Linker Redox Mediated Control of Morphology and Properties in Semiconducting Iron-Semiquinoid Coordination Polymers.

The emergence of conductive 2D and less commonly 3D coordination polymers (CPs) and metal-organic frameworks (MOFs) promises novel applications in many fields. However, the synthetic parameters for these electronically complex materials are not thoroughly understood. Here we report a new 3D semiconducting CP Fe 5 (C 6 O 6 ) 3 , which is a fusion of 2D Fe-semiquinoid materials and 3D cubic Fe x (C 6 O 6 ) y materials, by using a different initial redox-state of the C 6 O 6 linker. The material displays high electrical conductivity (0.02 S cm -1 ), broad electronic transitions, promising thermoelectric behavior (S 2 σ=7.0×10 -9  W m -1  K -2 ), and strong antiferromagnetic interactions at room temperature. This material illustrates how controlling the oxidation states of redox-active components in conducting CPs/MOFs can be a "pre-synthetic" strategy to carefully tune material topologies and properties in contrast to more commonly encountered post-synthetic modifications.