Isomerization of DASA Molecules in the Nanopores of Metal–Organic Frameworks: What Determines Its Reversibility?**

Abstract

In recent years, light‐responsive molecules have been incorporated in metal–organic frameworks (MOFs) to fabricate light‐responsive intelligent devices, where reversible isomerization of the guest molecules in the nanopores is crucial. However, how to design a porous environment of MOFs to achieve a reversible isomerization remains unknown until now. In this work, donor–acceptor Stenhouse adducts (DASAs), a new kind of visible light responsive compound, were confined in the nanopores of different MOFs to study their isomerization upon visible‐light irradiation/mild heating. We found that the polarity of the pore environment is the key to control the reversibility of isomerization of such guest molecules. Under the guidance of this principle, MIL‐53(Al) was screened to investigate the proton conductivity and switching performance of the DASA‐confined MOF. The proton conductance was up to 0.013 S cm−1 at 80 °C and 98 % RH, and at least 30 switching cycles were achieved thanks to the Grotthuss‐type mechanism and the low polarity of MIL‐53(Al) pore environment.

Visible-Light-Assisted Donor–Acceptor-Stenhouse-Adduct-Based Reversible Photoswitching on a Laser-Structurable OrmoComp Substrate

“…Furthermore, the peak shapes of O 1s and C 1s vary before and after illumination, indicating important structural changes (Figure 2F,G This could be explained by transformation of the OH group into part of an organic ring. 31,32 These results clearly show the light-induced molecular structure change from triene-2-ol to cyclopentenone conformation, as provided by the literature and depicted in Figure 1B.…”

Dissecting the Water Uptake Behavior of Metal–Organic Frameworks Using Their Isolated Linkers and Metal Nodes

“…In this study, we explored a very large water-MN/OL configurational space to indicate the lowest energy water-MN/OL cluster configurations. To evaluate any correlation between the adsorption energies of the best clusters and the Henry coefficient, we retrieved the K H values of several MOFs from the literature ,− and estimated the MOFs’ total adsorption energies as explained in the “Water Uptake Capacity” subsection. The list of the MOFs, their OL and MN components, and their corresponding energies and K H values are summarized in Table S16.…”

“…Correlation between Henry’s coefficients ( K H ) ,− and the estimated (a) total water adsorption energies (Δ E ad,tot ) and (b) Gibbs free energies (Δ G ad,tot ) (298.15 K and 1 atm). The light green area represents the 95% confidence band.…”