Synthesis and Hydrogen Storage Properties of Be12(OH)12(1,3,5-benzenetribenzoate)4

Abstract

The first crystalline beryllium-based metal-organic framework has been synthesized and found to exhibit an exceptional surface area useful for hydrogen storage. Reaction of 1,3,5-benzenetribenzoic acid (H(3)BTB) and beryllium nitrate in a mixture of DMSO, DMF, and water at 130 degrees C for 10 days affords the solvated form of Be(12)(OH)(12)(1,3,5-benzenetribenzoate)(4) (1). Its highly porous framework structure consists of unprecedented saddle-shaped [Be(12)(OH)(12)](12+) rings connected through tritopic BTB(3-) ligands to generate a 3,12 net. Compound 1 exhibits a BET surface area of 4030 m(2)/g, the highest value yet reported for any main group metal-organic framework or covalent organic framework. At 77 K, the H(2) adsorption data for 1 indicate a fully reversible uptake of 1.6 wt % at 1 bar, with an initial isosteric heat of adsorption of -5.5 kJ/mol. At pressures up to 100 bar, the data show the compound to serve as an exceptional hydrogen storage material, reaching a total uptake of 9.2 wt % and 44 g/L at 77 K and of 2.3 wt % and 11 g/L at 298 K. It is expected that reaction conditions similar to those reported here may enable the synthesis of a broad new family of beryllium-based frameworks with extremely high surface areas.