Multiple Structural and Phase Transformations of MOF and Selective Hydrocarbon Gas Separation in its Amorphous, Glass Phase States

Abstract The first wide‐view image of multiple structural and phase transformations for MOFs, ranging from crystal state transformations to the extreme limit approaching liquid/glass phase, was presented. The process involves i) an initial crystalline transformation from square‐ layer framework [Co 2 (pybz) 2 (CH 3 COO) 2 ] ⋅ DMF ( Co2 ) to a 3‐fold interpenetrated and ordered vacancies contained framework [Co(pybz) 2 (CH 3 OH) 2 ] ⋅ 2CH 3 OH ( CoM ) due to in situ disassemble‐reassemble, ii) thermal induced departure of a pair of cis ‐form coordinated methanol in CoM leads to amorphous framework a ‐dCoM , iii) glass transition to super‐cooled liquid scl ‐dCoM , iv) obtaining MOF glass g ‐dCoM upon quenching the super‐cooled liquid, and v) re‐crystallization of super‐cooled liquid generates 6‐fold interpenetrated dia ‐ net framework [Co(pybz) 2 ] 6n ( rec ‐dCoM ) under further heating. The access to glass from CoM , provides a new self‐perturbation strategy to create MOF glasses without melting. The wider pore size distribution in amorphous/glassy MOFs than crystalline precursor achieved the first time selective hydrocarbon gas separation by breakthrough experiments, which bring efficient separation of 1 : 99 C 2 H 2 /C 2 H 4 by either a ‐dCoM or g ‐dCoM and produce polymer grade C 2 H 4 with purity≥99.5 % after a single adsorption process. Furthermore, the mixture of 50 : 50 C 3 H 6 /C 3 H 8 can be separated by a ‐dCoM .