title: Aggregation-enhanced emissions of intramolecular excimers in disubstituted polyacetylenes.
abstract: 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.
authors.affiliation: Department of Chemistry, The Hong Kong University of Science & Technology, Kowloon, Hong Kong, China.
authors.forename: Anjun
authors.initials: A
authors.lastname: Qin
authors.forename: Cathy K W
authors.initials: CK
authors.lastname: Jim
authors.forename: Youhong
authors.initials: Y
authors.lastname: Tang
authors.forename: Jacky W Y
authors.initials: JW
authors.lastname: Lam
authors.forename: Jianzhao
authors.initials: J
authors.lastname: Liu
authors.forename: Faisal
authors.initials: F
authors.lastname: Mahtab
authors.forename: Ping
authors.initials: P
authors.lastname: Gao
authors.forename: Ben Zhong
authors.initials: BZ
authors.lastname: Tang
mesh_terms: 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
chemical_list: D005663:Furans; D014867:Water; D053279:Polyynes; C018674:tetrahydrofuran