The concept of a self-incompatible solvent is introduced as a molecule composed of two parts (compound 1 and 2) with unfavourable interactions. A third compound will be readily dissolved in this solvent to diminish this unfavourable interaction by dilution. The more incompatible compounds 1 and 2 are, the stronger this behaviour is expected to be. In this work, ionic liquids comprising non-polar carbon chain and polar ionic group are chosen to serve as a model of self-incompatible solvent. The interactions parameters k of the ionic liquids with active ingredients are investigated to examine the effect of self-incompatibility of the ionic liquid molecule. On the other hand, phase separation between compounds 1 and 2 will reduce the positive effect of self-incompatibility. The tendency of phase separation is increasing with increasing size of the two compounds. Thus, if compounds 1 and 2 are blocks tied together into a block copolymer, one expects a decreasing ability of the block copolymer to dissolve an active ingredient with increasing block length. In this work the ability of polybutadiene-block-poly(2-vinylpyridine) (PB-b-P2VP) block copolymers to dissolve the model compound anthracene is investigated. As expected, the solubility indeed decreases with increasing block length.

Photo sensitizers showing visible light induced DNA cleavage activity are of current importance for medicinal applications related to photodynamic therapy (PTD) considering greater skin penetration of light near 700 nm. While organic molecules and complexes of 4d-5d metal ions are extensively studied for their DNA photo-damage properties in UV and visible light, the chemistry of 3D metal complexes showing visible light-induced DNA cleavage activity is relatively unexplored efforts have been made in this thesis work to design new ternary copper (II) complexes having a-amino acids Such copper (II) complexes with tunable coordination geometry could find potential applications in PDT. Ternary Copper (II) complexes containing L-methionine, S-methy1-L-cysteine and phenanthroline bases are prepared and characterized. They display DNA binding and visible light induced DNA cleavage activity. An enhancement of the DNA cleavage activity is observed for analogous ternary copper (II) complexes contained L-lysine with a pendant cationic amine moiety as a photo-induced DNA Cleavage activity using binary and ternary copper (II) complexes of L-arginine and phenanthroline bases. We have observed AT selective DNA binding and visible light –induced DNA cleavage activity. The crescent-shaped bis-arginine Copper (II) complex mimics the natural antiviral antibiotic netropsin. T o investigate the role of the pendant groups of the amino acids, we have explored the DNA binding and DNA cleavage activity of analogues L-glutamine and L-asparagine complexes. We have prepared ternary copper (II) complexes containing two photosensitizers, viz., L-tryptophan (L-trp) and dipyridoquininoxaline/dipyridophenazine to achieve double strand breaks forming linear DNA. Complex [Cu(L-trp)(dppz)(H2O)+ shows a stacking arrangement of the indole and dppz rings giving a separation that fits with the base pair separation of ds-DNA. Photosensitizes in these complexes approach two different complementary stands of the ds-DNA, leading to double strand breaks and formation of linear DNA. Mechanistic studies on the DNA photocleavage reactions reveal the formation of singlet oxygen(1O2)species by a type-II pathway in preference to the hydroxyl radical generation. A process leading to an efficient DNA cleavage activity on visible light irradiation. The observation of sequence selectivity and double strand DNA cleavage on red light exposure by national design of the complexes is significant considering importance of the results in the chemistry of photodynamic therapy of cancer. The results of this dissertation open up new avenues for designing and developing 3d metal-based photosensitizers with potential utility in nulcleic acid chemistry.

Emerging energy storage applications are driving the demand for Li-ion battery positive electrode materials with higher energy densities and lower costs. The recent production of complete pseudo-ternary phase diagrams of the Li-Mn-Ni-O system generated using combinatorial methods has provided a greater understanding of the impact of initial composition, synthesis temperature, and cooling rate on the phases that form in the final materials. This thesis focuses on the synthesis and characterization of gram-scale positive electrode materials in the Li-Mn-Ni-O system. Structural analysis of these samples has resulted in the production of partial pseudo-ternary phase diagrams focusing on the positive electrode materials region of the Li-Mn-Ni-O system at 800°C and 900°C in air for both quenched and slow cooled compositions. These bulk-scale diagrams support the observations of the combinatorial diagrams, and show similar layered and cubic structures contained within several single- and multi-phase regions. The phases that form at each composition are shown to be dependent on both the reaction temperature and cooling rate used during synthesis. The electrochemical characterization of two composition series near Li2MnO3, one quenched and one slow cooled, is presented. The quenched compositions exhibited reversible cycling at 4.4 V, voltage plateaus and small increases in capacity above 4.6 V, and large first cycle irreversible capacity losses at 4.8 V. In the slow cooled series, all but one composition exhibited initial capacities below 100 mAh/g which began to continually increase with cycling, with several compositions exhibiting capacity increases of 300% over 150 cycles at 4.9 V. In both series, analysis of the voltage and differential capacity plots indicated that significant structure rearrangements are taking place in these materials during extended cycling, the possible origins of which are discussed. Finally, high precision coulometry studies of one Li-deficient and two Li-rich single-phase layered compositions are discussed. These materials exhibit minimal oxidation of simple carbonate-based electrolyte when cycled to high potential, with the Li-deficient composition producing less electrolyte oxidation at 4.6 V vs. Li/Li+ than commercial Li[Ni1/3Mn1/3Co1/3]O2 at 4.2 V. The inherent inertness of this composition may make it suitable for use as a thin protective layer in a core-shell particle.

