Charge Manipulation in Metal-Organic Frameworks: Toward Designer Functional Molecular Materials

Multi-dimensional coordination frameworks whose charge states are controllable by the sophisticated chemical modification of the components or by the application of stimuli are fascinating targets for the design of electronic/magnetic functional materials. A simple way to design such frameworks is to assemble electron donor (D) and electron acceptor (A) units in a D(m)A(n) ratio with electronically conjugated linkages; we call this type of framework a D/A metal-organic framework (D/A-MOF). In this account article, our previous studies on D/A-MOFs composed of carboxylate-bridged paddlewheel-type diruthenium units ([Ru-2]) and polycyano organic molecules such as N, N'-dicyanoquinodiimine (DCNQI) and 7,7,8,8-tetracyano-p-quinodimethane (TCNQ) as the D and A subunits, respectively, are summarized. In this family of D/A-MOFs, the charge distribution between the internal D and A subunits can be precisely tuned by varying their electronic structure, i.e., depending on what kind of D and A we choose. Crucially, the diverse charge states, as well as anisotropic framework and often porous nature, of D/A-MOFs are well correlated with their bulk electronic and magnetic properties.

Automated summary

Multi-dimensional coordination frameworks with controllable charge states offer fascinating targets for the design of electronic/magnetic functional materials. D/A metal-organic frameworks can be designed by assembling electron donor and electron acceptor units with electronically conjugated linkages, allowing precise tuning of charge distribution between internal subunits by varying their electronic structure. The diverse charge states, anisotropic framework, and porous nature of D/A-MOFs are correlated with their bulk electronic and magnetic properties.