Modulation of transversal conductivity of europium(III) bisphthalocyaninate ultrathin films by peripheral substitution

Shokurov, Alexander V.; Kutsybala, Daria S.; Martynov, Alexander G.; Raitman, Oleg A.; Arslanov, V. V.; Gorbunova, Yulia G.; Tsivadze, A. Yu.; Selektor, S. L.

doi:10.1016/j.tsf.2019.137591

Cited by 16 publications

(13 citation statements)

References 69 publications

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“…Apart from fundamental interest in this novel manifestation of redox-isomeric behavior, the described system can pave way to the development of novel optoelectronic devices where the studied bisphthalocyaninates can be incorporated as a functional component in the form of thin solid films. [20][21][22]…”

Section: Introductionmentioning

confidence: 99%

“…In the present work, we exploit this orientation-induced redox isomerization approach to tune the valent state of the europium cation in double-decker europium(III)octa- n -butoxyphthalocyaninate Eu[(BuO) 8 Pc] 2 , in order to achieve Eu(III)/Eu(II) redox isomerization. Apart from the fundamental interest in this novel manifestation of redox-isomeric behavior, the described system can pave way to the development of novel optoelectronic devices where the studied bisphthalocyaninates can be incorporated as a functional component in the form of thin solid films. − …”

Section: Introductionmentioning

confidence: 99%

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Long-Sought Redox Isomerization of the Europium(III/II) Complex Achieved by Molecular Reorientation at the Interface

et al. 2020

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Redox-isomerism, i.e. the change of metal cation valence state in organic complexes, can find promising applications in multistable molecular switches for various 2 molecular electronic devices. However, despite a large amount of studies devoted to such processes in organic complexes of multivalent lanthanides, redox-isomeric transformations were never observed for europium. In the present work, we demonstrate the unique case of redox isomerization of Eu(III)/Eu(II) complexes on the example of Eu(III) doubledecker octa-nbutoxyphthalocyaninate (Eu[(BuO)8Pc]2) under ambient conditions (air, room temperature). It is shown that assumption of the face-on orientation on the aqueous subphase surface, in which two of each phthalocyanine decks in Eu[(BuO)8Pc]2 are located in different media (air and water), leads to the intramolecular electron transfer that results in formation of divalent Eu(II) cation in the complex. Lateral compression of the thus formed monolayer brings on the reorientation of the bisphthalocyaninate to the edge-on state, in which the ligands can be considered identical, and occurrence of the reverse redox-isomeric transformation into the complex with trivalent Eu cation. Both redox-isomeric states were directly observed by XANES spectroscopy in ultrathin films formed under different conditions.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Long-Sought Redox Isomerization of the Europium(III/II) Complex Achieved by Molecular Reorientation at the Interface

et al. 2020

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“…However, unlike the previously studied europium and cerium complexes and the ytterbium complex described above, the lateral compression of the samarium crownsubstituted bis-phthalocyaninate monolayer, even to high values of surface pressure, does not lead to a reverse redox-isomer transition. The replacement of the substituents of the phthalocyanine macrocycle from 15-crown-5 to more donor butoxyl substituents [39] does not cause significant changes in the behavior of this complex upon transition to the interface, and also does not allow for a reverse redox-isomer transition upon monolayer compression.…”

Section: Resultsmentioning

confidence: 99%

Interface Asymmetry Induced and Surface Pressure Controlled Valence Tautomerism in Monolayers of bis-Phthalocyaninates of Lanthanides

et al. 2022

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Supramolecular systems based on transition metal complexes capable of reversible redox isomerization due to intramolecular electron transfer are one of the most interesting objects from the viewpoint of molecular switches’ design. In the present work, a comparative analysis of valence transformation of lanthanide complexes (Sm, Er, Tm and Yb) with donor-substituted bis-phthalocyaninates occurring during the formation and compression–extension of Langmuir monolayers was carried out using data of UV–Vis–NIR spectroscopy. It is shown that the numerical values of the Q-band positions in the absorption spectra for the extended monolayers of the complexes under study depend linearly on the ionic radius of the metal center, if the metals have an oxidation state of +2. This makes it possible to draw a direct analogy between the behavior of the studied compounds and analogous europium and cerium complexes, for which direct evidence of the valence tautomerism in such planar systems was obtained earlier. This led to the conclusion that the intramolecular electron transfer from the phthalocyanine ligand to the central metal ion [Ln3+(R4Pc2‑)(R4Pc•−)]0 → [Ln2+(R4Pc•−)2]0 occurs when solutions of donor-substituted bis-phthalocyaninates of samarium, erbium, thulium, and ytterbium are deposited onto the water subphase, and the reverse redox-isomeric transition is observed in most cases when the monolayer is compressed to high surface pressures. The first of these switches is related to the asymmetry of the air/water interface, and the second one is controlled by the lateral compression–expansion of the monolayer. It has been demonstrated that when bis-phthalocyanine monolayers of lanthanides with variable valence are transferred to solid substrates, the valence state of the metal center, and consequently, the redox-isomeric state of the complex, do not change. This means that we are able to form films with a predetermined state of the complex. Note that the redox-isomeric state of complexes should affect the entire range of physicochemical properties of such films.

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“…In the literature, there are a sufficient number of examples of the synthesis and study of the properties of peripherally and non-peripherally substituted double-decker phthalocyaninates of rare-earth elements with alkyl-, aryl-, etc. functional groups [ 24 , 25 ]. However, often these types of substitution lead to strong aggregation of molecules, which adversely affects all the properties they exhibit.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Spectroscopic Properties and Redox Behavior Kinetics of Rare-Earth Bistetrakis-4-[3-(3,4-dicyanophenoxy)phenoxy]phthalocyaninato Metal Complexes with Er, Lu and Yb

et al. 2021

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Novel bistetrakis-4-[3-(3,4-dicyanophenoxy)phenoxy]phthalocyaninato of complexes erbium, lutetium and ytterbium were synthesized using a template fusion method to prevent any polymerization process. The complexes were separated from the reaction mixtures and characterized by NMR, IR and electron absorption spectroscopy. The spectroscopic properties of the metal phthalocyaninates in chloroform, acetone and tetrahydrofuran were studied. The regular bathochromic shift in the Er–Yb–Lu series was determined. In acetone medium all the complexes obtained were found to exist in an equilibrium state between neutral and reduced forms. The linearity of Lambert-Bouger-Beer curves makes it possible to study the kinetics of redox processes in the presence of phenylhydrazine and bromine. The lutetium complex showed better reducing properties and turned fully into the reduced form, while the erbium and ytterbium ones changed only partially. Upon oxidizing all the phthalocyaninates transformed into a mixture of oxidized and neutral-radical forms. The extinction coefficients and effective redox constants were calculated.

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Modulation of transversal conductivity of europium(III) bisphthalocyaninate ultrathin films by peripheral substitution

Cited by 16 publications

References 69 publications

Long-Sought Redox Isomerization of the Europium(III/II) Complex Achieved by Molecular Reorientation at the Interface

Long-Sought Redox Isomerization of the Europium(III/II) Complex Achieved by Molecular Reorientation at the Interface

Interface Asymmetry Induced and Surface Pressure Controlled Valence Tautomerism in Monolayers of bis-Phthalocyaninates of Lanthanides

Synthesis, Spectroscopic Properties and Redox Behavior Kinetics of Rare-Earth Bistetrakis-4-[3-(3,4-dicyanophenoxy)phenoxy]phthalocyaninato Metal Complexes with Er, Lu and Yb

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