Το Η2 είναι το ελαφρύτερο και πλέον άφθονο στοιχείο στη φύση. Βρίσκεται παντού στη γη, στο νερό, στα ορυκτά καύσιμα και σε όλα τα έμβια όντα. Αν το Η2 αξιοποιηθεί κατάλληλα και χρησιμοποιηθεί για τροφοδοσία των κελιών καυσίμου, θα ελαχιστοποιηθεί η εξάρτηση του σύγχρονου πολιτισμού από τα ορυκτά καύσιμα, με συνεπακόλουθο τη μείωση των εκπομπών βλαβερών αερίων στην ατμόσφαιρα. Η χαμηλή θερμοκρασία λειτουργίας των κελιών καυσίμου πολυμερούς ηλεκτρολύτη (PEMFCs) προσφέρει πολλά πλεονεκτήματα και σε συνδυασμό με την υψηλή πυκνότητα ισχύος που αποδίδουν, τα καθιστά κύριους υποψήφιους για εφαρμογή στην αυτοκίνηση. Ωστόσο, η χαμηλή θερμοκρασία εγείρει και σημαντικά προβλήματα, όπως η χρήση ευγενών μετάλλων για την επιτάχυνση των αντιδράσεων και η ευαισθησία σε φαινόμενα δηλητηρίασης. Το κυριότερο δηλητήριο είναι το CO, βασικό παραπροϊόν των διεργασιών παραγωγής H2 από τους υδρογονάνθρακες, οι οποίοι προς το παρόν αποτελούν την κύρια πηγή του. Στην παρούσα διδακτορική διατριβή εξετάστηκαν τα φαινόμενα δηλητηρίασης από το CO της ανόδου του PEMFC. Καθώς το CO δεσμεύεται ισχυρότερα στην επιφάνεια του Pt από το καύσιμο Η2, η παρουσία του στην τροφοδοσία ακόμα και σε ίχνη απενεργοποιεί δραματικά τη λειτουργία της ανόδου. Έτσι, μελετήθηκαν διμεταλλικά και τριμεταλλικά καταλυτικά συστήματα, βασισμένα στο Pt, για την πιθανή αντιμετώπιση του προβλήματος, διαμέσου εξασθένισης του δεσμού Pt-CO ή ενίσχυσης της ηλεκτροχημικής οξείδωσής του από το Η2Ο, που είναι άφθονο στο περιβάλλον ενός PEMFC. Στο κεφάλαιο 1 περιγράφονται οι βιβλιογραφικές πληροφορίες για την τεχνολογία του Η2, όπως μέθοδοι παραγωγής του, καθαρισμού του και αποθήκευσης/μεταφοράς του. Στο κεφάλαιο 2 αναφέρονται οι βασικές αρχές λειτουργίας των κελιών καυσίμου, όσον αφορά στη θερμοδυναμική και στην κινητική, στα είδη τους και στις πιθανές εφαρμογές τους. Στο κεφάλαιο 3 γίνεται εκτενής περιγραφή των δομικών στοιχείων που απαρτίζουν ένα PEMFC, και βιβλιογραφική ανασκόπηση των καταλυτικών συστημάτων που έχουν μελετηθεί για τις βασικές αντιδράσεις. Στο κεφάλαιο 4 περιγράφονται συνοπτικά οι μέθοδοι χαρακτηρισμού και ανάλυσης καθώς και οι πειραματικές διατάξεις που χρησιμοποιήθηκαν. Στο κεφάλαιο 5 εξετάστηκε η επίδραση του υποστρώματος TiO2 στα χαρακτηριστικά του Pt, όσον αφορά την αλληλεπίδρασή του με το CO, σε διάταξη μονής κυψέλης καυσίμου. Παρουσιάστηκε αυξημένη ενεργότητα για την ηλεκτροοοξείδωση του CO και ασθενέστερη αλληλεπίδρασή του με την επιφάνεια του Pt, συντελώντας σε ενεργοποιημένη ρόφηση. Στο κεφάλαιο 6 με φασματοσκοπία υπερύθρου μελετήθηκαν τα χαρακτηριστικά της ρόφησης/εκρόφησης του CO σε μια σειρά καταλυτών Pt-Mo σε υπόστρωμα TiO2. Παρουσία των οξειδίων του Mo η θερμοκρασία εκρόφησης του CO ήταν σημαντικά μειωμένη σε σχέση με μονομεταλλικό Pt, υποδεικνύοντας ασθενέστερο δεσμό του CO με την καταλυτική επιφάνεια. Ωστόσο, παρουσία H2 ο δεσμός ισχυροποιείται, με αποτέλεσμα η εκρόφηση να πραγματοποιείται σε υψηλότερη θερμοκρασία. Αυτό εξηγήθηκε με βάση την ανταγωνιστική αντίδραση του H2 με τις οξειδικές ομάδες, τόσο του υποστρώματος TiO2, όσο και των οξειδίων του Mo. Στο κεφάλαιο 7 εξετάστηκε η οξείδωση του CO σε καταλύτη Pt4Mo/C, δεδομένου του αποσταθεροποιητικού ρόλου του Mo στα χαρακτηριστικά της αλληλεπίδρασης με το CO. Έτσι, αναγνωρίστηκε η ικανότητα των οξειδίων του Mo να διασπούν το Η2Ο σε δυναμικά που συμπίπτουν με τη λειτουργία της ανόδου ενός PEMFC, ενώ παρουσίασαν ενεργότητα για την οξείδωση του CO σε συνθήκες ανοιχτού κυκλώματος διαμέσου της αντίδρασης μετατόπισης με ατμό σε χαμηλή θερμοκρασία μέχρι και 60οC. Ωστόσο, η παραπάνω ιδιότητες δεν ήταν κατανεμημένες ομοιόμορφα στην καταλυτική επιφάνεια, παρά μόνο στη διεπιφάνεια Pt/MoOx, ενώ οι θέσεις μονομεταλλικού Pt παρουσίασαν έντονα φαινόμενα δηλητηρίασης. Επιπλέον, το Mo παρουσιάστηκε ευαίσθητο σε φαινόμενα διάλυσης στο όξινο υδατικό περιβάλλον του PEMFC για δυναμικά μεγαλύτερα από 0.2 V. Στο κεφάλαιο 8 μελετήθηκε η αλληλεπίδραση του CO με τριμεταλλικό καταλύτη Pt-Ru-Co σε σύγκριση με εμπορικό PtRu/C. Ο τριμεταλλικός καταλύτης παρουσιάστηκε ενεργότερος, με χαμηλότερη φαινόμενη ενέργεια ενεργοποίησης για την οξείδωση ροφημένου CO, εμφανίζοντας ισχυρότερη εξάρτηση από το εφαρμοζόμενο δυναμικό. / Hydrogen is the lighter and more abundant element in nature. It is everywhere in earth, water, fossil fuels and in all the living creatures. If H2 