M.Sc. / The dimeric structure of Lawesson’s reagent, (RPS2)2 (R = 4–MeOC6H4), or its ferrocenyl analogue (R = ferrocenyl, Fc) leads to symmetrical cleavage through nucleophillic attack by alcohols to form dithiophosphonic acids, which can be readily deprotonated by ammonia to form the corresponding ammonium salts, which can be further reacted with transition-metal halides to form new metal complexes. Among the phosphor-1,1-dithiolates as a generic class of compounds, the dithiophosphates, [S2P(OR)2]-, have been most intensely studied and the dithiophosphonates [S2PR(OR’)]-, the subject of the present study, to a far lesser extent. In this study, a large variety of new dithiophosphonate salts were synthesized from diverse alcohol functionalities derived from cholesterol, estrone, estradiol, pentaerythritol, ethandiol, hydroquinone, resorcinol, glucose and ribose. The salts were oxidized with iodine to yield various S-S oxidative products, of which two X-ray crystal structures of such compounds, the ethandiol and pentaerythritol derivatives, were obtained and they were subjected to further investigation by cyclic voltammetry due to the ferrocenyl-rich functionalities they contain. The reaction of these [S2PR(OR’)]- type salts with a number of gold(I) and palladium(II) precursors, yielded a variety of new complexes. The compounds containing multiple alcohol (hydroxy) sites have been reacted with gold(I) and palladium(II) starting materials ClAu(tht) and PdCl2(PPh3)2, respectively and also with other gold(I) variants, including the mono- and dinuclear phosphines ClAuPPh3, Au2Cl2dppe and Au2Cl2dppa. A new X-ray single crystal structure of a gold(I) complex could be obtained as a decomposition product. New products have been characterized through a combination of solution 1H and 31P NMR, EIS mass spectrometry, IR, elemental analysis, electro-chemistry and single crystal X-ray crystallographic studies.

The philosophy of green chemistry has seen much development in the past decade. The use of environmentally benign solvents is amongst the areas of green chemistry that have received the most attention. In this context, imidazolium ionic liquids have been widely reported to offer high product yields, fast reaction rates, excellent selectivity and generally mild working conditions, when used as reaction media. In addition, concerns about costs of solvents and the long-term environmental impact that can potentially result when solvents are discarded after their use have led to focused investigations into solvent-free procedures, as reported in recent literature. We have set out to explore the extent to which these advantages could be realized within our research. Non-volatile, non-flammable imidazolium ionic liquids [bmim][I], [bmim][BF4] and [bmim][PF6] were used as green solvents in ferrocene chemistry. Ferrocenoate esters were synthesised efficiently by the respective DCC/DMAP-promoted reactions of ferrocenecarboxylic acid and substituted benzoic acids or, alternatively, the DMAP-promoted reactions of ferrocenoyl fluoride with a range of substituted phenols in [bmim][BF4] and [bmim][PF6]. High yields and short reaction times were achieved. In addition, the ionic liquid was reused several times without a reduction in product yields. Under solvent-free conditions, DCC/DMAP-promoted reactions provided high yields within 3 min of reaction. The possible rearrangement of one of the intermediates in these reactions was modelled theoretically using density function theory (DFT) at the B3LYP/6-31G* level of approximation. Catalyst-free esterification was achieved by the application of microwave radiation to the reaction of ferrocenoyl fluoride and a range of substituted phenols. All the reactions were complete after 1 min of irradiation and products were isolated in high yield. DPAT, HfCl4, Sc(OTf)3 and Al(OTf)3 were screened as catalysts for esterification in [bmim][BF4] and under solvent-free conditions at various temperatures. All attempts at esterification of ferrocenecarboxylic acid with alcohols and phenols were unsuccessful. The Suzuki cross-coupling reaction was carried out in [bmim][BF4]. The isolated yields are, however, poor and suffer from poor reproducibility with different batches of [bmim][BF4] used.

