https://ri.ufs.br/jspui/handle/riufs/2422 Wed, 28 Oct 2026 14:06:59 GMT 2026-10-28T14:06:59Z http://ri.ufs.br:80/retrieve/f3358433-77a8-4745-b3b7-b6ec0350c338/PPGQ.jpg https://ri.ufs.br/jspui/handle/riufs/2422 https://ri.ufs.br/jspui/handle/riufs/26176 Title: Development and implementation of theoretical methodologies for the study of luminescent systems Authors: Silva, Gustavo de Santana Abstract: Accurate prediction of excited state energies is extremely important for studies in various fields. In lanthanide complexes, calculations for determining excited states are generally performed using ab initio methods, TDDFT, or the semi-empirical INDO/S-CIS method. The first two cases are limited to systems containing a few dozen atoms. Although capable of handling large molecules, the semi-empirical quantum INDO/S-CIS method exhibits high errors when excitation window adjustment is not performed. Thus, we propose two parameterizations of CIS methods based on the INDO and NDDO approximations, named INDO/S-CIS2 and NDDO/S-CIS, for calculating the singlet and triplet excited state energies of systems containing lanthanide ions. To validate the methods, we compared the results obtained against TDDFT methodologies, based on a benchmark study, and INDO/S-CIS. Both developed methods presented errors smaller than or equivalent to those of the TDDFT methodologies. The error ranges for INDO/S-CIS2 and NDDO/SCIS were 10.43 ± 9.53 and 9.52 ± 7.13, respectively, for the singlet energy, in a set of 41 structures. For the triplet energy, in a set of 87 structures, the error ranges were 9.46 ± 6.88 and 7.68 ± 5.65, respectively. Furthermore, we also present the second version of the LUMPAC software with the incorporation of new methods and resources. Methods for calculating Judd-Ofelt intensity parameters from the excitation spectrum were implemented, as well as a methodology for calculating energy transfer rates for Tb3+ compounds. A novel module for visualizing molecular orbitals was also introduced, facilitating the characterization of excited states centered on the ligands involved in the energy transfer process and the interpretation of the theoretical absorption spectrum. The molecule viewer was optimized. The corresponding Jablonski diagram is generated automatically. In addition, code improvements have been made. Thu, 30 Jul 2026 00:00:00 GMT https://ri.ufs.br/jspui/handle/riufs/26176 2026-07-30T00:00:00Z https://ri.ufs.br/jspui/handle/riufs/26108 Title: Avaliação de biocarvões na miniaturização da MSPD para determinação de resíduos de pesticidas em alimentos para bebês Authors: Nascimento, Roseane dos Santos Abstract: Commercially available foods based on fruits, vegetables, meat and cereals are offered to babies from the age of six months chemical such as pesticides are used in crop cultivation to boost production meeting market demand and controlling pests that hinder plant and fruit growth. Residues of these compounds can remain in the final product and potentially affect a baby’s health; consequently, analytical methods are developed to detect contaminants in various samples. The use of miniaturized methods emerged as a way to reduce solvent volume and the amounts of adsorbents, as well as to eliminate steps compared to conventional method. Thus, this study aimed to develop a miniaturized MSPD method using pipette tips to extract the pesticides abamectin, acephate, acetamiprid, azoxystrobin, bifenthrin, clothianidin, difenoconazole, dimethoate, epoxiconazole, flutriafol, imidacloprid, lufenuron, malathion, methomyl, permethrin, pyraclostrobin, teflubenzuron, thiacloprid, thiamethoxam and thiophanate – methyl from pasty baby foods, in conjunction with liquid chromatography and DAD/UV-Vis detection. Commercial adsorbents C18, sílica gel, PSA, florisil, neutral alumina and the synthetic adsorbent TEOS were tested, as were solventes including methanol, acetonitrile, and mixtures with dichloromethane and ethyl acetate, evaluated at various volumes and ratios. The optimal extraction conditions involved using 40 mg of sample (fortified at 1 µg mL 1 ), 60 mg of sílica gel and 1000 µL of MeOH:ethyl acetate (50:50 v,v), yielding recoveries between 70 – 108 %. Subsequently, the parameters of the sample preparation method using corn cob biochar the adsorbent material that proved most efficient for analyte extraction under the same conditions previously established for sílica, but employing MeOH for analyte elution recovery rates ranged from 62 % to 112 %. Finally, the two methods developed in this study were validated by evaluating the parameters of linearity, sensitivity, selectivity, limit of detection, limit of quantification, accuracy, and precision. Subsequently, the methods were applied to samples of different brands and compositions marketed in Sergipe, but the pesticides under study