can be properly extracted and utilized as a fuel in fuel cells, the dependence of the global economy on fossil fuels will be minimized, resulting in significant attenuation of the greenhouse gases emissions in the atmosphere. The low operation temperature of the polymer electrolyte membrane fuel cells (PEMFCs) offers a lot of advantages. In combination with the high power density yielded by the PEMFCs renders them as the main candidates for application in automotive industry. However, the low temperature raises significant problems, such as the use of noble metals for the acceleration of the basic reactions and the susceptibility in poisoning phenomena. The basic poison is carbon monoxide (CO), one of the main side-products of H2 production from fossil fuels, which for the moment is the main source of H2. In this thesis, the poisoning phenomena of the PEMFCs anode electrocatalysts from CO were investigated. Since CO is bounded on the surface of Pt stronger than the H2 fuel, its presence in the fuel feed in ppm levels deactivates the anode electrocatalyst. In order to eliminate this problem, bimetallic and ternary catalytic systems, based on Pt, were studied with the aim to reduce the Pt-CO bond strength or to promote the electrocatalytic oxidation of CO by water, which is abundant in the PEMFC environment. In chapter 1 is reported the literature information about H2 technology, such as H2 production and cleaning methods and the transport and storage infrastructure. In chapter 2, the basic thermodynamic and kinetic rules of fuel cells operation are referred together with the types of fuel cells and the possible applications. In chapter 3 the structural characteristics of the PEMFCs are outlined and the basic catalytic systems that have been studied for the fuel cell reactions are reviewed. The catalysts’ characterization methods, as well as the experimental procedures utilized in this thesis, are briefly described in chapter 4. In chapter 5 the effect of TiO2 support on the CO chemisorption’s and oxidative properties of Pt was investigated in a single PEMFC configuration. The activity of the CO electrooxidation reaction was enhanced and the Pt-CO bond was destabilized comparing to a commercial Pt/C catalyst. In chapter 6 the CO adsorption/desorption properties were studied by Infrared Spectroscopy, on a series of Pt-Mo catalysts supported on anatase TiO2. The presence of Mo oxides on the catalyst surface reduces significantly the CO desorption temperature in comparison to monometallic TiO2 supported Pt, suggesting the weak CO bonding on the catalytic surface. However, in the presence of H2, the Pt-CO bond strengthens, resulting in higher CO desorption temperature for all the catalysts tested. This was explained on the basis of competitive reaction of H2 with the oxidic surface species, originating from the TiO2 support and the surface Mo oxides. The CO electrooxidation activity of a Pt4Mo/C catalyst is described in chapter 7, considering the destabilizing effect of Mo on the Pt-CO bond. The surface Mo oxide species were able to dissociate H2O at potential values that coincide with the potential window of the PEMFC anode operation. This catalyst oxidized CO under open circuit conditions through the water gas shift reaction and at temperature as low as 60oC. However, the catalytic activity was not homogeneously distributed on the entire catalyst surface, but it was located at the Pt/MoOx interface, with the monometallic Pt sites to be strongly susceptible to CO poisoning. Furthermore, Mo was sensitive to dissolution phenomena in the hydrous acidic environment of the PEMFC for potentials higher than 0.2 V vs. rhe. Finally, in chapter 8 is described the interaction of CO with a ternary Pt-Ru-Co catalyst surface, in comparison to a commercial PtRu/C catalyst. The ternary catalyst was more active for the adsorbed CO electrooxidation, with a lower apparent activation energy than the bimetallic commercial one. The ternary catalyst exhibited zero reaction order with respect to CO partial pressure, while the PtRu/C showed negative reaction order due to competitive adsorption of CO and oxidic species for the same catalytic sites. The kinetic rate constant of the CO electrooxidation reaction for the ternary catalyst showed stronger dependence on the applied potential.