This research project is concentrated on tuning the properties of small organic molecules, namely polyacenes, tropones and thiepins, by incorporating redox-active transition metal centers π-bonded to terminal cyclopentadienyl ligands. Organometallic-fused acenequinones, tropones, thiepins and cyclopentadiene-capped polyacenes were synthesized and characterized. This work was divided into three parts: first, the synthesis of ferrocene-fused acenequinones, cyclopentadiene-capped acenequinones and their subsequent aromatization to polyacenes; second, the synthesis of ferrocene-fused tropones, thiotropones and tropone oxime; and third, the synthesis of ferrocene-fused thiepins. Ferrocene-fused quinones are the precursors to our target complexes. Our synthetic route to ferrocenequinones involved two-fold aldol condensation between 1,2-diformylferrocene and naphthalene-1,4-diol or anthracene-1,4-diol, and four-fold condensation between 1,2-diformylferrocene and 1,4-cyclohexanedione. Reduction of ferrocene-fused quinones with borane in THF resulted in ferrocene-fused dihydroacenes. Attempts to reduce ferrocene-fused acenequinones with sodium dithionite led to metal-free cyclopentadiene- (Cp-) capped acenequinones. Cp-capped acenequinones were aromatized to bis(triisopropylsilyl)ethynyl polyacenes by using lithium (triisopropylsilyl)acetylide (TIPSC≡CLi) with subsequent dehydroxylation by stannous chloride. The compounds were characterized by using spectroscopic methods and X-ray crystallography. Further, the electronic properties of these compounds were studied by using cyclic voltammetry and UV-visible spectroscopy. Cyclic voltammetry showed oxidation potentials of Cp-capped TIPS-tetracene and bis-Cp-capped TIPS-anthracene as 0.49 V and 0.61 V, respectively (vs. ferrocene/ferrocenium). The electrochemical band gaps were 2.15 eV and 2.58 eV, respectively. Organic thin-film transistor device performance of Cp-capped polyacenes was studied using solution deposition bottom-contact, bottom-gate (BCBG) device architecture and the resulting performance parameters are described herein. Similarly, we are also interested in potential applications of metallocene-fused tropones and derivatives as organic electronic materials. Condensation of 1,2-diformylferrocene with acetone or 1,3-diphenylacetone in the presence of KOH resulted in the ferrocene-fused tropone (η5-2,4-cyclopentadien-1-yl)[(1,2,3,3a,8a-η)-1,6-dihydro-6-oxo-1-azulenyl]iron (1, R = H, E = O) and its 5,7-diphenyl derivative (1, R = Ph, E = O) as previously reported by Tirouflet. The use of piperidine as base resulted in Michael addition of piperidine to one of the carbon-carbon double bonds of the tropones. Lawesson’s reagent converted the ferrocene-fused tropones to either a thiotropone (1, R = H, E = S) or a detached 5,7-diphenylazulenethiol (2). Reaction of the ferrocene-fused thiotropone with hydroxylamine gave the corresponding oxime (1, R = H, E = NOH). Products were characterized by using spectroscopic methods and X-ray crystallography. Their electronic properties were studied by using cyclic voltammetry and UV-visible spectroscopy. The third project involved the two-fold aldol condensation of 1,2-diformylferrocene with dimethylthioglycolate S-oxide in the presence of freshly distilled triethylamine, which gave mono- and di-dehydrated products. Deoxygenation of the ferrocene-fused thiepin S-oxide with 2-chloro-1,3,2-benzodioxaphosphole in the presence of pyridine resulted in the corresponding thiepin. The ester groups of the thiepin and thiepin S-oxide were hydrolyzed under basic conditions to give carboxylic acids, which were converted into acid chlorides using oxalyl chloride. Attempts to decarboxylate the thiepin and thiepin S-oxide diacids resulted in decomposition.

The efficiency and mechanism of electron- and energy transfer events occurring in both in natural and synthetic donor-acceptor systems depend on their distance, relative orientation, and the nature of the surrounding media. Fundamental knowledge gained from model studies is key in building efficient energy harvesting and optoelectronic devices. Faster charge separation and slower charge recombination in donor-acceptor systems is often sought out. In our continued effort to build donor-acceptor systems using near-IR sensitizers, in the present study, we report ground and excited state charge transfer in newly synthesized, directly linked, tetrads featuring bisdonor (donor = phenothiazine and ferrocene), BF2-chelated azadipyrromethane (azaBODIPY) and C60 entities. The tetrads synthesized using multi-step synthetic procedure revealed strong charge transfer interactions in the ground state involving the donor and azaBODIPY entities. The near-IR emitting azaBODIPY acted as a photosensitizing electron acceptor along with fullerene while the phenothiazine and ferrocene entities acted as electron donors. The triads (bisdonor-azaBODIPY) and tetrads revealed ultrafast photoinduced charge separation leading to D•+-azaBODIPY•–-C60 and D•+-azaBODIPY-C60•– (D = phenothiazine or ferrocene) charge separated states from the femtosecond transient absorption spectral studies in both polar and nonpolar solvent media. The charge separated states populated the triplet excited state of azaBODIPY prior returning to the ground state.

