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.