Philosophiae Doctor - PhD / Electroanalytical and optical properties of nanoscale materials are very important for biosensing applications as well as for understanding the unique one-dimensional carrier transport mechanism. One-dimensional semiconductor nanomaterials such as semiconductor quantum dots are extremely attractive for designing high-density protein arrays. Because of their high surfaceto-volume ratio, electro-catalytic activity as well as good biocompatibility and novel electron transport properties make them highly attractive materials for ultra-sensitive detection of biological macromolecules via bio-electronic or bio-optic devices. A genosensor or gene based biosensor is an analytical device that employs immobilized deoxyribonucleic acid (DNA) probes as the recognition element and measures specific binding processes such as the formation of deoxyribonucleic acid-deoxyribonucleic acid (DNA-DNA), deoxyribonucleic acid- ribonucleic acid (DNA-RNA) hybrids, or the interactions between proteins or ligand molecules with DNA at the sensor surface.In this thesis, I present four binary and two ternary-electrochemically and optically modulated selenide and telluride quantum dots, all synthesised at room temperature in aqueous media. Cationic gallium (Ga3+) synthesized in form of hydrated gallium perchlorate salt[Ga(ClO4)3.6H2O] from the reaction of hot perchloric acid and gallium metal was used to tailor the optical and electrochemical properties of the selenide and telluride quantum dots. The synthesized cationic gallium also allowed successful synthesis of novel water soluble and biocompatible capped gallium selenide nanocrystals and gallium telluride quantum dots. Cyclic voltammetric studies inferred that presence of gallium in a ZnSe-3MPA quantum dot lattice improved its conductivity and significantly increased the electron transfer rate in ZnTe-3MPA.Utraviolet-visible (UV-vis) studies showed that incorporation of gallium into a ZnSe-3MPA lattice resulted in a blue shift in the absorption edge of ZnSe-3MPA from 350 nm to 325 nm accompanied by decrease in particle size. An amphiphilic bifunctional molecule, 3-Mercaptopropionic acid (3-MPA) was used as a capping agent for all quantum dots. It was found that 3-MPA fully solubilised the quantum dots, made them stable, biocompatible, non agglomerated and improved their electron transfer kinetics when immobilized on gold electrodes.Retention of the capping agent on the quantum dot surface was confirmed by Fourier transform infrared spectroscopy (FTIR) which gave scissor type bending vibrations of C-H groups in the region 1365 cm-1 to 1475 cm-1, stretching vibrations of C=O at 1640 cm-1, symmetric and asymmetric vibrations of the C-H in the region 2850 cm-1 to 3000 cm-1 as well as stretching vibrations of –O-H group at 3435 cm-1. The particle size and level of non-agglomeration of the quantum dots was studied by high resolution transmission electron microscopy (HRTEM). The optical properties of the quantum dots were studied using UV-vis and fluorescence spectroscopic techniques.Quantum dot/nanocrystal modified gold electrodes were prepared by immersing thoroughly cleaned electrodes in the quantum dot/nanocrystal solution, in dark conditions for specific periods of time. The electrochemical properties of the modified electrodes were characterized by cyclic voltammetry (CV), square wave voltammetry (SWV), electrochemical impedance and spectroscopy (EIS). Six sensing platforms were then prepared using quantum dot/nanocrystal, one of which was used for detection of dopamine while the rest were used for detection of a DNA sequence related to 5-enolpyruvylshikimate-3-phosphate synthase, a common vector gene in glyphosate resistant transgenic plants.The first sensing platform, consisting of ZnSe-3MPA modified gold electrode (Au|ZnSe-3MPA) gave rise to a novel method of detecting dopamine in presence of excess uric acid and ascorbic acid. Using a potential window of 0 to 400 mV, the ZnSe-3MPA masked the potential for oxidation of uric and ascorbic acids, allowing detection of dopamine with a detection limit of 2.43 x 10-10 M (for SWV) and 5.65 x 10-10 M (for steady state amperometry), all in presence of excess uric acid (>6500 higher) and ascorbic acid (>16,000 times higher). The detection limit obtained in this sensor was much lower than the concentration of dopamine in human blood(1.31 x 10-9 M), a property that makes this sensor a potential device for detection of levels of dopamine in human blood.The other sensing platforms were prepared by bioconjugation of amine-terminated 20 base oligonucleotide probe DNA (NH2-5′-CCC ACC GGT CCT TCA TGT TC-3′) onto quantum dot modified electrodes with the aid of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). The prepared DNA electrodes were electrostatically hybridized with different sequences which included 5′-GAA CAT GAA GGA CCG GTG GG-3′ (complementary target), 5′-CATAGTTGCAGCTGCCACTG-3′ (non complementary target) and 5′-GATCATGAAGCACCGGAGGG-3′ (3-base mismatched target).The hybridization events were monitored using differential pulse voltammetry (DPV) and SWV by monitoring the guanine oxidation signal or using EIS by monitoring changes in the charge transfer resistance. The quantum dot genosensors were characterized by low detection limits (in the nanomolar range), long linear range (40 - 150 nM) and were able to discriminate among complementary, non-complementary and 3-base mismatched target sequences.

