Solid-state fluorescence modulation and DFT analysis of charge-transfer cocrystal of anthracene-chalcone-pyridine compounds

Charge transfer (CT) cocrystals formed via non-covalent interactions play a pivotal role in governing their optical behaviors. A CT cocrystals were synthesized using 1,2,4,5-tetracyanobenzene (TCNB) as the electron acceptor and chalcone (E)-3-(anthracen-9-yl)-1-(pyridin-3-yl)prop-2-en-1-one (A3BPO) as the electron donor. Structural analysis through single-crystal X-ray diffraction (SC-XRD) unveiled that this cocrystal predominantly comprise a mixed stacking arrangement guided by face-to-face π···π interactions, with the overall stability of CT cocrystal stacking bolstered by auxiliary hydrogen bonds. The relationship between structure and properties was scrutinized using various analytical techniques including Powder X-ray diffraction (PXRD), FT-IR, UV–visible absorption, and fluorescence spectroscopy. Density functional theory (DFT) simulations elucidated that the modified optical properties primarily stem from CT between acceptor and donor. These findings contribute significantly to a clearer understanding of how stacking modes in CT cocrystals influence the interplay between CT and optical properties.