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Substituted Styrene Molecules Included in Cyclodextrins: a Raman Spectroscopic Study. Part II
Author(s) -
RibeiroClaro Paulo J. A.,
Amado Ana M.,
TeixeiraDias J. J. C.
Publication year - 1996
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/(sici)1097-4555(199602)27:2<155::aid-jrs941>3.0.co;2-l
Subject(s) - conformational isomerism , raman spectroscopy , molecule , chemistry , styrene , crystallography , stereochemistry , organic chemistry , polymer , copolymer , physics , optics
Raman spectra of 3‐bromostyrene, 3‐nitrostyrene and 4‐methoxystyrene (4MeOS) included in α‐, β‐ and γ‐cyclodextrins (α‐, β‐ and γCDs) were recorded. For the 3‐substituted derivatives both the νC = C and νCH group wavenumbers were used for probing the guest molecules, whereas for 4MeOS two pairs of bands in the 300–600 cm −1 spectral region were analysed. On the whole, the spectral observations suggest that the αCD inclusion leads, in all cases, to a conformational selection of the guest molecule, as previously reported for some other meta ‐substituted styrene molecules. On the other hand, the γCD complexation keeps approximately the conformer distribution of the pure guest. In addition, temperature variation studies showed that even below 200 K the conformer ratio remained unchanged, suggesting that the inclusion process in this CD hinders the internal rotation of the vinyl group.