Tuning Solid-State Emission of 9-Anthraldehyde through Cocrystal Engineering

Abstract

The regulation of solid-state emission based on cocrystal engineering is an emerging strategy for developing next-generation luminescent materials. Here, three luminescent cocrystals (AA-DITFB, AA-TFTPA and AA-TCNB) of 9-anthraldehyde (9-AA) are reported, which exhibit a broad range of green-to-red emission. Tuning the photophysical properties of 9-AA via cocrystals is based on different mechanisms. Compared with single-component crystals, the difference in the emission properties of AA-DITFB and AA-TFTPA originates from the π–π interaction between chromophores. As for AA-TCNB, its prominent red-shifted emission is the result of the charge-transfer interaction, which is confirmed by infrared spectroscopy, “hole-electron” analysis and charge-transfer spectroscopy. This work not only reveals the relationship between molecular structure and fluorescent properties, but also proposes a strategy to develop multicolor luminescent systems with tunable efficiency and lifetime.

Solid-State Assembly and Photoluminescent Behavior of 5-(9H-Carbazol-9-yl)isophthalic Acid–Based Molecular Crystals Influenced by Solvents and Organic Counterparts

“…Molecular crystals with desirable structures and efficient photoluminescence are highly important for multiscenario field applications in displaying, , sensing, , optical waveguide, and optoelectronics devices. − Lots of organic crystalline materials with tunable emission color, long-lived lifetime, and/or high quantum yield have been designed and manufactured by powerful cocrystal engineering strategy. − Besides the enhanced charge transfer (CT) interactions between electron-rich donor (D) and electron-withdrawing acceptor (A), − weak intermolecular interactions (π–π stacking, hydrogen bond, halogen bond, dipole–dipole, and so on) have also become main forces to drive two or more components into highly ordered solid-state superstructures. − These weak interactions have precisely dominated the molecular packings in the rigid crystal matrix, resulting in unpredictable polymorphism, segregated AD and/or ADA alignments, and exciton coupling strgenth. , More importantly, the different stacking structures have well-tailored the band gaps and exciton couplings, responsible essentially for the unexpected geometry stability and optoelectronic characteristics . However, the stacking patterns are extremely complicated and highly sensitive to the molecular structure and crystal growth environment, and purposeful controls on the photoluminescence still remain a great challenge. ,− Great efforts have thus been devoted to the chemical modifications of the constitute part by introducing multiple interacting sites or skillful selection of the compatible D–A pairs to obtain high-emissive and high-stable molecular crystals …”