Coordination Rigidity Lock: An Effective Strategy for Ultralong-Lived Aqueous Room-Temperature Phosphorescence

Abstract

The design of ultralong-lived aqueous room-temperature phosphorescence (RTP) materials has emerged as a rapidly advancing yet challenging research field. In this work, we introduce a coordination rigidity locking strategy to achieve an ultralong aqueous RTP lifetime in lanthanum- and poly(pyromeric acid)-based phosphorescent materials (La/PMA-PMs). Compared to their dry state (212 ms), the La/PMA-PMs display a significantly increased lifetime of 974 ms upon the addition of a small amount of water (50 wt %). Notably, even in a fully nondeoxygenated aqueous environment (≥300 wt % water), La/PMA-PMs retain an ultralong aqueous RTP lifetime of approximately 800 ms. The water-enhanced RTP can be ascribed to the abundant La³⁺ sites and hydrophilic groups on the La/PMA-PMs surface. Specifically, water molecules coordinate with La³⁺ ions while also serving as bridging agents that bind to hydrophilic groups via hydrogen bonding. This interaction rigidifies the functional groups and restricts their molecular motions, thereby minimizing nonradiative decay. This work not only presents a robust coordination rigidity strategy for designing high-performance aqueous RTP materials but also highlights their potential as optical platforms for advanced anticounterfeiting applications.