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One of the notable advantages of molecular materials is the ability to precisely tune structure, properties, and function via molecular substitutions. While many studies have demonstrated this principle with classic carboxylate-based coordination polymers, there are comparatively fewer examples where systematic changes to sulfur-based coordination polymers have been investigated. Here we present such a study on 1D coordination chains of redox-active Fe 4 S 4 clusters linked by methylated 1,4-benzene-dithiolates. A series of new Fe 4 S 4 -based coordination polymers were synthesized with either 2,5-dimethyl-1,4-benzenedithiol (DMBDT) or 2,3,5,6-tetramethyl-1,4-benzenedithiol (TMBDT). The structures of these compounds have been characterized based on synchrotron X-ray powder diffraction while their chemical and physical properties have been characterized by techniques including X-ray photoelectron spectroscopy, cyclic voltammetry and UV–visible spectroscopy. Methylation results in the general trend of increasing electron-richness in the series, but the tetramethyl version exhibits unexpected properties arising from steric constraints. All these results highlight how substitutions on organic linkers can modulate electronic factors to fine-tune the electronic structures of metal–organic materials. 

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 CPFe₅(C₆O₆)₃, which is a fusion of 2D Fe‐semiquinoid materials and 3D cubicFe_x(C₆O₆)_ymaterials, by using a different initial redox‐state of the C₆O₆linker. The material displays high electrical conductivity (0.02 S cm⁻¹), broad electronic transitions, promising thermoelectric behavior (S²σ=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.

 

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 CPFe₅(C₆O₆)₃, which is a fusion of 2D Fe‐semiquinoid materials and 3D cubicFe_x(C₆O₆)_ymaterials, by using a different initial redox‐state of the C₆O₆linker. The material displays high electrical conductivity (0.02 S cm⁻¹), broad electronic transitions, promising thermoelectric behavior (S²σ=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.