[Cu2(trz-ia)2]─An Ultramicroporous Cu2 Paddle Wheel Triazolyl Isophthalate MOF: A Comparative Study of Its Properties in Dihydrogen Adsorption and Isotopologue Separation

Abstract

A Cu2 paddle wheel-based metal-organic framework, [Cu2(trz-ia)2] (trz-ia2- = 5-(4H-1,2,4-triazol-4-yl) isophthalate), is investigated for hydrogen adsorption and hydrogen isotopologue separation. Its ultramicroporous structure with pore diameters ranging from 0.35 to 0.53 nm allows for strong interactions with dihydrogen molecules, resulting in steep H2 uptake and heat of adsorption Qads = 9.7 kJ mol-1. Notably, the hydrogen density inside the pores is 43.9 g L-1 at 77 K and 100 kPa. Thermal desorption spectroscopy (TDS) after exposure to a H2/D2 mixture indicates dihydrogen isotopologue separation with a selectivity of S = 6 at 30 K and a high uptake of D2. These findings are compared with numerous other metal-organic frameworks (MOFs) and related to their pore size.