Electron-Transporting Bis(heterotetracenes) with Tunable Helical Packing.

A novel kind of electron-deficient bis(heterotetracenes) namely perylenotetrathiophenediimides (PTTIs) involving double S-hetero[5]helicene diimides, is developed by a fourfold thienannulation route via ortho-functionalization of perylene diimides (PDIs). PTTIs exhibit significantly red-shifted absorption capacity with lowest-energy transition maxima beyond 700 nm and narrowed HOMO-LUMO energy gaps. Through delicately tuning the side-chain substitution, the distorted propeller-like framework could self-assemble into unprecedented 1D helical π-stacking structures with short π-π contacts and rich nonbonding interactions from alternating arrangements of P/M enantiomeric couples or tetrads. Excellent electron transporting efficiency in racemate PTTI crystals with 0.40 cm2  V-1  s-1 for 5 a and 0.90 cm2  V-1  s-1 for 5 b, was witnessed in single-crystalline transistors, signifying the prospects of the chiral π-helix in optoelectronic applications.