In this work, semiconductor nanocrystal alloys (NCs), ZnCdTe and MgCdTe were obtained by the bottom-up approach in aqueous synthesis assisted by conventional and microwave-assisted hydrothermal route. Different synthesis variables such as pH, capping agent (mercaptopropionic acid and glutathione), Zn/Cd ratio and time were used for ZnCdTe nanocrystal synthesis. For MgCdTe synthesis, pH was kept constant while time, Mg/Cd ratio and capping agent were evaluated. UV-Vis absorption and emission spectra (PL) showed composition dependence (Zn / Cd and Mg / Cd) which was altered depending on the synthesis parameter. These results were corroborated by transmission electron microscopy (TEM) as well as for chemical analysis by atomic absorption spectrometry. Cyclic voltammetry was used as a complementary technique to optical characterizations in the determination of semiconductor NCs band gap, obtaining approximate results. Novel nanocomposites of graphene derivatives (from citric acid and graphite) modified with NCs of MgCdTe were satisfactorily prepared by in situ hydrothermal synthesis and characterized by PL and TEM. Homemade modified carbon paste electrodes were built to evaluate the electrochemical behavior of the new composites, being used for the first time to the study of epinephrine and lidocaine eletrooxidation and their mixtures. The differential pulse voltammetry, proved to be a sensitive technique in both determination of electroactive species with detection limits that reached 9.2x10-8 mol.L-1, for epinephrine and 9.5x10-7 mol.L - 1 for lidocaine. / Neste trabalho, as ligas de nanocristais semicondutores (NCs), ZnCdTe e MgCdTe foram obtidas via abordagem Bottom-up, em síntese aquosa assistida por rota hidrotermal convencional e rota hidrotermal assistida por micro-ondas. Para a síntese de NCs de ZnCdTe foram utilizados diferentes variáveis da síntese como, pH, estabilizantes (ácido mercaptopropiônico e glutationa), proporção Zn/Cd e tempo. Os diferentes parâmetros de síntese (tempo, composição e estabilizantes como, glutationa e glutationa/citrato de sódio) também foram investigados na obtenção de um sistema inédito de NCs semicondutores de MgCdTe. Os espectros de absorção UV-Vis e emissão (PL) mostraram dependência da composição (Zn/Cd e Mg/Cd) que foi alterada dependendo do parâmetro de síntese. Esses resultados foram corroborados pela microscopia eletrônica de transmissão (TEM) e para os NCs de MgCdTe, sendo que a composição foi estudada quantitativamente pela espectrometria de absorção atômica (AAS). A voltametria cíclica foi utilizada como uma técnica complementar as caracterizações ópticas na determinação do band gap dos NCs semicondutores, obtendo resultados aproximados. Novos compósitos de derivados de grafeno (a partir de ácido cítrico e grafite) modificados com NCs de MgCdTe foram preparados satisfatoriamente por síntese hidrotermal in situ e caracterizados por PL e TEM. Para avaliar o comportamento eletroquímico dos novos compósitos foram fabricados eletrodos de pasta de carbono home-made e modificados com os compósitos, que foram usados pela primeira vez, no estudo da eletrooxidação de Epinefrina e Lidocaína e suas misturas. A voltametria de pulso diferencial (DPV), demonstrou ser uma técnica sensível na determinação de ambas as espécies eletroativas com limites de detecção que chegaram a 9,2x10-8 mol.L-1 para Epinefrina e 9,5x10-7 mol.L-1 para a Lidocaína.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Synthesis of ternary polyurethanes (PUs) from hexamethylenediisocyanate, β- cyclodextrin and β-glycerophosphate (acid and calcium salt) was studied varying synthesis parameters such as monomer proportion, heating method (reflux and microwave), and catalyst amount. Favorable conditions were provided by microwave irradiation and use of β-glycerophosphoric acid although the results suggest that it is possible to obtain ternary PUs with the calcium salt. FTIR data indicated the existence of secondary urea linkages. After characterization of ternary PUs by FTIR spectroscopy, XRD and thermal analysis, as well as evidences that the cyclodextrin cavities remained active toward inclusion of guest molecules, the possibility of inclusion of the antibiotic ciprofloxacin was evaluated. Absence of ciprofloxacin melting peak in DSC curves indicated that it is molecularly dispersed within the polymer, possibly included in the cyclodextrin. In vitro release experiments suggested additional non-inclusion interactions, showing also that the use of dialysis membranes may mask the actual release profile. / Nesta Tese foi estudada a síntese de poliuretanos ternários (PUs) à base de diisocianato de hexametileno, β-ciclodextrina e β -glicerofosfato (na forma de ácido e de sal de cálcio), sendo avaliados diferentes parâmetros de síntese, tais como proporção monômero, método de aquecimento (refluxo e microondas), bem como a quantidade de catalisador. As condições mais favoráveis foram fornecidas pela irradiação de microondas e a utilização de ácido β -glicerofosfórico, embora os resultados sugiram que é possível obter PU ternário com o sal de cálcio. Dados de FTIR indicaram a existência de ligações de uréia secundárias na estrutura dos poliuretanos. Após a caracterização dos PU’s ternários por espectroscopia de FTIR, XRD e análise térmica, obtiveram-se evidências de que as cavidades de β-ciclodextrina permaneceram ativas para a inclusão de moléculas hóspedes, usando-se fenolftaleína (FF) como sonda. Na seqüência, foi avaliada a possibilidade de inclusão do antibiótico ciprofloxacina. A ausência do pico de fusão ciprofloxacina em curvas de DSC indicou que este fármaco está molecularmente disperso dentro do polímero, com as moléculas possivelmente incluídas nas cavidades β-ciclodextrina. Experiências de liberação in vitro sugeriram interações não-inclusivas, mostrando também que a utilização de membranas de diálise pode mascarar o perfil de liberação efetiva.

