Spin-dependent polarization effects of decoration of multi-walled carbon nanotubes by complexes of dithienylepyrrole derivatives with octahedral iron and lanthanides


H.V. Grushevskaya


Faculty of Physics Belarusian State University Minsk, 220030 BELARUS



Abstract:

Coordination mechanism for formation of organometallic compounds of such lanthanides (Ln) as Ce, Sm, Er and/or octahedral iron with dithienylepyrrole molecules (DTP) bonded with alkyl fragments has been established and studied. As provided by the compressibility analysis and the data of Raman, Mössbauer and NMR-spectroscopy, a valence state of iron in LB-monolayers tends to a high-spin state, and the organometallic compound is a complex of octahedral Fe (II) [1-3]. Since the transfer of an electron into conduction band changes the electronic configuration from 3d$^6$ to 3d$^5$, then the valence of iron is increased by one from Fe$^{2+}$ to Fe$^{3+}. Therefore, such coordination systems are called systems with mixed valence [4, 5]. An existence of the resonance between localized f-electron states and delocalized s(p)-electrons in the conduction band is known for inorganic compounds of rare-earth metals (Ln) [6]. In contrast to transition metal compounds with mixed valence, a mean or “fractional” valence of rare earth compounds is observed in experiments, and it is named as intermediate valence. It has been shown that the supramolecular compounds of dithienylepyrrole-pyrrole ligands with metal centers in intermediate valence states are formed. Complexes of dithienylepyrrole with octahedral iron and lanthanides have been deposited on multi-walled carbon nanotubes (MWCNTs) with the Langmuir - Blodgett technology. It has been established that such a decoration of carbon nanotubes by lanthanides and iron leads to spin-dependent dielectric polarization and does not degrade the electrophysical properties of MWCNTs. References [1] H. V. Grushevskaya, I. V. Lipnevich, T. I. Orekhovskaya. Coordination Interaction between Rare Earth and/or Transition Metal Centers and Thiophene Series Oligomer Derivatives in Ultrathin Langmuir-Blodgett Films, J. Mod. Phys. Vol. 4, 7-17 (2013). [2] H. V. Grushevskaya, N. G. Krylova, I. V. Lipnevich. Enhancement of Raman light scattering in dye-labeled cell membrane on metal-containing conducting polymer film, Int. J. Mod. Phys. B. Vol. 30, 1642018 (2016). [3] H V Grushevskaya, N G Krylova, I V Lipnevich. Design and compressibility of Langmuir monolayers from organometallic nanocyclic complexes, J. Phys. CS. Vol. 741, 012116 (2016). [4] J. Steed and J. Atwood, “Supramolecular Chemistry,” John Wiley & Sons, New York, Singapore City, 2000. [5] M. Alfimov, “Photonics of Supermolecular Nanosize Structures,” Izv. RAN, Ser. Chem., 2004, p. 1303. [6] D. Khomski, Uspekhi Phys. Nauk. Vol. 129, 443-485 (1979).