Tunable, high single crystal conductivity in a permanently porous metal-organic framework

Abstract

Conductive metal-org. frameworks combine low-energy charge transport pathways with high surface areas, opening up new opportunities for applications in energy and electronics. The ability to systematically control their phys. properties is crit. for realizing their potential. We report tunable single crystal cond. ranging over four orders of magnitude in an ironbased metal-org. framework by modulating the ratio of Fe(III) to Fe(II) in the compd. Cond. values exceed 1 S/cm, the highest reported to date for a single crystal of a porous metal-org. framework. Variable temp. cond. measurements reveal a very small activation energy on the order of 10 meV, consistent with low energy Fe(III) defect states predicted by electronic band structure calcns. These results illustrate the unprecedented realization of high single crystal cond. with a wide range of tunability in a permanently porous material.