Programa de Pós-graduação em Química

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Calixarenos como plataforma de luminóforos e de co-cristalização com nutracêuticos
(Universidade Federal de Goiás, 2024-08-15) Alvarenga, Meiry Edivirges; Martins, Felipe Terra; http://lattes.cnpq.br/0466799995060671; Martins, Felipe Terra; Gomes, Danielle Cangussu De Castro; Doriguetto, Antonio Carlos; Araújo Neto, João Honorato de; Santos Júnior, Sauli Dos
Calixarenes are notable macrocyclic compounds characterized by a variable number of phenolic units linked by methylene bridges. They possess a series of advantageous features, making them an ideal choice for diverse applications. Their ease of large-scale production from low-cost precursors, coupled with their chemical and thermal stability, as well as the ease of functionalization, elevate calixarenes to the status of highly versatile platforms. They can be utilized in the development of a broad range of materials with potential applications in technological and pharmacological areas. Based on the host-guest properties of calixarenes and the high efficiency of aminopyrazine as a blue light emitter, this research focused on the investigation of two calixarene-pyrazinamide hybrids. The primary goal was to combine hosting capabilities and light emission in a single molecular structure. Two compounds yielded three luminescent crystalline forms, whose structures and optical properties could be correlated. One of them crystallized in two forms, non-solvated and a DMF solvate, while the other, without t-butyl substitutions, formed three conformers with DMF. Variations in molecular substitution affected the conformation of the structures, influencing the coplanarity and conformational profile of the phenolic rings. Under an excitation of 388 nm, both emitted light in the 400-550 nm range, peaking at around 500 nm, but with low quantum efficiency. The low efficiency was attributed to the presence of DMF and π...π stacking interactions. Another aim of this research was to explore the use of calix[4]tube in forming cocrystals with resveratrol, an active nutraceutical known for its potential antibacterial, antioxidant, antiinflammatory, and anticarcinogenic benefits, yet with low aqueous solubility. This work represents the first successful attempt to form a neutral-state resveratrol cocrystal, doubling its water solubility. In summary, this study signifies a significant advancement in using calixarenes as molecular bases for luminophores and in the crystallization of the nutraceutical resveratrol. The employed process proved commercially viable, underlining the immense potential of these methods for future applications in technological and pharmaceutical fields. Therefore, the research focuses on the synthesis of calixarene hybrids with light-emitting properties and the development of cocrystals to enhance the solubility of pharmaceutical compounds, demonstrating the versatility of calixarenes in various areas of chemistry.
Desenvolvimento de uma metodologia fisicamente inspirada no princípio da mínima polarizabilidade para o cálculo de propriedades optoeletrônicas de polímeros orgânicos
(Universidade Federal de Goiás, 2025-02-24) Araujo, Ana Carolina Felisberto; Oliveira, Heibbe Cristhian Benedito de; http://lattes.cnpq.br/5995553993631378; Oliveira, Heibbe Cristhian Benedito de; Sanches Neto, Flávio Olimpio; Qadir, Muhammad Irfan
Polymers are macromolecules of significant industrial interest due to their versatility, including their potential application in the design of optical devices. Properties such as the refractive index and Abbe number are closely related to the optical performance of these materials and their technological applications. Therefore, predicting optical properties is essential, as they are directly dependent on the linear polarizability (α), which quantifies the susceptibility of a molecule’s or material’s electronic cloud to distortion under an external electric field. Density Functional Theory based methods employ the electronic density as a fundamental quantity for electronic structure calculations, providing computationally efficient and highly accurate predictions of optical properties in organic materials, such as α. This approach offers a variety of functionals with different levels of correction and approximation for the exchange-correlation potential. Among these, we employ range-separated hybrid (RSH) functionals, which explicitly account for electron-electron interactions by introducing a range-separation parameter (ω), allowing for a transition between short- and long-range interactions. In this study, we investigate the optimization of the ω parameter in RSH functionals based on a physically motivated principle known as the minimal polarizability principle (MPP). The core concept of this approach derives from the maximum hardness principle, which states that a system tends to evolve toward a minimum polarizability value to achieve greater stability. By applying this principle, we developed and assessed a new optimization scheme for the ω parameter in RSH functionals based on MPP and evaluated the impact of this optimization on the optoelectronic properties of organic polymers. The calculated α and refractive index values showed good agreement with experimental data, with higher ω values highlighting the increased contribution of long-range interactions in determining these properties. The polymers investigated to validate the proposed methodology were polythiophene (PT), poly(1,4-phenylene) (PB), trans-polyacetylene (trans-PA), cis-polyacetylene (cis-PA), and polybutadiene (PBT), while the optimized functionals were LC-BLYP, LC-HPBE, and B97XD.
Estudo da inserção de grafeno em catalisadores de PtSn para a oxidação de etanol
(Universidade Federal de Goiás, 2022-02-21) Bastos, Tarso Leandro; Colmati Junior, Flavio; http://lattes.cnpq.br/0231242349462585; Colmati Junior, Flávio; Ciapina, Eduardo Gonçalves; Martins, Paulo Roberto
Fuel cells are portable electrochemical converters that generate electricity using renewable fuels and can act as high-efficiency energy sources. When fed with ethanol, they lose performance due to electrode poisoning. To mitigate this problem, noble metals are used in the electrodes in addition to the addition of elements to the electrocatalysts, increasing the production cost while the problem persists. Thus, this study seeks to increase the efficiency of ethanol oxidation by modifying the carbon support with graphene, where the metallic phase is anchored, and to verify its influence on the general catalysis process. Electrocatalysts with carbon-graphene hybrid support were synthesized in different proportions, and a physical mixture of graphene with the carbon-supported electrocatalyst was prepared. Hybrid supported electrocatalysts showed higher electrochemical activity and stability in ethanol oxidation compared to carbon supported electrocatalyst, with an increase of 132% in alkaline medium. In the physical mixture, the addition of graphene generated a 10% decrease in the amount of metallic phase needed, obtaining the same performance as the pure electrocatalyst. While in acidic medium, in addition to the 10% decrease, the physical mixture exhibited a much superior performance to the pure electrocatalyst. The results showed that the influence of graphene depends on its interaction with the electrocatalyst, while promoting an increase in the performance of ethanol oxidation.
