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Molekularne materiały magnetyczne

Löffler M., Gałkowska A., Korabik M., Utko J., Lis T.

Wiadomości Chemiczne

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2018

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[Z] 72, 7-8

523--541

EN

The „molecular” term appears more and more often in the materials chemistry. The Nobel Prize in 2016 was awarded to Jean-Pierre Sauvage, Sir J. Fraser Stoddart and Bernard R. Feringa „for the design and synthesis of molecular machines”. Magnetism in molecular scale, also known as molecular nanomagnetism, has been developing intensively since the second half of the last century. This branch of science involves the magnetic properties of coordination compounds of d- and f-electron metals. The paper presents results of the magnetic studies of molecular magnets of copper(II) and dysprosium(III), which have been pursuing in two doctoral thesis. The compounds form trinuclear and triangular molecules. The spin frustration phenomenon observed in the triangular relationship of copper(II) has been described. Since dysprosium(III) ion is characterized by a large magnetic anisotropy, the triangular, trinuclear coordination compound of dysprosium(III) of the formula [Dy3L5HLCl4]∙HL (where HL = 2-methoxyethanol) presents the characteristic properties of molecular magnets (SMMs) behavior. Two values of the energy barier were determined as Ueff/kB = 84,6 K and 31,2 K with the corresponding relaxation times τ0 = 1,82·10-6 s and 5,19·10-5 s. The data are probably attributed to different geometry of the coupled dysprosium ions.

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Applicability of the DFT Augmented Symmetry Approach to Simulations of the Chromium-based Rings : Cross-validation Using the PBE Functional

Wojciechowski M., Brzostowski B., Kamieniarz G.

Computational Methods in Science and Technology

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2016

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Vol. 22, No. 2

109--121

EN

We present comprehensive convergence and accuracy tests for predictions of the augmented symmetry approach suggested to reduce computational complexity of the DFT calculations for molecular rings. Using the PBE functional, we demonstrate the numerical stability of magnetic couplings, magnetic moments and the HOMO-LUMO gaps with respect to the size of the basic parameters RKM, the number of k-points and types of the unit cells as well as to the presence of full or absence of any point group symmetry. We show that both the performance and the final results are equal to those obtained for the standard approaches but the computing time is significantly lower. We conclude that the value RKM = 3:0 and a single k-point in the irreducible Brillouin zone are enough to reach the uncertainty of magnetic couplings of the order of 0:1 meV and a distortion resulting from the approach is irrelevant as far as the magnetic properties are concerned.

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Flexible magnetic coordination networks sensitive to guest molecules

Heczko M., Nowicka B.

Journal of Education and Technical Sciences

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2015

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Vol. 2, nr 1

19--21

EN

Structurally flexible coordination networks that react to different external stimuli with structure deformation, and consequently changes in magnetic properties, are potential candidates for molecular switches and sensors. The design of guest-sensitive molecular magnetic materials based on the specific building blocks: [Ni(cyclam)]2+ (cyclam = 1,4,8,11-tetraazacyclotetradecane) cation and polycyanometallate anions is discussed. The examples of different dimensionality networks and the changes in their structure and magnetic properties in response to sorption of small molecules are presented.

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Mediation of Magnetic Interactions in Prussian Blue Family

Wasiutyński T., Bałanda M., Szeglowski Z., Zieliński P. M.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 2-3

377-384

EN

Results of the AC susceptibility and DC magnetization of the family ACo[Fe(CN)6] for different cations A: Li, Na, K, Rb, Cs,NH4, N(Et)4 are presented. Differences in magnetic properties are found that can be attributed to an indirect interaction mediated by the cations. Two other compounds: A2NiII[FeII(CN)6] (A = K, Na) were also studied. The strong influence on magnetic properties due to alkaline cations was again observed.