Mechanochemical Mediated Coexistence of B←N Coordination and Hydrogen Bonding

Abstract

Mechanochemistry afforded a photoactive cocrystal via coexisting (B)O−H⋅⋅⋅N hydrogen bonds and B←N coordination. Specifically, solvent‐free mechanochemical ball mill grinding and liquid‐assisted grinding of a boronic acid and an alkene resulted in mixtures of hydrogen‐bonded and coordinated complexes akin to mixtures of noncovalent complexes that can be obtained in solution in equilibria processes. The alkenes of the hydrogen‐bonded assembly undergo an intermolecular [2+2] photodimerization in quantitative conversion, effectively reporting the outcome of the self‐assembly processes. Our results suggest that interplay involving noncovalent bonds subjected to mechanochemical conditions can lead to functional solids where, in the current case, the structure composed of the weaker hydrogen bonding interactions predominates.

Nanoscale Dodecahedral and Fullerene-Type Organoboroxine and Borazine Cages from Planar Building Units

“…A prominent class of compounds derived from organoboronic acids is organoboroxines, which are based on trinuclear cyclic structures (Figure a). − The reversibility of boroxine formation and accessibility of the boron p-orbital by Lewis bases ,− ,− has led to significant interest in multicomponent covalent-organic frameworks (COFs) , where planar di- and/or multitopic boronic acids link the B 3 O 3 -ring systems in two (2D) and three (3D) dimensions (Scheme S1, Supporting Information).…”