This study consists of the theoretical analysis of some organic molecules and their inorganic similar compounds, through substitution of two carbon atoms by boron and nitrogen atoms. The methods DFT/B3-LYP/TZVPP and CC2/TZVPP were considered. Firstly, ethane, ethene, and ethyne molecules (based on C atoms and their BN/NB analogs) were studied. These molecules were considered as a reference for the analysis of other molecules with functional groups. These molecules with functional groups are: ethanol, ethanal (and its isomer ethenol), ethanoic acid (and its isomer ethenediol), ethylamine, ethylbenzene, propane, and fluoroethane. We studied the energies, bond length, population analysis, and bond order. The dative bonds (BN) are bigger and weaker than that covalent based on C atoms. The dative bond has π character when the BN bond is double and triple. It is possible to distinguish two different behaviors for BN bonds, one when the functional group is bounded to the B atom, and the other to the N atom. When the functional group is bounded to the B atom, the BN bond is weaker and lengthier than that when the same group is bounded to the N atom. However, the isomer with weaker BN bond is the most stable one. Graphical abstract Comparative studies of dative bonds among substituted inorganic molecules, e.g., BN-ethanol, show important differences in terms of length and energy in comparison to organic analogous. There is also a difference when comparing BN or NB molecules (according to witch atom the functional group is bonded to, B or N); bond length, for example, is bigger for BN molecules.

The degradation in water of the most widespread herbicide, glyphosate, is still under debate. Experimental disagreements on this process exist and there are only a few theoretical studies to support any conclusions. Moreover, the relationship between glyphosate and glycine is underestimated. Besides the structural similarity, glycine is a product of glyphosate degradation; hence, their studies are complementary. In this study, two mechanisms for the decomposition of the glyphosate molecule and glycine molecule in water are proposed. These mechanisms were explored by using quantum mechanical calculations. A combined microsolvation/PCM approach was employed to find and characterize their transition states, by which the reaction pathways were determined via the IRC method. The results have shown that the degradation processes might occur via a C-C bond cleavage, through a concerted mechanism, whereby the proton transfers and the CO2 detachments occur simultaneously. The second mechanism had two consecutive steps, a decarboxylation followed by the proton transfers. The water molecules served as a conduit for the proton transfers, away from the amine group (or the phosphonate, glyphosate case). Their function was to assist the reactions in a water-mediated decarboxylation. In these particular cases, the free energy of activation was 42.68 and 42.28 kcal mol-1 for the glycine structure and the glyphosate structure, respectively. These results agreed with the photodegradation and thermodegradation of glyphosate, as well as with the spontaneous decarboxylation of glycine. A concerted mechanism might be expected to yield C-P and C-N bond cleavages in the glyphosate molecule.

In this work, the spectroscopic information, stability and aromaticity of the boron-nitrogen azulene and naphthalene molecules are provided by the use of CC2 (geometry optimization, dipole moment, UV-vis spectrum calculations) and DFT (vibrational spectrum and NMR calculations) methodologies. One isomer of the investigated boron-nitrogen naphthalene (boroazanaphthalene) and two isomers of boron-nitrogen azulene, 1,3,4,6,8-pentaaza-2,3a,5,7,8a-pentaboraazulene (BN-azulene) and 2,3a,5,7,8a-pentaaza-1,3,4,6,8- pentaboraazulene (NB-azulene), are stable systems. However, these molecules have different properties, i.e., different stability, dipole moment, and aromaticity based on the NICS approach. BN-naphthalene has a high dipole moment magnitude showing high polar character, while naphthalene is apolar. BN- and NB-azulene are weakly polar, while ordinary azulene is highly polar in character. Also, substitution of C atoms by B and N atoms decreases the aromaticity. In the case of NB-azulene, the seven-membered ring has anti-aromaticity behavior while both rings of BN-azulene exhibit aromaticity. We expect that the new theoretical data provided in this work will be useful in identifying and characterizing experimentally the compounds investigated, and in helping our understanding of the chemistry of boron-nitrogen molecules. Graphical abstract Boron-nitrogen alternating analogs of azulene. Spectral distinction between isomers.

This work reports the synthesis, structure and catalytic activity of a novel ruthenium(II) complex, [RuCl(dppb)(44bipy)(4-pic)]PF6 (where dppb = 1,4-bis(diphenylphosphine)butane; 44bipy = 4,4’-dimethyl-2,2’-dipyridyl; 4-pic = 4-picoline). The molecular structure and catalytic activity were studied by Fourier transform infrared (FTIR), UV-Vis and nuclear magnetic resonance (NMR) spectroscopies, cyclic voltammetry, and X-ray crystallography, while the electronic structure was investigated by density-functional theory (DFT) and time dependent DFT (TD-DFT) methods. Electrochemical studies showed the substitution of the chlorido ligand from the precursor by the 4-pic ligand, exhibiting the RuII/RuIII process at 1.21 V. The structure of the compound was optimized using DFT simulations and showed data similar to the X-ray structure. The UV-Vis absorption spectrum showed a good agreement with TD-DFT simulations. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies were determined at the Becke, 3-parameter, Lee-Yang-Parr (B3LYP) level. The study of the catalytic activity in the transfer hydrogenation of ketones by the 1H NMR showed efficient transfer hydrogenation reaction at 60 ºC, employing acetophenone as substrate and resulting in a high conversion. The formation of two ruthenium-hydride species was observed.

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A adsorção de íons cobre (II), em esferas de quitosana e esferas de quitosana reticulada, foi investigada. A caracterização da quitosana e da quitosana reticulada com glutaraldeído foi realizada por espectroscopia de absorção na região do infravermelho e através da determinação do grau de desacetilação (GD). Os dados experimentais, obtidos por espectrofotometria de absorção atômica, foram ajustados pelos modelos de Langmuir e Freundlich. O modelo que melhor ajustou os dados experimentais foi o modelo de Freundlich. A isoterma de Langmuir mostrou uma capacidade máxima de 18,50 mg g -1 para as esferas sem modificação e 14,02 mg g -1 para as esferas modificadas. Palavras-Chave: quitosana; adsorção; cobre(II).The adsorption of copper (II) by chitosan spheres and modified chitosan spheres was investigated. The spheres were characterized by determination of DA (degree of acetylation) infrared spectroscopy. The adsorption's experiments were analyzed by atomic absorption spectrophotometer, quantifying the initial and equilibrium concentrations of copper(II). The data were fitted by Langmuir and Freundlich's models. The model that best fit the experimental data for both the chitosan spheres and intercrossed chitosan spheres was the Freundlich's model. The Langmuir isotherm showed a maximum capacity of 18.50 mg g -1 for chitosan spheres and 14.02 mgg -1 for the modified spheres.