A novel target-promoted DNA alkylation system was designed, which consists of a DNA intercalating/alkylating quinone methide (QM) precursor, a removable amine linker, and a sequence-specific delivery. The QM in this system was regenerated by eliminating the amino linker promoted by the hydrophobic interaction between the target DNA and the intercalating QM precursor. Three alkylation model systems (methoxyl polycyclic system, intramolecular hydrogen bonding system and biaryl system) were proposed and synthesized. The potential DNA QM alkylation was investigated by deoxyadenosine (dA) and deoxyguanosine (dG) alkylation with the biaryl system. Only one deoxynucleoside adduct was observed when dA or dG reacted with quinoline or naphthalene QM precursor, in which both dA adducts degraded with time, while dG adducts remained unchanged after 72h at room temperature. The quinoline dG adduct was fully characterized as quinoline dG N1 adduct by NMR techniques. Naphthalene dG was found as a 1:1 mixture of diastereomers.

Efetuaram-se as reações de nucleófilos de oxigênio (MeONa, EtONa, PhONa e t-BuOK) com o aduto de Diels-Alder cloranil-ciclopentadieno, com o objetivo de se obterem os correspondentes adutos poli-substituídos. Nas reações com MeONa e EtONa foram empregadas tanto quantidades estequiométricas como excesso destes alcóxidos. Nestes últimos casos, foram obtidos dois produtos. Um destes, quando se empregou MeONa, apresentou a mesma estrutura que o aduto cis,endo-2,5-dicloro- 3,6-dimetóxi-p-benzoquinona-ciclopentadieno. O outro produto (B), isolado na forma de óleo, apresentou dados de RMN e de composição que indicaram tratar-se do aduto trans-2,5-dicloro-3,6-dimetóxi-p-benzoquinona-ciclopentadieno ou trans-2,6- dicloro-3,5-dimetóxi-p-benzoquinona-ciclopentadieno, com os grupos OMe e Cl em posições endo e exo, respectivamente. Experiências conduzidas com EtONa levaram a produtos semelhantes. As tentativas de substituir o átomo de cloro ligado ao sistema enodiônico de B foram bem sucedidas quando se empregaram PhSNa ou MeSNa, mas falharam quando se usou o PhSO2Na. Estes produtos de substituição, B-SPh e B-SMe, foram isolados como sólidos amorfos, o que não permitiu que tivessem as suas estruturas determinadas por difração de raios-X. Outros experimentos com o aduto de Diels-Alder cloranil-ciclopentadieno envolveram o uso de PhONa, PhSO2Na e dimetilamina como nucleófilos. Enquanto no caso de PhONa e dimetilamina obtiveram-se os adutos mono-substituídos correspondentes, no caso de PhSO2Na, em metanol, obteve-se a substituição dos dois átomos de cloro do aduto de Diels-Alder cloranil-ciclopentadieno pelos grupos OMe e PhSO2. / The reactions between the chloranil-cyclopentadiene Diels-Alder adduct and alkoxides (MeONa, EtONa, PhONa e t-BuOK) were carried out aiming the synthesis of the corresponding poly-substituted adducts. In the case of reactions with MeONa and EtONa, equimolar and excess of such nucleophiles were employed. When MeONa was in excess, two products were obtained. One of them was proved to be the cis,endo-2,5-dichloro-3,6-dimethoxy-p-benzoquinone-cyclopentadiene adduct. The other product (B), isolated as an oil, exhibited elemental composition and NMR data that indicate its structural identity with the trans-2,5-dichloro-3,6-dimethoxy-p-benzoquinone-cyclopentadiene or the trans-2,6-dichloro-3,5-dimethoxy-p- benzoquinone-cyclopentadiene adduct, lying the OMe and Cl groups in an endo and exo positions, respectively. The experiments conducted with EtONa lead to the similar products. Aiming the substitution of the chlorine atom that remains attached to the enedionic system of B, this latter compound was successfully reacted with PhSNa and MeSNa, but was unable to react with PhSO2Na.. The corresponding B-SPh and and B-SMe derivatives were isolated as amorphous solids thus precluding their use for their structural determination by X-ray crystallography. Other reactions with chloranil-cyclopentadiene Diels-Alder adduct included the use of PhONa, PhSO2Na and dimethylamine as nucleophiles. In the case of PhONa and However, the reaction of chloranil-cyclopentadiene Diels-Alder adduct and PhSO2Na, in methanol, lead to the substitution of both enodionic chlorine atoms by the OMe and PhSO2 groups.