Abordagens para análise de n-nitrosaminas em medicamentos utilizando DPX-LC-MS e DART-MS
(Universidade Federal de Goiás, 2023-12-19) Batista Junior, Almir Custodio; Chaves, Andréa Rodrigues; http://lattes.cnpq.br/6064014965252121; Chaves, Andréa Rodrigues; Coltro, Wendell Karlos Tomazelli; Freitas, Carla Santos de
N-Nitrosamines (NAs) are molecules characterized by a deprotonated amine group linked to a nitroso group, usually formed through the reaction of secondary or tertiary amines with nitrosating agents. NAs are commonly found as impurities in various products, such as processed foods and cosmetics. These molecules are the subject of study due to their potential mutagenic and carcinogenic properties. In 2018, NAs were discovered in medicines containing the active ingredient valsartan. In sartan medicines, the occurrence of NAs was initially linked to the synthesis of the active pharmaceutical ingredient (API), as the reaction medium may contain precursor amines for NAs, as well as a nitrosating agent. Through more in-depth studies, it has been confirmed that the degradation of the API or its interaction with the packaging material could lead to the formation of NAs. These discoveries prompted global regulatory agencies to establish guiding principles regarding the presence and maximum allowable concentrations of these molecules in such medicines. Aiming to assess the content of NAs in medicines, efficient and sensitive analytical methods have been developed. The challenge in analyzing NAs in medicines lies in the low concentration of these analytes, as they are found in this matrix in the order of ng of N-nitrosamine per mg of the medicines. The literature presents various chromatographic methods coupled with mass spectrometry (MS) applied in such analyses. Both liquid chromatography (LC) and gas chromatography (GC) techniques provide sensitive and selective methods for the analysis of NAs in medicines. However, LC methods have advantages over GC as it allows the analysis of thermally unstable and non-volatile compounds. Due to the presence of the API in the sample and the low concentration of these impurities, the determination of NAs can be compromised by various factors, such as matrix effects, carryover effects, and the compromise and contamination of the LC-MS system. Thus, the sample preparation step proves to be important, aiming at the extraction, purification, and pre-concentration of NAs. Additionally, advances in mass spectrometry have led to the development of ambient ionization techniques designed to analyze samples that are either unprocessed or minimally modified in their native environment. These techniques enable the analysis of samples in situ, often in a non-destructive manner. Another important factor currently is the adaptation of analysis protocols with sustainable principles advocated by green chemistry, which aim to reduce the use of solvents and samples, minimize risks, decrease energy consumption, and reduce waste generation. Therefore, the present study introduces new approaches to the analysis of NAs in medicines that have not yet been explored in the literature. Chapter I demonstrates the use of a miniaturized sample preparation technique for the separation and pre-concentration of NAs in medicines followed by LC-MS analysis. Conversely, Chapter II presents the application of an ambient ionization technique coupled with mass spectrometry for the assessment and quantification of NAs in medicines.
Estudo de degradação forçada e de compatibilidade do ciprofibrato com excipientes farmacêuticos
(Universidade Federal de Goiás, 2022-08-31) Brito, Camila Cíntia Sousa Melo; Leles, Maria Inês Gonçalves; http://lattes.cnpq.br/1614912440064013; Leles, Maria Inês Gonçalves; Siqueira, Adriano Buzutti de; Chaves, Andrea Rodrigues; Ionashiro, Elias Yuki; Ribeiro, Elton Brito
Ciprofibrate-CPF is a hypolipidemic that promotes the reduction of serum levels of cholesterol and triglycerides by stimulating activated nuclear receptors for peroxisome proliferation-alpha-PPAR-α. In this work, the stability of CPF was studied using forced degradation and compatibility studies. The Active Pharmaceutical Ingredient-API (SQC) was characterized by Thermogravimetric Analysis/Derivative Thermogravimetric AnalysisTGA/DTGA, Differrential Scanning Calorimetry-DSC, Differrential Scanning Calorimetry coupled to the Photovisual system-DSC-Photovisual, Absorption spectroscopy in the mid-infrared region with Fourier Transform-FTIR, Nuclear Magnetic Resonance-RMN, Powder X-ray Diffractometry-DRXP, High Resolution Mass Spectrometry-EMAR and High Performance Liquid Chromatography coupled with Diode Array Detector and High Resolution Mass Spectrometry-CLAE/DAD/EMAR. The forced degradation study was carried out for CPF (SQC) under the following conditions: acid hydrolysis, basic hydrolysis, oxidative and thermal at 70 °C 240 hours using EMAR and CLAE/DAD/EMAR. The compatibility study between the CPF and the excipients was carried out by preparing binary mixtures in the proportions 50:50 and 92:08 (m/m), where the isolated components (CPF (SQT) and excipients), Simulated Excipients Sample-ASE (excipients) and the binary mixtures (CPF-excipient or CPF-excipients) were analyzed by TGA/DTGA, DSC, DSC-Photovisual, FTIR, and DRXP. The EMAR and CLAE/DAD/EMAR results suggested the degradation of CPF when subjected to basic hydrolysis, with some degradation products previously reported in the literature being observed and a new product identified. In the other exposure conditions, the CPF remained stable. The DSC technique suggested signs of interaction between the CPF and the excipients (Sodium Starch Glycolate-AGS, Sodium Lauryl Sulfate-LSS, Silicon Dioxide-DOS and Hydrogenated Vegetable OilOVH) when prepared in a proportion 50:50 (m/m) and between CPF and the excipient (OVH) in a proportion (92:08 m /m). However, the FTIR and DRXP techniques did not confirm the sings of interaction observed in the DSC, except when DOS was used at 50%. The compatibility study indicated the use of the CPF-ASE binary mixture in the proportion 50:50 (m/m) as a candidate for pre-formulation.
