Efficient Luminescent Microtubes of Charge-Transfer Organic Cocrystals Involving 1,2,4,5-Tetracyanobenzene, Carbazole Derivatives, and Pyrene Derivatives

A series of binary charge-transfer (CT) cocrystals and microtubes involving 9-formylcarbazole, 9-acetylcarbazole, 1-formylpyrene, and 1-acetylpyrene as CT donors and 1,2,4,5-tetracyanobenzene as CT acceptor were obtained via molecular self-assembly. Crystal structural analysis revealed that these organic cocrystals were constructed with D··A··D··A··D ( Ia and IIb ) and DAD···DAD ( Ib and IIa ) modes through π···π, hydrogen bond, C–H···π, and C–N···π interactions. Infrared spectroscopy, thermal property profiles, and solid-state absorption spectroscopy were recorded to understand physicochemical properties of all CT materials. The morphology and structure of microtubes were detected by scanning electron microscopy and powder X-ray diffraction. Investigation of luminescent properties shows that a stepwise increase of luminescent efficiency from pristine donors to microtubes can be realized. These results provide an effective way for exploring new luminescent materials.