Phosphorescent Sensing of ADN Using Copper(I) Coordination Polymers

Abstract Rapid, selective, and field-deployable detection of ammonium dinitramide (ADN) is important for the safe production, handling, and monitoring of energetic materials. Herein, we report a distinct synthetic strategy for the known Cu(I) coordination polymer [Cu(pz)]n and reveal its previously unexplored phosphorescent sensing capability toward ADN. Inspired by the thermal reduction of related Cu(II) imidazolate frameworks, Pbca-[Cu(pz)]n was prepared from Cu(pz)2 via high-temperature reduction and vapor deposition, affording diffraction-quality single crystals for accurate structural refinement and photophysical analysis. To the best of our knowledge, this work represents the first application of [Cu(pz)]n as a phosphorescent sensing platform for ADN. Upon exposure to ADN, [Cu(pz)]n shows phosphorescence quenching mainly via competitive absorption (CA), with possible photoinduced electron transfer (PET) contribution. The Stern–Volmer response shows a linear relationship over the ADN concentration range of 0–80 μM (R2 = 0.987), with a Stern–Volmer constant (KSV) of 2.7 × 104 M–1 and a detection limit of 5.56 μM. Although previously reported graphene-based voltammetric and AuNP-based colorimetric methods achieve lower detection limits of 2.0 μM and approximately 0.10 μM, respectively, they rely on electrode-based measurements or multistep UV-assisted chemical conversion and derivatization. In contrast, [Cu(pz)]n enables direct phosphorescence sensing of ADN without such pretreatment and shows high selectivity over the tested energetic materials. Furthermore, [Cu(pz)]n can be incorporated into test strips for visual ADN detection, demonstrating its potential as a simple and convenient platform for rapid on-site screening.