Modulation of Solid-State Fluorescence Properties for Anthracene Chalcone Heterocyclic Compounds by Charge-Transfer Cocrystal Self-Assembly: Molecular Stacking Mode and DFT Analysis

Abstract

The supramolecular self-assembly of two anthracene chalcone charge transfer (CT) cocrystals with modifiable photoluminescence properties was investigated, which are mainly stacked by π···π interactions. Electron-rich (2E)-3-(9-anthracenyl)-1-(2-thienyl)-2-propen-1-one (ATPO) and (2E)-3-(9-anthracenyl)-1-(2-furanyl)-2-propen-1-one (AOPO) were used as donors (D), electron-deficient 1,2,4,5-benzenetetracarbonitrile (TCNB) was used as an acceptor (A), and supramolecular self-assembly was achieved through CT induction as the driving force. The formation of the cocrystal was confirmed by X-ray diffraction and infrared spectroscopy, and the optical property modulation of the cocrystal was characterized by solid-state ultraviolet (UV) diffuse reflection absorption spectroscopy and fluorescence property testing. The stacking mode of cocrystal AOPO–TCNB was D–A–D–A, while that of cocrystal ATPO–TCNB was D–A–D. Compared with the donor, the UV absorption band and fluorescence emission peak of the cocrystal exhibited a significant red-shift, and the fluorescence quantum yield and lifetime were also improved, which was closely related to the CT effect caused by the π···π interaction between the donor and acceptor. Based on the obtained crystal structure, density functional theory (DFT) analysis was used to quantitatively analyze the intensity of the CT effect. This study quantitatively analyzes the CT effect based on atomic charges, which is of great significance for the prospective design of new solid-state luminescent materials.