Kinetically stabilized 1,3-diarylisobenzofurans and the possibility of preparing large, persistent isoacenofurans with unusually small HOMO-LUMO gaps

Submitting author affiliation:
University of New Hampshire, Durham, United States

Beilstein Arch. 2023, 202355.

Published 05 Dec 2023

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We show that isoacenofurans of any size possess smaller HOMO-LUMO gaps than the corresponding acene bearing an isoelectronic p-system (i.e., the same total number of rings). Large isoacenofurans show limited stability due in part to the highly reactive 1,3-carbons of the furan ring. Placing sterically congesting phenyl substituents bearing ortho alkyl groups at the 1,3-positions of 1,3-diarylisobenzofurans force these molecules to adopt non-planar conformations with the ortho alkyl groups above and below the most reactive 1,3-carbons of the furan ring. These bulky substituents provide a strong measure of kinetic stabilization. Thus, 1,3-dimesitylisobenzofuran and 1,3-di(2’,4’,6’-triethylphenyl)isobenzofuran are at least 500 times less reactive than 1,3-diphenylisobenzofuran in their reactions with the strong dienophiles DMAD and acrylonitrile. The insights gained here suggest that the synthesis of large, persistent, kinetically stabilized isoacenofurans with unusually small HOMO-LUMO gaps is within reach. As such, these molecules deserve increased attention as potential p-type organic semiconductors.

Keywords: Isoacenofuran, Isobenzofuran, Isonaphthofuran, Isoanthracenofuran, Isotetracenofuran, Isopentacenofuran, 1,3-Diphenylisobenzofuran, 1,3-Dimesitylisobenzofuran, 1,3-Di(2’,4’,6’-triethylphenyl)isobenzofuran, 1,3-Di(2’,4’,6’-triisopropylphenyl)isobenzofuran, 1,3-Di(2’,4’,6’-tri-t-butylphenyl)isobenzofuran, Organic semiconductor, p-Type organic semiconductor, Acene, Small band-gap, Small HOMO-LUMO gap, Kinetically stabilized, Highly delocalized p-system, Sterically congesting substituent, Synthesis, DFT calculation

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Liu, Q.; Miller, G. P. Beilstein Arch. 2023, 202355. doi:10.3762/bxiv.2023.55.v1

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