Covalent Dimers of 1,3-Diphenylisobenzofuran for Singlet Fission: Synthesis and Electrochemistry

The
synthesis of covalent dimers in which two 1,3-diphenylisobenzofuran
units are connected through one phenyl substituent on each is reported.
In three of the dimers, the subunits are linked directly, and in three
others, they are linked via an alkane chain. A seventh new compound
in which two 1,3-diphenylisobenzofuran units share a phenyl substituent
is also described. These materials are needed for investigations of
the singlet fission process, which promises to increase the efficiency
of solar cells. The electrochemical oxidation and reduction of the
monomer, two previously known dimers, and the seven new compounds
have been examined, and reversible redox potentials have been compared
with results obtained from density functional theory. Although the
overall agreement is satisfactory, some discrepancies are noted and
discussed.