1 research outputs found
Pentaleno[1,2‑<i>a</i>:4,5′]diacenaphthylenes: Uniquely Stabilized Pentalene Derivatives
We
demonstrate the preparation of diacenaphthopentalene derivatives
via a palladium-catalyzed dimerization of 1-iodo-2-arylethynyl-acenaphthylenes.
The resulting 7,14-diarylpentaleno[1,2-<i>a</i>:4,5<i>a</i>′]diacenaphthylenes, which
contain four linearly fused five-membered rings, are benchtop stable
and behave as hole-transporting or ambipolar semiconductors in organic
field effect transistors. The X-ray crystal structure shows the important
role of the fused naphthalene unit that enforces a formal pentalene
subunit at the central five-membered rings and [5]-radialene-like
structures at the proximal five-membered rings. Nucleus-independent
chemical shift (NICS) calculations show the internal pentalene rings
are intermediate in antiaromaticity character between known pentalene
and dibenzopentalenes derivatives. The diacenaphthopentalene
derivatives give high optical gap materials owing to a forbidden HOMO
to LUMO transition, yet have narrow electrochemical gaps and are reduced
at small negative potentials giving LUMO energy levels of −3.57
to −3.74 eV