Origins of the differences in solvation by alkanes and perfluoroalkanes: Evidence from the S2-S0 spectra of jet-cooled van der Waals complexes of xanthione and azulene
✍ Scribed by H.K. Sinha; O.K. Abou-Zied; M. Ludwiczak; A. Maciejewski; R.P. Steer
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 753 KB
- Volume
- 230
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
The S& fluorescence excitation spectra of xanthione (XT) and azulene (AZ) complexed with 1 or 2 molecules of the C, to Cl0 n-alkanes and the C, to C, perfluoro-n-alkanes have been measured. The 1: I complexes exhibit microscopic solvent shifts, A& which are larger for the alkanes than the corresponding perfluoroalkanes, despite the larger molecular polarizability of the latter. The values of Aflincrease monotonically with carbon number of the adduct to C,O in 1: 1 n-alkane complexes with XT and to Cs in 1: 1 n-alkane complexes with AZ. However, AI? exhibits no further increase beyond Cz in 1: 1 perfluoro-n-alkane complexes with XT and beyond C, in 1: 1 pertluoro-n-alkane complexes with AZ. The results are interpreted in terms of a model in which the n-alkanes stretch out along the long axis of the chromophore and 'wet' its surface whereas the peffluoro-n-alkanes with carbon numbers 2 3 away from the surface of the chromophore and are 'non-wetting'.