Solid state conformation and crystal packing of methyl-substituted quaterthiophenes

The solid state structures of a series of methyl substituted neutral quaterthiophenes have been analysed. Structures have been retrieved from the Cambridge Structural Database and investigated in terms of crystal cohesion and intermolecular interactions. In these thiophene oligomers, it can be shown that crystal packing efficiency and optimisation of S---S, C-H---S and C-H---pi interactions constitute the driving force for their solid state geometry and configuration. A detailed discussion of their packing arrangement is reported and shown to be based on either a herringbone or pi-pi stacking of thiophene units.