Free-standing, accessible thiol (−SH) functions have been installed in robust, porous coordination networks to provide wide-ranging reactivities and properties in the solid state. The frameworks were assembled by reacting ZrCl4 or AlCl3 with 2,5-dimercapto-1,4-benzenedicarboxylic acid (H2DMBD), which features the hard carboxyl and soft thiol functions. The resultant Zr-DMBD and Al-DMBD frameworks exhibit the UiO-66 and CAU-1 topologies, respectively, with the carboxyl bonded to the hard Zr(IV) or Al(III) center and the thiol groups decorating the pores. The thiol-laced Zr-DMBD crystals lower the Hg(II) concentration in water below 0.01 ppm and effectively take up Hg from the vapor phase. The Zr-DMBD solid also features a nearly white photoluminescence that is distinctly quenched after Hg uptake. The carboxyl/thiol combination thus illustrates the wider applicability of the hard-and-soft strategy for functional frameworks.

Free-standing, accessible thiol (−SH) functions have been installed in robust, porous coordination networks to provide wide-ranging reactivities and properties in the solid state. The frameworks were assembled by reacting ZrCl4 or AlCl3 with 2,5-dimercapto-1,4-benzenedicarboxylic acid (H2DMBD), which features the hard carboxyl and soft thiol functions. The resultant Zr-DMBD and Al-DMBD frameworks exhibit the UiO-66 and CAU-1 topologies, respectively, with the carboxyl bonded to the hard Zr(IV) or Al(III) center and the thiol groups decorating the pores. The thiol-laced Zr-DMBD crystals lower the Hg(II) concentration in water below 0.01 ppm and effectively take up Hg from the vapor phase. The Zr-DMBD solid also features a nearly white photoluminescence that is distinctly quenched after Hg uptake. The carboxyl/thiol combination thus illustrates the wider applicability of the hard-and-soft strategy for functional frameworks.

A combined theoretical and experimental study is performed in order to elucidate the effects of linker functional groups on the photoabsorption properties of UiO-66-X materials. This study, in which both mono- and difunctionalized linkers (with X = OH, NH2, or SH) are investigated, aims to obtain a more complete picture of the choice of functionalization. Static time-dependent density functional theory calculations combined with molecular dynamics simulations are performed on the linkers, and the results are compared to experimental UV/vis spectra in order to understand the electronic effects governing the absorption spectra. The disubstituted linkers show larger shifts than the monosubstituted variants, making them promising candidates for further study as photocatalysts. Next, the interaction between the linker and the inorganic part of the framework is theoretically investigated using a cluster model. The proposed ligand-to-metal-charge transfer is theoretically observed and is influenced by the differences in functionalization. Finally, the computed electronic properties of the periodic UiO-66 materials reveal that the band gap can be altered by linker functionalization and ranges from 4.0 down to 2.2 eV. Study of the periodic density of states allows the band gap modulations of the framework to be explained in terms of a functionalization-induced band in the band gap of the original UiO-66 host.