Browsing by Author "Shatruk, Michael"

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    Electronic structure of cobalt valence tautomeric molecules in different environments
    (RSC, 2023-02) Mishra, Ezra; Ekanayaka, Thilini K.; Panagiotakopoulos, Theodoros; Le, Duy; Rahman, Talat S.; Wang, Ping; McElveen, Kayleigh A.; Phillips, Jared P.; Zaz, M. Zaid; Yazdani, Saeed; N'Diaye, Alpha T.; Lai, Rebecca Y.; Streubel, Robert; Cheng, Ruihua; Shatruk, Michael; Dowben, Peter A.; Physics, School of Science
    Future molecular microelectronics require the electronic conductivity of the device to be tunable without impairing the voltage control of the molecular electronic properties. This work reports the influence of an interface between a semiconducting polyaniline polymer or a polar poly-D-lysine molecular film and one of two valence tautomeric complexes, i.e., [CoIII(SQ)(Cat)(4-CN-py)2] ↔ [CoII(SQ)2(4-CN-py)2] and [CoIII(SQ)(Cat)(3-tpp)2] ↔ [CoII(SQ)2(3-tpp)2]. The electronic transitions and orbitals are identified using X-ray photoemission, X-ray absorption, inverse photoemission, and optical absorption spectroscopy measurements that are guided by density functional theory. Except for slightly modified binding energies and shifted orbital levels, the choice of the underlying substrate layer has little effect on the electronic structure. A prominent unoccupied ligand-to-metal charge transfer state exists in [CoIII(SQ)(Cat)(3-tpp)2] ↔ [CoII(SQ)2(3-tpp)2] that is virtually insensitive to the interface between the polymer and tautomeric complexes in the CoII high-spin state.
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    Evidence of dynamical effects and critical field in a cobalt spin crossover complex
    (Royal Society of Chemistry, 2022-01) Ekanayaka, Thilini K.; Wang, Ping; Yazdani, Saeed; Phillips, Jared Paul; Mishra, Esha; Dale, Ashley S.; N'Diaye, Alpha T.; Klewe, Christoph; Shafer, Padraic; Freeland, John; Streubel, Robert; Wampler, James Paris; Zapf, Vivien; Cheng, Ruihua; Shatruk, Michael; Dowben, Peter A.; Physics, School of Science
    The [Co(SQ)2(4-CN-py)2] complex exhibits dynamical effects over a wide range of temperature. The orbital moment, determined by X-ray magnetic circular dichroism (XMCD) with decreasing applied magnetic field, indicates a nonzero critical field for net alignment of magnetic moments, an effect not seen with the spin moment of [Co(SQ)2(4-CN-py)2].