A novel crystalline template for the structural determination of flexible chain compounds of nanoscale length

A novel metal-organic framework, BTB-MOF-24 [Fe3(BTB)2⋅(DMF)2]∞, was constructed from H3BTB linker and [Fe3(CO2)6(DMF)2]∞ rod SBU to realize a 3D structure featuring narrow channels and asymmetric sandwich cavities located between the BTB3−. This motif allows BTB-MOF-24 to firmly accommodate and minimize the disorder of guests via the interaction of substrates with a π-system at the asymmetric sandwiching cavities, thereby allowing a wide range of organic substrates to be determined by single-crystal X-ray diffraction without single crystals. In particular, BTB-MOF-24 showed an excellent performance in determining the structure of flexible-chain-based compounds, such as fatty-acid-based compounds (length ∼ 3 nm), at the detection level of a few micrograms and an adsorption time of <9 h. The easiness in the structural characterization is highlighted because long, flexible, and/or chiral-chain-based compounds could be realized without or with a limited number of restraints, thus allowing for the practical characterization of new and/or complicated substrates.