In this Letter, the photoluminescence of 1,1,2,3,4,5-hexaphenylsilole (HPS) and poly {1,1-[(1, 2,3,4,5-pen taphenylsiloly)oxy]-1 phenyl-1-undecyne} (PS9PA) was studied in detail by time-resolved fluorescence technique to investigate possible mechanisms of their unique aggregation-induced emissions. Enhanced emissions and long lifetimes of HPS and PS9PA films were detected in PMMA matrix compared to those of their solutions. Furthermore, strong fluorescence with nanosecond lifetimes was also obtained in the single crystal of HPS. These results show that intramolecular vibrational and torsional motions can act as efficient nonradiative pathways for the excited states to decay in the solutions and that suppression of these motions by restricting intramolecular vibrations in the solid state leads to enhanced fluorescence. (C) 2005 Elsevier B.V. All rights reserved.