The chemical composition of Acacia mearnsii wood extract is described in this paper for the first time. This wood is cultivated in Brazil and has been used to complement the demand for hardwood in the pulp industry. In this study, we performed extractions with acetone (total extracts) and dichloromethane (lipophilic extracts responsible for the pitch formation), with the obtained percentages being 1.68 and 0.68%, respectively. The lipophilic extracts were derivatized and analyzed by Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC-MS) before and after alkaline hydrolysis. The results showed that 57 compounds were detected in the lipophilic extracts and these are mainly constituted by fatty acids ca. 32.8 mg kg-1 and sterols 26.9 mg kg-1. These chemical classes have always been present in pitch deposits in the pulp industry. Therefore, these results may be used by pulp mills to establish strategies for pitch control and represent an important advance in the knowledge of A. mearnsii.

In this work, semi-empirical AM1 and DFT B3LYP/6-31G** calculations were applied in the study of the interconversion among tautomers of several naphthazarin and 5-amino-8-hydroxy-1,4-naphthoquinone β-substituted derivatives bearing electron-donor or electron-withdrawing groups. Using a semi-empirical method, detailed potential energy landscapes for proton transfers were built, from which four tautomers and four transition states of interconversions were identified for each compound. These structures were recalculated without restraints and, using the Boltzmann distribution, the populations for each of the four tautomers and their respective molar fractions were calculated. The calculations showed that the tautomeric equilibrium is shifted to the tautomer where the ring with the substituent has a quinonic nature and is more pronounced when the β-substituent is an electron donor group. For derivatives of 5-amino-8-hydroxy-1,4-naphthoquinone, an equilibrium between an aromatic and a 1,5-naphthoquinonic non-aromatic enamine was observed, being the former the most stable.

Tannins from trees are an abundant renewable resource. The use of tannins is safe for the environment and human health, making it possible to develop environmentally friendly products, such as adhesives, flocculant agents for water treatment, flame retardant foams and anticorrosives. In this study, a methodology was developed for the identification of six commercial tannin extracts (chestnut, valonea, tara, myrobalan, quebracho and black wattle) using digital images on mobile devices. The identification of the extracts was based on principal component analysis using the PhotoMetrix® mobile application. In the evaluation of the principal components, it was possible to define the separation between the six classes of extracts by color evaluation, according to the extract origin. In the analysis of PC1 × PC2, black wattle was very close to quebracho and chestnut was close to valonea; these extracts are chemically similar. The methodology developed for the analysis of tannin extracts obeys the principles of green chemistry requiring no reagents, and is fast, non-destructive and inexpensive.

In this work, the synthesis, characterization and photophysical study of new derivatives of triazinyl-benzazoles with fluorescence by excited-state intramolecular proton transfer (ESIPT) are presented. It regards the synthesis of cyanuric chloride with different 2-(2’-hydroxyphenyl) benzazoles, two quite attractive groups from the synthetic and technological point of view. These new compounds have several potential applications such as biological markers and new photoluminescent materials. The derivatives were characterized by 1H and 13C nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), high-resolution mass spectrometry (HRMS), UV-Vis absorption and fluorescence emission. The dyes are fluorescent by an excited-state ESIPT in the blue-orange region, with a large Stokes’ shift.

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.