Aerogel-Based Single-Ion Magnets: A Case Study of a Cobalt(II) Complex Immobilized in Silica.

Autor: Kottsov SY; Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow 119991, Russia., Shmelev MA; Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow 119991, Russia., Baranchikov AE; Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow 119991, Russia., Kiskin MA; Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow 119991, Russia., Sharipov AU; Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow 119991, Russia.; Faculty of Technology of Inorganic Substances and High Temperature Materials, Mendeleev University of Chemical Technology of Russia, Moscow 125047, Russia., Efimov NN; Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow 119991, Russia., Rubtsova IK; Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow 119991, Russia., Nikolaevskii SA; Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow 119991, Russia., Kopitsa GP; St.-Petersburg Nuclear Physics Institute, National Research Center 'Kurchatov Institute', Gatchina 188300, Russia.; Grebenshchikov Institute of Silicate Chemistry, Russian Academy of Sciences, St.-Petersburg 199034, Russia., Khamova TV; Grebenshchikov Institute of Silicate Chemistry, Russian Academy of Sciences, St.-Petersburg 199034, Russia., Roslyakov IV; Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow 119991, Russia.; Department of Materials Science, Lomonosov Moscow State University, Moscow 119991, Russia., Eremenko IL; Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow 119991, Russia., Ivanov VK; Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow 119991, Russia.; Faculty of Chemistry, National Research University Higher School of Economics, Moscow 109028, Russia.
Jazyk: angličtina
Zdroj: Molecules (Basel, Switzerland) [Molecules] 2023 Jan 03; Vol. 28 (1). Date of Electronic Publication: 2023 Jan 03.
DOI: 10.3390/molecules28010418
Abstrakt: The chemical immobilization of cobalt(II) ions in a silica aerogel matrix enabled the synthesis of the first representative example of aerogel-based single-ion magnets. For the synthesis of the lyogels, methyl-trimethoxysilane and N-3-(trimethoxysilyl)propyl ethylenediamine were co-hydrolyzed, then the ethylenediamine groups that were immobilized on the silica matrix enabled the subsequent binding of cobalt(II) ions. Lyogels with various amounts of ethylenediamine moieties (0.1-15 mol %) were soaked in isopropanol solutions of cobalt(II) nitrate and further supercritically dried in carbon dioxide to obtain aerogels with a specific surface area of 210-596 m 2 ·g -1 , an apparent density of 0.403-0.740 cm 3 ·g -1 and a porosity of 60-78%. The actual cobalt content in the aerogels was 0.01-1.50 mmol per 1 g of SiO 2 , which could easily be tuned by the concentration of ethylenediamine moieties in the silica matrix. The introduction of cobalt(II) ions into the ethylenediamine-modified silica aerogel promoted the stability of the diamine moieties at the supercritical drying stage. The molecular prototype of the immobilized cobalt(II) complex, bearing one ethylenediamine ligand [Co(en)(MeCN)(NO 3 ) 2 ], was synthesized and structurally characterized. Using magnetometry in the DC mode, it was shown that cobalt(II)-modified silica aerogels exhibited slow magnetic relaxation in a nonzero field. A decrease in cobalt(II) concentration in aerogels from 1.5 mmol to 0.14 mmol per 1 g of SiO 2 resulted in a weakening of inter-ion interactions; the magnetization reversal energy barrier likewise increased from 4 to 18 K.
Databáze: MEDLINE
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