A C 3-Symmetric Phloroglucinol Derivative for Tuning the Structures and Luminescence of Solvates

Abstract

Organic molecules forming solvates often adopt different molecular conformations depending on the included solvent molecules, leading to variations in their photophysical properties. In this study, a conformationally flexible luminescent phloroglucinol derivative afforded eight solvates upon crystallization from ethyl acetate, chloroform, THF, pyridine, benzene, toluene, o-dichlorobenzene, and iodobenzene solutions. Based on single-crystal X-ray diffraction analysis, these solvates were classified into two space groups according to the size of the included solvent molecules: substituted benzene derivatives and smaller solvent molecules. In addition, crystallization from a mixed solution of dichloromethane and cyclohexane yielded a heterosolvate containing two types of solvent molecules, in which distinct cavities corresponding to the size of each solvent molecule were formed. Photophysical investigations confirmed that, although all solvates exhibited yellow to orange emission, a significant shortening of the average fluorescence lifetime was observed in the iodobenzene solvate. These results are expected to support the development of design principles for luminescent crystalline materials in which photophysical properties can be tuned by the choice of crystallization solvent.