No description available.

A variety of organometallic-fused heterocycles and acene quinones were prepared and characterized. This work was divided into three parts: first, the synthesis of 5,5-fused heterocyclic complexes of tricarbonylmanganese and (1’,2’,3’,4’,5’-pentamethylcyclopentadienyl)ruthenium; second, the synthesis of 1,2-diacylcyclopentadienyl p-cymene complexes of ruthenium(II); and third, synthesis of cyclopentadienyl-fused polyacenequinone complexes of ruthenium, iron and manganese. The first examples of the convenient, versatile and symmetric cyclopentadienyl-fused heterocycle complexes of (1’,2’,3’,4’,5’-pentamethylcyclopentadienyl)ruthenium(II) and tricarbonylmanganese(I) were synthesized starting from (1,2-dicarbophenoxycyclopentadienyl)sodium. The sodium salt was transmetalated using [MnBr(CO)5] and 1/4 [Ru(μ3-Cl)(Cp*)]4 to give [Mn(CO)3{η5-C5H3(CO2Ph)2-1,2}] and [Ru{η5-C5H3(CO2Ph)2-1,2}(Cp*)]. The diester complexes were saponified under basic conditions to obtain the corresponding dicarboxylic acids. The dicarboxylic acids were used to synthesize unique cyclopentadienylmetal complexes including diacyl chlorides, anhydrides, thioanhydrides and p-tolyl imides of ruthenium and manganese. Similarly, a series of 1,2-diacylcyclopentadienyl-p-cymene cationic complexes of ruthenium were synthesized using thallium salt of 2-acyl-6-hydroxyfulvene and [Ru(η6-p-cymene)(μ-Cl)Cl]2 in a 2:1 ratio with an intension of converting them into heterocycle-fused cationic sandwich complexes. However, our attempts of ring closing on 1,4-diketons with sulfur or selenium were unsuccessful. A methodology involving the synthesis of metallocene-fused quinone complexes was employed starting from pentamethylruthenocene-1,2-dicarboxylic acids. The diacyl chloride was prepared in situ from the dicarboxylic acids and used for Friedel-Crafts acylation. We observed single-step room-temperature diacylation of aromatics, including benzene, o-xylene, toluene, 1,4-dimethoxybenzene and ferrocene with pentamethylruthenocene-1,2-diacyl chloride to obtain the corresponding quinone complexes. Similarly, we synthesized mononuclear and binuclear γ-quinones by aldol condensation of 1,2-diformylcyclopentadienylmetal complexes with cyclohexane-1,4-dione or 1,4-dihydroxyarenes. The third methodology involves the Friedel-Crafts acylation of ferrocene with 2-carbomethoxyaroyl chlorides followed by saponification, carbonyl reduction, and ring closing by second Friedel-Crafts acylation to give Ferrocene-capped anthrone-like tricyclic and tetracyclic ketones. The oxidation of the ketones gave [3,4-c]-fused α-quinone complexes of iron. The oxidative and reductive coupling, enolization and C-alkylation of the anthrone complex were studied. Solvolysis of α-carbinol gave α-ferrocenylcarbenium salt, which underwent dimerization on treatment with non-nucleophilic base. We were successful to trap the in situ generated trimethylsilylenol ether of ferrocene-anthrone using dienophiles like N-phenylmaleimide or dimethylacetylenedicarboxylate under Diels-Alder conditions.

