http://www.bdtd.uerj.br/handle/1/3709 2026-06-22T20:25:38Z http://www.bdtd.uerj.br/handle/1/25689 Título: Preparo e caracterização de complexos polieletrolíticos à base de ágar e quitosana aplicáveis na remoção de óleo em sistemas aquosos Autor: Barbosa, Luiz Paulo Botelho Primeiro orientador: Ferreira, Ivana Lourenço de Mello Abstract: In this study, hydrogels were produced physically from the combination of two oppositely charged polysaccharides, agar and chitosan (AG:CHI), at different volumetric ratios, intended for oil absorption in aqueous systems. The pH of the medium after mixing the polysaccharides was varied in the range of 4 to 7. The pH of the agar solution was varied from 4 to 8, while the chitosan pH was kept at 3.5. The concentration of both polysaccharide solutions was 1.0% w/v, and the volumetric ratio of the AG:CHI mixture was 1:1, 1:2, and 2:1. The hydrogels were characterized in terms of water and organic solvent absorption through the swelling degree (SD), Fourier-transform infrared spectroscopy (FTIR), X-ray diffractometry, scanning electron microscopy (SEM), and laser scanning confocal microscopy (CLSM). The hydrogel was evaluated for oil removal from an aqueous system, for which an oil absorption study was conducted. FTIR and XRD analyses revealed the interaction between these polysaccharides. SEM and CLSM micrographs showed a rough and porous surface of the material. The oil used in the work had an API gravity of 32°. The seawater used in the tests was collected from Leblon beach. According to the results obtained in this work, the composition that achieved the best performance in terms of swelling, yield, and floatability was the one prepared under the conditions AG:CHI (1:1), pH 7 of the agar solution, and pH 6 after mixing the solutions. The sample was able to sorb the oil from seawater and float after the oil sorption process. Instituição: Universidade do Estado do Rio de Janeiro Tipo do documento: Dissertação 2026-03-30T00:00:00Z http://www.bdtd.uerj.br/handle/1/25685 Título: Investigação Teórico-Experimental da Extração do Corante DO39 Usando Quitosana Autor: Campos, Antônio Alexandre Fernandes de Primeiro orientador: Silva, Haroldo Candal da Abstract: The pollution of water bodies due to anthropogenic activities is a global issue that requires special attention, as it affects all forms of life on the planet. In this context, dyes stand out as substances widely used in several industrial sectors, particularly in the textile industry, where their usage is widespread. Therefore, this work addresses the problem of aquatic pollution caused by textile dyes, such as Direct Orange 39 (DO39), an azo dye with toxic and carcinogenic potential.The objective of this study was to investigate, at the molecular level, the thermodynamic viability and sequestration of the dye by the biopolymer chitosan through an adsorption process,highlighting its role as a sustainable, abundant, and low-cost adsorbent. A combined approach involving computational chemistry and experimental measurements was employed.In molecular modeling studies, performed at the ωB97X-D/6-31G(d,p) - PCM (water) level of theory, nine supramolecular complexes with point and parallel approaches were analyzed to represent the adsorption of the dye onto chitosan. Thermodynamic and NCI (Non-Covalent Interaction) analyses were carried out to understand the stability, intermolecular interactions, and overall behavior of the system. Additionally, a 10, ns molecular dynamics simulation was performed using chitosan (represented by its icosamer) and DO39, in which the relative positions between the species were monitored. Experimentally, the adsorption of DO39 onto purified commercial chitosan was conducted at room temperature, and the process was monitored using UV-Vis and infrared (IR) spectroscopy. The thermodynamic analysis of Gibbs free energy (∆f G) showed that only the parallel approach complexes (8 and 9) are thermodynamically spontaneous (∆f G < 0), being at least 25.0, kcal, mol−1 more stable than the other conformations, thus dominating the Boltzmann population. NCI analysis confirmed the presence of strong hydrogen bonding interactions (especially involving the sulfonate group SO3−) and van der Waals (vdW) forces, with stabilization attributed to the maximization of the contact area. UV-Vis data indicated a decrease in solution absorbance, which, after mathematical treatment, corresponded to a ecolorization of 20.8%. The comparison between calculated and experimental infrared spectra reinforced the formation of the supramolecular complex (presence of O–H and C–O bands). However, the spectra were inconclusive in determining the preferred structural conformation. Molecular dynamics results revealed that DO39 molecules remaining close to the chitosan icosamer adopted a parallel orientation, in agreement with the theoretical calculations.It is concluded that chitosan is an effective and sustainable adsorbent for DO39. Instituição: Universidade do Estado do Rio de Janeiro Tipo do documento: Dissertação 2026-03-23T00:00:00Z http://www.bdtd.uerj.br/handle/1/25652 Título: Síntese e caracterização estrutural de complexos de Cu2+ e Zn2+ com uma N-acil-hidrazona inédita contendo morfolina visando aplicações em processos de desfosforilação proteica patológica Autor: Evangelista, Beatriz Nico Primeiro orientador: Cukierman, Daphne Schneider Abstract: Neurodegenerative diseases have become more prevalent with the increase in life expectancy, with Alzheimer's and Parkinson's being the most common manifestations. Both have a very similar pathophysiological mechanism, involving conformational changes that result in the aggregation of proteins which, in turn, lose their physiological