Synthesis, structure and luminescence of Co-crystals with hexagonal channels: arranging disposition and π-π interactions

Co-crystallization of asymmetric building blocks 5-(4-pyridyl)pyrimidine (A) and 5-(4-(1-imidazolyl)phenyl) pyrimidine (B) with resorcinol and hydroquinone, respectively, was investigated. Four new organic co-crystals (1-4) were generated. The X-ray single crystal analysis indicates that the crystal packing in 1, 2 and 4 generates open hexagonal channels with resorcinol or hydroquinone molecules encapsulated through hydrogen bonding interactions. In 3, {B-2(resorcinol)(2)} macrocycle is generated from clip-like resorcinol and asymmetric B molecules. In addition, the luminescent properties of A, B and 1-4 were investigated primarily in the solid state. The luminescent property is dependent on the molecular vertical arranging disposition and the intermolecular pi-pi contacting characteristic. The results display more interesting tunability of the emission intensity of the building modules by the incorporation of coformers into the co-crystals.