Chemistry / The efforts described in this thesis were bifurcated along two distinct projects, but generally were directed toward the development of new materials to solve outstanding issues in contemporary electrochemical applications. The first project involved the synthesis and application of redox-switchable olefin metathesis catalysts. N-heterocyclic carbenes (NHCs) bearing ferrocene and other redox-active groups were designed, synthesized, and incorporated into model iridium complexes to evaluate their intrinsic electrochemical and steric parameters. Using these complexes, the ability to switch the electron donating ability of the ligands via redox processes was quantified using a variety of electrochemical and spectroscopic techniques. The donicity was either enhanced or attenutated upon reduction or oxidation of the redox-active group, respectively. The magnitude of the change in donicity upon reduction or oxidation did not vary significantly as a function of the proximity of the redox-active group from the metal center. Thus, other factors, including synthetic considerations, sterics, and redox potential requirements, were determined to guide ligand design. Regardless, redox-active NHCs were adapted into ruthenium-based olefin metathesis catalysts and used to gain control control over various ring-opening metathesis polymerizations and ring-closing metathesis reactions. The second project was focused on the development of new basic polymers for acid/base crosslinked proton exchange membranes intended for applications in direct methanol fuel cells. Polymers containing pendant pyridinyl and pyrimidinyl groups were obtained via the post polymerization functionalization of UDEL® poly(sulfone) and then blended with sulfonated poly(ether ether ketone) (SPEEK). Fuel cells containing these blends were found to exhibit reduced methanol crossover, higher open circuit voltages, and higher maximum power densities compared to plain SPEEK. The differences in fuel cell performance were attributed to the basicity and sterics of the pendant N-heterocycles. / text

This thesis is concerned with the synthesis and study of novel anion templated rotaxanes and catenanes for electrochemical anion sensing, as well as interlocked structures that possess different anion binding properties, higher-order topologies and the ability to undergo molecular motion. Chapter One provides an introduction to anion recognition and the preparation of interlocked structures. A short summary of fundamental aspects of supramolecular chemistry is followed by detailed surveys of current approaches to anion binding and sensing, as well as the templated synthesis of rotaxanes and catenanes. Chapter Two describes the preparation of rotaxanes and catenanes appended with ferrocene to allow for electrochemical anion sensing. The anion recognition properties of a [2]rotaxane and a [2]catenane, as investigated by ¹H NMR spectroscopy and electrochemical methods, are presented. The utilization of a ferrocene-appended macrocycle in the construction of surface confined anion templated rotaxanes and catenanes is also discussed. Chapter Three reports the work carried out to achieve electrochemical anion sensing by the incorporation of redox-active groups into the integral structures of interlocked structures. The syntheses of a bis-stoppered 1, 2, 3, 4, 5-pentaphenylferrocene [2]rotaxane and a ferrocene containing [3]rotaxane are presented, along with their subsequent anion recognition studies. In addition, attempts to incorporate ferrocene into the macrocyclic components of rotaxanes and catenanes are outlined. Chapter Four details further investigations into the use of interlocked structures to achieve anion recognition. Doubly-charged [2]catenanes able to bind anions in aqueous solvent media, as well as the incorporation of alternative anion binding motifs into interlocked architectures are reported. The exploitation of anion templated synthesis to allow for the construction of higher order structures (including [3]catenanes, a “handcuff” catenane and a Janus [2]rotaxane), as well as a [2]catenane system with anion controlled molecular motion is also described. Chapter Five presents the experimental procedures and characterization data relating to the compounds prepared in Chapters Two, Three and Four. Chapter Six summarizes the main conclusions of the work contained within this thesis. Supplementary experimental information relating to titration protocols, investigations into self-assembled monolayers (SAMs) and crystallographic data are provided in Appendices I, II and III.

