Formation and fine-tuning of metal–organic frameworks with carboxylic pincers for the recognition of a C(2)H(2) tetramer and highly selective separation of C(2)H(2)/C(2)H(4)

Highly efficient ethylene (C(2)H(4)) and acetylene (C(2)H(2)) 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 C(2)H(2) tetramer and afford NTU-72 with high adsorption C(2)H(2)/C(2)H(4) selectivity (56–441, 298 K) as well as unprecedented recovery of both highly pure C(2)H(4) (99.95%) and C(2)H(2) (99.36%). Furthermore, the effective binding of a C(2)H(2) 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.