Quantum chemical computations and photophysical spectral features studies of two coumarin compounds

An attempt was made to determine the ground state and excited state dipole moments and quantum chemical computations of two coumarin compounds, namely 3-hydroxy-3-[2-oxo-2-(2-oxo-2H-chromen-3-yl)-ethyl]-1,3-dihydro-indol-2-one (3HOCE) and 3-[2-(8-methoxy-2-oxo-2H-chromen-3-yl)-2-oxo-ethylidene]-1,3-dihydro-indol-2-one (3MOCE). Both compounds displayed a red shift with enhancement in solvent polarity. The larger excited state dipole moment indicated the more polar nature of the selected compounds in the excited state than in the ground state. Kinetic stability and chemical reactivity of the selected compounds were studied with help of the quantum chemical properties of the compounds such as frontier molecular orbital analysis using density functional theory calculations with B3LYP/6?311+G (d, p) basis sets. Molecular electrostatic potential, Mulliken charges, natural bond orbital, and nonlinear optical properties were further studied. NBO analysis showed proton transfer within the selected donor?acceptor, depicting the large energy of stabilization for the compounds. The calculated Fukui function inferred the local softness and electrophilicity indices of used solute compounds.Scopu

Recommandations pour une récolte durable de biomasse forestière pour l'énergie - Focus sur les menus bois et les souches

Les modalités d'exploitation du bois pour la production d'énergie ont fortement évolué ces dix dernières années, notamment dans le contexte de la transition énergétique. Des compartiments de bois laissés en forêt (menus bois notamment), sont ainsi de plus en plus mobilisés. Le prélèvement accru de bois pour l'énergie peut engendrer, dans certaines conditions, des perturbations de l'environnement (sols, biodiversité, eaux). Ce document de recommandations s'adresse aux acteurs de la filière bois-énergie et fait état des précautions à prendre lors de la récolte des menus bois (diamètre < 7 cm) et des souches, et pour réduire au maximum l'exportation de feuillage. Les autres formes de bois énergie, en particulier le bois bûche, ne sont pas concernés. Les recommandations se fondent sur le diagnostic de la sensibilité des sols à faire face à l'exportation de nutriments et sur la situation éventuelle de chantier envisagé au sein d'une zone protégée vis-à-vis de la biodiversité

Determination of ground and excited state dipole moments of amino-benzimidazole by solvatochromic shift methods and theoretical calculations

International audienceSolvatochromic behavior of 2-aminobenzimidazole (2-AB) has been studied in different solvents at room temperature. The observation of the bathochromic shift in the absorption and fluorescence spectra of molecules indicates a strong interaction with solvents in the excited state. The difference in the excited-state (μe) and the ground-state (μg) dipole moments has been estimated by using the theory of solvatochromism from Bakhshiev, Bilot–Kawski, and Dimroth–Reichardt equations. Higher values of dipole moment have been observed for excited state compared to the corresponding ground state values indicating an intramolecular charge-transfer (ICT). Then in order to carry out a theoretical investigation, the values of dipole moments were calculated in the gas phase with TDDFT/B3LYP. Based on these results, we propose a solvation model consistent with theoretical and experimental results wherein we showed the specific interactions between solvent molecules and aminobenzimidazole at the excited state