No description available.

A series of binuclear coordination complexes of 4-(2′-pyrimidal)-1,2,3,5-dithiadiazolyl and its selenium analogue have been prepared to examine their structural and magnetic properties. The zinc(II) coordination complex is the first example of a DTDA radical ligand N-coordinated to a diamagnetic metal center. The magnetic properties reveal that it exhibits Curie behaviour and can be used as a benchmark to compare the analogous coordination complexes which possess paramagnetic metal ions. The nickel(II) coordination complex of the selenium containing radical pymDSDA was shown to dimerize in the solid state and is the only binuclear complex thus far that has done so. The manganese(II) complex of pymDSDA is by far the most interesting and is isomorphous to the DTDA analogue. For both complexes, one of the two molecules in the asymmetric unit form chains in the solid state joined by intermolecular contacts between a sulfur or selenium atom from the radical, and an oxygen atom coordinated to a neighbouring molecule. This feature gives rise to a ground state spin greater than that of an individual binuclear coordination complex. The radical ligand is however disordered in the solid state and so these random chain lengths are dependent on the orientation of the ligands in adjacent complexes. The 1,2,3-DTA species examined herein are related to the 4,5-dioxo-4,5-dihydronaphtho[1,2-d][1,2,3]dithiazolyl radical and the related protonated species 4-hydroxy-5H-naphtho[1,2-d][1,2,3]dithiazol-5-one. The proton from this latter compound has shown that it can be substituted with alkyl groups and this was achieved using acetyl chloride to place an acetyl group in this position. The above radical did not exhibit the strong donor properties required for metal coordination and preliminary investigations of the radical dianionic suggest that it is chemically irreversible by cyclic voltametry. The acetyl group unfortunately did not provide the chemically reversibility of interest although has established a potential route toward the substitution chemistry of this compound. The other 1,2,3-DTA compounds discussed herein are not complete, although the data acquired on the precursor compounds leading up to the radical will be discussed.

This Thesis aims to examine the effects of substituents on the adjacent proton accepting phenyl ring with respect to a new type of excited state intramolecular proton transfer (ESIPT) process discovered by Wan and co-workers. Therefore, a number of 2-phenylphenols 23-28 were synthesized with electron-donor and electron-acceptor substituents such as methyl, methoxy, and ketone moieties on the adjacent proton accepting phenyl ring. The results obtained from examination of photochemical deuterium exchange showed that all derivatives except for ketone 27 underwent deuterium exchange (Фex = 0.019 - 0.079), primarily at the 2’-position on photolysis in D2O-CH3CN. In general, compounds with methoxy moiety (ies) on the adjacent proton accepting ring showed higher deuterium exchange yields. Diol 28 has the potential to undergo photosolvolysis as well as ESIPT process since it has both a benzyl alcohol and a phenol chromophore on the same molecule. Irradiation of 28 in 1:1 H2O-CH3OH gave the corresponding methyl ether product in high yield. Photolysis of 28 in 1:1 D2O-CH3OH also showed that ESIPT competes very well with photosolvolysis. Thus, this work has established that ESIPT can compete efficiently with photosolvolysis. Semi-empirical AM1 (examination of HOMOs and LUMOs) calculations show a large degree of charge transfer in the electronic excited state (except 27), from the phenol ring to the attached phenyl ring of the studied compounds. The AM1 calculation for ketone 27 showed that the carbonyl oxygen is more basic than the carbon atoms of the benzene ring, which explains the lack of deuterium exchange observed for 27.

