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.