A Hexanuclear Cadmium Metal-Organic Framework Exhibiting Dual Mechanisms to Trigger a Fluorescence-Quenching Response toward Iron(III) Ions.

A hexanuclear Cd^II metal-organic framework (1) based on 4-(1H-pyrazole-4-carboxamido)benzoic acid (H₂L) and featuring a three-dimensional microporous framework was synthesized. Notably, 1 shows a unique fluorescence-quenching response toward Fe³⁺ ions with high selectivity and sensitivity (Stern-Volmer constant K_SV = 2.07 × 10⁴ M^-1). The response is attributable to the coaction of absorption competition and energy-transfer (ET) mechanism. Furthermore, spectral analysis indicates that the energy-transfer mechanism makes the dominant contribution to the fluorescence quenching of 1. [ABSTRACT FROM AUTHOR]