A 3D Robust and Microporous B←N Framework with 8-connected Sandwich Nodes for Efficient Separation of Hexane Isomers

Recently B←N organic frameworks (BNFs) have gained substantial attention owing to their unique dative bond energy, which imparts them with specialized functionalities across a broad spectrum of applications. Despite previous reports on BNFs with permanent porosity, research endeavors towards three-dimensional (3D) BNFs with similar properties are scarce, with no report of robust 3D BNFs featuring permanent porosity to date. Herein, electrostatic complementary strategy is proposed to construct the first example of 3D robust and microporous BNF, BNF-100, featuring a reo topology with 8-connected sandwich nodes assembled via dative B←N bonds. The activated form BNF-100 a exhibits excellent chemical stability and permanent porosity with Langmuir surface area of 645.9 m² g^-1 and pore volume of 0.23 cm³ g^-1. BNF-100 a can efficiently separate hexane isomers through sieving mechanisms, as confirmed by vapor adsorption experiments and dynamic breakthrough tests, surpassing the performance of most MOF materials. Finally, we achieved the purification of different branched hexane isomers using a single breakthrough column in a combined breakthrough and purging experiment, which is the first reported instance in the literature on hexane isomer separation.