role and acquire a pathological function. Many factors are related to the instability of the protein structure, such as, for example, the deregulation of phosphorylation. The protein aggregates present in these diseases are hyperphosphorylated, indicating that this process plays a fundamental role in the development of these pathological conditions and, therefore, have been gaining relevance in literature as a promising therapeutic target. Many coordination compounds have been reported as effective phosphate receptors, in addition to exhibiting dephosphorylation activity. The present work comprehends the development of copper(II) and zinc(II) complexes capable of interfering and modulating the pathological phosphorylation present in the context of Alzheimer's and Parkinson's diseases. A new N-acylhydrazone was synthesized from 2-morpholine acetohydrazide and 1-methylimidazole-2-carboxaldehyde, which was then used as ligand to obtain the copper and zinc complexes. Both the ligand and the complexes were thoroughly characterized in the solid state and in solution in order to elucidate their structural, electronic, and chemical properties. The new ligand HX1MPH was obtained in the (Z)-amide form. In the new trinuclear copper(II) complex, named Cu(X1MPH), the ligand acts as a binucleating agent: tridentate at the first metal center, coordinating through the Nimidazole, Namide, and Nmorpholine donor atoms, and bidentate at the second center via the Nazomethine and Ocarbonyl. The coordination spheres are completed by 2Cl‒ ions and 2 H2O, respectively. In the mononuclear zinc(II) complex, Zn(X1MPH), the ligand behaves as a bidentate species through the Nimidazole and Namide system, being the coordination center completed by two Cl‒. Since the complexes possess labile sites, both are expected to exhibit fosfatase-like activity and, therefore, to be capable of interfering with pathological protein phosphorylation, which may have implications for the treatment of neurodegenerative diseases. Thus, this project aims to thoroughly characterize the structure of complexes derived from a new N-acylhydrazone containing the morpholine moiety, in order to contribute to a deeper understanding of their chemical and electronic environments. Instituição: Universidade do Estado do Rio de Janeiro Tipo do documento: Dissertação 2026-03-30T00:00:00Z http://www.bdtd.uerj.br/handle/1/25651 Título: Revisitando a síntese e caracterização do complexo de Cu(II) com beta-ciclodextrina como catalisador para a obtenção de diarilaminas com potencial fotoativo Autor: Reis, Amanda Beatriz Silva Quirgo dos Primeiro orientador: Senra, Jaqueline Dias Abstract: The need for efficient, sustainable, and accessible energy generation has become increasingly critical. Photovoltaic solar energy is promising in all of these aspects. However, the currently available solar cells (first and second generation) on the market are associated with high costs and/or the use of scarce and toxic components. To address this issue, dye-sensitized solar cells (DSSCs), third-generation solar cells, are a class of devices that use sensitizing dyes as solar radiation absorbers to generate electricity through the photovoltaic effect. In this context, donor-π-acceptor conjugated systems that incorporate carbazole (9H-carbazole) and di or triarylamines based donor units have shown promise when employed as sensitizers for photocurrent generation. The Chan-Lam C-N cross-coupling reaction, catalyzed by copper species, demonstrates great potential for catalytic application involving the principles of sustainable chemistry. In this context, the complex based on copper(II) and β-cyclodextrin (β-CD) is noteworthy for being non-toxic and having already been efficiently explored in some aqueous reactions. Following part of the protocol traditionally described in the literature, the reaction between Cu(II) ions and β-CD occurred in alkaline solution, and a blue solid was obtained at the end. The complex was characterized by UV-Vis, DRS, AAS, FTIR, Raman, XPS, XRD, and TGA. The UV-Vis and DRS spectra confirmed the formation of the complex by the presence of absorption bands at 672 and 676 nm, respectively, and indicated aspects regarding the stability of the complex over time in solution and solid phase. The AAS, FTIR, Raman, XPS, and XRD spectra revealed information regarding the structural composition of the complex and present species. AAS analysis revealed a Cu content of 4.3%, suggesting that the studied system is presumably mononuclear, and enabled the estimation of the complex's molar mass. FTIR and Raman analyses provided strong evidence of copper coordination to the β-cyclodextrin structure, with characteristic bands at 877 cm⁻¹ and 576 cm⁻¹ in the FTIR spectrum and minor shifts in the Raman data, alongside indications of possible hydroxo ligands bound to the copper. XPS and XRD analyses pointed to aspects of the complex's degradation. Finally, TGA showed that the complex is stable until about 175 °C. Additionally, the complex proved to be a promising catalyst for the synthesis of diarylamines via the Chan-Lam reaction, utilizing phenylboronic acid and p-anisidine as reagents, potassium carbonate or cesium carbonate as bases, and water as the solvent. Three different activation methods were evaluated, such as magnetic stirring, heating under reflux, and ultrasound activation, and all of which afforded considerable yields. The highest chromatographic yield, reaching 74.2%, was achieved using 1 equivalent of cesium carbonate, 39.9 mol% catalyst loading, and conventional magnetic stirring at room temperature. Instituição: Universidade do Estado do Rio de Janeiro Tipo do documento: Dissertação 2026-03-25T00:00:00Z