Síntese seletiva de tiocarbonatos cíclicos utilizando catalisadores básicos
(Universidade Federal de Goiás, 2024-11-18) Camargo, Maria Eduarda de Souza; Chagas, Rafael Pavão Das; http://lattes.cnpq.br/9712618482518275; Chagas, Rafael Pavão Das; Matos, Gabriela Ferreira; Ferreira, Leonildo Alves
The search for new carbon sources for the production of plastic polymers, pharmaceuticals and agrochemicals, among others, is essential. The use of carbon disulfide (CS2) is a viable alternative and can be used as a raw material for the production of thiocarbonates and various other industrially relevant substances. The aim of this work is to develop a methodology that employs mild conditions to produce cyclic thiocarbonates from CS2 and epoxides, using basic catalysts such as metal hydrides and hydroxides. Experiments were carried out to evaluate the catalytic capacity of various hydrides and hydroxides, in which sodium hydride and sodium hydroxide stood out significantly, leading to quantitative and totally selective conversions of CS2 into the respective cyclic dithiocarbonates. It is believed that the nucleophilicity of the hydroxide anion and the solubility of these substances were decisive for these results. The reaction conditions of the catalytic system were optimized, with the best results obtained at a temperature of 50 °C, reaction time of 2 hours and catalytic load varying between 2 and 5 mol%, depending on the type of epoxide used. Finally, a variety of epoxides were tested to assess the replicability of the method. Evaluation of the results revealed that epoxides with electron-withdrawing substituents, capable of increasing the electrophilicity of the ring, showed higher conversion rates while maintaining high selectivity. On the other hand, epoxides without these groups or containing bulky groups close to the epoxide ring showed low conversion rates or were not converted at all. This work has shown that a simple, low-cost substance such as sodium hydroxide can be used as a highly efficient and selective catalyst for the production of cyclic dithiocarbonates from CS2 and epoxides.
Compostos de coordenação visando o desenvolvimento de eletrodos para armazenamento e conversão de energia
(Universidade Federal de Goiás, 2025-04-29) Campos, Iara Schlag Durães; Martins, Paulo Roberto; http://lattes.cnpq.br/0107474250870898; Martins, Paulo Roberto; http://lattes.cnpq.br/0107474250870898; Gomes, Danielle Cangussu de Castro; http://lattes.cnpq.br/5709288358367849; Gonçalves, Josué Martins; http://lattes.cnpq.br/8271818229699538
In this work, two materials based on ZIF-67/Ni(OH)2 and CoFe-ZIF-67/Ni(OH)2 were obtained in order to evaluate their electrochemical performances in both energy storage and conversion. A class of compounds called MOFs are three-dimensional structure consisting of a metal center and organic ligands. One class of MOFs is called ZIFs, which are materials with a tetrahedral zeolite-type topology with a central element – typically Zn or Co – that connects to each other through oxygen atoms. Therefore, two MOFs (ZIF-67 and CoFe-ZIF-67) were synthesized through the reaction between their metal precursors (cobalt acetate and iron sulfate) with 2- methylimidazole, while Ni(OH)2 was synthesized, in-situ, using the Tower method followed by electrochemical treatment of the electrodes. The composites were obtained by deposition of MOFs on a 1 cm2 of a fluorine-doped tin oxide substrate (FTO), using the drop-casting technique, followed by the deposition of Ni(OH)2 on the modified electrodes with the MOFs using the spin-coating technique. Through the X-Ray Diffraction technique it was possible to identify that the MOFs are in their amorphous form. Nickel hydroxide is in fact a nickel glycerolate, with a single characteristic diffraction peak located in the region close to 2θ = 10°, and the composites are strongly influenced by the structure of the nickel glycerolate, since the only diffraction peak presented is in the same region of 2θ = 10°, however with less intensity. In addition, the morphology of the MOFs was studied through Transmission Electron Microscopy, demonstrating their nanoparticle structures with the presence of interference fringes with an average distance of 0,130 nm (CoFe-ZIF67) and 0,125 nm (ZIF-67). The Scanning Electron Microscopy technique was also used in morphological studies, helping to understand the way in which the material is deposited on the FTO substrate. Energy dispersive spectroscopy (EDS) also contributed to the identification of the chemical elements present in the samples, such as cobalt, nitrogen, carbon, nickel, iron and oxygen, depending on the sample analyzed.The oxidation states of the metals in the composites were defined by means of X-Ray Photoelectron Spectroscopy, and for both ZIF-67/Ni(OH)2 and CoFe-ZIF67/Ni(OH)2 there is the presence of Co2+, Co3+, Ni2+ and Ni3+ ions, in addition to Fe2+ and Fe3+ ions being found in the CoFe-ZIF-67/Ni(OH)2 composite. Through electrochemical studies, such as cyclic voltammetry processes and galvanostatic charge and discharge curves, it was possible to identify that the most promising material in the area of energy storage was ZIF-67/Ni(OH)2, since it presented the highest specific capacity (106,99 mAh.g-1 at 1 A.g-1 ) and its capacity retention was 71,63% after 5000 consecutive charge and discharge cycles at 12 A.g-1 , in addition to their energy storage processes being characterized as diffusional and faradaic. Electrochemical Impedance Spectroscopy studies were performed to investigate the charge transfer resistance values for the five materials. Based on the values found, the CoFe-ZIF-67/Ni(OH)2 composite exhibits the lowest charge transfer resistance value related to the oxygen evolution process (7,6 Ω). Focused on the area of energy conversion, the material that presented the lowest overpotential value (at a current of 10 mA) in the water oxidation process during linear voltammetry readings was CoFe-ZIF-67/Ni(OH)2, with a value of 0,43 V, in addition to exhibiting good stability x and durability over 10 consecutive hours of application of a fixed current of 10 mA. The development of these new composites aggregatesin different areas: ZIF67/Ni(OH)2 for energy storage systems and CoFe-ZIF-67/Ni(OH)2 for energy conversion systems. Both materials showed positive results in their respective areas of study.
