Centro UTN QUITEX - Difusión Científica - Artículos de Revista

Permanent URI for this collectionhttp://48.217.138.120/handle/20.500.12272/3851

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Start date: 2019End date: 2019

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    Impact of confinement in multimolecular inclusion compounds of melamine and cyanuric acid
    (2019-02-25) Petelski, Andre Nicolai; Pamies, Silvana Carina; Sejas, Agustín Gabriel; Peruchena, Nélida María; Sosa, Gladis Laura
    Supramolecular cavities can be found in clathrates and self-assembling capsules. In these computational experiments, we studiedthe effect of folding planar hydrogen-bonded supramolecules of melamine (M) and cyanuric acid (CA) intostablecage-like quartets. Based on dispersion-corrected density functional theory calculations at the wB97XD/6-311++G(d,p) level, we show the flexibility of M and CA molecules to form free confined spaces. Our bonding analysis indicatesthat only CA can form a cage which is more stable than their planar systems. We then studied the capacity of the complexes to host ionic and neutral monoatomic species like Na+, Cl-and Ar. The encapsulation energies range from -2 to -65 kcal mol-1. A detailed energy decomposition analysis (EDA) support the fact that the triazine ring of CA is superior to the M one to capture chloride ions. In addition, the EDA and the topology of the electron density, by means of the Atoms in Molecules (AIM) theory and electrostatic potential maps, reveal the nature of the host-guest interactions in the confined space. The CA cluster appears to be the best multimolecular inclusion compound because it can host the three species by keeping its cage structure, and therefore could also act as a dual receptor of the ionic pair Na+Cl-. We think these findings could inspire the design of new heteromolecular inclusion compounds based on triazines and hydrogen bonds.
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    Hydrothermal treatment to remove tannins in wholegrains sorghum, milled grains and flour
    (2019-10-30) Acquisgrana, María del Rosario; Gómez Pamies, Laura Cecilia; Benítez, Elisa Inés
    Pigmented sorghum with high content of tannins were studied in this work. Tannins bind to proteins and reduce their availability. A hydrothermal treatment was carried out to reduce tannins. A control sample of non-pigmented pericarp variety was used. After the treatment, grains were milled, and a part was separated for wholegrain flour elaboration. Several determinations were done after treatment: tannins (T), total antioxidant capacity (TAC) and total polyphenols (TPP) content. TPP and TAC in wholegrain pigmented sorghum were 3.9 to 12.3 and 2.3 to 3.5 times higher than those of non-pigmentedsorghum, respectively. In all sorghum varieties the extractions of TPP decreased with milling. TAC in flour increased 3.3 times the initial value for non-pigmentedsorghum, whereas for the other sorghum samples it increased slightly from 1.1 to 1.3 times the initial value. In flours there was a noticeable reduction in T, with respect to the wholegrain. It was possible to conclude that the hydrothermal treatment allowed lower levels of tannins than those established in the Codex for both wholegrain sorghum and flour. This reduction makes it possible to obtain flour which may be suitable for food processing and the recovery of tannins for other uses.
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    Designing self-assembled rosettes : why ammelineis a superior building block to melamine
    (2019-02-01) Petelski, Andre Nicolai; Fonseca Guerra, Célia
    In supramolecular chemistry, the rational design of self-assembled systems remains a challenge. Herein, hydrogen-bonded rosettes of melamine and ammeline have been theoretically examined by using dispersion-corrected density functional theory (DFT-D). Our bonding analyses, based on quantitative Kohn Sham molecular orbital theory and corresponding energy decomposition analyses (EDA), show that ammeline is a much better building block than melamine for the fabrication of cyclic complexes based on hydrogen bonds. This superior capacity is explained by both stronger hydrogen bonding and the occurrence of a strong synergy.