Harnessing Photocycloreversion for Dimer Construction and Photoactivation: From Molecule to Aggregate

Abstract

Despite extensive investigations into photophysics at the molecular level, the complex interplays between intermolecular interactions, hierarchical assembly, and photoluminescence properties remain a fundamental challenge in materials science, particularly concerning emergent phenomena in molecular aggregates. Herein, we construct different dimeric structures in both solution and aggregate states through cycloreversion upon photoirradiation from a series of nonemissive phenanthrene cycloadducts, exhibiting state-dependent photoactivatable luminescence. Specifically, the excimer in solution is nonemissive due to its antiparallel cofacial structure. In contrast, the dimer in the crystal exhibits nonclassical excimer emission according to its cross-stacked stacking within the restriction of the crystal lattice. Prominently, the luminescent behavior in aggregate is uniquely accessible through photocycloreversion and cannot be achieved through spontaneous crystallization of their parent phenanthrene molecules. Moreover, the photoactivatable nature of these materials is successfully demonstrated in thin films, showcasing their potential applications in information encryption. This work expands the possibilities for constructing new functional aggregate materials by photochemistry and deepens our understanding of dimer-luminescence relationships in different states.

Keywords

aggregate science / excimer / luminescence / photoactivation / photocycloreversion

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