Dispositivos sob demanda: desenvolvimento de sistemas microfluídicos e sensores eletroquímicos por impressão 3D
(Universidade Federal de Goiás, 2020-11-30) Duarte, Lucas da Costa; Coltro, Wendell Karlos Tomazelli; http://lattes.cnpq.br/8302650734477213; Coltro, Wendell Karlos Tomazelli; Lago, Claudimir Lucio do; Muñoz, Rodrigo Alejandro Abarza; Bonacin, Juliano Alves; Vaz, Boniek Gontijo
3D printing technology has been widely explored as an alternative method of manufacturing analytical microdevices. This technology has been solving many limitations of conventional microfabrication techniques due to its ability to build microstructures with different materials and geometries in a simple, fast and low-cost way. In this sense, this thesis describes the use of 3D printing to manufacture analytical platforms for applications involving counting E. coli cells embedded in droplets based on contactless conductometric detection (C4D), online monitoring of chemical reactions by mass spectrometry (MS) and estradiol detection in electrochemical analysis. For C4D measurements, microfluidic devices were printed containing Tjunction microchannels and two electrodes integrated in the antiparallel arrangement. The droplets with incorporated cells were monitored in real time using the C4D system. The proposed approach demonstrated the ability to detect E. coli cells in the concentration range between 86.5 and 8650 CFU droplet-1 with a detection limit of 63.66 CFU droplet-1. For the development of the miniaturized reactor used in the monitoring of chemical reactions by MS, a microfluidic device was built containing a channel in the shape of a 3D serpentine and another one containing a channel in the Y-shaped. Both devices were evaluated for monitoring the Katritzky reaction, injecting simultaneously 2,4,6-triphenylpriryllium (TPP) and amino acid (glycine or alanine) solutions and the reaction product were monitored online by MS at different flow rates. The acquired spectra demonstrated that the relative abundances of the products obtained with the device containing the 3D serpentine channel had an order of magnitude up to three times greater than those obtained with the Y-shaped device. The device performance in 3D serpentine was also evaluated comparing with the traditional ESI(+)-MS technique. The 3D serpentine printed reactor promoted the reaction quickly and with a higher rate of product formation compared to the ESI(+)- MS technique. The electrochemical cell containing integrated electrodes was entirely manufactured by 3D printing. The electrochemical device was manufactured in a single step with a manufacturing time of 12 min and a cost of US$ 0.08. Preliminary tests for the detection of 17β - estradiol by DPV reached an LOD of 0.1 μmol L-1 and an analytical curve with a linear range of 0.19 to 25 μmol L-1. These results demonstrate the excellent versatility of 3D printing technology being applied in different areas of bioanalytical chemistry. The counting method of counting bacteria, the device for online monitoring of chemical reactions, as well as the electrochemical cell for detection of hormones offer instrumental simplicity, low cost, high sensitivity, allowing the opening of new application possibilities in different areas of chemistry.
Implantação das técnicas espectroscópicas de Laser FlashFotólise e de fosforescência para estudos fotofísicos de sistemas porfirínicos e suas interações com biomoléculas e nanoestruturas
(Universidade Federal de Goiás, 2023-12-14) Ducas, Eli Silveira Alves; Gonçalves, Pablo José; http://lattes.cnpq.br/0515343409614452; Gonçalves, Pablo José; Coelho , Felipe Lange; Gomes, Danielle Cangussu de Castro; Lopes, Jefferson Marcio Sanches; Patrocínio, Antônio Otávio de Toledo
The photophysical characterization allows the assessment of processes following the phenomenon of light absorption, which is of interest for various applications, both in the field of materials chemistry and in photomedicine. This work aimed at the photophysical characterization of potential porphyrinic photosensitizers and their interaction with biomolecular systems and nanostructures. To achieve this, the spectroscopic techniques of Transient Absorption (or Laser Flash-Photolysis) and a Spectrophosphorimeter were implemented, and their usage protocols were established. With these techniques in operation, an alternative method for determining the triplet state formation yield and obtaining the singlet oxygen formation yield was proposed, fundamental properties for the characterization of photosensitizers. It was possible to investigate the interaction of water-soluble porphyrins with bovine serum albumin and verify that this interaction affects the triplet states lifetimes and singlet oxygen yields. These parameters were strongly influenced by the presence of oxygen and the porphyrin's location at the interaction sites in the protein structure. Another study conducted was the interaction of cationic porphyrins with manganese ferrite (FeMn2O4) anionic ferrofluids in which the interaction leads to the suppression of fluorescence and singlet oxygen (1O2) generation of the photosensitizers. Interestingly, this interaction is not predominantly governed by electrostatic interactions but mainly through chemsorptives and physisorptives interactions. Additionally, it was demonstrated that photothermal heating breaks the interaction with the nanostructure, restoring the photophysical properties of the photosensitizer, making this system a multifunctional nanostructure with luminescent and theranostics properties.
