Dibenzoarsepins: Planarization of 8π‐Electron System in the Lowest Singlet Excited State. Issue 34 (24th July 2019)

• Record Type: Journal Article
• Authors: Kawashima, Ikuo; Imoto, Hiroaki; Ishida, Masatoshi; Furuta, Hiroyuki; Yamamoto, Shunsuke; Mitsuishi, Masaya; Tanaka, Susumu; Fujii, Toshiki; Naka, Kensuke
• Is Part Of: Angewandte Chemie international edition. Volume 58:Issue 34(2019)
• Page Start: 11686
• Page End: 11690
• Publication Date: 2019-07-24
• Subjects: aromaticity -- arsepins -- Baird's rule -- excited-state aromaticity; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201904882
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Dibenzo[b, f]arsepins possessing severely distorted cores compared to those of other heteropins were synthesized. These derivatives exhibited dual photoluminescence in the green‐to‐red region (500–700 nm) and the near‐ultraviolet region (<380 nm), which could be attributed to the planarization of the arsepin core in the lowest singlet excited (S1 ) state. The computational approach for the assessment of the aromatic indices revealed that the dibenzoarsepins studied show aromaticity (8π system) in the S1 states in line with Baird's rule. The lone pair electrons of the arsenic atoms play a crucial role in the aromaticity in the S1 states. Abstract : Aromaticity in the excited state : Dibenzoarsepins possessing formally 8π‐electron systems show highly bent structures in the ground states, while quasi‐planar structures are favored in the singlet excited states. The drastic conformational change upon photoexcitation is in line with Baird's rule.