Cover Feature: Tetrathienyl Corannulene Compounds with Highly Sensitive Photochromism (Chem. Eur. J. 49/2022)

Abstract

Tetrathienyl corannulene compounds showed highly sensitive photochromism with a large molar absorption coefficient and photocyclization quantum yield close to 1, although dithienyl phenanthrene compounds showed no photoreactivity. Such a high photoreactivity was rationalized by the predominance of the photoreactive atropisomers amplified by energy migration, and the curvature‐induced short distance between photoreactive carbons. More information can be found in the Research Article by M. Yamada, T. Kawai, and co‐workers (DOI: 10.1002/chem.202201286).

Synthesis and Photochromic Properties of Diaryl [5]Helicene Derivatives

“…The decay kinetics followed the first‐order bleaching kinetics, and the activation energy ( E a ) of cycloreversion of 2 b and 3 b were estimated to be 87 and 86 kJ mol −1 , respectively, using the Arrhenius plot. As shown in Table 1, the activation energy is obviously smaller than that typical terarylenes and diarylethenes [13,30] . In particular, the frequency factors of 2 b and 3 b are considerably larger than those of diarylethenes, which also contribute to the rapid bleaching of 2 b and 3 b , in combination with the smaller activation energy.…”

“…As shown in Table 1, the activation energy is obviously smaller than that typical terarylenes and diarylethenes. [13,30] In particular, the frequency factors of 2 b and 3 b are considerably larger than those of diarylethenes, which also contribute to the rapid bleaching of 2 b and 3 b, in combination with the smaller activation energy. Table 1.…”

“…Thanks to the nonaromatic 20π-electron system and excited-state energy delocalizing among dual DAE reaction centers, it demonstrated a significantly large photochemical quantum yield. [30] Helicenes are ortho-condensed polycyclic aromatic compounds in which benzene rings are connected one by one to form nonplanar helically shaped chiral molecules. [31] Herein, we designed new DAE derivatives with a [5]helicene unit as the central ethene bridge, and investigated their photochromic behaviors along with the photoinduced aromatic changes of the central helicene unit.…”

“…The present authors recently synthesized a DAE derivative with a curved aromatic corannulene at the central ethene bridge. Thanks to the nonaromatic 20π‐electron system and excited‐state energy delocalizing among dual DAE reaction centers, it demonstrated a significantly large photochemical quantum yield [30] …”