Ultralong Room-Temperature Phosphorescence with Second-level Lifetime in Water Based on Cyclodextrin Supramolecular Assembly

Organic solid-state materials with long-lived room-temperature phosphorescence (RTP) emission have been widely developed and applied in many fields, while works in developing solution-phase phosphorescence materials were rarely reported owing to the ultrafast nonradiative relaxation and quenchers from the liquid medium. Herein, we report an ultralong RTP system in water through assembly based on a β-cyclodextrin host and <i>p</i>-biphenylboronic acid guest with a lifetime of 1.03 s under ambient conditions. It is worth noting that the long-lived phosphorescence depends on the host-guest inclusion as well as intermolecular hydrogen bonding interactions, which suppress nonradiative relaxation and avoid quenchers effectively. Furthermore, the addition of fluorescent dyes to the assembly system achieved the tuning of the afterglow color through radiative energy transfer of reabsorption.