A cristalografia por difração de raios X (DRX) é uma ciência eminentemente interdisciplinar, cujo desenvolvimento tem possibilitado o avanço de várias outras áreas científicas. A determinação das estruturas tridimensionais de substâncias, sejam elas naturais ou sintéticas, tem sido fundamental para o estudo e compreensão das relações entre propriedades físicas, químicas e terapêuticas, e a estrutura a nível atômico. Neste trabalho serão apresentados alguns aspectos teóricos sobre complexos ferrocenos e a teoria envolvida na determinação de estruturas cristalinas e moleculares por DRX, bem como a resolução e caracterização de dois complexos ferrocenos. Os resultados obtidos foram comparados com estruturas similares encontradas no Cambridge Structural Database. Nos compostos estudados no presente trabalho, 1,1\'- bis(difenilfosfina)ferroceno e oCHCl3, o Fe apresentou-se complexado a dois anéis de ciclopentadienila, em conformação estrela, os quais estão dispostos de forma equidistante do átomo de Fe, não apresentando distorções significativas. Devido à alta toxicidade da cis-platina no tratamento de neoplasias, muitos grupos de pesquisa têm dedicado seus esforços a encontrar fármacos análogos compatíveis, sendo os derivados de paládio muito visados por terem propriedades eletrônicas e estruturais semelhantes. Sabe-se que a geometria em torno do átomo de platina, na cis-Pt, é quadrado planar, como no presente caso, o que torna o composto oCHCl3 passível de ser estudado quanto à sua possível atividade. Uma das grandes incógnitas dentro da área de farmacologia é saber exatamente quais são os produtos oriundos da degradação de um determinado fármaco e através da determinação por DRX das estruturas cristalinas e moleculares dos dois compostos estudados, concluiu-se que os mesmos são oriundos da degradação do composto [Pd2(C2, N-(dmpa) 2 (μ-dppf)Cl2], uma vez que os compostos estudados tiveram suas estruturas determinadas a partir de um tubo contendo o composto inicial. Portanto, o presente trabalho possui uma considerável importância no estudo deste fármaco o qual pode ser usado no combate ao câncer. / X-ray diffraction is a highly interdisciplinary science, whose development has enabled the advancement of several other scientific areas. The determination of three-dimensional structures of substances, whether natural or synthetic, have been fundamental to the study and understanding of the relationships between physical, chemical, therapeutic and structure at the atomic level. This work will present some theoretical aspects of ferrocene complexes and the theory involved in determining of molecular and crystal structures by XRD, as well as resolution and characterization of two ferrocene complexes. The results were compared with similar structures found in the Cambridge Structural Database. At the compounds studied in the present work, 1,1\'-bis(diphenylphosphine)ferrocene e {(Dichloride)[bis (diphenylphosphine)-ferrocene]Palladium(II)}oCHCl3, the Fe complexes with two cyclopentadyenil rings, at star conformation, which are disposed equidistant from Fe atom, without significant distortions. Due to the elevated toxicity of cis-platine at neoplasms, many research groups have been dedicated efforts to found compatible analog drugs, which the palladium derivatives are the most researched, because of their electronic and structural properties. It has been known that the geometry around the Pt is square planar, as like as the present case, which makes the {(Dichloride)[bis (diphenylphosphine)-ferrocene] Palladium(II)}oCHCl3, possible to be study at his possibly activity. One of the great unknowns in the area of pharmacology is to know exactly which are the products of degradation of a certain drug and determining by XRD the crystal and molecular structures of both studied compounds, concluded that they are derived from the degradation of the compound [Pd2(C2, N-(dmpa) 2 (μ-dppf)Cl2], since such compounds has their structures determined from a tube containing the [Pd2(C2, N-(dmpa) 2 (μ-dppf)Cl2]. So, the present work has considerable importance in the study of this drug which can be used against cancer.

