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Since the discovery of single molecule magnetism in lanthanide complexes on the example of Tb(Pc)2, sandwich phthalocyaninates have become attractive objects to study the influence of structural and electronic effects on their magnetic properties. In our work, we focus on the combination of static and dynamic factors that can control the behavior of SMM. Among the dynamic factors, we focus on supramolecular assembly, which can be induced by the interaction of crown-substituted sandwiches with alkali metal ions. To broaden the range of possible effects under study, we developed triple-decker complexes containing one terminal tetra-15-crown-5-substituted ligand and two octa-n-butoxy-substituted phthalocyanine ligands, [(BuO)8Pc]M[(BuO)8Pc]M*[(15C5)4Pc]. A convenient synthesis ensured by the stabilization of the complexes with electron-donor substituents and an easy chromatographic purification provided by the high solubility of the complexes made it possible to obtain a series of homo- and heteronuclear compounds, where M and M* = Tb and/or Y. Varying the metal centers in such triple-deckers can be used to study relatively strong intramolecular f-f interactions at distances Ln...Ln ca. 3.5 Å, while supramolecular assembly can be used to study weaker f-f interactions in the range of distances from 6.2 to 13.1 Å. In addition, the synthesized complexes are interesting objects for NMR studies of correlations between the conformational state of the sandwiches and their magnetic properties. We have shown that changing the solvent used for such studies can switch the coordination polyhedron of the metal "M" center from square-antiprismatic in toluene to distorted prismatic in chloroform. This switch manifests itself in an increase in the axial component of the magnetic susceptibility tensor, which leads to an increase in the lanthanide-induced shifts in the NMR spectra. Thus, the chosen molecular architecture of the complexes allows advanced studies of structural and supramolecular effects in SMM, including aggregation and solvation.
№ | Имя | Описание | Имя файла | Размер | Добавлен |
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1. | Полный текст | ICPP-12_BOA_Martynov.pdf | 1,2 МБ | 11 февраля 2023 [martynov.alexandre] |