Orientador: André Luiz Barboza Formiga / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-24T11:05:13Z (GMT). No. of bitstreams: 1 Santos_SabrinaGraciados_M.pdf: 7184130 bytes, checksum: a334f9344fec73d7b0af53f37a86c3f1 (MD5) Previous issue date: 2014 / Resumo: Foram sintetizados dois ligantes 5 fenildipirrometeno (2) e 5-(4-piridil)dipirrometeno (4) através da oxidação de seus respectivos intermediários (1) e (3). Um terceiro intermediário, bisdipirrometeno (5) foi sintetizado e oxidado resultando no ligante bisdipirrometeno (6) parcialmente oxidado. Essas moléculas foram caracterizadas através das técnicas de 1HRMN e MS. Realizou-se a síntese com complexo [CulL24]que foi caracterizado por FT-IR, espectroscopia no UV-Vis e MS. Comparando-se os dados de UV-Vis com os resultados de TD-DFT, um modelo de quatro orbitais moleculares de simetria "Pi" foi proposto para a interpretação dos espectros eletrônicos dos ligantes (2), (4), e (6) e do complexo, similar ao já existente para porfirinas. Também foram estudadas via modelagem molecular três supermoléculas distintas derivadas dos ligantes sintetizados, duas lineares e uma em forma de grade. As estruturas e distâncias entre os centros metálicos (entre 12,6 A e 20,2 A) foram então comparadas / Abstract: Abstract: In this work, three ligands and its intermediaries were synthesized and caracterized (5-phenildipyrromethene (2), 5-(4-pyridil)dipyrromethene (6) and bisdipyrromethene (4)), aiming a future complexation of each one of them with transition metals to form metallic complexes. The ligands (4), (6) and its intermediaries have two coordination sites in their structures, making them interesting for coordination polymers and metal organic frameworks synthesis. The intermediaries were synthesized and caracterized by hydrogen nuclear magnetic ressonance (1H NMR) and mass spectrometry (MS). The ligands (2), (4) and (6) were obtained through the oxidation of their respectives intermediaries, with (2) and (6) being known in the literature, while there are no reports of the ligand (4). The final products were caracterized also by 1H NMR and MS. With the ligand \pyreno \ caracterized, we performed the complexation of this ligand with copper, originating the complex [Cu(4-pyrdpm)2], caracterized by infrared spectroscopy (IR), UV-Vis spectroscopy and MS. All the analyses confirmed the complex. We studied the ligands, complexes and coordination polymers with Density Functional Theory / Mestrado / Quimica Inorganica / Mestra em Química

Supramolecular chemistry - chemistry of non-covalent bonds including different type of intermolecular interactions viz., ion-pairing, ion-dipole, dipole-dipole, hydrogen bonding, cation-p and Van der Waals forces. Applications based on supramolecular concepts for developing catalysts, molecular wires, rectifiers, photochemical sensors have been evolved during recent years. Mimicking natural photosynthesis to build energy harvesting devices has become important for generating energy and solar fuels that could be stored for future use. In this dissertation, supramolecular chemistry is being explored for creating light energy harvesting devices. Photosensitization of semiconductor metal oxide nanoparticles, such as titanium dioxide (TiO2) and tin oxide (SnO2,), via host-guest binding approach has been explored. In the first part, self-assembly of different porphyrin macrocyclic compounds on TiO2 layer using axial coordination approach is explored. Supramolecular dye sensitized solar cells built based on this approach exhibited Incident Photon Conversion Efficiency (IPCE) of 36% for a porphyrin-ferrocene dyad. In the second part, surface modification of SnO2 with water soluble porphyrins and phthalocyanine resulted in successful self-assembly of dimers on SnO2 surface. IPCE more than 50% from 400 - 700 nm is achieved for the supramolecular self-assembled heterodimer photocells is achieved. In summary, the axial ligation and ion-pairing method used as supramolecular tools to build photocells, exhibited highest quantum efficiency of light energy conversion with panchromatic spectral coverage. The reported findings could be applied to create interacting molecular systems for next generation of efficient solar energy harvesting devices.

