Zinc Sulfate Open Frameworks with Nonconventional Room-Temperature Phosphorescence for Selective Amine Vapor Detection

Molecular-based afterglow materials have garnered significant attention due to their diverse applications. However, most studies focus on conventional luminophores, leaving nonconventional systems underexplored, particularly regarding the screening of new material subclasses and the development of applications such as sensing. Herein we report the successful preparation of two new two-dimensional ZnSO₄-based open-framework materials (OFMs)─(H₂DABCO)[Zn₃(μ₃-OH)₂(SO₄)₃]·H₂O (<b>1</b>) and (H₂DABCO)[Zn(SO₄)₂] (<b>2</b>)─through self-assembly of Zn²⁺/SO₄^2- with nonaromatic triethylenediamine (DABCO). Both compounds exhibit distinct delayed emission characteristics with lifetimes of 259.10 ms (<b>1</b>) and 49.62 μs (<b>2</b>), respectively. Frontier orbital analysis reveals the key role of charge transfer between sulfate groups to (H₂DABCO)²⁺ cations in the luminescence. Notably, <b>1</b> demonstrates exceptional performance as an afterglow probe for the selective detection of <i>n</i>-propylamine and <i>n</i>-butylamine vapors, achieving detection limits of 32.99 and 47.18 ppm, respectively. The sensing mechanism involves a phase-transition process, and the luminescence change can be observed by the naked eye. This work pioneers the integration of sulfate-based OFMs with nonconventional room-temperature phosphorescence properties, demonstrating their potential as afterglow probes for industrial and environmental monitoring.