The self-assembly between zinc dimer and 1,3,5-tris(2H-tetrazol-5-yl)benzene (H3BTT), promoted by a urea derivative, leads to a highly porous 3D framework with a large percentage (67%) of N-donor sites unused for bonding with metals. The material exhibits high gas storage capacity (ca. 1.89 wt % H-2 at 77 K and 1 atm; 98 cm(3)/g CO2 at 273 K and I atm), even in the absence of open metal sites. The high percentage of open N-donor sites, coupled with the low framework density resulting from single-walled channels, is believed to contribute to the high uptake capacity.