Boronic Esters as a System for Crystallization-Induced Dynamic Self-Assembly Equipped with an “On−Off” Switch for Equilibration

We report dynamic self-assembly utilizing boronic ester formation with special emphasis on the following six points:  (1) two kinds of host molecule are constructed spontaneously with benzene or toluene as the guest molecule under neutral conditions simply by mixing a di(boronic acid) and a bis(1,2-diol) in methanol; (2) the precipitation process is essential for this selective preparation of host molecules; (3) recognition of the enantiomers of bis(1,2-diol) is achieved during host formation in this system; (4) it is possible to freeze or free the conversion between the two host molecules, thus enabling formation of complexes that cannot be prepared under thermodynamic conditions typical for such self-assembly; (5) naphthalene and triphenylene are even more efficient guest molecules in this system; and (6) almost complete separation of naphthalene and 1-methylnaphthalene is achieved utilizing this guest-induced precipitation process.