The Interaction Strength, Frequency-shifts and Covalence of the C2H4O∙∙∙HOCl and C2H5N∙∙∙HOCl Heterocyclic Complexes

A theoretical study of the structural parameters, electronic properties and vibration modes of the C2H4O∙∙∙HOCl and C2H5N∙∙∙HOCl complexes. The great particularity of these complexes is the O–Cl s-hole, which is considered a proton donor center due to the depletion of charge density along the bonding axis. The examination of the interaction strength complexes was conducted through the intermolecular length, interaction energy and charge transference. The red shifts in the stretch frequencies of the H–O and O–Cl bonds as well as the identification of the new vibration modes were also presented.  Regarding the hybrid orbitals, the contributions of the s and p orbitals were used to value the red shifts in the H–O and O–Cl bonds. The covalence of the O∙∙∙H and N∙∙∙H hydrogen bonds was also examined. DOI: http://dx.doi.org/10.17807/orbital.v9i2.85

II Chemistry Conference of West Bahia

The II Chemistry Conference of West Bahia, also well-known as II JornaQui [1], it has become a traditional regional event in the state of Bahia. It was conceived with a proposal on behalf of the Núcleo de Ensino, Pesquisa e Extensão de Química (NEPEQ) of the Universidade Federal do Oeste da Bahia (UFOB) in order to improve the quality of the researches in chemistry of the west Bahia. This special issue brings a bit of works presented as poster along the II JornaQui, although henceforth, they were selected as full manuscripts for editorial evaluation. As can be seen, this special issue presents researches on theoretical chemistry with application of computational calculations for intermolecular systems, biological evaluations of nature compounds, determination of physical chemistry parameters of water used for agriculture, studies of inorganic compounds on rice husk produced in west region, as well as a full and brief overview of the pesticides used in this regard. Boaz Galdino de Oliveira (UFOB) Chairman  [1]          Conference website: http://jornaqui.ufob.edu.br/</p

I Chemistry Conference of West Bahia

The I Chemistry Conference of West Bahia [1] is an event carried out by the Núcleo de Ensino, Pesquisa e Extensão de Química (NEPEQ), and aims to disseminate chemical researches developed on the Universidade Federal do Oeste da Bahia (UFOB) at undergraduate level as well as on the master’s program. This special issue contains some of works presented throughout the JornaQui, such as those from analytical chemistry, natural products, theoretical chemistry, medicinal chemistry, chemistry teaching, spectroscopy, materials science, catalysis and photochemistry. In this context, we would like to highlight the researches of bioactive compounds is by molecular modeling or phytochemistry, studies of intermolecular systems in the infrared spectrum, environmental monitoring by using experimental techniques, new nanocompounds characterized by X-ray diffraction, photochemical degradation organic material, for example. DOI: http://dx.doi.org/10.17807/orbital.v1i1.844</p

Um Estudo Químico-quântico da Covalência Intermolecular em Sistemas Estabilizados por Ligações de Hidrogênio π∙∙∙H e N∙∙∙H: Cálculos DFT, ChelpG, NBO e QTAIM

In this work, density functional calculations at BHandHLYP/6-311++G(d,p) theoretical level of structural parameters, electronic properties and vibration modes of the C2H2∙∙∙HCN∙∙∙HF and C2H4∙∙∙HCN∙∙∙HF T-shaped hydrogen complexes is presented. As is well-known, the formation of these complexes is ruled by weak and strong hydrogen bonds recognized as p∙∙∙H and N∙∙∙H, respectively. In line with this interaction strength, a correlation between the structural modifications and frequency shifts was investigated, although the non-covalent character of these complexes has been unveiled through the QTAIM calculations. The absorption intensity ratios of the proton donors correlate well with the charge transfer amounts, whose values were computed through the ChelpG approach. Even by taking into account the cooperative profile of these systems, the hydrogen bond energies were determined, and actually, the values are unapproachable to be distributed in different moieties, such as punctual strong hydrogen bonds possessing covalent character, if exist. At last, the NBO calculations were applied to compute the&nbsp;s- and&nbsp;p-contributions on the hybrid orbitals in order to explain the frequency shifts on the H–C and H–F proton donor bonds. DOI:&nbsp;http://dx.doi.org/10.17807/orbital.v1i1.70

