Strategically Engineered Fluorescent Zn(II) and Redox-Active Cu(II) Coordination Polymers for Comparative Dual-Signal Sensing of Nitroaromatic Explosives

Abstract

Two luminescent one-dimensional coordination polymers (1D CPs), [Zn(4-avp)(ita)] (CP1) and [Cu(4-avp)2(ita)(H2O)]·H2O (CP2), were synthesized via a slow diffusion approach using a mixed-ligand system comprising itaconic acid (H2ita) and 4-[2-(9-anthryl)vinyl]pyridine (4-avp). Single-crystal structural analysis reveals that ita ligands bridge Zn(II) and Cu(II) centers to generate 1D polymeric chains, which further assemble into two-dimensional (2D) supramolecular architectures through intermolecular π···π stacking interactions, while the 4-avp ligands remain pendant. The presence of an electron-rich anthracene unit within the highly luminescent 4-avp ligand makes both CPs promising candidates for sensing electron-deficient nitroaromatic compounds (NACs), known for their environmental and health risks. Among these, 2,4,6-trinitrophenol (TNP), a widely used and highly explosive industrial compound, demands rapid and reliable detection. The synthesized CPs exhibit selective detection of TNP through fluorescence-based techniques, supported by electrochemical studies, and the sensing mechanisms are discussed in detail. Notably, the more luminescent d10 system, CP1, exhibits superior performance in fluorometric detection, whereas the redox-active d9 system, CP2, shows enhanced performance in electrochemical sensing. Furthermore, recyclability and stable fluorescence in complex environments enable the implementation of NOT–NAND–NOT operations, allowing the system to function as an INHIBIT logic gate.