Nanosheets of Two-Dimensional Magnetic and Conducting Fe(II)/Fe(III) Mixed-Valence Metal–Organic Frameworks

We
report the synthesis, magnetic properties, electrical conductivity,
and delamination into thin nanosheets of two anilato-based Fe­(II)/Fe­(III)
mixed-valence two-dimensional metal–organic frameworks (MOFs).
Compounds [(H3O)­(H2O)­(phenazine)3]­[FeIIFeIII(C6O4X2)3]·12H2O [X = Cl (1) and Br (2)] present a honeycomb layered structure
with an eclipsed packing that generates hexagonal channels containing
the water molecules. Both compounds show ferrimagnetic ordering at
ca. 2 K coexisting with electrical conductivity (with room temperature
conductivities of 0.03 and 0.003 S/cm). Changing the X group from
Cl to Br leads to a decrease in the ordering temperature and room
temperature conductivity that is correlated with the decrease of the
electronegativity of X. Despite the ionic charge of the anilato-based
layers, these MOFs can be easily delaminated in thin nanosheets with
the thickness of a few monolayers.