The presence of coordinatively unsaturated metal centers in metal-organic frameworks (MOFs) provides an accessible way to selectively functionalize MOFs through coordination bonds. In this work, we describe thiol-functionalization of MOFs by choosing a well known three-dimensional (3D) Cu-based MOF, i.e. [Cu-3(BTC)(2)(H2O)(3)](n) (HKUST-1, BTC = benzene-1,3,5-tricarboxylate), by a facile coordination-based postsynthetic strategy, and demonstrate their application for removal of heavy metal ion from water. A series of [Cu-3(BTC)(2)](n) samples stoichiometrically decorated with thiol groups has been prepared through coordination bonding of coordinatively unsaturated metal centers in HKUST-1 with -SH group in dithioglycol. The obtained thiol-functionalized samples were characterized by powder X-ray diffraction, scanning electron microscope, energy dispersive X-ray spectroscopy, infrared spectroscopy, and N-2 sorption-desorption isothermal. Significantly, the thiol-functionalized [Cu-3(BTC)(2)](n) exhibited remarkably high adsorption affinity (K-d = 4.73 x 10(5) mL g(-1)) and high adsorption capacity (714.29 mg g(-1)) for Hg2+ adsorption from water, while the unfunctionalized HKUST-1 showed no adsorption of Hg2+ under the same condition. (C) 2011 Elsevier B.V. All rights reserved.