Condensed Derivatives of Thiadiazoloquinoxaline as Strong Acceptors

Three novel thiadiazoloquinoxaline
(TQ) derivatives, TIPS-APhTQ, TIPS-PhTQ,
and TIPS-BDTTQ, were synthesized
by introducing two triisopropylsilylethynyl groups and alternating
the aromatic ring units in the condensed moiety of TQ. The synthetic
route is very efficient, providing high yields. Cyclic voltammetry
suggests high electron affinity values of −3.82, −3.95,
and −3.99 eV for TIPS-APhTQ, TIPS-PhTQ, and TIPS-BDTTQ, respectively. Single-crystal X-ray
diffraction reveals that three molecules form corresponding dimers
by intermolecular S–N interaction and have very similar two-dimensional
π-stacking. The π-stacking distances between them are
as close as 3.34–3.46 Å.