Efetuaram-se as reações de nucleófilos de oxigênio (MeONa, EtONa, PhONa e t-BuOK) com o aduto de Diels-Alder cloranil-ciclopentadieno, com o objetivo de se obterem os correspondentes adutos poli-substituídos. Nas reações com MeONa e EtONa foram empregadas tanto quantidades estequiométricas como excesso destes alcóxidos. Nestes últimos casos, foram obtidos dois produtos. Um destes, quando se empregou MeONa, apresentou a mesma estrutura que o aduto cis,endo-2,5-dicloro- 3,6-dimetóxi-p-benzoquinona-ciclopentadieno. O outro produto (B), isolado na forma de óleo, apresentou dados de RMN e de composição que indicaram tratar-se do aduto trans-2,5-dicloro-3,6-dimetóxi-p-benzoquinona-ciclopentadieno ou trans-2,6- dicloro-3,5-dimetóxi-p-benzoquinona-ciclopentadieno, com os grupos OMe e Cl em posições endo e exo, respectivamente. Experiências conduzidas com EtONa levaram a produtos semelhantes. As tentativas de substituir o átomo de cloro ligado ao sistema enodiônico de B foram bem sucedidas quando se empregaram PhSNa ou MeSNa, mas falharam quando se usou o PhSO2Na. Estes produtos de substituição, B-SPh e B-SMe, foram isolados como sólidos amorfos, o que não permitiu que tivessem as suas estruturas determinadas por difração de raios-X. Outros experimentos com o aduto de Diels-Alder cloranil-ciclopentadieno envolveram o uso de PhONa, PhSO2Na e dimetilamina como nucleófilos. Enquanto no caso de PhONa e dimetilamina obtiveram-se os adutos mono-substituídos correspondentes, no caso de PhSO2Na, em metanol, obteve-se a substituição dos dois átomos de cloro do aduto de Diels-Alder cloranil-ciclopentadieno pelos grupos OMe e PhSO2. / The reactions between the chloranil-cyclopentadiene Diels-Alder adduct and alkoxides (MeONa, EtONa, PhONa e t-BuOK) were carried out aiming the synthesis of the corresponding poly-substituted adducts. In the case of reactions with MeONa and EtONa, equimolar and excess of such nucleophiles were employed. When MeONa was in excess, two products were obtained. One of them was proved to be the cis,endo-2,5-dichloro-3,6-dimethoxy-p-benzoquinone-cyclopentadiene adduct. The other product (B), isolated as an oil, exhibited elemental composition and NMR data that indicate its structural identity with the trans-2,5-dichloro-3,6-dimethoxy-p-benzoquinone-cyclopentadiene or the trans-2,6-dichloro-3,5-dimethoxy-p- benzoquinone-cyclopentadiene adduct, lying the OMe and Cl groups in an endo and exo positions, respectively. The experiments conducted with EtONa lead to the similar products. Aiming the substitution of the chlorine atom that remains attached to the enedionic system of B, this latter compound was successfully reacted with PhSNa and MeSNa, but was unable to react with PhSO2Na.. The corresponding B-SPh and and B-SMe derivatives were isolated as amorphous solids thus precluding their use for their structural determination by X-ray crystallography. Other reactions with chloranil-cyclopentadiene Diels-Alder adduct included the use of PhONa, PhSO2Na and dimethylamine as nucleophiles. In the case of PhONa and However, the reaction of chloranil-cyclopentadiene Diels-Alder adduct and PhSO2Na, in methanol, lead to the substitution of both enodionic chlorine atoms by the OMe and PhSO2 groups.