Um Estudo Químico-quântico da Covalência Intermolecular em Sistemas Estabilizados por Ligações de Hidrogênio π∙∙∙H e N∙∙∙H: Cálculos DFT, ChelpG, NBO e QTAIM

In this work, density functional calculations at BHandHLYP/6-311++G(d,p) theoretical level of structural parameters, electronic properties and vibration modes of the C2H2∙∙∙HCN∙∙∙HF and C2H4∙∙∙HCN∙∙∙HF T-shaped hydrogen complexes is presented. As is well-known, the formation of these complexes is ruled by weak and strong hydrogen bonds recognized as p∙∙∙H and N∙∙∙H, respectively. In line with this interaction strength, a correlation between the structural modifications and frequency shifts was investigated, although the non-covalent character of these complexes has been unveiled through the QTAIM calculations. The absorption intensity ratios of the proton donors correlate well with the charge transfer amounts, whose values were computed through the ChelpG approach. Even by taking into account the cooperative profile of these systems, the hydrogen bond energies were determined, and actually, the values are unapproachable to be distributed in different moieties, such as punctual strong hydrogen bonds possessing covalent character, if exist. At last, the NBO calculations were applied to compute the s- and p-contributions on the hybrid orbitals in order to explain the frequency shifts on the H–C and H–F proton donor bonds. DOI: http://dx.doi.org/10.17807/orbital.v1i1.70

In silico Studies Combining QSAR Models, DFT-based Reactivity Descriptors and Docking Simulations of Phthalimide Congeners with Hypolipidemic Activity

In this current study, a selected group of physicochemical descriptors extracted from the formalism of the density functional theory were used for modeling a series of phthalimide congeners with tested hypolipidemic activity once. Based on unsupervised pattern recognition of HCA and PCA followed by the PLS regressions, the final content may be considered trustful for predicting the biological activity due to the results of r2cal&nbsp;= 0.937, r2CV&nbsp;= 0.591 and r2test&nbsp;= 0.85. Moreover, the molecular modeling was performed through the docking protocol for predicting the ligand pose on the HMG-CoA reductase. The protocols of the AutoDock Tools and AutoDock Vina were used for determining the interaction scores (ΔG) and inhibition constants (Ki). Among all congeners studied, the docking results pointed out a potential compound. By taking into account the widely known top selling drugs, and just as is well-known that atorvastatin is one of them due its capability to lower the cholesterol levels, the structure of this drug was subjected to a docking study in order to guide us to a better understanding of the results available here. DOI:&nbsp;http://dx.doi.org/10.17807/orbital.v13i3.149

QSAR-3D e Docking Molecular de Derivados de Ácidos N-arilantranílicos com Atividade Inibitória na Enzima Catepsina L

In this work, a molecular modeling study of N-arylanthranilic acid derivatives with inhibitory action on the Cathepsin L enzyme in presented. Firstly, a 3DQSAR study was carried out in order to identify the most important molecular fields, in particular those formed by the C=O, C─O─C and ─NO2 groups, by which the experimental biological activity data were satisfactorily predicted through the correlation (R2 = 0.99) and determination (Q2 = 0.66) coefficient values. In agreement with the noncompetitive inhibition mechanism, the molecular docking calculations revealed that preferential interactions pose outside of the Cathepsin L active site. The correlation between the docking scores and biological activity data are fairly linear, indicating that the strongest and weakest bonded compounds are those with highest and lowest biological activities, respectively. DOI: http://dx.doi.org/10.17807/orbital.v1i1.71