Na presente tese investigou-se a adsorção induzida de um cátion metálico (cádmio(II)) na presença simultânea de dois ligantes (um pseudo-haleto e uma amina ou haleto) na interface eletrodo de mercúrio/solução aquosa, com vistas a uma melhor compreensão desse processo. Os estudos de adsorção foram precedidos por estudos de equilíbrio dos compostos de coordenação formados em solução aquosa. Medidas experimentais foram feitas por potenciometria com eletrodo de amálgama, em força iônica 1,00 M, ajustada com NaCl04. Análise dos dados por programas computacionais adequados levou à quantificação das constantes de estabilidade de 7 espécies binárias e 9 espécies mistas para o sistema Cd(II)/ SCN-/C6H12N4 e de 8 espécies binárias e 6 mistas para o sistema Cd(II)/I-/SCN-, sendo todas estas espécies mononucleares. Para possibilitar um maior grau de automação das medidas cronocoulométricas de adsorção, o eletrodo de gota pendente de mercúrio, anteriormente desenvolvido no IQ-USP, teve seu sistema mecânico aperfeiçoado e passou a ser controlado por computador. O \"software\" se incumbe de calcular e comandar o tempo de abertura da micro-válvula do eletrodo para gerar gotas com a área solicitada. Aproveitando a possibilidade de realizar aquisição (de dados de carga durante e após a formação das gotas de mercúrio, introduziu-se um novo método para corrigir a componente faradaica que interfere nos experimentos de determinação da carga absoluta do eletrodo por extrusão. Após provar o bom funcionamento do método, conseguiu-se a combinação inédita do método de extrusão de gotas com acronocoulometria num único experimento automatizado feito com a mesma gota de mercúrio. Com as informações assim geradas, torna-se possível conhecer e optar entre o potencial e a carga absoluta como parâmetro que define o estado elétrico da interface eletrodo/solução. Com esta combinação de técnicas, foi investigada a adsorção de cádmio induzida por tiocianato e hexametilenotetramina. Este sistema apresentou um interessante comportamento: a hexametilenotetramina, ao contrário do tiocianato, não induz a adsorção de ions cádmio, mas na presença desse pseudo-haleto provoca um intenso reforço na adsorção induzida que pode alcançar um fator de 50 vezes. Também foi possível realizar estimativas sobre as espécies que adsorvem preferencialmente, e da área média ocupada pelos complexos na condição de máxima adsorção. A energia livre de adsorção pode ser estimada pela isoterma de Henry, para baixas concentrações de ligantes. A adsorção de cádmio induzida por iodeto e tiocianato foi investigada de maneira preliminar. Nos estudos deste sistema ficou bem evidenciada a importância da utilização da carga como variável independente, ao invés do potencial. / The induced adsorption of a metallic cation (cadmium (II)) in the presence of two ligands, simultaneously (a pseudo-halide and an amine or halide), has been investigated at the mercury electrode/aqueous solution interface with the purpose of gaining a better understanding about such kind of process. The adsorption studies have been preceded by studies of the equilibria of the coordination compounds formed in aqueous solutions. Experimental measurements have been made by potentiometry with an amalgam electrode with 1,00 M ionic strength adjusted with NaClO4. Analysis of the data with adequated software allowed the quantification of the stability constants of 7 binary and 8 mixed species for the system Cd(II)/ SCN-/C6H12N4</sub and 8 binary and 6 mixed species for the system Cd(II)/I-/SCN-, all species being mononuclear. To provide a greater degree of automation of the chronocoulometric measurements of adsorption, the hanging drop mercury electrode, formely developed at the Chemistry Institute-USP, has had its mechanical parts perfectioned and wasput under computer control. A software was written to calculate and control the opening and closure of the micro-solenoid valve of the electrode to generate drops with the required area. A new method for the correction of the faradaic component that interferes with the absolute electrode charge during extrusion experiments was introduced and applied to charge measurements obtained making data aquisition during and shortly after the drop formation. Once proved that the method works, efforts were directed to combine the extrusion with the chronocoulometric measurements in one automated experiment dane with the same mercury drop. As a result, it is now a simple matter to make a choice between potential or charge on the electrode to define the electric state of the electrode/solution interface. With this combination of techniques, the adsorption of cadmium(II) induced by thiocyanate and hexamethylenetetramine has been investigated. An interesting behavior whas observed: the hexamethylenetetramine alone, doesn\'t induce adsorption of cadmium (II) as does the thiocyanate but provides a strong reinforcement (up to a factor of 50) of the induced adsorption when it is present simultaneously with the pseudo-halide. Some estimatives about the species that can adsorb preferentially has been made, as well as an evaluation of the mean area ocupied by the complexes at the maximum adsorption condition. The free energy of adsorption has been calculated, considering an Henry isotherm for the lowest concentration range. Preliminary studies of the induced adsorption of the Cd(II)/I-/SCN- system revealed a slight reinforcement of the adsorption, when both ligands are presente. The iodide always controls the process. The advantage of using the charge in place of potential as the independent variable is evident for this system.

