Preparation of three new metal-organic frameworks by adjusting reaction conditions

Three metal-organic frameworks (MOFs), CoBTB-1, -2, and -3 have been prepared by the solvothermal reactions between cobalt ions and benzene-l,3,5-tribenzoic acids (H₃BTB). Crystal structures revealed that their framework structures are very different among themselves. CoBTB-1 is composed of two interpenetrating frameworks with (3,6)-coordinated net, CoBTB-2 is a single framework of (3,3,6)-coordinated net, and CoBTB-3 has two independent frameworks of (3,8)-coordinated net. This structural diversity with the same building blocks is attributed to different types of inorganic secondary building blocks, which could be prepared by adjusting the amount of water in the reaction solution. CoBTB-3 has a Langmuir surface area of 620 m²/g and uptakes 0.93 mg/g of hydrogen at 77 K and 1 bar.