鈥淪PACIOUS and amply proportioned with plenty of storage space.鈥� If MOF 鈥� 177 were an apartment, that鈥檚 probably how the vendor鈥檚 patter would go. But MOF 鈥� 177 isn鈥檛 a dwelling, it鈥檚 a record-breaking crystal whose internal surface area, per gram, is some 4500 square metres, the area of 17 tennis courts. That鈥檚 1300 square metres more than the previous record holder (Nature, vol 427, p 523). The substance was created by a team at the University of Michigan, Ann Arbor.
The crystal, of a type known as a metal organic framework, is made up of alternating organic molecules and zinc oxide clusters. The organic component is a compound called 1,3,5 鈥� benzentribenzoate which is a triangular molecule comprising three benzene rings branching off a central benzene ring. These large triangular organic molecules branch from the vertices of tetrahedral zinc oxide 鈥� based complexes, and this structure is what yields a high surface area relative to the crystal鈥檚 volume.
While the compound couldn鈥檛 look more ordinary 鈥� it is a white, crystalline solid 鈥� its attributes are not. 鈥淢OF-177 has really spectacular properties,鈥� says Pierre Jacobs, a chemist at the Catholic University of Leuven (KUL) in Belgium. He says the major breakthrough is that the holes within the crystal are large enough to accommodate relatively big molecules, more than 1 nanometre across, such as Pharmaceuticals, hydrocarbons or buckyballs. This could allow it to be used to separate different molecules in chemical manufacture. If MOF 鈥� 177鈥檚 lattice turns out to weakly hold hydrogen molecules, like other MOFs, its huge Internal surface area might let it act as a hydrogen store in fuel 鈥� cell 鈥� powered vehicles.
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