Crystalline Polymers Based on Dative Boron–Nitrogen Bonds and the Quest for Porosity

Crystalline
networks based on dative boron–nitrogen bonds
were obtained by combining polytopic N-donor ligands with polyboronic
esters. The utilization of a tetrahedral boronate ester gave rise
to a sheet structure, whereas either a linear polymer or a diamond-like
network was observed for a tetrahedral N-donor ligand. The intrinsic
flexibility of B←N
linkages favors tight intermolecular packing and interpenetration
in the crystalline state. Amorphous B←N networks, on the other
hand, were found to possess porosity with BET surface areas of up
to ∼300 m2 g–1. These materials
display processability in organic solvents, and hydrolytic damage
can be repaired by simple heating-cooling cycles.