The relative hydrogen-bond acceptor abilities of amino and cyano N atoms have been investigated using data retrieved from the Cambridge Structural Database and via ab initio molecular orbital calculations. Surveys of the CSD for hydrogen bonds between HX (X = N, O) donors, NÐTÐ CN (push±pull nitriles) and NÐ (Csp 3 ) n ÐCN molecular fragments show that the hydrogen bonds are more abundant on the nitrile than on the amino nitrogen. In the push±pull family, in which T is a transmitter of resonance effects, the hydrogen-bonding ability of the cyano nitrogen is increased by conjugative interactions between the lone pair of the amino substituent and the CN group: a clear example of resonanceassisted hydrogen bonding. The strength of the hydrogenbonds on the cyano nitrogen in this family follows the experimental order of hydrogen-bond basicity, as observed in solution through the pK HB scale. The number of hydrogen bonds established on the amino nitrogen is greater for aliphatic aminonitriles NÐ(Csp 3 ) n ÐCN, but remains low. This behaviour re¯ects the greater sensitivity of the amino nitrogen to steric hindrance and the electron-withdrawing inductive effect compared with the cyano nitrogen. Ab initio molecular orbital calculations (B3LYP/6-31+G** level) of electrostatic potentials on the molecular surface around each nitrogen con®rm the experimental observations.
This work deals with the efficient management of industrial liquid discharges from soap factories (ILDS) in the region of Abidjan. The aim of this work is to evaluate the physico-chemical quality of these discharges as well as the different types of pollution generated. Seventeen (17) industrial soap sources were studied through fourteen (14) global pollution parameters (T, pH, electrical conductivity EC, redox potential E H , suspended matter SM, COD, BOD 5 , biodegradability factor BF, 4
The molecular structure, the Natural Bond orbital (NBO) and the Time Dependent-DFT of both isomers cis or γ-Cl and trans or δ-Cl of RuCl 2 (L) 2 , where L stands respectively for 2-phenylazopyridine (Azpy), 2,4-dimethyl-6-[phenylazo]pyridine (Dazpy), 2-[(3,5-dimethylphenyl)azopyridine] (Mazpy) and 2-pyridylazonaphtol (Nazpy) were calculated with DFT method at B3LYP/LANL2DZ level. The prediction of the frontier orbitals (Highest Occupied Molecular Orbital or HOMO and Lowest Unoccupied Molecular Orbital or LUMO) shows that the most active complexes suitable for electronic reactions are admitted to be the trans isomers. Moreover, δ-RuCl 2 (Azpy) 2 is discovered to react more actively as photo-sensitizer since its energy gap is the minimum. Besides, electronic structures of all complexes through NBO calculation indicate that Ru-N bonds are made of delocalization of occupancies from lone pair orbital of N atoms to the ruthenium. Moreover, Ru was assumed to have almost the same charge regardless the structure of the azopyridine ligands in the complex indicating that the ligands provide only a steric effect that is responsible for the ruthenium's selectivity. Concerning the transition state, NBO analysis also highlights that the transition LP(Ru)π*(N 1 -N 2 ) does correspond to t 2g π*(L). This transition is assumed to correspond to Metal to Ligand Charge Transfer (MLCT) that is responsible for the photo-sensitiveness of the metallic complex. Besides, TDDFT calculation of complexes showed that δ-RuCl 2 (Nazpy) 2 displays the largest band during the absorption. For that reason, it is admitted to be the best photosensitizer due to a large system of conjugation provided by Nazpy ligand.
This QSAR study, which involved a series of Azetidinones derived from 4,4'-diaminodiphenylsulfone (dapsone), yielded two models based on molecular descriptors and the antibacterial activities Escherichia coli and Staphylococcus aureus.The molecular descriptors were obtained by applying the methods of quantum chemistry at the B3LYP/6-31G (d) level. The statistical indicators of the first model which is a function of the Escherichia coli activity are: the coefficient of determination R<sup>2</sup> equals 0.992, the standard deviation S equals 0.342, the Fischer coefficient F equals 185.088 and the cross-validation coefficient Q<sup>2</sup><sub>CV</sub> equals 0.992. Those of the second model showing the activity of Staphylococcus aureus are: the regression coefficient R<sup>2</sup>= 0.987, a standard deviation S=0.193, the Fischer coefficient F=114.955 and the cross-validation coefficient Q<sup>2</sup><sub>CV</sub>= 0.987. These models have good statistical performances. The quantum descriptors of dipole moment (μ), global softness (σ) and electronegativity (χ) are responsible of the antibacterial activity of the Azetidinones derived from dapsone. In addition, the dipole moment is the priority descriptor for the prediction of the antibacterial activity of the studied compounds. The Eriksson et al. acceptance criteria used for the test set is verified. The values of the dtheo/dexp ratio of the theoretical and experimental activities for the test set tend towards unity.
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