Modulating Paratropicity Strength in Diareno-Fused Antiaromatics

Understanding and
controlling the electronic structure of molecules
is crucial when designing and optimizing new organic semiconductor
materials. We report the regioselective synthesis of eight π-expanded
diarenoindacene analogues based on the indeno­[1,2-b]­fluorene framework along with the computational investigation of
an array of diareno-fused antiaromatic compounds possessing s-indacene, pentalene, or cyclobutadiene cores. Analysis
of the experimental and computationally derived optoelectronic properties
uncovered a linear correlation between the bond order of the fused
arene bond and the paratropicity strength of the antiaromatic unit.
The Ered1 for the pentalene and indacene core molecules correlates
well with their calculated NICSπZZ values. The findings
of this study can be used to predict the properties of, and thus rationally
design, new diareno-fused antiaromatic molecules for use as organic
semiconductors.