were not found. Thu, 30 Jul 2026 00:00:00 GMT https://ri.ufs.br/jspui/handle/riufs/26108 2026-07-30T00:00:00Z https://ri.ufs.br/jspui/handle/riufs/26085 Title: Investigação teórica de complexos luminescentes de eu3+: elucidação dos mecanismos de transferência de energia e desenvolvimento de um protocolo computacional para predição do rendimento quântico Authors: Rodrigues, Jocelia Silva Machado Abstract: This work aimed to theoretically investigate the luminescent propertiesof Eu3+complexes containing β-diketonate ligands, focusing on understandingtheenergytransfer and backtransfer mechanisms responsible for the luminescent efficiencyofthese systems. Using semi-empirical methodologies, four complexes withpotential technological applications were studied: [Eu(tta)3(5,5’-dmbpy)] and [Eu(btfa)3(5,5’-dmbpy)], applied in the construction of OLED devices, and [Eu(tta)3(δ-val)(H2O)] and[Eu(btfa)3(δ-val)(H2O)], investigated as luminescent markers for gunshot residue.The theoretical investigation of these systems was necessary to understand, at themicroscopic scale, the photophysical processes that govern the luminescentperformance of the complexes, allowing them to be correlated withtheoptical properties observed experimentally. The theoretical results obtained agreedwell withthe experimental data provided by collaborators, demonstrating that thecalculatedproperties consistently describe the luminescent behavior of the studiedcompoundsand explain their efficiency in different technological applications. Inadditiontophotophysical studies, this thesis also involved the development of anewcomputational protocol for predicting the quantum yield in Eu 3+ complexes. Themodel was parameterized and validated using experimental quantumyield dataavailableinthe literature for a library composed of 17 Eu 3+ complexes. The results demonstratedhigh accuracy in reproducing the experimental quantum yields, presentingameanabsolute error of around 10%, a value significantly lower than those observedfortheanalytical models traditionally employed in the literature, whose mean errorsrangedbetween approximately 20% and 55%. Thus, this work contributes to theelucidationof the photophysical mechanisms of Eu 3+ complexes and presentsanewcomputational methodology for the precise prediction of quantumyield. Mon, 27 Jul 2026 00:00:00 GMT https://ri.ufs.br/jspui/handle/riufs/26085 2026-07-27T00:00:00Z https://ri.ufs.br/jspui/handle/riufs/25794 Title: Estudo sistemático da transferência de energia e de espectros de absorção em complexos de európio(III): aplicações da TDDFT e análise quimiométrica Authors: Santos, Gabriel Silva Abstract: In this work, the performance of different TDDFT(Time-dependent density-functional theory) functionals in describing absorption spectra and energy transfer (ET) in Eu3+ complexes was evaluated. Initially, three β-diketonate complexes were studied: [Eu(DPTB)3(H2O)2] (Eu-1), [Eu(DPTB)3(BathPhen)] (Eu-2), and [Eu(hfaa)3(Nap-TerPyr)] (Eu-3), modeled using the DFT PBE0/TZVP/MWB52 method. TDDFT CAM-B3LYP results satisfactorily reproduced the experimental spectra of Eu-1 and Eu-2, with absorption dominated by β-diketonate ligands. ET occurred mainly through the T1→5D0 and T1→5D1 channels, with rates on the order of 107 s -1 . The higher sensitization efficiency of Eu-1 (η = 52.6%; exp.: 56.3%) compared to Eu-2 (η = 45.0%; exp.: 44.5%) was attributed to a lower T1→S0 deactivation rate. For Eu-3, Principal Component Analysis (PCA) grouped the functionals into three distinct clusters. The spectra predicted by PBE0, B1P, X3LYP, B1LYP, REVPBE0, TPSS0, PW1PW, mPW1PW, and mPW1LYP showed better agreement with experiment. The INDO/S-CIS method reproduced the spectrum well but significantly underestimated the T1 energy. TDDFT results indicated a relevant contribution of the neutral ligand to electronic absorption and of the β-diketonate ligands to ET via T1→Eu3+, with a calculated yield of 52.8% (exp.: 48.8%). Subsequently, the influence of methodological parameters on TDDFT spectra was investigated. PCA clustering of 122 experimental spectra revealed three distinct groups. The projection of theoretical spectra in PCA space, combined with Mahalanobis distances, indicated that the B3LYP functional is the most globally consistent among those studied. Therefore, it was adopted for the factorial design parameter study. The fractional factorial design (25-2 ) showed that the effects of basis set, number of excited states, use of TDA, implicit solvent, and dispersion depend on the spectral cluster: in group 1, effects were minimally relevant; in group 2, the absence of TDA improved agreement; and in group 3, dispersion corrections and absence of TDA were decisive for better reproduction of experimental profiles. Thu, 05 Feb 2026 00:00:00 GMT https://ri.ufs.br/jspui/handle/riufs/25794 2026-02-05T00:00:00Z