Face-to-Face Packing of 2,3,9,10-Tetrasubstituted Pentacene Derivatives Revealed through a Solid State [4 + 4] Thermal Cycloaddition and Molecular Dynamic Simulation

2,3,9,10-Substituted
pentacene tetraesters and pentacene diester-dinitriles were synthesized.
These pentacene derivatives underwent an unusual solid state [4 +
4] thermal dimerization with good efficiency and complete stereoselectivity.
This observation indicates this series of pentacene derivatives adopt
π–π stacking geometry with large mutual overlap
in solid state. This notion was confirmed by molecualr dynamic simulation.