Self-Healing B ← N-Based Hydrogen-Bonded Organic Framework for Exclusive Recognition and Separation of Toluene from Methyl-Cyclohexane

The effective separation of aromatic and aliphatic hydrocarbons remains a notable challenge in the petrochemical industry. Herein, we report a self-healing three-dimensional B ← N-based hydrogen-bonded organic framework (HOF), BN-HOF-1, constructed from discrete B ← N inclusive dimers through weak C-H···F and C-H···N hydrogen-bonding interactions. To make use of the specific recognition of the B ← N inclusive dimers for the toluene molecules and the reversible ad/desorption nature of this novel HOF, BN-HOF-1 can exclusively recognize and separate toluene from the mixtures of toluene-methylcyclohexane, thus generating 99.6% pure toluene from its mixtures after gentle heating, the recorded value among any reported materials for toluene purification. After the toluene molecules were released from the framework, it becomes the condensed BN-HOF-1a, which can be further reused for the highly selective recognition and purification of toluene from its binary mixtures, through the reversible structural recovery back to BN-HOF-1. Single-crystal X-ray diffraction and molecular modeling studies reveal that the high specific toluene recognition is attributed to the complementary electrostatic potential between the host B ← N inclusive dimers and the guest toluene, while the self-healing and recovery nature of this HOF is attributed to weak intermolecular hydrogen-bonding interactions.

Three-dimensional covalent organic frameworks with nia nets for efficient separation of benzene/cyclohexane mixtures

The synthesis of three-dimensional covalent organic frameworks with highly connected building blocks presents a significant challenge. In this study, we report two 3D COFs with the nia topology, named JUC-641 and JUC-642, by introducing planar hexagonal and triangular prism nodes. Notably, our adsorption studies and breakthrough experiments reveal that both COFs exhibit exceptional separation capabilities, surpassing previously reported 3D COFs and most porous organic polymers, with a separation factor of up to 2.02 for benzene and cyclohexane. Additionally, dispersion-corrected density functional theory analysis suggests that the good performance of these 3D COFs can be attributed to the incorporation of highly aromatic building blocks and the presence of extensive pore structures. Consequently, this research not only expands the diversity of COFs but also highlights the potential of functional COF materials as promising candidates for environmentally-friendly separation applications.

A nanoporous organic polymer using 1, 3-dibromoadamantane as a crosslinker for adsorption/separation of benzene and cyclohexane

The development of nanoporous organic polymers with cycloaliphatic components for effective benzene (Bz) and cyclohexane (Cy) adsorption/separation poses a significant challenge. This work focuses on synthesizing NOP-Ad-1, a nanoporous organic polymer derived from a Friedel-Crafts reaction between cycloaliphatic 1,3-dibromadantane and aromatic hexaphenylbenzene. At 298 K and P/P0 = 0.95, NOP-Ad-1 can uptake 989 mg g-1 benzene and 441 mg g-1 cyclohexane. Moreover, as the benzene vapor ratio increased from 20% to 80%, the Bz/Cy selectivity of NOP-Ad-1 gradually decreased from 1.75 to 1.24. These findings highlight the potential application of NOP-Ad-1 in the adsorption/separation of Bz/Cy mixtures.

Covalent triazine frameworks for the dynamic adsorption/separation of benzene/cyclohexane mixtures

High adsorption selectivities for benzene and cyclohexane of three covalent triazine frameworks have been prepared via Friedel–Crafts reactions.