Dense thiol arrays for metal-organic frameworks: boiling water stability, Hg removal beyond 2 ppb and facile crosslinking

We report a breakthrough in the synthesis of metal-organic frameworks (MOFs) extensively equipped with thiol groups. The main motivation arises from the versatile reactivity of the thiol function, which imparts to the porous host unique potential in metal-uptake, catalytic and electronic properties. The synthesis of thiol-equipped molecules for MOF construction, however, remains challenging, because of the lack of efficient, wide-scope synthetic protocols. By utilizing nucleophilic substitution between benzyl thiol and aromatic halides, and AlCl₃-promoted deprotection of the resultant benzyl thioether, we succeeded in attaching thiol groups onto the carboxylate linker backbone in a dense array. The widened access of thiol-equipped MOFs facilitates in-depth exploration of open framework sulfur chemistry, achieving, for instance, fast removal of Hg to below the drinking limit of 2 ppb.