Gels are colloidal states of matter in which a solid matrix is dispersed in a liquid phase. Supramolecular gels are formed due to the self-assembly of small gelator molecules in a suitable solvent as a result of specific weak non-covalent interactions between the gelators. The last several decades have witnessed an upsurge in research activities in the area of supramolecular gels not only for academic interests but also for applications in material science. Gels have been investigated as potential avenues for drug delivery and oil recovery applications. Despite their huge potential, the properties of gels are discovered through trial-and-error approaches, which makes control of properties a challenging task. The control becomes extremely hard in a multicomponent gel system, which is a common model for applications in material science. The aim of this thesis is to design a pathway to gain a fundamental understanding on how multiple components in the gel contribute to new properties. This pathway is an attempt to move away from trial-and-error approaches for the development of gels and allows us to make correlations between structure, dynamics and function. The studies reported in this thesis were performed on a two-component gel system comprising a gelator and an additive. The gelator, sodium deoxycholate (NaDC), is a bile salt known for its ability to form a supramolecular gel within a certain pH range. NaDC gels are made up of aggregates distributed between the aqueous phase and the gel structure. NaDC gels are reversible and considered as promising candidates from a functional point of view. The additive, cucurbit[6]uril (CB[6]), is a macrocycle and is known to affect the mechanical properties of NaDC gels at the macroscopic level. In the first project, I studied the effect of CB[6] on the NaDC gel at the microscopic level using dynamic light scattering and fluorescence microscopy experiments. These techniques were used to determine the effect of CB[6] on the gel’s morphology, size of NaDC aggregates, thermo-reversible properties of NaDC gels and the kinetics of NaDC gel formation. My results showed that the effect of CB[6] on NaDC aggregates begins in solutions and is translated to sols and gels. Thermo-reversibility and kinetic studies showed that the effect of CB[6] on NaDC gels goes beyond changes to the gel’s structure and CB[6] was also shown to affect both the gel-sol transition temperatures and time of the gel formation. In the second project, I studied how the release of dyes of different hydrophobicities from NaDC gels was affected by the addition of CB[6]. The release of the dyes pyrene and rhodamine 6G was investigated using a static diffusion method, which was referred to as the top layer method. My results showed that CB[6] has a different effect on the release kinetics of a hydrophilic dye compared to the release of a hydrophobic dye. The observed difference in the release kinetics was attributed to differences in the localization of the dyes in NaDC gels and the role of CB[6] in affecting the distribution of dyes in different regions in the gel. In the third project, I studied the colocalization of a hydrophobic and a hydrophilic dye in NaDC-CB[6] gels with the goal to confirm my hypothesis from the release studies. Dynamics of diffusion of dyes within NaDC-CB[6] gels was investigated using the fluorescence recovery after photobleaching (FRAP) technique. Results from colocalization experiments showed that the addition of CB[6] changes the distribution of hydrophilic dye in the gel. Through colocalization experiments, I was able to showcase the active role of CB[6] in incorporating aggregates from the aqueous phase into the gel structure. Results from FRAP studies showed that, in the presence of CB[6], recovery after bleaching of a hydrophobic dye in the gel structure is slower compared to the dye in the NaDC gel structure. / Graduate

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18595号 / 工博第3956号 / 新制||工||1608(附属図書館) / 31495 / 京都大学大学院工学研究科合成・生物化学専攻 / (主査)教授 濵地 格, 教授 松田 建児, 教授 秋吉 一成 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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In order for a drug, or any material used for the purpose of eliciting a change in an organisms’ physical or chemical state, to be effective it must reach the intended target intact and for a sustained rate over time. Drug delivery systems encapsulate a drug to protect it from degradation, prevent side reactions, increase solubility, improve accumulation rates at target sites, and release drugs at a controlled rate. Controlled and sustained release of drugs is achieved by degradation of the carrier triggered by breaking dynamic chemical bonds caused by changes in the chemical environment such as pH or redox conditions. Slow, first order kinetic release of drugs increase therapeutic efficacy while also reducing side effects and other cytotoxicity issues. Up and coming drug delivery systems include hydrogels and nanocarriers such as vesicles. Hydrogel drug delivery systems are unique three-dimensional networks of crosslinked hydrophilic polymers that contain anywhere from 50-90 wt% of water. Drugs can be loaded via encapsulation during the gelation process or may be covalently bound to the polymer backbone before gelation. Amphiphilic molecules or polymers that self-assemble in aqueous solutions to form supramolecular nanostructures, such as vesicles, can encapsulate hydrophilic drugs in the aqueous interior or hydrophobic drugs in the lipophilic bilayer membrane. This study seeks to embed vesicles into a hydrogel to create a hybrid drug delivery system which may be applied as a coating to medical devices to prevent bacterial adhesion and growth, injected directly to a target site, or as an additive for wound dressings. This hybrid system mitigates burst release from the hydrogel, as well as stabilizes the vesicles to afford a longer shelf life. Vesicles are prepared from a novel supramolecular amphiphile composed of thio-alkyl modified��-cyclodextrin as a macrocyclic host, and an adamantyl-dithiopropionic acid modified poly(ethylene glycol) as a linear guest. This host-guest system forms inclusion complexes that self-assemble to bilayered vesicles, which may encapsulate a payload, in aqueous solutions. These vesicles serve as three-dimensional multivalent junctions to form a hydrogel, which may encapsulate a second payload, through a dynamic disulfide exchange crosslinking reaction. This novel drug delivery system will be capable of dual and selective release of two different encapsulated payloads. A pH sensitive acid labile bond embedded in the crosslinker will cleave under acidic conditions to release the payload enclosed in the hydrogel matrix, while a disulfide bond embedded in the supramolecular amphiphile of the free vesicle can be cleaved in the presence of naturally occurring antioxidant glutathione, GSH, to release the second payload. It has been discovered that vesicles efficaciously form, can encapsulate a payload, and are stable for several weeks, up to a month. Vesicle stability is examined in the presence of both intracellular and extracellular concentrations of GSH, and it is found that vesicles are more stable in extracellular concentrations of GSH. Crosslinking of vesicles is attempted at several molecular weights of linear thiol terminated poly(ethylene glycol) crosslinker, concentrations ratios of crosslinker: vesicle, pHs, and temperatures. It can be concluded that the crosslinking density with the linear crosslinker is not high enough to form a hydrogel. Future studies will include 4-arm crosslinkers which are predicted to increase the number of crosslinking points and hence the crosslinking density.

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