Aqueous-phase phosphors are of utmost importance for a myriad of applications. However, the emission wavelengths of the current aqueous organic room-temperature phosphorescent (RTP) materials are limited to green and red bands, while the blue part is rarely reported, thus limiting the development of a full-color RTP system. Theoretically, carboxylated benzene is expected to be blue phosphorescence-emissive, but only green phosphorescence is observed in solid, due to the strong intermolecular π-π stacking that decreases the energy gap. Herein, the use of water-dispersible layered double hydroxide (ZnAl-LDH) is proposed for isolating Ph-(COOH)