Diastereoisomer-Induced Morphology Tunable Self-Assembled Organic Microcrystals of Conjugated Molecules for Ultraviolet Laser

Precisely controlling self-assembly behavior and micro/nanostructure morphology of conjugated materials is significant for constructing optoelectronic devices. Inspired by natural functional materials, molecular stereoisomerism strategy (MSS) is an effective and convenient means to tune their molecular arrangement and macroscopic property of conjugated materials. Herein, a supramolecular chiral difluorenols, 9,9′-diphenyl-9H,9′H-[2,2′-bifluorene]-9,9′-diol (DPFOH), is set as a desirable model to reveal the diastereomeric effects of conjugated molecules toward controlling the micro/nanostructure morphology and optoelectronic behavior for deep-blue organic laser. Two diastereomers, raceme (rac)- and mesomer (meso)-DPFOH, are obtained and unambiguously elucidated by X-ray crystallography. It is common sense to observe the slight diastereomeric effects on photophysical properties and electrochemical characteristics in solution or pristine film state for the isotropic phase. Interestingly, as a consequent of the disparate multi-dimensional intermolecular interaction, rac-DPFOH molecule can self-assemble into 1D rod-shaped but rectangular plate-shaped microcrystals for meso-DPFOH. Impressively, rac-DPFOH microrod presents a well-defined emission with an excellent ultraviolet microlasing behavior at 398 nm, whereas the 2D microplate of meso-DPFOH show a broad emission centered at 420 nm without gain processing. Therefore, MSS provides a new approach to design conjugated molecules and tune superstructure morphology for optoelectronic applications.