The content of this work, divided into four chapters, is facing a crystallochemical study of a derivative of lapachol and one derivatives N-Sulfonamida, here called 3-Iodo-β-lapachone (3198), LASSBio 959. In chapter 1 is made a brief comment on the drug market, as well as a summary involving Chagas disease, asthma and the importance of the studied compounds. The study was conducted in order to characterize one quinone and N-sulfonamide (molecular conformation and crystallochemical packaging), possible drug candidates for diseases mentioned derivative. The theoretical foundation, without which the work could not be done, much less understood is contained in Chapter 2. The method used in this work is based on the X-ray diffraction by monocrystalline sample and condensed in Chapter 3. The goal of Chapter 4 is focused the results and interpretation. These results are summarized below. The compound 3198 called crystallizes in monoclinic system, P21/c, with parameters a = 12.2739(3)Å, b = 8.1762(2)Å and c = 14.3995(3)Å; β = 107.2260(1)º, Z = 4 molecules / cell. The final disagreement factor R was 0.0393 for the reflexions considered observed and 0.0668 for all the reflexions. The LASSBio 959 crystallizes in the monoclinic system P21 / c, with parameters a = 9,3208(2) Å, b = 28.3330(2)Å and c = 7.5188(1)Å; β=107.412(1), Z = 4 molecules / cell. The final disagreement factor R was 0,0505 for the reflexions considered observed and 0,0778 for all the reflexions. The analysis of experimental data showed good agreement with published data for compounds similar to those studied here. They were also important to validate structural models obtained by other methods performed by laboratories (NPPN and LASSBio) for the target compounds of this dissertation. / Conselho Nacional de Desenvolvimento Científico e Tecnológico / O conteúdo deste trabalho, dividido em quatro capítulos, está voltado para um estudo cristaloquímico de um derivado do lapachol e um derivados NSulfonamida, aqui denominados de 3-Iodo-β-lapachona (3198) e LASSBio 959. No capítulo 1 é feito um breve comentário sobre o mercado de fármacos, bem como um resumo envolvendo a doença de Chagas, a asma e a importância dos compostos estudados. O trabalho foi realizado visando caracterizar cristaloquimicamente um derivado quinonico e N-sulfonamida (conformação molecular e empacotamento cristaloquímico), possíveis candidatos a fármacos para doenças mencionadas. A fundamentação teórica está contida no capítulo 2. O método utilizado neste trabalho esta fundamentado na difração de raios X por amostra monocristalino e condensado no capítulo 3. O foco do capítulo 4 está centrado nos resultados obtidos e na interpretação dos mesmos. Estes resultados são sumarizados a seguir. O composto denominado 3198 cristaliza no sistema monoclínico, P21/c, com parâmetros a = 12,2739(3)Ǻ, b = 8,1762(2)Ǻ e c = 14,3995(3) Ǻ; β=107,2260(1)o, Z = 4 moléculas/cela. O R final obtido considerando-se todas as reflexões foi de 0,0668 e de 0,0393 considerando-se apenas as reflexões observadas. A LASSBio 959 cristaliza no sistema monoclínico P21/c, com parâmetros a = 9,3208(2)Ǻ, b = 28,3330(2)Ǻ e c = 7,5188(1)Ǻ; β=107,412(1)o, Z = 4 moléculas/cela. O R final obtido considerando-se todas as reflexões foi de 0,0778 e de 0,0505 considerando-se apenas as reflexões observadas. A analise dos dados experimentais revelou boa concordância com dados publicados na literatura para compostos semelhantes aos aqui estudados. Eles também foram importantes para validar os modelos estruturais obtidos por outros métodos realizados pelos laboratórios (NPPN e LASSBio) para os compostos alvo dessa dissertação.

When a material is adhered onto a specific surface it is relevant to know how to make thematerial stay on the surface. By investigating different primers to use with a triazine-basedadhesive, further improvements to using the adhesive on metals can be achieved. This studyfound that an adhesive of (2,4,6-trioxo-1,3,5-triazinane-1,3,5-triyl)tris(ethane-2,1-diyl)tris(3-mercaptopropanoate) (TEMPIC) and 1,3,5-triallyl-1,3,5-triazinane-2,4,6-trione(TATATO) adhered to titanium and stainless steel, two clinically used metal surfaces. Itfurther found that between a phosphonic acid primer, a biomimetic catechol primer and acommercially available silane primer the phosphonic acid primer gave the best adhesion.These results could be because of a higher amount of crosslinking for the phosphonic acidprimer. For further testing increased pH and increased amount as well as increasedhydrolysation time for the catechol and silane primers respectively is suggested. Shearstrength testing was used to determine the adhesion strength. The shear strength testswere done with conditioning in phosphate buffer saline (PBS) solution for 24h beforehand

