High-Temperature Liquid-Phase Phosphorescence of Carbon Dot-Zinc Hydroxide Nitrate Coordination Networks

Achieving persistent phosphorescence in liquid phases at elevated temperatures remains a formidable challenge, as thermally induced structural disruption and solvent-assisted exciton quenching severely accelerate the nonradiative deactivation of triplet states. Herein, we report carbon dot-zinc hydroxide nitrate nanoflower coordination networks (CD@ZHNs) that exhibit tunable multicolor phosphorescence spanning from green to yellow. Notably, these materials deliver robust high-temperature liquid-phase phosphorescence (HTLP) in both aqueous and organic solvents, accompanied by outstanding resistance to repeated thermal cycling. Comprehensive structural characterization combined with theoretical analysis reveals that the persistent HTLP originates from the formation of additional coordination bonds, which rigidify and reinforce the coordination network to effectively suppress nonradiative pathways. Meanwhile, the excellent recoverability is attributed to the intrinsic structural memory effect of ZHNs, enabling reversible reconstruction of the coordination framework after thermal perturbation. This work establishes a general coordination-engineering strategy for constructing persistent and recoverable HTLP systems, opening new avenues for real-time temperature monitoring in harsh liquid environments, advanced anti-counterfeiting technologies, and in situ diagnostics of high-temperature equipment.