Chameleonic layered metal-organic frameworks with variable charge-ordered states triggered by temperature and guest molecules.

ABSTRACT: Molecular materials whose electronic states are multiply varied depending on external stimuli are among the most promising targets for the development of multiply accessible molecular switches. Here, we report a honeycomb layer composed of tetraoxolene-bridged iron (Fe) subunits whose charge-ordered states are multiply variable via thermal treatments and solvation/desolvation with the crystallinity intact. The compound is (NPr₄)₂[Fe₂(Cl₂An)₃] (1-d; NPr₄ ⁺ = tetra-n-propylammonium; Cl₂An^2- = 2,5-dichloro-3,6-dihydroxo-1,4-benzoquinonate), which possesses three charge-ordered states: a low-temperature (LT) phase [(Fe³⁺)₂(Cl₂An^2-)(Cl₂An˙^3-)₂]^2-; an intermediate (IM) phase [(Fe^2.5+)₂(Cl₂An^2-)(Cl₂An^2.5-)₂]^2-; and a high-temperature (HT) phase [(Fe²⁺)₂(Cl₂An^2-)₃]^2- that varies according to temperature. In addition, the LT phase of 1-d is reversibly changeable to another IM phase in its solvated compound 1 via a solvation/desolvation process at room temperature. This example demonstrates a new multiple-switching system based on electron transfer and host-guest chemistry in a charge-flexible metal-organic framework.

SUBMITTER: Chen J 

PROVIDER: S-EPMC8152584 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature