Redox-switchable breathing behavior in tetrathiafulvalene-based metal\u2013organic frameworks

Jian Su,Lan Huang,Hong-Cai Zhou,Jing-Yuan Ge,Junsheng Qin,Tahir Cagin,Hai-Ying Wang,Elizabeth Joseph,Jing-Lin Zuo,Shuai Yuan

doi:10.1038/s41467-017-02256-y

Abstract

Metal–organic frameworks (MOFs) that respond to external stimuli such as guest molecules, temperature, or redox conditions are highly desirable. Herein, we coupled redox-switchable properties with breathing behavior induced by guest molecules in a single framework. Guided by topology, two flexible isomeric MOFs, compounds 1 and 2, with a formula of In(Me2NH2)(TTFTB), were constructed via a combination of [In(COO)4]− metal nodes and tetratopic tetrathiafulvalene-based linkers (TTFTB). The two compounds show different breathing behaviors upon the introduction of N2. Single-crystal X-ray diffraction, accompanied by molecular simulations, reveals that the breathing mechanism of 1 involves the bending of metal–ligand bonds and the sliding of interpenetrated frameworks, while 2 undergoes simple distortion of linkers. Reversible oxidation and reduction of TTF moieties changes the linker flexibility, which in turn switches the breathing behavior of 2. The redox-switchable breathing behavior can potentially be applied to the design of stimuli-responsive MOFs.

Highlights

Metal–organic frameworks (MOFs) that respond to external stimuli such as guest molecules, temperature, or redox conditions are highly desirable
The host structures in flexible MOFs can be altered by external stimuli, potentially altering the availability of the cavity to guest molecules
The TTF moiety was incorporated into the linker of a MOF as a redox switch to control the flexibility of the framework

Summary

Introduction

Metal–organic frameworks (MOFs) that respond to external stimuli such as guest molecules, temperature, or redox conditions are highly desirable. The TTF moiety was incorporated into the linker of a MOF as a redox switch to control the flexibility of the framework. The TTF moieties allow for the reversible oxidation by I2 and reduction via treatment with N,N-dimethylformamide (DMF), which switches the linker flexibility and the breathing behavior of compound 2.

Results

Conclusion