Trace-level selective detection of nitroaromatic compounds and actinide ions using a 3D cyclotriphosphazene-based...

In recent years, cyclic cyclophosphazene polycarboxylate ligands have been widely applied in the synthesis of metal-organic frameworks (MOFs) due to their coordination number and topological diversity, thermal stability and functional integration. Here, Zn-DPCP was designed and synthesized firstly by the reaction of Zn(NO₃)₂·6H₂O and hexakis(3,5-dicarboxylatephenyloxy)-cyclotriphosphazene (H₁₂DPCP). Structural analysis revealed that the 3D framework of Zn-DPCP consists of two distinct secondary building units (Zn₃O₄(COO)₅ and Zn₂O₂(COO)₂), which collaboratively define its unique luminescent behavior. This architecture endows the MOF with dual functionality: selective detection of nitroaromatic compounds (NACs) and actinide ions (Th⁴⁺/UO₂²⁺) in aqueous media. Specifically, the LODs for TNP, Th⁴⁺, and UO₂²⁺ are as low as 2.09 nM, 2.74 nM, and 3.87 nM, respectively. Furthermore, a novel composite membrane material (Zn-DPCP@PVA) was successfully fabricated by incorporating Zn-DPCP into a polyvinyl alcohol (PVA) matrix. This material maintains the exceptional sensing capabilities of the parent MOF, demonstrating sensitive detection of 2,4,6-trinitrophenol, Th⁴⁺, and UO₂²⁺, while significantly enhancing the processability and practical applicability of MOF-based sensors.