Porous Supramolecular Crystalline Probe that Detects Non-Covalent Interactions Involved in Molecular Recognition of Furanic Compounds

Selective separation and conversion of furan-based biomass-derived compounds, which are closely related to biorefineries, is currently an important issue. To improve their performance, it is important to deepen the understanding of non-covalent interactions that act on the molecular recognition of furanic compounds on separation or catalyst matrices. Here, a new method is reported to comprehensively visualize such intermolecular interactions using a porous supramolecular crystalline probe with polar and non-polar binding sites within a low-symmetric nanochannel consisting of four isomeric PdII3-macrocycles. Single-crystal X-ray diffraction analysis of the crystals including 5-hydroxymethylfurfural, furfural, furfuryl alcohol, or 2-acetylfuran reveals a variety of interactions involving their furan rings and polar substituents. It is also found that cooperative and competitive effects between guest and solvent molecules significantly change their recognition mode. A method is reported for visualizing non-covalent interactions acting on molecular recognition of furanic compounds with a supramolecular probe, which has polar and non-polar sites in low-symmetric cavities. Crystallographic analysis demonstrates that furans are recognized not only through interactions on their polar substituents but also on the furan ring itself. image