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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Item Designing self-assembled rosettes : why ammelineis a superior building block to melamine(2019-02-01) Petelski, Andre Nicolai; Fonseca Guerra, CéliaIn 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.Item 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 LauraSupramolecular 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.Item 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 InésPigmented 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.Item Impact of moisture and grinding on yield, physical, chemical and thermal properties of wholegrain flour obtained from hydrothermally treated sorghum grains(2020-02-03) Acquisgrana, María del Rosario; Gómez Pamies, Laura Cecilia; Martinez Amezaga, Nancy María Jimena; Quiroga, Fernanda Micaela; Ribotta, Pablo Daniel; Benítez, Elisa InésThe present work evaluates the potential of sorghum with high content of tannins for wholegrain flour production. Two types of mills were used: a roller mill (RM) and a blade (BM) mill. The impact of moisture and grinding on yield, physical, chemical and thermal properties were evaluated. Maximum yield was obtained using a BM with 25% moisture in the grain, resulting in 60.9% versus 28% (g flour g -1 wholegrain sorghum) for the RM. Grain moisture and milling type affected flour colour and ashes. For both mills, the pasting and thermal properties of flour with grain moisture variation were significantly different from the untreated control sample. By studying the procedures for flour production and quality characteristics, it is possible to produce flour with good physical attributes, which can contribute to the development of gluten-free foods based on sorghum for the coeliac population.Item Understanding the chloride affinity of barbiturates for anion receptor design(2021-02-25) Petelski, Andre Nicolai; Márquez, María Josefina; Pamies, Silvana Carina; Sosa, Gladis Laura; Peruchena, Nélida MaríaDue to their potential binding sites, barbituric acid (BA) and its derivatives have been used in metal coordination chemistry. Yet their abilities to recognize anions remain unexplored. In this work, we were able to identify four structural features of barbiturates that are responsible for a certain anion affinity. The set of coordination interactions can be finely tuned with covalent decorations at the methylene group. DFT-D computations at the BLYP-D3(BJ)/aug-cc-pVDZ level of theory show that the C—H bond is as effective as the N—H bond to coordinate chloride. An analysis of the electron charge density at the C—H···Cl— and N—H···Cl— bond critical points elucidates their similarities in covalent character. Our results reveal that the special acidity of the C—H bond shows up when the methylene group moves out of the ring plane and it is mainly governed by the orbital interaction energy. The amide and carboxyl groups are the best choices to coordinate the ion when they act together with the C—H bond. We finally show how can we use this information to rationally improve the recognition capability of a small cage-like complex that is able to coordinate NaCl.Item How procyanidin C1 sticks to collagen : the role of proline rings(2021-05-29) Petelski, Andre Nicolai; Pamies, Silvana Carina; Sosa, Gladis LauraMolecular interactions between proteins and polyphenols are responsible for many natural phenomena like colloidal turbidity, astringency, denaturation of enzymes and leather tanning. Although these phenomena are well known, there are open questions about the specific interactions involved in the complexation process. In this work, Molecular Dynamic (MD) simulations and the topology of the electron density analysis were used to study the interactions between the flavonoid procyanidin C1 and a collagen fragment solvated in water. Root mean square deviation; root mean square fluctuation and hydrogen bonds occupancy were examined after 50 ns. The interactions were also analyzed by means of the quantum theory of atoms in molecules. Our results show that the main interactions are hydrogen bonds between –OH groups of the polyphenol and C––O groups of the peptide bond. Stacking interactions between proline rings and phenol rings, that is C–H⋯π hydrogen bonds, also stabilize the dynamic structure of the complex.Item The impact of pirodextrin addition to improve physicochemical parameters of sorghum beer(2021-06-28) Goméz Pamies, Laura Cecilia; Lataza Rovaletti, María Mercedes; Martinez Amezaga, Nancy María Jimena; Benítez, Elisa InésThe traditional sorghum beer brewed by African communities differs from the traditional beer obtained from barley, mainly in the absence of hops and in a higher acidity level. People diagnosed with celiac disease find it as an alternative option when enjoying a good beer; however, some of the technological differences could be improved with the use of pyrodextrins obtained from the same cereal. In this work the use of pyrodextrins obtained by a treatment at 120 ◦C with acid during 360 min is proposed. A composite central design was made varying the concentration of pyrodextrins between 5 and 15 g/L and hop between 30 and 60 mg/L. The results indicate that the use of pyrodextrins up to a concentration of 10 g/L improves α-acid utilisation, bitterness and viscosity of the drink, achieving values similar to a typical lager beer obtained from barley. For 10 g/L pyrodextrin addition the increase in the wort and beer viscosity was 4.4% and 4.9%, respectively.Item Impact of sorghum grain processing on morphological characteristics of particles of wholegrain sorghum flour(2021-07-09) Acquisgrana, María del Rosario; Goméz Pamies, Laura Cecilia; Quiroga, Fernanda; Ribotta, Pablo Daniel; Benítez, Elisa InésThis work studies the physical characteristics of sorghum whole flour particles produced with grains reduced in tannins by hydrothermal treatment. Flours ground with two types of mills: a roll mill and a blade mill were used; grains were hydrated with a moisture content of 25%. For this moisture the maximum yield was obtained. The effect of the grain moisture during the grinding was evaluated regarding the morphological characteristics, the granulometry and fractal dimension (Df) of particles. In all the analysed samples, bimodal size distribution curves were obtained. The treated