evaluate the antifungal and antibacterial activity of each compound, using the technique of microdilution in a 96-well flat bottom plate. The evaluation of the antimicrobial activity was performed with ten microorganisms and with the five potential drugs. Three novel compounds showed antimicrobial activity. The binders NMH (hydrazone) and MTHC (semicarbazone) showed no antimicrobial activity at the concentrations tested (1024 mgL-1 to 0.5 mgL-1) on the ten tested microorganisms. The binder NMHC (thiosemicarbazone) only showed activity against Candida albicans strain tested at a concentration of 64 mgL-1. The metal complexes presented antibacterial activity against seven strains and antifungal activity against the strains of Candida albicans and Candida parapsilosis. MICs of the NMHC + Sn and NMH + Sn complex ranged from 16 mgL-1 to 32 mgL-1. With these promising results we will continue the studies on the biological effects of these molecules unpublished in the scientific literature. / A multirresistência bacteriana é para a saúde pública mundial um grave problema. Com o surgimento de bactérias multirresistentes a indústria farmacêutica foca no desenvolvimento de novos medicamentos que sejam efetivos na terapia antimicrobiana, que apresente baixo custo, alto rendimento e tenha reduzidos efeitos colaterais. Por isso são necessários novas pesquisas e investimentos. Diversos estudos têm mostrado que as Bases de Schiff, são potenciais compostos com efeito farmacológico, alguns exemplos destes compostos são: as semicarbazida, tiossemicarbazidas e as hidrazinas. Reações de condensação destes compostos com aldeído ou cetona, e metais permitem a geração de novas modificações estruturais que podem produzir relevantes efeitos biológicos frente a fungos e bactérias patogênicas. Dessa forma o objetivo deste trabalho foi avaliar o potencial biológico de ligantes orgânicos a base de tiossemicarbazonas, semicarbazonas, hidrazonas e seus complexos metálicos em fungos e bactérias. Os ligantes orgânicos da classe das semicarbazonas, tiossemicarbazonas e hidrazonas foram obtidos através de uma reação de condensação de uma semicarbazida, tiossemicarbazida ou hidrazina com um aldeído ou cetona e sequencialmente com um metal de transição. Foram obtidos três ligantes e dois complexos metálicos: NMHC, NMHC+ Sn, MTHC, NMH, NMH+Sn. A verificação da atividade biológica foi realizada por meio de teste microbiológicos de avaliação da atividade antifúngica e antibacteriana de cada composto, por meio da técnica de microdiluição em placa de 96 poços de fundo chato. A avaliação da atividade antimicrobiana foi realizada com dez microrganismos e com os cinco potenciais fármacos. Três compostos inéditos apresentaram atividade antimicrobiana. Os ligantes NMH (hidrazona) e MTHC (semicarbazona) não apresentaram atividade antimicrobiana nas concentrações testadas (1024 mgL-1 a 0,5 mgL-1) sobre os dez microrganismos testados. O ligante NMHC (tiossemicarbazona) apresentou atividade apenas contra a cepa testada de Candida albicans, na concentração de 64 mgL-1. Os complexos metálicos apresentaram atividade antibacteriana contra sete cepas e atividade antifúngica frente as cepas de Candida albicans e Candida parapsilosis. As MIC's do complexo NMHC+Sn e do NMH+Sn variaram de 16 mgL-1 a 32 mgL-1. Com estes resultados promissores continuaremos os estudos sobre os efeitos biológicos destas moléculas inéditas na literatura científica.