Series of charge transfer complexes obtained as crystals in a confined environment

A series of charge transfer complexes (CTCs) were successfully formed by solvent free processing techniques, using the 1,2,4,5-tetracyano benzene (TCNB) as π A molecule and a series of p -dihydroquinones (H 2 Qs) as π D counterparts. Additionally to the classical co-evaporation techniques, we obtained CTCs in less than an hour, in a very simple confined environment, between two 100 μm - spaced glass plates. A systematical study by Raman spectroscopy on crystals highlighted the CTCs formation. Moreover, three new crystalline structures were obtained, namely TCNB-H 2 Q that crystallizes in columns connected to each other by H-bonds, while with the methoxy- and dimethoxy-H 2 Qs the CTC forms crystals with the stoichiometry 1 : 2, TCNB-(H 2 Q OMe ) 2 and TCNB-(H 2 Q OMe 2 ) 2 . In TCNB-(H 2 Q OMe ) 2 layers are formed due to intermolecular hydrogen bonds, while in TCNB-(H 2 Q OMe 2 ) 2 molecules arrange in triads, with π A -π D interactions. In all cases, strong π A -π D interactions exist with intermolecular distances lower than the van der Waals distances, which results in strong absorption bands in the visible range. A series of charge transfer complexes (CTCs) were successfully formed by solvent free processing techniques, using the 1,2,4,5-tetracyano benzene (TCNB) as π A molecule and a series of p -dihydroquinones (H 2 Qs) as π D counterparts.