O presente trabalho é composto por 4 capítulos distintos. No primeiro intitulado \"Ciclodextrinas: tecnologia para melhoria da solubilidade de fármacos pouco solúveis\" aborda-se uma revisão das ciclodextrinas e de seus derivados, como também a formação dos complexos de inclusão. No segundo capítulo, \"Obtenção e caracterização de complexos ternários de saquinavir, &#946;-ciclodextrina e polivinilpirrolidona\", foram avaliadas condições que poderiam influenciar na obtenção dos complexos, tais como: tempo de agitação na formação dos complexos, proporção equimolar de fármaco e ciclodextrina, solvente para solubilização do fármaco e porcentagem de polímero hidrossolúvel, concluindo-se que as melhores condições para obtenção dos complexos são 48 horas de agitação, razão equimolar 1:2 e 1:4, água para solubilização do fármaco e acréscimo de1% de polímero ao sistema. O terceiro capítulo, \"Influência do método de secagem na obtenção de complexos ternários de saquinavir\", teve o objetivo de obter e caracterizar complexos ternários de saquinavir, &#946;-ciclodextrina e polivinilpirrolidona pelos métodos de secagem em estufa e liofilização, bem como, comparar a influência dos métodos de obtenção na solubilidade do fármaco, chegando-se ao aumento de 44 vezes da solubilidade do fármaco quando na forma de complexo SAQ:&#946;CD:PVP de proporção equimolar 1:2 obtido por liofilização. O quarto, \"Perfil de dissolução de cápsulas e comprimidos contendo complexos ternários de saquinavir, ciclodextrina e polivinilpirrolidona\", teve o objetivo de comparar o perfil de dissolução de cápsulas de gelatina dura e comprimidos contendo sistemas ternários SAQ:&#946;CD:PVP, obtidos pelos métodos de secagem em estufa e liofilização e o produto referência (Fortovase®). Os resultados indicam que os perfis de dissolução das formas farmacêuticas contendo complexos liofilizados apresentaram melhores resultados de eficiência de dissolução e que as cápsulas liberam mais prontamente o ativo que os comprimidos. / The present study has 4 captions. The first is called \"Cyclodextrins: Technology to improve the solubility of the little soluble drugs\" show a review of the cyclodextrins and its derivates, as well the formations of inclusion complexes. At the second caption, \"Preparation and characterization of the ternary complexes of the saquinavir, &#946-cyclodextrin and polyvinylpyrrolidone\", were evaluated some conditions that could influence in an obtention of the complexes like stirring time at the formation of the complexes, equimolar ratio of the drug and cyclodextrin, solvent for the solubility of the drug and percentage of the hydrosoluble polymer concluding that the best conditions for the formation of the complexes are: 48 hours of the stirring, equimolar ratio 1:2 and 1:4, water to solubilize the drug and addition of 1% of the polymer in the system. The third caption, \"Influence of the drying method at the formation of the ternary complexes of the saquinavir\", had the aim to prepare and characterize ternary complexes of the saquinavir, &#946-cyclodextrin and polyvinylpyrrolidone by the method of drying in equipment and lyophilization, as well to compare the influence of the methods of the obtention at the solubility of the drug, reaching the increasing of 44 times the solubility of the drug when at the form of the ternary inclusion complex (SAQ:&#946;CD:PVP) at the equimolar ratio 1:2 obtained by lyophilization. The fourth and the last caption, \"Dissolution rate of the capsules and tablets of ternary complex of the saquinavir, cyclodextrin and polyvinylpyrrolidone, had the aim to compare the dissolution profile of capsules of the hard gelatine and tablets of ternary complexes SAQ:&#946;CD:PVP obtained by the method of drying in equipment and lyophilization and the reference product (Fortovase®). The results indicate that the dissolution profiles of the pharmaceutical forms of lyophilized complexes show better results of the efficience of the dissolution and that the capsules liberate more efficient the active than the tablets.

