A cyclotriphosphazene-based luminescent Cd-MOF for differential sensing of harmful ions and pesticides

A novel 3D porous Cd-MOF was hydrothermally synthesized from a cyclotriphosphazene-based organic linker (H 12 DPCP). • The luminescent Cd-MOF exhibits contrasting turn-off/turn-on responses toward hazardous ions (UO 2 2+ , Th 4+ , and Cr 2 O 7 2− ) and pesticide molecules (fenoxaprop-p- ethyl and dicamba), with low detection limits. • Mechanistic studies reveal that the quenching is driven by competitive absorption, while the enhancement arises from photoinduced electron transfer. A cadmium-based metal-organic framework (denoted as Cd-DPCP) with a three-dimensional porous structure was successfully designed and synthesized using hexakis(3,5-dicarboxylatephenyloxy)-cyclotriphosphazene (H 12 DPCP) as the organic linker and Cd(NO 3 ) 2 ‧4H 2 O as the metal source. Notably, Cd-DPCP exhibits excellent multifunctional luminescent sensing performance, capable of efficiently detecting harmful ions (UO 2 2+ , Th 4+ , and Cr 2 O 7 2− ) and pesticide molecules with high reusability rates. The fluorescence response mechanism was systematically investigated through powder X-ray diffraction, ultraviolet-visible absorption and fluorescence spectroscopy, together with theoretical calculations performed using Gaussian. Experimental results reveal that the fluorescence quenching of Cd-DPCP toward harmful ions is dominated by competitive absorption, whereas its fluorescence enhancement in the presence of pesticide molecules is primarily attributed to photoinduced electron transfer. These findings suggest that Cd-DPCP holds great promise as a multifunctional luminescent sensor for detecting hazardous substances in environments. This study successfully synthesized a three-dimensional porous Cd-MOF material via a hydrothermal method. Based on its excellent fluorescence properties, the material enables fluorescence quenching detection towards hazardous metal ions (UO 2 2+ , Th 4+ , Cr 2 O 7 2− ) and fluorescence enhancement detection towards pesticide molecules, demonstrating dual-mode sensing functionality with high selectivity and sensitivity. Download: Download high-res image (323KB) Download: Download full-size image