Photo- and solvatochromic properties of nitrobenzospiropyran in ionic liquids containing the [NTf2]- anion
Byrne, Robert, Diamond, DermotORCID: 0000-0003-2944-4839, Fraser, Kevin J.ORCID: 0000-0002-9718-5405, Izgorodina, Ekaterina, Forsyth, Maria and MacFarlane, Douglas R.
(2008)
Photo- and solvatochromic properties of nitrobenzospiropyran in ionic liquids containing the [NTf2]- anion.
Physical Chemistry Chemical Physics, 10
.
pp. 5919-5924.
ISSN 1463-9084
The photo-, thermo- and solvatochromic properties of 2,3-dihydro-10,30,30-trimethyl-6-nitrospiro-
[1-benzopyran-2,20-1H-indole] (BSP-NO2) were studied in ILs containing the anion [NTf2]- by UV-Vis absorption spectroscopy, ab initio molecular orbital theory and density functional theory (DFT) calculations. It was found that the kinetics and thermodynamics of the BSP-NO2 MC (merocyanine) equilibrium was sensitive to the nature of the cation. It was also observed that the imidazolium cation can form a through-space orbital interaction with the MC isomer, rather than a simple electrostatic interaction, thus preventing the MC conversion back to the BSP-NO2 isomer. The BSP-NO2 MC equilibrium thus serves as a model system for studying modes of interaction of the cations in ionic liquids.