The implementation of energy storage systems in the current electrical grid will increase the grid's reliability and e ciency. Room temperature sodium batteries are seen as potential technology, especially to assist renewable energy generation sources. Currently, suggested negative electrode materials, however, are still not satisfactory for practical use in terms of fabrication costs, gravimetric /volumetric energy densities, cyclability, and irreversible capacity losses occur at the rst cycle. The literature describes various strategies that enhance the specific capacity and/or the cyclability of negative electrode materials but all involve increasing the fabrication costs due to the chosen synthesis or the complexity of the electrode's design. Furthermore, strategies, that reduce the irreversible capacity loss at first cycle, are not discussed. In this present experimental research work, presodiating bulk metallic negative electrode materials prior to cycling, prepared via a simple, cheap and easy-to-scaleup synthesis route, is introduced as a new strategy to improve the cyclability and to effectively reduce the first cycle irreversible capacity loss. Electrochemical and structural experiments were carried out to investigate sodiumtin-antimony powders. Presodiating mechanically bulk Sn-Sb negative electrode materials e ectively reduces the irreversible capacity loss at first cycle and enhances the specific capacity when compared to the non-presodiated powder, while the proper choice of electrode composite and electrolyte formulation improves the cycle life of the electrodes. The enhancement of the electrochemical properties of the presodiated NaSnSb powder, composed of the ternary phase Na5Sb3Sn and an unknown ternary phase crystallising in a hexagonal setting P6, is associated with the stabilisation of the SnSb as desodiation product. Presodiating bulk SnSb negative electrode material is a viable strategy to reduce the first cycle irreversible capacity loss, alleviating the volume changes. With an optimised system, this approach may be extended to other negative electrode materials, reducing the fabrication costs of high capacity negative electrode materials for room temperature sodium batteries. Presodiated NaSnSb negative electrode material may be combined with non-sodiated positive electrode material, such as sulphur to develop competitive room temperature sodium-sulphur batteries. / Die Implementierung von Energiespeichersystemen im bereits bestehenden Stromnetz ist eine der Lösungen, um die Zuverlässigkeit und die Effizienz des Netzes zu nutzen. Raumtemperatur Natrium-Batterien gelten als erfolgsversprechende Technologie insbesondere zur Unterstützung erneuerbarer Energieerzeugungsquellen. Jedoch sind die naheliegenden negativen Elektrodenmaterialien für eine praktische Anwendung hinsichtlich Herstellungskosten, gravimetrischer oder volumetrischer Energiedichte, Zyklenfestigkeit und irreversiblen Kapazitätsverlusten im ersten Zyklus noch nicht zufriedenstellend. Die Literatur beschreibt verschiedene Strategien, die die spezifische Kapazität und / oder die Zyklenfestigkeit von negativen Elektrodenmaterialien verbessern. Diese führen jedoch alle zu einer Erhöhung der Herstellungskosten aufgrund der gewählten Synthese oder des Designs der komplexierten Elektrode. Darüber hinaus werden Strategien zur Reduzierung des irreversiblen Kapazitätsverlusts im ersten Zyklus nicht erörtert. Diese experimentelle Forschungsarbeit präsentiert mit Natrium angereicherte metallische negative Elektrodenmaterialien vor der Wechselbeanspruchung/dem periodischen Durchlaufen, die durch einen schlichten, billigen und einfach zu skalierenden Syntheseweg hergestellt wurden, als eine neue Strategie zur Verbesserung der Zyklenfestigkeit und zur wirksamen Verringerung des irreversiblen Kapazitätsverlusts im ersten Zyklus. Elektrochemische und strukturelle Experimente wurden durchgeführt, um mit Natrium angereichertes Zinn-Antimon-Pulver zu untersuchen. Die mechanischen mit Natrium angereichertes Sn-Sb-negativen Elektrodenmaterialien verringert effektiv den irreversiblen Kapazitätsverlust im ersten Zyklus und erhöht die spezische Kapazität im Vergleich zu dem ohne Natrium angereicherte Pulver, während die richtige Wahl der Elektrodenzusammensetzung und der Elektrolytformulierung die Lebenszyklus der Elektroden verbessert. Die Verbesserung der elektrochemischen Eigenschaften des mit Natrium angereicherten NaSnSb-Pulvers, bestehend aus der ternären Phase Na5Sb3Sn und einer unbekannten ternären Phase, die in einer hexagonalen Aufbau P6 kristallisiert, ist mit der Stabilisierung des Enddesodiationsproduktes beim periodischen Zyklus verbunden, wobei das intermetallische SnSb nach Rekristallisation vorliegt. Mit Natrium angereicherte SnSb negativen Elektrodenmaterialien sind eine tragfähige Strategie zur Verringerung des irreversiblen Kapazitätsverlustes im ersten Zyklus, die Volumenänderungen abschwächen. Mit einem optimierten System kann dieser Ansatz auf andere negative Elektrodenmaterialien erweitert werden um die Herstellungskosten von negativen Elektrodenmaterialien mit hoher Kapazität für Raumtemperatur-Natrium-Batterien zu verringern. Mit Natrium angereichertes NaSnSb-negatives Elektrodenmaterial kann mit nicht mit Natrium versetztem positivem Elektrodenmaterial wie Schwefel kombiniert werden, um realisierbare Raumtemperatur Natrium-Schwefel-Batterien zu entwickeln.