By adjustment of the arm lengths of two triphenylamine-based ligands, two nearly isostructural metal-organic frameworks (MOFs), namely, the reported nanoporous FIR-29 (FIR = Fujian Institute of Research) and the new microporous FJI-Y9 (FJI = Fujian Institute), are obtained, and all exhibit honeycomb lattices of hexagonal channels with Ca-COO chains connected by tris[(4-carboxyl)-phenylduryl] amine (H(3)TCPA) ligands and 4,4',4 ''-nitrilotribenzoic acid (H3NTB) ligands, respectively. Although the Brunauer-Emmett-Teller (BET) surface area (1117 m(2) g(-1)) and pore size (8.5 angstrom) of FJI-Y9 are much lower than those (BET surface area of 2061 m(2) Cl and pore size of 16 angstrom) of the reported FIR-29 because of the shorter arm lengths of H3NTB, the activated FJI-Y9-ht shows high H-2 (202.3 cm(3) Cl) and D-2 (221.9 cm(3) g(-1)) uptake under 77 K and 1 bar and C2H2 uptake of 168.9 cm(3) g(-1) under 273 K and 1 bar, which are all at least 48% enhancement over those of FIR-29-ht. The above results indicate that small pores in MOFs are beneficial to the uptake of some special gases including H-2, D-2, C2H2, etc.