Determinação de pesticidas em amostras de leite materno por espectrometria de massas ambiente empregando paper spray ionization
(Universidade Federal de Goiás, 2024-12-17) Ferreira, Pedro Augusto Barbosa; Chaves, Andréa Rodrigues; http://lattes.cnpq.br/6064014965252121; Chaves, Andréa Rodrigues; Soares, Francielle Queiroz; Oliveira, Gisele Augusto Rodrigues De
The increase in agricultural production in Brazil has driven the excessive and indiscriminate use of pesticides. These substances are often present, even at trace levels, in various environmental and food matrices. However, given their widespread dissemination and persistence in these environments, combined with human exposure to these residues, they can be detected in different biological fluids, including breast milk. Due to the complexity of this matrix and the low levels of analytes present, the development of strategies for sample preparation is necessary to achieve the desired sensitivity. One strategy to overcome this challenge lies in ambient mass spectrometry employing the ionization technique known as paper spray ionization (PSI-MS). The PSIMS technique typically uses a triangularly cut chromatographic paper substrate for sample application. This substrate allows for chemical modifications that can enhance the sensitivity and selectivity of the desired methods. Modifying the paper using molecularly imprinted polymers (MIPs) and restricted access materials (RAMs) are promising choices to improve the sensitivity and selectivity of PSI-MS analyses. MIPs enable highly selective extraction of target analytes, while RAMs help eliminate endogenous matrix compounds that could reduce the analytical sensitivity of the PSI-MS approach. Thus, in this study, MIP and RAM immobilizations were synthesized and characterized to evaluate their use as modifiers for the paper substrate in PSI-MS applied to pesticide analysis in breast milk samples. The MIP was synthesized using glyphosate as the template molecule, methacrylic acid as the functional monomer, diethylene glycol dimethacrylate as the crosslinking agent, and azobisisobutyronitrile as the radical initiator, under reaction conditions of 24 hours at 60°C in a nitrogen atmosphere. The RAM was produced using C-18 particles, onto which bovine serum albumin (BSA) was immobilized on the surface. The polymers developed were characterized by thermogravimetric analysis/derivative thermogravimetric analysis-simultaneous differential thermal analysis (TGA/DTGADTA), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR). The results confirmed that the materials were obtained as expected. After characterization, the polymers were immobilized on the paper surface and subjected to PSI-MS analysis for the determination of glyphosate in breast milk samples. Among the modifying phases evaluated, the highest analytical sensitivity was obtained using the RAM phase, which was selected for subsequent tests. The developed PSI-MS method exhibited linearity in the range of 50 to 600 µg mL⁻¹ with R² = 0.9915. The method's figures of merit—precision, accuracy, recovery, and matrix effect—were evaluated. The precision ranged from 1.3% to 8.7%, and recovery ranged from 104.7% to 113.7%. Preliminary results for glyphosate determination indicated that the synthesized polymers are promising as modifiers for PSI-MS substrates, allowing the selective determination of glyphosate in breast milk. Breast milk samples from volunteer patients were analyzed, and glyphosate was detected at quantifiable levels within the working range in five samples, with two above the limit of detection (LOD) and one below. In twelve samples, the analyte was not detected. The developed RAM-PSI-MS methodology proved to be a promising alternative for glyphosate determination in breast milk samples.
Uso de terapia fotodinâmica antimicrobiana para o tratamento de Klebsiella pneumoniae produtora de carbapenemase (KPC-Kp)
(Universidade Federal de Goiás, 2025-03-28) Freitas, Alysson Benite de; Souza, Guilherme Rocha Lino de; http://lattes.cnpq.br/1127532567066692; Gonçalves, Pablo José; http://lattes.cnpq.br/0515343409614452; Gonçalves, Pablo José; Bailão, Elisa Flávia Luiz Cardoso; Chagas, Rafael Pavão das; Iglesias, Bernardo Almeida; Chaves, Andréa Rodrigues
Embargado
Síntese de selanil-(hetero)arenos via selenilação da ligação C(sp2)-H promovida por Ácido Tricloroisocianúrico (TCCA)
(Universidade Federal de Goiás, 2025-02-03) Granja, Isis Juliane Arantes; Saba, Sumbal; http://lattes.cnpq.br/0113770075520231; Saba, Sumbal; Silva, Fabiana Ourique da; Barbosa, Martin Schwellberger; Alisson Rodrigues Rosário, Alisson Rodrigues Rosário; Goncalves, Pablo Jose
This thesis proposes a sustainable and efficient methodology for the direct selenylation of (hetero)arenes via selective C(sp2)-H bond functionalization, usmg trichloroisocyanuric acid (TCCA) as an oxidizing agent. The goal was to develop a synthetic strategy that eliminates the need for metal catalysts and toxic solvents, aligning with Green Chemistry principies. The methodology involved mild reaction conditions, employing TCCA as the oxidant and ethanol as a green solvent. Various reaction conditions were explored to optimize the selective introduction of organoselenium groups into N-heteroarenes such as imidazo[l,2-a]pyridine, imidazo[2, 1-b ]thiazole, and indole. The experiments yielded impressive results, ranging from 39% to 97%, with an average of 75%. Mechanistic investigations revealed two main pathways for functionalization, with the electrophilic activation of diselenides proving to be the most efficient. The results highlight the methodology's high selectivity and broad functional group tolerance, setting it apart from traditional approaches. Additionally, this strategy enables efficient functionalization of aromatic and heterocyclic substrates without the need for directing groups or metal catalysts, expanding its synthetic scope. The versatility of this approach opens new possibilities for future research in organic chemistry, including the selective modification of 1tconjugated systems and the construction of novel molecular structures. Overall, the findings reinforce the importance of sustainable chemistry in the synthesis of organochalcogen compounds, providing an efficient and environmentally friendly method for obtaining selenylated derivatives with potential applications across various fields of organic chemistry.
