Aggregation-enhanced emissions of intramolecular excimers in disubstituted polyacetylenes.
Whereas chain aggregation commonly quenches light emission of conjugated polymers, we here report a phenomenon of aggregation-induced emission enhancement (AIEE): luminescence of polyacetylenes is dramatically boosted by aggregate formation. Upon photoexcitation, poly(1-phenyl-1-alkyne)s and poly(diphenylacetylene)s emit blue and green lights, respectively, in dilute THF solutions. The polymers become more emissive when their chains are induced to aggregate by adding water into their THF solutions. The polymer emissions are also enhanced by increasing concentration and decreasing temperature. Lifetime measurements reveal that the excited species of the polymers become longer-lived in the aggregates. Conformational simulations suggest that the polymer chains contain n=3 repeat units that facilitate the formation of intramolecular excimers. The AIEE effects of the polymers are rationalized to be caused by the restrictions of their intramolecular rotations by the aggregate formation.
Qin
Anjun
A
Department of Chemistry, The Hong Kong University of Science & Technology, Kowloon, Hong Kong, China.
Jim
Cathy K W
CK
Tang
Youhong
Y
Lam
Jacky W Y
JW
Liu
Jianzhao
J
Mahtab
Faisal
F
Gao
Ping
P
Tang
Ben Zhong
BZ
D003198:Computer Simulation; D005663:Furans / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D053279:Polyynes / Q000138:chemical synthesis / Q000737:chemistry*; D013053:Spectrophotometry; D014867:Water / Q000737:chemistry
D005663:Furans; D014867:Water; D053279:Polyynes; C018674:tetrahydrofuran