Interplay between Electronic, Magnetic, and Transport Properties in Metal Organic–Radical Frameworks

Abstract

Development of modern electronic and spintronic technologies depends in large part on the ability to design materials exhibiting switchable magnetic and electrical properties. Here, motivated by the successful demonstration of reversible redox switching of magnetic order and electrical conductivity in 2dimensional metal-organic frameworks (MOFs) based on benzoquinoid linkers, we perform hybrid density functional theory calculations to investigate this phenomenon at the atomistic level. Electronic, magnetic and charge transport properties have been systematically investigated for oxidized and reduced forms of Mn and Fe benzoquinoid frameworks (i.e., (Me 4 N) 2 [Mn 2 L 3 ], (Me 4 N) 2 [Fe 2 L 3 ] and Na 3 (Me 4 N) 2 [Mn 2 L 3 ], Na(Me 4 N) 2 [Fe 2 L 3 ], respectively with deprotonated chloranilic acid as L). We demonstrate that the experimentally observed large increase in electronic conductivity upon ligand-centered reduction in the Mn MOF (10 9 S•cm −1), is due to cooperative effects arising from band gap reduction and the presence of electrons with lower effective mass. Superior conductivity (by at least 3 orders of magnitude) of the redox pair of the Fe benzoquinoid framework as compared to the Mn analog stems from similar factors and, notably, a large increase in electron delocalization for the reduced Fe compound.