Novas abordagens para determinação de melatonina e metabólitos em leite materno e aplicação da metabolômica para fins de diferenciação de cultivares de alface
(Universidade Federal de Goiás, 2024-09-11) Machado, Lucas Santos; Roque, Jussara Valente; http://lattes.cnpq.br/7154037221725381; Chaves, Andréa Rodrigues; http://lattes.cnpq.br/6064014965252121; Chaves, Andréa Rodrigues; Bottoli, Carla Beatriz Grespan; Silva, Bruno José Gonçalves da; Faria, Anízio Márcio de; Sgobbi, Lívia Flório
In analytical chemistry, there is a constant search for methodologies that require less cost and analysis time, but at the same time offer precision and accuracy. In this sense, various methodologies and technologies have been evaluated, among which we can highlight those that employ miniaturized sample preparation techniques and those that use ambient ionization sources for mass spectrometry. This thesis is divided into two chapters presenting the potential of modern sample preparation techniques for liquid chromatography analysis and ambient mass spectrometry analysis. The first chapter describes the use of disposable pipette extraction, utilizing a sorbent phase based on molecularly imprinted polymers (DPX-MIP), for the determination of melatonin and its metabolites (AFMK and AMK) in breast milk by liquid chromatography coupled with mass spectrometry (LC-MS). Different MIPs were synthesized and evaluated for their selectivity in analyzing melatonin and its metabolites, experimentally obtained results were compared with molecular simulation data, showing consistency between the theoretical physicochemical parameters and the experimental data. The application of DPX-MIP in conjunction with LC-MS enabled the development of a method for determining melatonin and its metabolites in breast milk, with recovery values ranging from 87-111% and precision between 2-13%, analysis of patient samples produced values consistent with those reported in the literature. The second chapter explores the application of the paper spray ionization mass spectrometry (PSI-MS) technique to study the metabolomics of lettuce cultivars and the potential differentiation according to their cultivation method and variety. PSI-MS, an ambient ionization technique, uses chromatographic paper as a substrate for the sample ionization process. In this study, lettuce samples were successfully differentiated according to variety and cultivation method through the application of chemometric tools (PARAFAC, PCA, PLS-DA, and OPSDA), identifying 36 metabolites responsible for this differentiation, with choline, mannose, and citric acid being the most influential. Additionally, green chemistry metrics, such as AGREEprep and AGREE, were applied to assess the sustainability of the developed methodologies. The results confirmed that DPX-MIP and PSI-MS are more sustainable, offering appropriate analytical performance with shorter analysis times and generating low volumes of chemical waste
Compostos de coordenação com um ligante do tipo oxamato derivado do ácido 4-aminobenzóico: Síntese, Caracterização e estudo das propriedades ópticas e magnéticas
(Universidade Federal de Goiás, 2024-12-01) Maciel, Jhonny Willians de Oliveira; Gomes, Danielle Cangussu de Castro; http://lattes.cnpq.br/5709288358367849; Gomes, Danielle Cangussu de Castro; Silva, Hermínia Veridiana dos Santos Pessoni e; Ferreira, Leonildo Alves; Gonçalves, Pablo José; Simão, Tatiana Renata Gomes
In this work, we present the syntheses, characterizations, and studies of the optical and magnetic properties of various novel coordination compounds. We obtained supramolecular systems based on complexes with the ligand Sodium 4- (carboxylatoformamido)benzoate (Na2Hpcpa) and the heavy metal ions Cd2+ and Pb2+, as well as a series of isostructural complexes containing the rare earth metal ions Y3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, and Yb3+. The studies of the optical properties of the Cd2+ and Pb2+ compounds show a shift in the emission band position towards white light when compared to the matrix's emission. The Eu3+ and Tb3+ compounds exhibit red and green emissions, respectively, with high thermal stability over the entire temperature range studied, between 16 and 300 K. The external quantum yield for the Tb3+ compound was considerably improved compared to compounds containing oxamate-type ligands reported in the literature, indicating that the ligand Hpcpa2- may be an efficient sensitizer for energy transfer through the so-called antenna effect to Tb3+ ions. Magnetic properties studies of the Eu3+, Gd3+ , Tb3+, and Er3+ compounds were conducted, and ac susceptibility measurements reveal that the Gd3+, Tb3+, and Er3+ compounds exhibit slow relaxation of magnetization induced by the magnetic field, thus representing new examples of field-induced single-molecule magnets (SMMs). Despite the Y3+, Eu3+, Ho3+, Er3+, and Yb3+ compounds not having well-defined single-crystal X-ray diffraction structures, other structural characterizations indicate that all rare earth Ln3+ compounds obtained in this work are isostructural to the Eu3+, Gd3+, and Tb3+ compounds with defined structures. Therefore, among the compounds obtained in this work, the Tb3+ compound can be classified as multifunctional with possible dual technological applications, optical and magnetic.
Desenvolvimento de metodologias miniaturizadas de preparo de amostras para a avaliação de pesticidas multiclasses em amostras ambientais
(Universidade Federal de Goiás, 2023-09-05) Martins, Rafael Oliveira; Silva, Bruno José Gonçalves da; http://lattes.cnpq.br/6550581465780888; Chaves, Andréa Rodrigues; http://lattes.cnpq.br/6064014965252121; Chaves, Andréa Rodrigues; Nascentes, Clésia Cristina; Coltro, Wendell Karlos Tomazelli; Hantao, Leandro Wang; Sgobbi, Lívia Flório
The presence of pesticides in the environment is primarily due to the excessive use of these chemical compounds in the global agricultural scenario. In recent decades, the search for new approaches to the analysis and monitoring of these compounds in such matrices has focused on the introduction of sample preparation methodologies as analytical strategies responsible for assessing such complex matrices. Furthermore, the evolution of these sample preparation methodologies over the decades has brought with it the introduction of miniaturized systems capable of overcoming classical challenges faced by conventional sample preparation method-ologies. Thus, this study presents the evaluation of three miniaturized approaches for pesticide extraction in environmental samples. Chapter II presents the development and application of the Hollow Fiber Liquid-Phase Microextraction (HF-LPME) technique for the assessment of 13 multi-class pesticides in soil samples. The methodology reported in the first chapter resulted in R² values >0.98 for all pesticides and detection and quantification limits (LOD and LOQ, re-spectively) in the range of ng L-1 and recovery values between 75.2%-118.8%. The evaluation of the methodology proposed by the AGREEprep software indicated that approximately 70% of the method adhered to the principles of green chemistry adopted by the software. Furthermore, a comparison with classical methods of pesticide extraction in soil identified the HF-LPME method as an efficient approach for monitoring pesticides in soil. Chapter III describes the application of the Electromembrane Extraction (EME) technique for the evaluation of the same set of analytes in soil samples. In this second approach, a special focus was placed on com-paring the proposed method with the one applied in Chapter II, regarding analytical frequency, green aspects, and analytical performance of both methods. Differences were observed in an-alytical aspects, where the EME technique showed higher LOD (76.1 -171.4 μg kg-1) and LOQ (270.7 -516.1 μg kg-1) values than the HF-LPME technique (66.1 -198.1 μg kg-1) and (92.7 -331.2 μg kg-1), respectively. Despite this, values closer to 100% were obtained with the EME technique. A higher analytical frequency was achieved with the EME technique (4 extractions/h) compared to HF-LPME (2 extractions/h). Regarding green chemistry aspects, due to the use of external energy, the methodology proposed by EME showed significant energy consumption. Finally, Chapter IV presented a detailed study of the influence of parameters involved in the on-chip electromembrane extraction technique of the pesticides Carbofuran and Carbendazim in river water samples. This chapter focused on two main aspects: (I)the optimization of the device to reduce leakage during extraction, as it is a disadvantage of the conventional system, and (II)evaluating the differences in the extraction of ionizable and neutral compounds by the on-chip electromembrane extraction system. The optimization of the device introduced the OSTE sealing material as an approach to prevent leaks, allowing for the use of flow rates of 300 μl/min-1 without observing leaks. The evaluation of the parameters involved in the technique showed the dependence of the physicochemical characteristics of the pesticides on the pro-posed system, revealing the extraction of the pesticides in their charged and neutral forms. The analytical evaluation of the method showed LOD and LOQ values ranging from 158.4 to 256.2 μg L-1and 528.1 to 854.1 μg L-1, respectively, and recovery values ranging from 26.3% to 53.8%, indicating an influence of the matrix that was confirmed by the matrix effect study. The study of the pesticides Carbaryl and Carbendazim proved to be an important approach to further expand the field of applications of the on-chip electromembrane extraction technique. The methods described here have proven to be effective analytical strategies for assessing pesticides in en-vironmental samples. The development of the methodologies presented here further expands the possibilities for monitoring pesticides in such complex samples as environmental ones. The application of the proposed methodologies offers a possible strategy for evaluating the effects of these compounds on the environment and proposing ways to identify contaminants in differ-ent environmental compartments.
