title: Ring-shaped silafluorene derivatives as efficient solid-state UV-fluorophores: synthesis, characterization, and photoluminescent properties.
abstract: Four ring-shaped silafluorene-containing compounds (1-4) were synthesized and characterized as potentially promising monomers for fluorescent polymers. Their optical properties in solution and solid state (thin film and powder) were studied. These compounds have low quantum yields in solution (Φ(fl)=0.13-0.15) with fluorescence maxima at about 355 nm, but high quantum yields in the solid state (powder, Φ(fl)=0.35-0.54) with fluorescence maxima at about 377 and 488 nm. Influence of the substituents and the number of silafluorene units in 1-4 on their optical properties was investigated. Extensive study of the X-ray crystal structures of 1-4 was undertaken to analyze and qualitatively estimate the role, extent, and influence of silafluorene moieties' interactions on solid-state fluorescent properties. Excited state UV/Vis and theoretical molecular orbital (MO) calculations were performed to explore possible fluorescence mechanisms and differences in quantum yields among these compounds.
authors.affiliation: School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070 (P. R. China); Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison Wisconsin 53706 (USA), Fax: (+1) 608-265-6815.
authors.forename: Yuanjing
authors.initials: Y
authors.lastname: Cai
authors.forename: Kerim
authors.initials: K
authors.lastname: Samedov
authors.forename: Brian S
authors.initials: BS
authors.lastname: Dolinar
authors.forename: Haley
authors.initials: H
authors.lastname: Albright
authors.forename: Ilia A
authors.initials: IA
authors.lastname: Guzei
authors.forename: Rongrong
authors.initials: R
authors.lastname: Hu
authors.forename: Chaocan
authors.initials: C
authors.lastname: Zhang
authors.forename: Robert
authors.initials: R
authors.lastname: West
keywords: cyclosiloxanes; packing interactions; silafluorene; solid-state fluorescence; theoretical calculations