Nesta dissertação o processo de adsorção da tiossemicarbazona do formilferroceno (TFF) em eletrodos de prata e ouro, em soluções aquosas 0,1 mol.L-1 de KCl e de acetonitrila. 0,1 mol.L-1 de NaClO4, foi caracterizado através da técnica espectroscópica SERS. Verificou-se através das variações espectrais que a adsorção da TFF ocorre através dos átomos N1 do grupo imínico e do S do grupo tiocarbonílico. Os processos faradáicos do TFF foram monitorados pela técnica SERS e de absorção no UV-visível. Os espectros SERS para potencial de -1,4 V (Ag/AgCl) sugerem a formação de um novo composto, produto de redução da TFF, o aminometilferroceno. Através da técnica de absorção no UV-visível verificou-se, neste potencial, o aparecimento no espectro de absorção de uma nova banda em 240 nm, atribuída à formação de tiouréia. A identificação deste dois produtos de redução indica que, para o composto TFF, o mecanismo geral de redução dos derivados de tiossemicarbazonas é obedecido. Nenhuma variação espectral, tanto utilizando a técnica SERS como a absorção no UV-visível, foi detectada durante o processo redox FeII/FeIII (E1/2=0,55 V). Os comportamentos de adsorção e faradáico da tiossemicarbazida (TSC), em eletrodo de prata em soluções aquosas neutra e ácida, foram estudados através da técnica SERS. Verificou-se que em meios neutro e ácido, a TSC está adsorvida na configuração cis para potenciais próximos de 0,0 V, interagindo com a superfície através do átomo de S do grupo tiocarbonílico e dos átomos de H ligados ao N1 hidrazínico, através da formação de pares iônicos com os ânions Cl- adsorvidos. Para potenciais mais negativos, os íons cloreto deixam a superfície e a TSC sofre reorientação, assumindo a conformação trans. Não foi observado através da técnica SERS nenhum processo faradáico em solução ácida para potenciais negativos, como havia sido proposto na literatura. A não redução do composto foi confirmada através da técnica de eletroforese capilar. Foi estudado o comportamento Raman ressonante da TFF, verificando-se a ocorrência de um mínimo no perfil de excitação experimental devido à interferência destrutiva das transições dos grupos tiossemicarbazona e ferrocenil. Os perfis de excitação teóricos foram calculados utilizando o método da transformada e os resultados dos ajustes obtidos indicam que existe considerável distorção dos modos do grupo ferrocenil na transição eletrônica em 312 nm, atribuída a n-p* do grupo tiossemicarbazona, caracterizando uma grande interação eletrônica entre os cromóforos da TFF. Para comparar o comportamento Raman ressonante do TFF com o do ferroceno, os espectros Raman ressonante deste composto foram obtidos. Verificou-se que o ferroceno apresenta, também, o efeito Raman anti-ressonante, mas as bandas vibracionais do ferroceno apresentam perfis distintos dos apresentados no composto TFF, indicando que a incorporação do grupo tiossemicarbazona no anel ciclopentadienil modifica a estrutura eletrônica do grupo ferrocenil. / In this dissertation, the adsorption process of the formylpyridine thiosemicarbazone (TFF) at silver and gold surfaces in aqueous and in acetonitrile solutions has been characterized by using the SERS (Surface-enhanced Raman Scattering) technique. It has been verified that TFF adsorbs through N1’ and S atoms on the metallic surfaces. The faradaic processes of TFF have been monitored through the SERS and UV-visible absorption spectroscopies. The SERS spectra at -1,4 V (Ag/AgCl) suggest aminomethylferrocene as one of the reduction products of TFF. By using the UV-visible absorption technique, it has been verified, at this potential, a new band at 240 nm in the spectrum, which indicates the presence of thiourea. The observation of these two reduction products has confirmed that the general reduction mechanism for thiosemicarbazonas works for TFF. Neither SERS nor UV-vis spectral changes have been observed during the redox process of FeII/FeIII (E1/2= 0,55 V). The adsorption and faradaic processes of thisemicarbazide (TSC) at silver electrode have also been studied by SERS technique. It has been verified that, in acidic and neutral media, the TSC is adsorbed through a cis-configuration at a potential close to 0,0 V, showing an interaction of the S atom through bond formation with the surface and through the H atoms bonded to N1 via ion pair formation with the adsorbed Cl- anions. At more negative potentials, the chloride anions leave the electrode surface and the TSC changes to trans-configuration. No faradaic process has been observed as reported in the literature. This result has been confirmed by using the capillary electrophoresis technique. The resonance Raman effect of the TFF has been studied, and the excitation profiles of the bands have been shown as minimum, which indicates an electronic interaction between the two cromophores of the TFF (thiosemicarbazone and ferrocenyl). The theoretic excitation profiles have been calculated by using the transform method, and the results of the obtained adjustment has indicated that there has been a distortion of the ferrocenyl vibrational modes for an electronic transition at 312 nm, assigned to the n-p* of thiosemicarbazone moiety. This result has indicated a great interaction between the two cromophores of TFF. In order to compare the resonance Raman behavior of the TFF with that of the ferrocene, the resonance Raman spectra of the ferrocene have been obtained. It has been verified that the two compounds present an anti-resonant Raman effect, even though the bands have presented very different excitation profiles from those observed in the TFF, which indicates that the incorporation of the thiosemicarbazone group into the ciclopentadienyl has changed the electronic structure of the ferrocenyl group.