The nature of binding between bovine serum albumin (BSA) and the antidepressant tianeptine and a new series of esters derivatives were studied in this paper. The interactions with BSA were investigated by UV-Vis and fluorescence spectroscopy at three different temperatures. The fluorescence quenching experiments showed that BSA interactions with tianeptine could be dynamic while to its esters a static mechanism was observed. The results showed that tianeptine quenches the intrinsic fluorescence of BSA more efficiently than its esters due to the presence of the free acid portion. The number of binding sites determined by fluorescence spectroscopy is approximately equal to 1 indicating that there is one binding site between BSA tianeptine esters, but the presence of a second interaction site for tianeptine at higher temperatures could be not ruled out. Molecular docking calculations point out a strong affinity of tianeptine and its esters to the site IIA of protein, supporting the hypothesis of a static quenching mechanism.

This study aimed to analyze the contribution of the methodology of Case Studies to the development of conceptual, procedural and attitudinal contents inherent to the future professionals of Chemistry. In this sense, Cases on Carbohydrate Chemistry were elaborated to be solved by the students who studied the discipline of Organic Chemistry of Biomolecules of UFRGS. This research has a qualitative nature and it is a Case Study. For the data collection we used the Field Diary where the events were recorded along the activities developed through Participant Observation, audio recordings and the material produced by the participants as reports and presentations. In order to understand the students' perceptions about the activities, we used questionnaires with open questions and likert type. For the analysis of the data obtained were analyzed through coding categories, these elaborated using the guidelines of Bogdan and Biklen. According to the data analysis, the teaching methodology contributed to the development of knowledge related to the conceptual contents of carbohydrates, procedural contents such as oral and written argumentation, and attitudinal contents such as the investigative spirit.

Uma série de cristais líquidos derivados de ésteres arilaldoximas foi sintetizada e caracterizada via espectroscopia de ¹H, 13C RMN, ATR/IV-FT e análise elementar. A estabilidade química e fotofísica desses compostos foram dependentes dos ciclos de aquecimento e resfriamento, com a decomposição sendo induzida pelo calor. As mudanças nas propriedades durante os ciclos de aquecimento foram acompanhadas através dos respectivos espectros de infravermelho. Todas as amostras se decompõem termicamente, gerando as respectivas nitrilas e ácidos carboxílicos como evidenciado pelos espectros de infravermelho e de ¹H NMR. As propriedades mesomórficas foram avaliadas apenas no primeiro ciclo de aquecimento, devido à decomposição térmica observada após a primeira transição para o estado isotrópico. Espectros de absorção em solventes orgânicos apresentam três bandas entre 230 e 340 nm, e uma banda de emissão, larga e sem estrutura, em 430 nm. Cálculos teóricos ab initio foram realizados para a obtenção de informações estruturais dos ésteres arilaldoximas.

We report the synthesis of a series of liquid-crystalline materials based on arylaldoxime esters and the characterization of these materials by ¹H, 13C NMR, ATR/FT-IR spectroscopy and elemental analysis. The chemical stability and liquid-crystalline as well as photophysical properties of the compounds are described being dependent on the heating/cooling cycles. The changes in chemical stability and the liquid crystals properties of arylaldoxime esters were observed during these thermal cycles by IR analysis. All samples underwent a thermal degradation yielding the corresponding nitriles and carboxylic acid as evidenced by IR and ¹H NMR spectra. Due to the decomposition process, information about the mesomorphic behaviour is lost. The UV-Vis absorption spectra in solution display three absorption bands between 230 and 340 nm. The fluorescence spectra exhibit a broad and structureless emission band located at 430 nm. Ab initio calculations were performed to obtain information on the molecular structure and properties of the title compounds.

Uma série de quatro compostos fotoativos derivados da triazina foi obtida a partir da substituição nucleofílica aromática no cloreto cianúrico. Os compostos foram caracterizados por espectroscopia de infravermelho (IR) e ressonância magnética nuclear (NMR de ¹H e 13C), além de espectrometria de massas de alta resolução (HRMS MALDI). A espectroscopia de absorção na região do UV-Vis e a emissão de fluorescência (no estado sólido e em solução) foram também utilizadas para estudar o comportamento fotofísico destes compostos. Os derivados obtidos são fluorescentes na região do azul-laranja por um mecanismo de transferência protônica intramolecular no estado excitado e apresentam um grande deslocamento de Stokes (6365-10290 cm-1). Os derivados sintetizados neste trabalho reagiram com sucesso com fibras de celulose para dar novos compostos celulósicos fluorescentes.

Four new reactive fluorescent triazine derivatives were obtained from nucleophilic aromatic substitution of cyanuric chloride. The compounds were characterized by infrared spectroscopy (IR), nuclear magnetic resonance (13C and ¹H NMR) and high resolution mass spectrometry (HRMS MALDI). UV-Vis and steady-state fluorescence (in solution and in solid state) spectroscopies were also applied to characterize the photophysical behavior. The dyes are fluorescent by an intramolecular proton transfer mechanism (ESIPT) in the blue-orange region, with a large Stokes shift between 6365-10290 cm-1. The fluorescent cyanuric derivatives could successfully react with cellulose fibers to give new fluorescent cellulosic materials.