Molecular confinement within ammonium bis(biureto)borate nanosheets enables ultrastable room-temperature phosphorescence.

Although host-guest phosphorescent materials have been extensively investigated, their environmental stability remains a formidable challenge largely rooted in the host matrix itself. To address this issue, we developed a nanosheet host material, ammonium bis(biureto)borate (NH4[B(biu)2], AB), which features a dense hydrogen-bonding network that confers exceptional rigidity and structural stability upon the overall framework. Thus, utilizing AB as the host, we constructed a series of multicolor phosphorescent systems achieving a phosphorescence quantum yield (PQY) of 23.5% and an afterglow lifetime of up to 676.21 ms. Notably, the obtained samples demonstrate remarkable resilience under elevated thermal conditions, extreme pH environments, and prolonged aqueous immersion spanning 20 days. The phosphorescence-based sensor enables specific discrimination of tetracycline, with a low limit of detection of 1.78 μM. Furthermore, a high-security multi-layer information encryption system was constructed based on dot matrix arrays with resolution in both time and color, utilizing dual-signal outputs of phosphorescence color and lifetime. This work offers a direct reliable route to construct universal host matrices with robust hydrogen bond networks and stability, and opens new avenues for rational design of intelligent luminescent materials for anticounterfeiting and data storage.