Density Functional Studies on Photophysical Properties of Boron-Pyridyl-Imino-Isoindoline Dyes: Effect of the Fusion

• Published in: ACS omega 2020-08, Vol.5 (33), p.21067-21075
• Main Authors: Jin, Jun-Ling, Yang, Lixia, Ding, Xiang, Ou, Li-Hui, Chen, Yuan-Dao, Gu, Hao-Yu, Wu, Yong, Geng, Yun
• Format: Article
• Language: English
• ISSN: 2470-1343; 2470-1343
• DOI: 10.1021/acsomega.0c02669

In this work, to make out the aryl-fusion effect on the photophysical properties of boron-pyridyl-imino-isoindoline dyes, compounds 1–5 were theoretically studied through analyses of their geometric and electronic structures, optical properties, transport abilities, and radiative (k r) and non-radiative decay rate (k nr) constants. The highest occupied molecular orbitals of aryl-fused compounds 2–5 are higher owing to the extended conjugation. Interestingly, aryl fusion in pyridyl increases the lowest unoccupied molecular orbital (LUMO) level, while isoindoline decreases the LUMO level; thus, 4 and 5 with aryl fusion both in pyridyl and isoindoline exhibit a similar LUMO to 1. Compounds 4 and 5 show relatively low ionization potentials and high electron affinities, suggesting a better ability to inject holes and electrons. Importantly, the aryl fusion is conducive to the decrease of k IC. The designed compound 5 exhibits a red-shifted emission maximum, low λh, and low k IC, which endow it with great potential for applications in organic electronics. Our investigation provides an in-depth understanding of the aryl-fusion effect on boron-pyridyl-imino-isoindoline dyes at molecular levels and demonstrates that it is achievable.