We have detected the first example of open porous metal–organic frameworks (MOFs) that functions as an activity site for the reduction of water into hydrogen molecules in the presence of Ru(bpy)₃ ²⁺, MV²⁺, and EDTA–2Na under visible light irradiation. This activity is highly efficient: the turnover number based on MOFs and the apparent quantum yield are 8.16 and 4.82%, respectively. Furthermore, this material enables the adsorption of various gases into its pores; its hydrogen uptake capacity is 1.2 wt% at 77.4 K.

Heterogeneous dinuclear rhodium(II) coordination polymer, [Rh2(p-BDC)2]n (p-BDC = 1,4-benzenedicarboxylate), which formed self-assembly infinite two-dimentional slit sheets structure was performed as hydrogen production catalyst for photochemical reduction of water under visible light irradiation in the presence of a multicomponent system containing Ru(bpy)32+, MV2+, and EDTA–2Na.