Design Strategies for Enhanced Conductivity in Metal-Organic Frameworks

Abstract

Metal-organic frameworks (MOFs) are a class of materials which exhibit permanent porosity, high surface area, and crystallinity. As a highly tunable middle ground between heterogeneous and homogeneous species, MOFs have the potential to suit a wide variety of applications, many of which require conductive materials. The continued development of conductive MOFs has provided an ever-growing library of materials with both intrinsic and guest-promoted conductivity, and factors which limit or enhance conductivity in MOFs have become more apparent. In this Outlook, the factors which are believed to influence the future of MOF conductivity most heavily are highlighted along with proposed methods of further developing these fields. Fundamental studies derived from these methods may provide pathways to raise conductivity across a wide range of MOF structures.

Figure 1

Semiquinoid-type triphenylene and benzene-based 2D MOF structures.

Figure 2

2D structure of [Fe₂(Cl₂ dhbq)₃]^2– along the c (A) and a (B) axes and 3D structure of single layer (C) and interpenetrated (D) [Fe₂(dhbq)₃]^2– with the interpenetrated layers shown in red and blue. The cubic space group of the 3D MOF means that the a, b, and c axes are identical. Reprinted with permission from refs ( and 23). Copyright 2015 American Chemical Society. Copyright 2020 American Chemical Society.

Figure 3

Effect of pore size on conductivity in MOFs. Reprinted with permission from ref (75). Copyright 2020 American Chemical Society.

Figure 4

(A) Schematic representation of MOF thin films. Reprinted with permission from ref (90). Licensed under a Creative Commons Attribution (CC BY) license. (B) Charge transport in NU-1000 films through the ab plane and along the c axis. Reprinted with permission from ref (95). Copyright 2020 American Chemical Society.