Metal-Organic Frameworks (MOFs) are porous materials consisting of organic ligands connected by inorganic nodes. Their structural uniformity, high surface area, and synthetic tunability, position these frameworks as suitable active materials to achieve efficient and clean electrochemical energy storage. In spite of recent demonstrations of MOFs undergoing diverse electrochemical processes, a fundamental understanding of the mechanism of electron, proton, and ion transport in these porous structures is needed for their application in electronic devices. The current work focuses on contributing to such understanding by investigating proton-coupled electron transfer, capacitance performance, and the relative contribution of electron and ionic transport in the voltammetry of zirconium-based MOFs. First, we investigated the effects that the quinone ligand orientation inside two new UiO-type metal-organic frameworks (2,6-Zr-AQ-MOF and 1,4-Zr-AQ-MOF) have on the ability of the MOFs to achieve proton and electron conduction. The number of electrons and protons transferred by the frameworks was tailored in a Nernstian manner by the pH of the media, revealing different electrochemical processes separated by distinct pKa values. In particular, the position of the quinone moiety with respect to the zirconium node, the effect of hydrogen bonding, and the amount of defects in the MOFs, lead to different PCET processes. The ability of the MOFs to transport discrete numbers of protons and electrons, suggested their application as charge carriers in electronic devices. With that purpose in mind, we assembled 2,6-Zr-AQ-MOF and 1,4-Zr-AQ-MOF into two different types of working electrodes: a slurry-modified glassy carbon electrode, and as solvothermally-grown MOF thin films. The specific capacitance and the percentage of quinone accessed in the two frameworks were calculated for the two types of electrodes using cyclic voltammetry in aqueous buffered media as a function of pH. Both frameworks showed an enhanced capacitance and quinone accessibility in the thin films as compared to the powder-based electrodes, while revealing that the structural differences between 2,6-Zr-AQ-MOF and 1,4-Zr-AQ-MOF in terms of defectivity and the number of electrons and protons transferred were directly influencing the percentage of active quinones and the ability of the materials to store charge. Additionally, we investigated in detail the redox-hopping electron transport mechanism previously proposed for MOFs, by utilizing the chronoamperometric response (I vs. t) of three metallocene-doped metal-organic frameworks (MOFs) thin films (M-NU-1000, M= Fe, Ru, Os) in two different electrolytes (TBAPF6 and TBATFAB). We were able to elucidate, for the first time, the diffusion coefficients of electrons and ions (De and Di, respectively) through the structure in response to an oxidizing applied bias. The application of a theoretical model for solid state-voltammetry to the experimental data revealed that the diffusion of ions is the rate-determining step at the three different time stages of the electrochemical transformation. Remarkably, the trends observed in the diffusion coefficients (De and Di) of these systems obtained in PF61- and TFAB1- based electrolytes at the different stages of the electrochemical reaction, demonstrated that the redox hopping rates inside frameworks can be controlled through the modifications of the self-exchange rates of redox centers, the use of large MOF channels, and the utilization of smaller counter anions. These structure-function relationships provide a foundation for the future design, control, and optimization of electronic and ionic transport properties in MOF thin films. / PHD

The main aim of the work reported is the design of proof-of-concept of at point-of-use hydrogen peroxide electrogeneration from air. The experimental work discussed within this thesis explores five major areas: the kinetics of electrocatalysis, ion-pairing, change of solvent media, the electrode surface modication by a redox mediator, and the electrochemical reduction of oxygen within enhanced mass transport systems. The electrocatalytic rates and mass transport of two oxygen reduction redox meditors, viz. anthraquinone and methyl viologen, are studied in aqueous solutions. The investigation is facilitated through the use of a boron-doped diamond electrode, allowing the catalytic response to be clearly delineated from that of the direct oxygen reduction process. The use of simulation software is highlighted in combination with experimental voltammograms to extract kinetic data. Specifically, the voltammetric features, such as the `reverse' peak and the `split waves', are given particular attention. Consequently, it is possible to deconvolute the electrocatalytic reaction mechanisms. The reactivity of the viologen radical cation is comparable to the semiquinone radical anion in aqueous solution ((4.8~6)x10^9 M^-1 s^-1), but over a far wider pH range (pH 2.5 - pH 8.5). The change of local proton concentration, and sequential electron transfers play key roles here. Moreover, the reduced reactivity of semiquinone is observed upon formation of ion-pairs with tetrabutylammonium cations in alkaline solutions. The electro-reduction of oxygen and its mediated pathways are also investigated in non-aqueous media; in particular the thermodynamics, the kinetics, and mass transport involved in these processes. Through a variable temperature study in electrolytic acetonitrile solution, the oxygen dissolution is quantitatively shown to be an endothermic process. Moreover, the diffusion coeficients and concentration of oxygen upon change of acetonitrile mole fraction is also explored in water-acetonitrile mixtures. The rates of bimolecular reactions are extracted from simulation programs, involving semiquinone in anhydrous acetonitrile and viologen radical cation in ethanol, and show a 3 - 4 orders of magnitude reduction compared to that in aqueous solution. Although the solubility of oxygen is ca. 6 - 8 times larger in non-aqueous solvents, the much reduced homogeneous rates limit the electrogeneration of hydrogen peroxide in pure organic media. Novel surface modification methodologies for graphitic surfaces with covalently attached anthraquinonyl groups are studied and characterised. The anthraquinonyl-modified carbon surfaces show much reduced overpotentials required for oxygen reduction. In the final chapter, utilising the new surface modification methodology and novel designs, two gravity-feed flow cells for electrochemical reduction of oxygen in aqueous solutions are proposed and characterised, one based upon the tubular electrode geometry. The other exhibits much enhanced current conversion by using a porous reticulated vitreous carbon electrode. The latter may provide a prototype hydrodynamic system to produce dilute hydrogen peroxide solution at point-of-use.