Synthesis, optical properties and crystal structure of (E,E)-1,3-(3,4:9,10-dibenzododeca-1,11-diene-5,7-diyne-1,12-diyl)benzene

Hikaru Watanabe, Takuma Sato, Michiki Sumita, Mei Shiroyama, Daichi Sugawara, Tomoki Tokuyama, Yasuhiro Okuda, Kan Wakamatsu, Haruo Akashi, Akihiro Orita

The dehydrobenzannulene (E,E)-1,3-(3,4:9,10-dibenzododeca-1,11-diene-5,7-diyne-1,12-diyl)benzene, C26H16, was successfully synthesized via photocatalyst-assisted stereoselective reductive desulfonylation of 1,3-bis{1-phenylsulfonyl-2-[2-(trimethylsilyl ethynyl)phenyl]ethenyl}benzene, C44H42O4S2Si2, and subsequent desilylative cyclization of the resulting (E,E)-bis-silyl-protected dienyne, C32H34Si2. The structure of the dehydroben zannulene thus obtained was confirmed by single- crystal X-ray anal.; three benzene rings are connected to one another by a 1,3-butadiynylene and a pair of ethenylene arrays. Although the π- system expanded efficiently in the dehydrobenzannulene, it was observed that the butadiynylene and ethenylene arrays were strained, showing smaller [171.3 (2)-172.6 (2) °] and larger bond angles [122.5 (2)-131.9 (2)°] than the conventional bond angles, resp. In CH Cl3, the dehydrobenzannulene showed the longest absorption band at 377 nm. When irradiated by U V light, it emitted fluorescence at 468 nm (ΦF = 0.26) and 504 nm (Φ F = 0.24) in C HCl3 and in the powd. state, resp.

Acta Cryst.

E79

8

757

761

10.1107/S2056989023006187