Fixação química de CO2 em epóxidos para a produção de carbonatos cíclicos utilizando-se catalisadores metaloporfirínicos
(Universidade Federal de Goiás, 2024-06-27) Mata, Álvaro Farias Arruda da; Martins, Dayse Carvalho da Silva; http://lattes.cnpq.br/3157693434749669; Rafael Pavão Das Chagas, Rafael Pavão Das Chagas; http://lattes.cnpq.br/9712618482518275; Chagas, Rafael Pavão das; http://lattes.cnpq.br/9712618482518275; Oliveira, Cecília Maria Alves de; http://lattes.cnpq.br/3152041311943092; Batista, Alzir Azevedo; http://lattes.cnpq.br/6469642481998660; Silva Filho, Juvenal Carolino da; http://lattes.cnpq.br/1223323473808888; Andrade, Fabiano Molinos de; http://lattes.cnpq.br/8880807687863294
Growing concern over significant increases in anthropogenic carbon dioxide (CO2) levels in the atmosphere, along with the dependence on finite fossil carbon resources for the production of high-value-added molecules, has driven research into the catalytic conversion of CO2. CO2 data from the Mauna Loa Observatory, an atmospheric reference station located in Hawaii, show rising monthly concentrations, reaching about 421 ppm in 2023, with projections of 450 ppm by 2030 and 540-970 ppm in the next century. Although CO2 is used in various sectors of the chemical industry, its application in fine chemistry is limited, indicating the need to explore technologies for its sustainable utilization. CO2 is considered a promising carbon source due to its abundance, renewability, and economic accessibility. Recent research has focused on its conversion into high-value-added products such as alcohols, amines, carboxylic acids, and carbonates. Replacing phosgene with CO2 in the synthesis of organic carbonates represents a significant advance, not only economically but also environmentally. The cycloaddition reaction between CO2 and epoxides to form cyclic carbonates is a process of interest, with various industrial applications. Metal catalysts with porphyrinic ligands have demonstrated efficiency in this process, standing out due to their high activity and selectivity. Macrocyclic ligands, such as porphyrins, have been widely investigated due to their versatility and robustness, proving promising for this application. In this study, the synthesis of six metalloporphyrin complexes and the selective production of cyclic carbonates through cycloaddition reactions between CO2 and epoxides are presented. A theoretical kinetic study was conducted, enabling the determination of an activation energy of 39.76 KJ mol-1 and the thermodynamic parameters in the intermediate states of the cycloaddition reaction of CO2 and styrene oxide. High-resolution mass spectrometry allowed the determination of the activation intermediate of the CO2 cycloaddition, where two styrene oxide molecules are simultaneously activated by one catalyst molecule. Catalysts based on porphyrins, coordinated with metals such as zinc, manganese, and copper, showed efficacy in this process. The continuous development of efficient catalysts and IV the understanding of the mechanisms involved are essential to advance the catalytic conversion of CO2 into high-value-added products
Síntese de tri-heterociclos pentadienos e estudo de suas propriedades luminescentes
(Universidade Federal de Goiás, 2023-05-09) Matos, Gabriela Ferreira; Kato, Lucilia; http://lattes.cnpq.br/1362891438631386; Kato, Lucilia; Coelho, Felipe Lange; Barros, Olga Soares do Rego; Gonçalves, Pablo José; Santos Neto, José Sebastião dos
This study presents the synthesis of diois (1-4(a-h) and 5, Scheme 1), building blocks commonly used in designing and preparing heteroporphyrins. The synthesis of compounds 1 and 2 has been largely reported in the literature. On the other hand, there are few or no examples of synthetic routes for chalcogen-heteroaryl-substituted compounds such as 3 and 4 (Scheme 1), which constitutes a great challenge. Among the obtained products, thirty-seven molecules are new: five diols, thirty triheteropentadienylmethanes and two porphyrins. Chemical and structural characterization of the compounds 1-4(a-h), 5a and 6 were confirmed through a variety of analytical and spectroscopic techniques: High-Resolution Mass Spectrometry (HRMS), Nuclear Magnetic Resonance (NMR) by 1D and 2D, IR and UV spectroscopy. In addition, X-ray quality single-crystals of 3a allowed the determination of its relative stereochemistry as being (-)-RR-2,5-bis((4-methoxyphenyl)(thiophen-2yl)methyl)thiophene or (-)-SS-2,5-bis((4-methoxyphenyl)(thiophen-2-yl)methyl)thiophene. Unexpected fluorescence emission was observed when compounds triheteropentadienylmethanes were exposed to UV radiation, as shown in Figure 1. The photophysical studies of compounds 2a and 3a revealed a similar absorption profile, with the absorption bands in the violet-to-blue region (between 440-470 nm). Moreover, neither the distinct solvents (ACN, Dioxane, EtOH and CH2Cl2) nor the aryl-substituents (R, Scheme 1) nor the heteroatom (X, Scheme 1) affect significantly the HOMO-LUMO transition energy. In 2a, there is a dependence of the emission wavelength with the excitation wavelength. This fact may indicate that these compounds are examples of molecules exhibiting the non-traditional intrinsic luminescence phenomena.
