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B 2 N 2 ‐Embedded Polycyclic Aromatic Hydrocarbons with Furan and Thiophene Derivatives Functionalized in Crossed Directions
Author(s) -
Chen Yijing,
Chen Weinan,
Qiao Yanjun,
Zhou Gang
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201901782
Subject(s) - chemistry , thiophene , lewis acids and bases , anthracene , furan , benzene , electrophile , aryl , medicinal chemistry , stereochemistry , photochemistry , organic chemistry , catalysis , alkyl
A series of polycyclic aromatic hydrocarbons (PAHs), consisting of two pairs of BN units, have been designed and their synthesis has been achieved by electrophilic C−H borylation. Two conjugation extension directions can be found in these B 2 N 2 ‐embedded PAHs. The B 2 N 2 ‐containing backbone with shorter effective conjugation length is isoelectronic with diaryl‐fused anthracene, whereas the second derivative, with longer effective conjugation length, is isoelectronic with bis( trans ‐arylvinyl)benzene. By incorporating different aryl groups, i.e., furyl, thienyl, benzo[ b ]furyl, and benzo[ b ]thienyl groups, into the two crossed directions of the B 2 N 2 ‐embedded PAHs, their electronic and optical properties have been comparatively investigated by photophysical, electrochemical, and theoretical approaches. It is found that both the substituents and their conjugation extension directions have significant effects on the aromatic and photophysical properties of the B 2 N 2 ‐embedded PAHs. The conjugation extension in the shorter backbone is more pronounced on the effective conjugation length than the longer backbone. Moreover, all the B 2 N 2 ‐embedded PAHs behave as both Lewis acids and Lewis bases, and reversible photoluminescence switching can be observed by simply neutralizing the added Lewis acid or Lewis base.