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / The aim of this work is to study the surface modification of gold electrode with the trans-[Ru(NH3)4(tina)(SO4)]+ (Au/trans-[Ru(NH3)4(tina)(SO4)]+) and trans-[Fe(cyclam)(NCS)2]+ (Au/trans-[Fe(cyclam)(NCS)2]+) complexes ion, emplyoing the electrodeposition and self-assembled monolayer techniques, respectively; and evaluate the potentiality of these modified electrodes as electrochemical sensors for detection and quantification of NO. Cyclic voltammetry and electrochemical quartz crystal microbalance results suggest that the deposition of trans-[Ru(NH3)4(tina)(SO4)]+ complex ion on the gold surface. Cyclic voltammetry and surface enhanced raman spectroscopy results confirm the modification of gold electrode surface by the trans-[Fe(cyclam)(NCS)2]+ complex ion. Peak current (Ip) observed in cyclic voltammograms for the oxidation of NO on the modified electrodes were higher than that observed for the unmodified gold electrode, and the modified electrode Au/trans-[Fe(cyclam)(NCS)2]+ showed the highest Ip for the oxidation of NO. The values of detection limit and quantification limit obtained for the electrode Au/trans-[Ru(NH3)4(tina)(SO4)]+ were 7.73 x 10-8 mol L-1 and 2.58 x 10-7 mol L-1, and for the electrode Au/trans-[Fe(cyclam)(NCS)2]+ were 5.15 x 10-8 mol L-1 and 1.72 x 10-7 mol L-1, respectively, being this values smaller by an order of magnitude as the same obtained for the unmodified gold electrode. Computational simulations suggest that the increase in Ip oxidation of NO on the electrode Au/trans-[Fe(cyclam)(NCS)2]+ is due to the interaction energy between molecules of NO and the complex trans-[Fe(cyclam)(NCS)2]+, adsorbed on the gold surface, to be stronger than the energy of interaction of NO with the gold surface. The dopamine and serotonin molecules and the nitrite ion interfere in electrochemical detection of NO and dopamine and serotonin showed greater interference in the detection of NO in relation to the nitrite ion. The electrode Au/trans-[Fe(cyclam)(NCS)2]+ showed the greatest stability when compared to the electrode Au/trans-[Ru(NH3)4(tina)(SO4)]+. The results obtained in this work showed the potentiality of modified electrodes as sensors for deteccion and quantification of NO, among which stands out the electrode Au/trans-[Fe(cyclam)(NCS)2]+ due to the further intensification of the signal current for the oxidation of NO and provided greater stability. / O objetivo deste trabalho à estudar a modificaÃÃo da superfÃcie do eletrodo de ouro com os Ãons complexos trans-[Ru(NH3)4(tina)(SO4)]+ (Au/trans-[Ru(NH3)4(tina)(SO4)]+) e trans-[Fe(cyclam)(NCS)2]+ (Au/trans-[Fe(cyclam)(NCS)2]+), empregando as tÃcnicas de eletrodeposiÃÃo e formaÃÃo de camadas auto-organizadas, respectivamente; e avaliar a potencialidade destes eletrodos modificados como sensores eletroquÃmicos para detecÃÃo e quantificaÃÃo de NO. Os resultados de voltametria cÃclica e de microbalanÃa eletroquÃmica a cristal de quartzo sugerem a deposiÃÃo do Ãon complexo trans-[Ru(NH3)4(tina)(SO4)]+ sobre a superfÃcie de ouro. Os resultados de voltametria cÃclica e de espalhamento raman amplificado por superfÃcie comprovam a modificaÃÃo da superfÃcie do eletrodo de ouro pelo Ãon complexo trans-[Fe(cyclam)(NCS)2]+. As correntes de pico (Ip) observadas nos voltamogramas cÃclicos para a oxidaÃÃo do NO sobre os eletrodos modificados foram maiores que as observadas para o eletrodo de ouro sem modificaÃÃo, sendo que o eletrodo modificado Au/trans-[Fe(cyclam)(NCS)2]+ apresentou a maior Ip para a oxidaÃÃo de NO. Os valores de limite de detecÃÃo e de quantificaÃÃo obtidos para o eletrodo Au/trans-[Ru(NH3)4(tina)(SO4)]+ foram de 7,73 x 10-8 mol L-1 e 2,58 x 10-7 mol L-1, e para o eletrodo Au/trans-[Fe(cyclam)(NCS)2]+ foram de 5,15 x 10-8 mol L-1 e 1,72 x 10-7 mol L-1, respectivamente, sendo estes valores menores em uma ordem de grandeza que os mesmos