samples showed medium size particles bigger than the samples without treatment. The samples without hydrothermal treatment presented particles with lower damage than the treated samples for both mills. The difference in Df between samples indicated more roughness for the samples with treatment. The proposed treatment could contribute to the development of sorghum whole flour with different properties for the development of gluten-free food.Item Impact of covalent modifications on the hydrogen bond strengths in diaminotriazine supramolecules(2022-04-14) Petelski, Andre Nicolai; Pamies, Silvana Carina; Márquez, María Josefina; Peruchena, Nélida María; Sosa, Gladis LauraMelamine (M) is a popular triamine triazine compound in the field of supramolecular materials. In this work, we have computationally investigated how substituents can be exploited to improve the binding strength of M supramolecules. Two types of covalent modifications were studied: the substitution of an H atom within an amine group NHR, and the replacement of the whole NH2 group (R=H, F, CH3 and COCH3). Through our dispersion-corrected density functional theory computations, we explain which covalent modification will show the best self-assembling capabilities, and why the binding energy is enhanced. Our charge density and molecular orbital analyses indicate that the best substituents are those that generate a charge accumulation on the endocyclic N atom, providing an improvement of the electrostatic attraction. At the same time the substituent assists the main N H···N hydrogen bonds by interacting with the amino group of the other monomer. We also show how the selected group notably boosts the strength of hexameric rosettes. This research, therefore, provides molecular tools for the rational design of emerging materials based on uneven hydrogen-bonded arrangements.Item Understanding the influence of alkali cations and halogen anions on the cooperativity of cyclic hydrogen-bonded rosettes in supramolecular stacks(2022-11-07) Petelski, Andre Nicolai; Fonseca Guerra, CéliaHydrogen-bonded supramolecular systems are known to obtain extra stabilization from the complexation with ions, like guanine quadruplex (GQ). They experience strong hydrogen bonds due to cooperative effects. To gain deeper understanding of the interplay between ions and hydrogen-bonding cooperativity, relativistic dispersion-cor rected density functional theory (DFT-D) computations were performed on triple layer hydrogen-bonded rosettes of ammeline interacting with alkali metal cations and halides. Our results show that when ions are placed between the stacks, the hydrogen bonds are weakened but, at the same time, the cooperativity is strengthened. This phenomenon can be traced back to the shrinkage of the cavity as the ions pull the monomers closer together and therefore the distance between the monomers becomes smaller. On one hand this results in a larger steric repulsion, but on the other hand, the donor-acceptor interactions are enhanced due to the larger overlap between the donating and accepting orbitals leading to more charge donation and therefore an enhanced electrostatic attraction.Item Nature and strength of weak O···O interactions in nitryl halide dimers(2022-12-14) Petelski, Andre Nicolai; Duarte, Darío Jorge Roberto; Peruchena, Nélida MaríaThe use of real space functions and molecular graphs has pushed some chemists to wonder: Are interactions between negatively charged oxygen atoms possible? In this contribution we analyze whether there is a real interaction between oxygen atoms in nitryl halide dimers (XNO2)2 (X=F, Cl, Br and I) and in tetranitromethane and derivatives. Based on ab-initio and density functional theories (DFT) methods, we show these complexes are weakly stabilized. Energy decomposition analy ses based on local molecular orbitals (LMOEDA) and interacting quantum atoms (IQA) reveal both dispersion and exchange play a crucial role in the stabilization of these complexes. Electron charge density and IQA analyses indicate that the oxygen atoms are connected by privileged exchange channels. In addition, electrostatic interactions between O and N atoms are also vital for the stabilization of the complexes. Finally, a reasonable explanation is given for the dynamic behavior of nitryl groups in tetranitromethane and derivatives.Item Acidity of isomorphic substituted zeolites with B, Al and Ga revisited(2024-02-13) Petelski, Andre Nicolai; Peruchena, Nélida María; Zalazar, María FernandaEn este trabajo se analiza cómo afecta a a la acidez la sustitución de átomos de Silicio por átomos de Boro, Aluminio y Galio en tres tipos de zeolitas microporosas: BEA, FAU y MOR.Item Augmentation of inductive effects through short range intramolecular hydrogen bonds for the improvement of cooperativity of trimeric rosettes(2024-02-26) Petelski, Andre Nicolai; Bundrea, Tamara; Peruchena, Nélida MaríaThree key design elements improve the binding strength of trimeric rosettes: the direction of hydrogen bonds, the addition of groups with inductive effects, and the presence of ambifunctional intramolecular hydrogen bonds between the substituents.Item Improving craft beer style classification through physicochemical determination and the application of deep learning techniques(2024-04-09) Gómez Pamies, Laura Cecilia; Bianchi, María Agostina; Farco, Andrea Paola; Vázquez, Raimundo Damián; Benítez, Elisa InésThe consumption of craft beer at fairs and festivals is a phenomenon that keeps growing in the world. For this reason, it is important to control the quality characteristics of the different styles. This study aimed to analyze the different styles of beer, classify them according to their physicochemical parameters, and propose a predictive pattern-based model known as deep learning that best defines the styles that are presented at festivals. Physicochemical analyses of final gravity, color, alcohol, bitterness, and α-acids were carried out on eight styles of beer. The first four parameters are those that characterize the styles according to the Beer Judge Certification Program style guide. The incorporation of the α-acid determination allowed a more realistic classification that considers the brewers’ new tendencies. This study will lay the foundations to improve local recipes, implement standardization, and provide training to local brewers