The importance of metal-support interfaces is widely known in commercial and fundamental heterogeneous catalysis; however, it is difficult to characterize the active interface sites. In this study, we synthesize a new class of compound comprising tetragonal [Ti8O8(OH)(4)](12+) clusters interlinked by terephthalates (bdc) and [Cu-2(OH)(6)](2-) linkers {Ti8O8(OH)(4)center dot(bdc)(2)center dot[Cu-2(OH)(6)](4)}. The crystalline structure was refined for X-ray diffraction and direct links between [Cu-2(OH)(6)](2-) and [Ti8O8(OH)(4)](12+) are confirmed by extended X-ray absorption fine structure. This compound functions very well (k = 0.117 min(-1) in CO 63 Pa + O-2 76 Pa at 323 K) as a catalytic model of interface Cu sites on ultra-dispersed Ti [hydro]oxide for preferential oxidation of CO in predominantly H-2 gas, that is important for the purification of hydrogen used in fuel cells. In comparison, mean 1.7-nm CuO nanoparticles embedded inside the pores of MIL125 were inert (k = 0.0035 min(-1)) because of the absence of links between Cu and [Ti8O8(OH)(4)](12+) clusters. In CO 0.51 kPa + O-2 0.51 kPa at 323 K, the conversion to CO2 and CO PROX selectivity using Ti8O8(OH)(4)center dot(bdc)(2)center dot[Cu-2(OH)(6)](4) (76% and 99%) was significantly higher than that using CuO/CeO2 (28% and 96%, respectively) for 24 h. (C) 2015 Elsevier Inc. All rights reserved.