Working Paper 12-10 - De milieudruk van de huishoudelijke consumptie in België in 2002: een sociologische analyse

Household consumption, Environmental satellite accounts

Unraveling the effects of co-crystallization on the UV/Vis absorption spectra of an N-salicylideneaniline derivative:A computational RI-CC2 investigation

This work aims at unraveling the effects of co-crystallization on the optical properties of an N-salicylideneaniline-derived molecular switch transforming between an enol and a keto form. This is achieved by way of a two-step multi-scale method where (i) the molecular geometry and unit cell parameters are optimized using a periodic boundary conditions density functional theory method and (ii) the optical properties are computed for a selection of clusters embedded in an array of point-charges that reproduce the crystal field electronic potential. The optical properties (vertical excitation energies and oscillator strengths) are obtained at the RI-CC2/def2-TZVPD level of approximation. This method allows us to decompose the effects of co-crystallization into (i) indirect effects, the geometry changes of the chromophore due to crystal packing with the coformer, and (ii) direct ones, the polarization due to the interacting coformer and to the crystal field. For the former effects, variations of a crucial torsion angle lead to modification of the p-conjugation and therefore to the decrease or increase of the excitation energies. About the latter, they are antagonistic: (i) the coformer is not directly involved in the excitations but its polarization decreases the excitation energies while (ii) the crystal field has the opposite effect. For the co-crystals with succinic and fumaric acids, combining these direct and indirect effects leads to a hypsochromic shift of the first absorption band with respect to the reference crystal, in agreement with experimental data

Periodic DFT Study of the Effects of Co‐Crystallization on a N‐Salicylideneaniline Molecular Switch

This work aims at better understanding the complex effects of co‐crystallization on a single salicylideneaniline molecular switch, (E)‐2‐methoxy‐6‐(pyridine‐3‐yliminomethyl)phenol (PYV3), which can tautomerize between an enol and a keto form. A combination of periodic boundary conditions DFT and molecular wavefunction calculations has been adopted for examining a selection of PYV3 co‐crystals, presenting hydrogen bonds (H‐bonds) or halogen bonds (X‐bonds), for which X‐ray diffraction data are available. Three aspects are targeted: i) the energy (H‐bond strength, enol to keto relative energy, and geometry relaxation energies), ii) the geometrical structure (PYV3 to co‐crystal and enol to keto geometrical variations), and iii) the electron distribution (PYV3 to co‐crystal and enol to keto Mulliken charge variations). These allow i) explaining the preference for forming H‐bonds with the nitrogen of the pyridine of PYV3 with respect to the oxygens and the importance of the crystal field, ii) distinguishing the peculiar behavior of the SulfonylDiPhenol (SDP) coformer, which stabilizes the keto form of PYV3, iii) describing the relative stabilization of the enol form upon co‐crystallization (with the exception of SDP) and therefore iv) substantiating the co‐crystallization‐induced reduction of thermochromism observed for several PYV3 co‐crystals

Periodic DFT Study of the Effects of Co‐Crystallization on a N‐Salicylideneaniline Molecular Switch

This work aims at better understanding the complex effects of co‐crystallization on a single salicylideneaniline molecular switch, (E)‐2‐methoxy‐6‐(pyridine‐3‐yliminomethyl)phenol (PYV3), which can tautomerize between an enol and a keto form. A combination of periodic boundary conditions DFT and molecular wavefunction calculations has been adopted for examining a selection of PYV3 co‐crystals, presenting hydrogen bonds (H‐bonds) or halogen bonds (X‐bonds), for which X‐ray diffraction data are available. Three aspects are targeted: i) the energy (H‐bond strength, enol to keto relative energy, and geometry relaxation energies), ii) the geometrical structure (PYV3 to co‐crystal and enol to keto geometrical variations), and iii) the electron distribution (PYV3 to co‐crystal and enol to keto Mulliken charge variations). These allow i) explaining the preference for forming H‐bonds with the nitrogen of the pyridine of PYV3 with respect to the oxygens and the importance of the crystal field, ii) distinguishing the peculiar behavior of the SulfonylDiPhenol (SDP) coformer, which stabilizes the keto form of PYV3, iii) describing the relative stabilization of the enol form upon co‐crystallization (with the exception of SDP) and therefore iv) substantiating the co‐crystallization‐induced reduction of thermochromism observed for several PYV3 co‐crystals