Charge Transfer Versus Arene–Perfluoroarene Interactions in Modulation of Optical and Conductivity Properties in Cocrystals of 2,7-Di-tert-butylpyrene

Herein, we have demonstrated switching of the n-type semiconductor to insulator nature by utilizing π···π stacking interactions viz. charge transfer (CT) and arene–perfluoarene (A–AP) in cocrystals of π-donor 2,7-di-tert-butylpyrene. The binary (1:1) cocrystals were obtained with π-acceptors, fluoranil, and octafluoronaphthalene via CT and A–AP interactions. Hirshfeld surface, natural bond orbital, and energy decomposition analyses (EDA) confirmed that the CT interaction is stronger than the A–AP interaction. The difference between two π···π interactions was further ascertained by spectroscopic studies including UV–vis and fluorescence in the solid state, EPR, and infrared. The CT cocrystal showed the n-type semiconductor behavior and prominent fluorescence quenching, while the A–AP interaction led to small fluorescence quenching with insulator property.