Self-Assembly of Nanometer-Sized Boroxine Cages from Diboronic Acids

By use of the reversible trimerization of boronic acids, the series of boroxine cages 3-mer, 6-mer, and 12-mer were constructed from rationally designed diboronic acids whose bond angles between two C-B bonds are 60 degrees, 84 degrees, and 117 degrees, respectively. Boroxine cages 6-mer and 12-mer have 1.5 and 2.5 nm sized cavities, respectively.