Molecule configurations modulate packing array and charge transfer in cocrystal engineering.

Organic cocrystal as an emerging assembly strategy has received increasing attention in constructing multiple functional materials, through continually screening suitable constituent monomers or changing their stoichiometry ratios. However, the role of molecule configuration in the cocrystal field is rarely explored despite the fascinating potential in regulating the packing mode. In this study, the N,N′-diphenyl-5,10-dihydrophenazine derivatives (DPPs) with the flexible scaffold and different methyl substitutions are selected as the donors bearing various molecular configurations. In a simple collaborative way, a series of cocrystals based on DPPs and OFN (octafluoronaphthalene) are fabricated, exhibiting two self-adaptive molecular stacking arrays. X-ray crystallographic analysis and theoretical calculation unveil their different π...π interactions and charge transfer characters, leading to the significant emission redshift up to 125 nm compared with individual DPPs. As a result, controllable molecule stacking structure, tunable emission, and charge transfer properties can be achieved. The study provides a new perspective to reveal the structure-property relationships at the molecular level by controlling the molecule configuration in cocrystal engineering, contributing to the development of cocrystal theoretical physics and organic functional materials. [ABSTRACT FROM AUTHOR]