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Updated: Sep 20, 2026
Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks
Published on: June 9, 2023
Optical charge-transfer in iron(III)hexacyanoferrate(II): electro-intercalated cations induce
David R Rosseinsky1, Hanyong Lim, Hongjin Jiang
1Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075, Singapore. d.r.rosseinsky@exeter.ac.uk
Abstract:
The maximum of the color-conferring charge-transfer (CT) band in Prussian Blue (PB) varies with the electrochemically introduced cation M(z+) incorporated (as "supernumerary") for charge neutrality, and the dependence on particular properties of the M(z+) has been sought. With alkali-metal ions, the CT-maximum shifts are in the same sequence as the PB mass changes on M+ insertion; the effect on the CT ground state of the intra-lattice interaction of an M+ with the ferrocyanide CN- moiety (competing with cation hydration), is then implicated in shifts of the maxima, as the ferrocyanide is the donor center in the optical CT. More definitely, for M2+ and Ag+, solubility-products of the insoluble M(z+) ferrocyanides (that provide direct indicators of the intra-lattice M(z+)-[Fe(II)(CN)(6)](4- interactions) show a strong correlation with the spectral shifts. The determining interaction of M(z+) with ferrocyanide within PB is enhanced in some cases by the accessibility of M(z+) oxidation states +/- 1 different from the common values. PB lattice energies and the ground states of the optical CTs thus appear closely interlinked. The electrochemical uptake of appreciable amounts of the M(z+) within the lattices was confirmed by XPS.
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