Cu(II)- and Zn(II)-based coordination polymers as fluorescent sensors for 1,10-phenanthroline detection

Two coordination polymers, CP1 and CP2, based on Cu(II) and Zn(II) ions, were synthesized and structurally characterized as fluorescent sensors for 1,10-phenanthroline, an important nitrogen-containing chelating agent widely used in coordination chemistry and industrial systems. Both materials exhibit good crystallinity, thermal stability, and intrinsic fluorescence. Their fluorescence sensing behaviors toward 1,10-phenanthroline were systematically investigated in aqueous media. CP1 and CP2 show high selectivity and sensitivity toward 1,10-phenanthroline, with Stern–Volmer constants of 1.11 × 10⁵ M⁻¹ and 6.95 × 10⁴ M⁻¹, and detection limits of 3.2 µM and 4.5 µM, respectively. In addition, both coordination polymers display good anti-interference ability and recyclability. Comparative studies reveal that the different sensing efficiencies of CP1 and CP2 are closely related to the distinct electronic properties of the Cu(II) and Zn(II) centers. Mechanistic investigations indicate that the fluorescence quenching mainly arises from coordination interactions between 1,10-phenanthroline and the metal centers. This work not only demonstrates the potential of coordination polymers as effective fluorescent sensors for phenanthroline detection, but also provides insight into the role of metal centers in regulating fluorescence sensing performance.