Synthesis and investigation of mono- and multinuclear molecular coordination compounds with physical and chemical induced electronic multistability

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Synthesis and investigation of mono and multinuclear molecular coordination compounds, which can be trapped in various electronic states (accessing unprecedented high-spin transitions, e.g. S = 6 to S größer gleich 8, or S = 5/2 to S = 10/2). This electronic multistability is physically (light, p, T) or chemically (solvates, etc.) induced and physically investigated (4 - 400 K; excited in UV-VIS and IR region via T and lasers: diodes, Ar+-ion, Ti-sapphir) monitored microscopically by Mössbauer spectroscopy and UV/VIS/NIR electron spectra and macroscopically by SQUID magnetometer. Molecular switches (synthons) are combined to molecular coordination compounds expecting synergistic interplays between molecular effects with magnetic responses. Used types of synthons compounds: (1) nitro-metal complex (metal-to-ligand charge transfer; e.g. nitroprussiat, Na2[Fe(CN)5NO]2H2O, light interconverts between ground state and two long lived metastable exited states), (2) metal complex with light induced isomerism (ligand isomerisation with change of spin state; e.g. cis-trans), (3) metal-to-metal charge transfer (e.g. cobalt-iron cyanides), and (4) metal-centered excitation (e.g. iron(II) compounds). Such multistable compounds are under consideration for technical application as high density storage, as adaptive materials, in displays, towards nanoscopic machines and serve as model to explore biological processes.