Redox-Active Metal-Organic Framework Nanocrystals for the Simultaneous Adsorption, Detection, and Detoxification of...

The widespread contamination of water by heavy metals requires materials capable of efficient capture, in situ detoxification, and real-time monitoring. This work examines a series of redox-active metal-organic frameworks (MOFs) constructed from hexahydroxytriphenylene (HHTP) ligands coordinated to cobalt, nickel, and copper (Co-HHTP, Ni-HHTP, and Cu-HHTP), revealing how framework architecture and metal coordination environment dictate adsorption capacity, redox activity, and detection performance toward cadmium (Cd²⁺), mercury (Hg²⁺), and lead (Pb²⁺) ions. Among the series, Co-HHTP exhibits the highest uptake capacities of 169, 733, and 554 mg g^-1 for Cd²⁺, Hg²⁺, and Pb²⁺, respectively, attributed to its trigonal stacking and intercalated layers that expose labile water-capped metal sites. These sites facilitate electron transfer, enabling a redox-active capture pathway in which heavy metal cations are partially reduced, with concurrent oxidation of the HHTP ligand. In contrast, Cu-HHTP, with an eclipsed stacking arrangement and limited redox complementarity to the heavy metal ions examined, remains redox-inert and exhibits the lowest performance. Deposition of Co-HHTP onto cotton, silk, and polyester yields MOF@textile composites that retain adsorption efficiency and enable rapid detection of heavy metals at low-ppm concentrations. These findings establish a structure-function correlation, emphasizing how stacking configuration, metal accessibility, and redox-active ligands collectively govern multimechanistic heavy metal remediation.