Synthesis and Photophysical Properties of Dibenzobarrelene‐Incorporated 1,4‐Diphenyl‐1,3‐pentadienes and a 5‐Sila Derivative Having High Fluorescence Efficiency

Two dibenzobarrelene‐incorporated 1,3‐pentadienes and a 5‐sila derivative have been synthesized by intramolecular cycloaddition reactions between (9‐anthryl)methyl, (9‐anthryl)hydroxymethyl, or (9‐anthryl)dimethylsilyl groups and a phenylethynyl group linked by an ethene moiety with a cis conformation. The three compounds exhibit blue luminescence ( λ em = 432–445 nm) in CH 2 Cl 2 with high quantum yields ( Φ F = 0.83–0.92). In the solid state, the methylene and dimethylsilyl derivatives luminesce ( λ em = 442 and 438 nm, respectively) with narrow full‐width at half‐maxima (FWHM, 40 and 37 nm, respectively), whereas the hydroxymethylene compound shows a broad and slightly redshifted emission ( λ em = 488 nm, FWHM = 112 nm) due to intermolecular hydrogen bonding. The fluorescence intensity of the dimethylsilyl compound was decreased by desilylation with Bu 4 NF. The structures of the compounds were characterized unambiguously by NMR spectroscopy and X‐ray crystallography, and their photophysical properties were elucidated both experimentally as well as by TD‐DFT calculations.