obtidos para o eletrodo de ouro nÃo modificado. As simulaÃÃes computacionais sugerem que o aumento de Ip da oxidaÃÃo de NO sob o eletrodo Au/trans-[Fe(cyclam)(NCS)2]+ à devido à energia de interaÃÃo entre as molÃculas de NO e o complexo trans-[Fe(cyclam)(NCS)2]+, adsorvido na superfÃcie de ouro, ser mais forte que a energia de interaÃÃo do NO com a superfÃcie de ouro. As molÃculas dopamina e serotonina e o Ãon nitrito interferem na detecÃÃo eletroquÃmica de NO e a dopamina e a serotonina apresentaram maior interferÃncia na detecÃÃo de NO em relaÃÃo ao Ãon nitrito. O eletrodo Au/trans-[Fe(cyclam)(NCS)2]+ apresentou maior estabilidade quando comparado ao eletrodo Au/trans-[Ru(NH3)4(tina)(SO4)]+. Os resultados obtidos neste trabalho demonstram a potencialidade dos eletrodos modificados como sensores para detecÃÃo e quantificaÃÃo de NO, dentre os quais se destaca o eletrodo Au/trans-[Fe(cyclam)(NCS)2]+, devido à maior intensificaÃÃo no sinal de corrente para a oxidaÃÃo de NO e a maior estabilidade apresentada.

O objetivo principal deste trabalho é aplicar complexos de cobre(II), níquel(II), zinco(II) e nióbio(V) como fontes de metais em banhos de eletrodeposição. Os íons metálicos foram coordenados aos ligantes íon oxalato, íon citrato, etilenodiamina (EDA) ou tetraetilenopentamina (TEPA), os quais são aditivos orgânicos típicos em banhos de eletrodeposição. Os complexos foram caracterizados por análise elementar, espectroscopias nas regiões do infravermelho e ultravioleta-visível e voltametria cíclica. Foram realizadas eletrólises em presença de dois complexos de coordenação em ausência de quantias adicionais de aditivos, usando aço 1010 como substrato a pH = 4.5 (H2SO4/Na2SO4), resultando em depósitos com dois elementos metálicos. Os depósitos apresentaram aspectos morfológicos com boas qualidades e sem falhas. Em adição, os depósitos foram analisados por EDX, reflectância difusa e espectroscopia de raio-X e também foram realizadas medidas de curvas de polarização. Os depósitos obtidos a partir dos complexos gerados ex-situ mostraram morfologias melhores do que depósitos obtidos de soluções preparadas com os sais dos metais na presença dos aditivos, mediante as mesmas condições de trabalho. É sugerido que os metais de partida, coordenados a aditivos influenciam o processo de eletrodeposição, propiciando depósitos com potenciais de corrosão deslocados por até +200 mV em 0.5 mol.L-1 NaCl (1 mV.s-1). / The main goal of this work is to use copper(II), nickel(II), zinc(II) and niobium(V) complexes as metal plating source in electrodeposition baths. The metal ions were coordinated with oxalate, citrate, ethylenediamine (EDA) or tetraethylenepentamine (TEPA) as ligands, which are typical organic additives in electroplating. The complexes were characterized by elemental analysis, infrared and ultraviolet spectroscopies and cyclic voltammetry. The electrolyses in presence of two coordination complexes in the baths were carried out in absence of extra amount of additive, using 1010 steel as substrate at pH = 4.5 (H2SO4/Na2SO4). Deposits with two metal elements from the ex-situ generated complexes showed good quality morphologic aspect without crashes. Further, the deposits were analyzed by EDX, diffuse reflectance and X-ray spectroscopy and polarization curves were recorded. The deposits showed better morphologies than deposits obtained from the metal salt solutions in presence of additives under similar conditions. It is suggestive that the starting metal plating coordinated with additives influences the electrodeposition processes, affording deposits with corrosion potentials shifted over +200 mV in 0.5 mol.L-1 NaCl (1 mV.s-1).