Formation and fine-tuning of metal–organic frameworks with carboxylic pincers for the recognition of a C2H2 tetramer and highly selective separation of C2H2/C2H4

Highly efficient ethylene (C₂H₄) and acetylene (C₂H₂) separation is a great challenge and an important process in current industries. Herein, we finely tune a new family of 6-c metal-organic frameworks (MOFs) with crab-like carboxylic pincers for the recognition of a C₂H₂ tetramer and afford NTU-72 with high adsorption C₂H₂/C₂H₄ selectivity (56-441, 298 K) as well as unprecedented recovery of both highly pure C₂H₄ (99.95%) and C₂H₂ (99.36%). Furthermore, the effective binding of a C₂H₂ tetramer by NTU-72's carboxylic pincers has been revealed by gas-loaded crystallography and Raman spectral studies. Our work provides a novel approach for the selective binding of a small molecular cluster for designing high-performance MOFs.