Abstract: Room-temperature phosphorescence (RTP) has been attracting attention in recent years due to its long light-emitting lifetime, large Stokes shift, and sensitivity to the environment, which have important application prospects in the fields of bio-imaging, illumination display, and anti-counterfeiting. Hydrogen-bonded networks are widely employed in the design of solid-state RTP materials owing to their ability to suppress nonradiative transitions and stabilize triplet excited states; however, effective regulation of phosphorescence lifetimes in such systems remains challenging. In this work, a hydrogen-bonded assembly based on melamine and isophthalic acid (MA-IPA) was constructed through carboxylic acid–amine hydrogen-bond interactions, and the assembly process was modulated by introducing benzene derivatives bearing different numbers of carboxyl substituents as molecular dopants. The results show that the introduction of dopant molecules does not alter the fundamental building units of the hydrogen-bonded network of MA-IPA but significantly affects the ordered packing mode and mesoscopic structural features. As a consequence, the particle size and specific surface area of the assemblies are effectively regulated, leading to different degrees of oxygen quenching of triplet excitons under ambient conditions. The resulting materials exhibit stable RTP, with phosphorescence lifetimes of up to 1.7 s. This study provides a viable strategy for the structural regulation of long-lived RTP materials based on hydrogen-bonded networks.

Key words: room-temperature phosphorescence (RTP), hydrogen-bonded network, phosphorescence lifetime, molecular doping