Ra. Agbaria et al., EXCIMER FLUORESCENCE OF TRANS-STILBENE IN TERNARY AQUEOUS-SOLUTIONS OF GAMMA-CYCLODEXTRIN, Journal of physical chemistry, 99(24), 1995, pp. 10056-10060
A dual fluorescence of trans-stilbene (TS) is reported which involves
an apparent ternary complex of TS/gamma-cyclodextrin/cyclohexane. This
dual fluorescence is not observed to an appreciable extent in the abs
ence of cyclohexane. Only monomer fluorescence of TS is observed in th
e latter samples. These observations are interpreted in terms of spati
al and screening restrictions on the TS photoisomerization and cycload
dition. The cyclohexane in the ternary complex is believed to induce r
estrictions by co-inclusion into the cyclodextrin cavity. As a result,
formation of the cis-isomer upon irradiation is reduced. Consequently
, the excimer yield of TS is increased. The inclusion of cyclohexane a
s a partition between two included stilbene molecules in the cyclodext
rin cavity is also proposed. This is the first reported excimer of TS
in fluid or aqueous cyclodextrin solutions which does not involve cova
lently linked or severely constrained TS molecules. Alcohols and other
hydrophobic compounds such as toluene, xylene, and hexane are also ex
amined as ternary components.