From hydrogen-bond networks to multilevel encryption: Full-color fluorescence and controllable RTP activation of...

Arylboronic acid derivatives have attracted much attention due to their inherent room-temperature phosphorescence (RTP). However, clarifying the structural basis of photoluminescence (PL) and guiding applications poses challenges. Using 4-bromophenylboronic acid (BrBA) as a model, the decisive regulation mechanism of hydrogen-bond networks on PL is first elucidated via cocrystal engineering. Specifically, the cross-shaped assemblies in BrBA cocrystals feature two distinct types of hydrogen-bond channels: the α-channel governs fluorescence (FL), whereas the β-channel specifically controls phosphorescence. The co-crystalline solvents, n-hexane and methanol, mediate the construction and dissociation of these hydrogen-bonding networks by modulating molecular packing, thereby precisely regulating PL behavior. Based on this solvent-mediated strategy, FL color regulation of BrBA and phenylboronic acid (BA) over nearly the entire visible spectrum (covering blue, green, yellow, orange), and controllable RTP activation are achieved without chemical modification. Furthermore, multilevel information encryption, including graphical, computational, and textual encryption is successfully demonstrated using the multicolor BrBA fluorescent powders. This study establishes a novel paradigm for the rational design and controllable preparation of pure organic RTP materials.