TY - JOUR
T1 - s-Indacene Revisited
T2 - Modular Synthesis and Modulation of Structures and Molecular Orbitals of Hexaaryl Derivatives
AU - Jhang, Shun Jie
AU - Pandidurai, Jayabalan
AU - Chu, Ching Piao
AU - Miyoshi, Hirokazu
AU - Takahara, Yuta
AU - Miki, Masahito
AU - Sotome, Hikaru
AU - Miyasaka, Hiroshi
AU - Chatterjee, Shreyam
AU - Ozawa, Rumi
AU - Ie, Yutaka
AU - Hisaki, Ichiro
AU - Tsai, Chia Lin
AU - Cheng, Yen Ju
AU - Tobe, Yoshito
N1 - Publisher Copyright:
© 2023 American Chemical Society.
PY - 2023/3/1
Y1 - 2023/3/1
N2 - Though s-indacene is an intriguing antiaromatic hydrocarbon of 12 π-electrons, it has been underrepresented due to the lack of efficient and versatile methods to prepare stable derivatives. Herein we report a concise and modular synthetic method for hexaaryl-s-indacene derivatives bearing electron-donating/-accepting groups at specific positions to furnish C2h-, D2h-, and C2v-symmetric substitution patterns. We also report the effects of substituents on their molecular structures, frontier molecular orbital (MO) levels, and magnetically induced ring current tropicities. Both theoretical calculations and X-ray structure analyses indicate that the derivatives of the C2h-substitution pattern adopt different C2h structures with significant bond length alternation depending on the electronic property of the substituents. Due to the nonuniform distribution of the frontier MOs, their energy levels are selectively modulated by the electron-donating substituents. This leads to the inversion of the HOMO and HOMO-1 sequences with respect to those of the intrinsic s-indacene as theoretically predicted and experimentally proven by the absorption spectra at visible and near-infrared regions. The NICS values and the 1H NMR chemical shifts of the s-indacene derivatives indicate their weak antiaromaticity. The different tropicities are explained by the modulation of the HOMO and HOMO-1 levels. In addition, for the hexaxylyl derivative, weak fluorescence from the S2 excited state was detected due to the large energy gap between the S1 and S2 states. Notably, an organic field-effect transistor (OFET) fabricated using the hexaxylyl derivative exhibited moderate hole carrier mobility, a result which opens the door for optoelectronic applications of s-indacene derivatives.
AB - Though s-indacene is an intriguing antiaromatic hydrocarbon of 12 π-electrons, it has been underrepresented due to the lack of efficient and versatile methods to prepare stable derivatives. Herein we report a concise and modular synthetic method for hexaaryl-s-indacene derivatives bearing electron-donating/-accepting groups at specific positions to furnish C2h-, D2h-, and C2v-symmetric substitution patterns. We also report the effects of substituents on their molecular structures, frontier molecular orbital (MO) levels, and magnetically induced ring current tropicities. Both theoretical calculations and X-ray structure analyses indicate that the derivatives of the C2h-substitution pattern adopt different C2h structures with significant bond length alternation depending on the electronic property of the substituents. Due to the nonuniform distribution of the frontier MOs, their energy levels are selectively modulated by the electron-donating substituents. This leads to the inversion of the HOMO and HOMO-1 sequences with respect to those of the intrinsic s-indacene as theoretically predicted and experimentally proven by the absorption spectra at visible and near-infrared regions. The NICS values and the 1H NMR chemical shifts of the s-indacene derivatives indicate their weak antiaromaticity. The different tropicities are explained by the modulation of the HOMO and HOMO-1 levels. In addition, for the hexaxylyl derivative, weak fluorescence from the S2 excited state was detected due to the large energy gap between the S1 and S2 states. Notably, an organic field-effect transistor (OFET) fabricated using the hexaxylyl derivative exhibited moderate hole carrier mobility, a result which opens the door for optoelectronic applications of s-indacene derivatives.
UR - http://www.scopus.com/inward/record.url?scp=85148449304&partnerID=8YFLogxK
U2 - 10.1021/jacs.2c13159
DO - 10.1021/jacs.2c13159
M3 - Article
C2 - 36796008
AN - SCOPUS:85148449304
SN - 0002-7863
VL - 145
SP - 4716
EP - 4729
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 8
ER -