Development of disposable microfluidic devices for bioanalytical applications
(Universidade Federal de Goiás, 2024-11-21) Mendes, Geovana de Melo; Duarte, Gabriela Rodrigues Mendes; http://lattes.cnpq.br/9005971441891787; Varenne, Anne; Duarte, Doutora Gabriela Rodrigues Mendes; Coltro, Wendell Karlos Tomazelli; Silva, José Alberto Fracassi da; Varenne, Anne; Lunte, Susan
This thesis was conducted as part of a joint supervision between the Universidade Federal de Goiás (Goiânia, Brazil) and Chimie ParisTech PSL. Initiated in Brazil at the onset of the pandemic, the work developed during the Ph.D. at the Brazilian institution focused on developing LAMP-based methodologies for COVID-19 diagnosis. Loop-mediated isothermal amplification (RT-LAMP) was used to create a simple and low-cost test during the COVID-19 pandemic. This test was implemented at the point of care in an overwhelmed hospital where standard tests were not feasible, providing rapid and accurate diagnoses. Additionally, we proposed a non-invasive tracking method based on RNA extracted from the saliva of essential workers during the pandemic, which proved practical and effective for frequent testing. The preliminary transposition of this methodology to a paper-based platform showed promising results for realtime monitoring of infections, particularly SARS-CoV-2, at the point of care. Within the scope of the cotutella, subsequent work was carried out in the French laboratory to develop and optimize a paper-based platform for protein isoelectric focusing, aiming to integrate proteomic analysis steps into a microdevice. In this thesis, we developed diagnostic systems for biomolecules applied or applicable at the point of care. For protein analysis, isoelectric focusing on a paper-based platform allowed precise and reproducible protein separation, including in real samples, with acceptable resolution and efficiency. This system represents a significant step forward in a broader project aimed at integrating all proteomic steps into a single chip. The successful development of biomolecule analysis methods prioritizing cost-effectiveness, speed, and simplicity highlights the potential of paper as a platform for these diagnostic tests. Paper proved to be a suitable and accessible platform for conducting these tests, emphasizing its potential in resource-limited settings.
Sensores miniaturizados para COVID-19 e paracetamol: uma abordagem simples e de baixo-custo
(Universidade Federal de Goiás, 2024-10-09) Moreira, Nikaele Sousa; Coltro, Wendell Karlos Tomazelli; http://lattes.cnpq.br/8302650734477213; Coltro, Wendell Karlos Tomazelli; Souza , Endler Marcel Borges de; Pedrino, Gustavo Rodrigues; Meloni, Gabriel Negrão; Chaves, Andrea Rodrigues
This work describes the development of miniaturized sensors on accessible and low-cost substrates to detect the spike protein (S) of the SARS-CoV-2 virus and paracetamol in whiskey samples. Protein S is a marker associated with COVID-19, which is present on the external part of the virus and has an affinity with the human angiotensin-converting enzyme 2 (hACE2), allowing the infection of human cells. Therefore, its detection is of great importance for an early diagnosis of the disease. In this context, polyester microplates were developed for the colorimetric detection of this protein in biological samples based on a direct ELISA assay for rapid detection and with less use of reagents, in addition to good clinical accuracy. A linear range was obtained in protein S concentrations of 0-10 μg mL-1, with a coefficient of determination (R2) equal to 0.991 and a limit of detection 0.44 μg mL-1. The proposed methodology revealed satisfactory intraplate and interplate repeatability with standard deviation values below 7.7%. Thirty-seven saliva and swab samples from positive and negative patients were evaluated for the presence of the virus. The results were consistent with the RT-PCR method, showing 100% sensitivity and 85.71% specificity for saliva samples. For nasopharyngeal samples, sensitivity was 90% and specificity was 100%. In addition, it revealed diagnostic accuracy above 94%, indicating that the proposed method can predict more than 94% of the samples correctly. Adulteration of whiskey is a common practice in nightclubs due to the high cost of these original drinks. Counterfeiters often add medications or pharmaceuticals to mask the effects of a hangover, for example, paracetamol, as it is an over-the-counter analgesic indicated for the treatment of headaches. Therefore, distance-based detection of paracetamol in whiskey samples using a paper-based microfluidic analytical device (μPAD) is imperative since the use of paper substrate offers excellent benefits, such as accessibility, portability, and the ability to detect paracetamol without expensive instrumentation. Optimal detection conditions were achieved by introducing 5 μL of a mixture containing 7.5 mmol L-1 of Fe(III) and K3[Fe(CN)6] into the detection zone, together with 12 μL of whiskey samples into the sample zone. The method showed linear behavior in the 15 to 120 mg L-1 concentration range, with R2 equal to 0.998. Paracetamol was quantified in spiked samples using the proposed method, and the results were compared with those of a spectrometric method. No significant differences were observed at the 95% confidence level. The method determined approximately 1 drop of the drug paracetamol of 200 mg mL-1 in 1 L of solution, demonstrating excellent sensitivity. Therefore, the proposed methods are alternatives for practical, simple and economical analyses and reduce the consumption of samples, reagents and waste. Then, they have great potential to be used in the field for clinical applications in diagnosing COVID-19 and forensic applications for detecting paracetamol in beverages.
Peptideos antimicrobianos IDR 1002 e TS-MAP1: Ressonância Magnética Nuclear para determinação das estruturas tridimensionais
(Universidade Federal de Goiás, 2024-12-17) Mundim, Higor de Moraes; Lião, Luciano Morais; http://lattes.cnpq.br/2647529909397336; Lião, Luciano Morais; http://lattes.cnpq.br/2647529909397336; Bataus, Luiz Artur Mendes; http://lattes.cnpq.br/5637230378599476; Campos, Ivan Torres Nicolau de; http://lattes.cnpq.br/5450204304438682; Apparecido, Rafael do Prado; http://lattes.cnpq.br/8919390126756314; Santos Neto, José Sebastião dos; http://lattes.cnpq.br/5538841038654451
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