Cobalt substitution in a flexible metal–organic framework: modulating a soft paddle-wheel unit for tunable gate-opening adsorption

Abstract

We achieved a tunable Pgo for gas adsorption in a flexible framework by modulating the dynamic rearrangement of coordination bonds of paddle-wheel unit via cobalt substitution.

Pillared cobalt metal–organic frameworks act as chromatic polarizers

“…Rather, they are related to d-d transitions of electrons in the Co-dimers. 36,37 In fact, the absorption bands are very close to those reported for similar Co-paddlewheel MOFs, 32,[38][39][40] as well as for cobalt complexes with a comparable coordination environment. [41][42][43] The tetragonal crystal structure of the framework suggests that the distinct axis (i.e., c) corresponds to the long dimension of their square prism habit.…”

Tunable Flexibility and Porosity of the Metal–Organic Framework DUT-49 through Postsynthetic Metal Exchange

“…Observation of homogeneous blue color for the crystal faces of all the crystals eliminates the possibility for obtaining a physical mixture of individual MOFs. Further, the location of the newly added Cu sites is established through SEM-EDX mapping analysis of the crystals . Analysis of DUT-49­(Zn 0.5 Cu 0.5 ) showed uniform distribution of both Zn and Cu atoms throughout the whole surface of the individual crystal (Figure b).…”

“…Further, the location of the newly added Cu sites is established through SEM-EDX mapping analysis of the crystals. 42 Analysis of DUT-49(Zn 0.5 Cu 0.5 ) showed uniform distribution of both Zn and Cu atoms throughout the whole surface of the individual crystal (Figure 4b). These findings confirm the uniform distribution of the Cu−Cu SBU along with the other SBUs in the partially Cu exchanged frameworks.…”

Gating effect for gas adsorption in microporous materials—mechanisms and applications

“…34 The deformation of paddle-wheel units frequently brought about gating effects in CO 2 and CO adsorption. [35][36][37] The Ni-based paddle-wheel distortion of MOF DUT-8 (Ni) Ni 2 (2,6-ndc) 2 dabco (ndc = naphthalene dicarboxylate, dabco = 1,4-diazabicyclo[2.2.2]octane) drastically expanded the unit cells in the presence of N 2 , CO 2 , and C 4 H 10 , and triggered a two-step transformation in the presence of C 2 H 6 and C 2 H 4 . 38 By partially substituting the nickel with cobalt, the gate opening pressure of N 2 in DUT-8 can be continuously tuned from P/P 0 = 0.1 (0% Co) to 0.75 (75% Co).…”