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Updated: Jun 17, 2025
Hyperspectral Imaging as a Tool to Study Optical Anisotropy in Lanthanide-Based Molecular Single Crystals
Published on: April 14, 2020
Triple-Decker Hexaazamacrocyclic Lanthanide(III) Complexes: Structure, Magnetic Properties, and Temperature-Dependent
Paula Gawryszewska1, Katarzyna Ślepokura1, Jerzy Lisowski1
1Department of Chemistry, University of Wrocław, 14 F. Joliot-Curie, Wrocław 50-383, Poland.
Abstract:
The reaction of fluoride anions with mononuclear rare-earth(III) complexes of the hexaazamacrocycle derived from 2,6-diformylpyridine and ethylenediamine affords trinuclear coordination compounds [LnL(μ-F)(NO)](NO). The X-ray crystal structures of these complexes show triplex cationic complexes where the three roughly parallel macrocyclic lanthanide(III) units are linked by bis-μ2-F bridges. The detailed analysis of the photophysical properties of the [EuL(μ-F)(NO)](NO)·2HO and [TbL(μ-F)(NO)](NO)·3HO complexes reveals different temperature dependence of luminescence intensity and luminescence decay time of the Eu(III) and Tb(III) derivatives. The spectra of mixed species of average composition [EuTbL(μ-F)(NO)](NO)·3HO are in accordance with the ratiometric luminescent thermometer behavior. Measurements of the direct-current (dc) magnetic susceptibility of the [DyL(μ-F)(NO)](NO)·2HO complex indicate possible ferromagnetic interactions between the Dy(III) ions. Alternating current (ac) susceptibility measurements of this complex indicate single-molecule magnet behavior in zero dc field with magnetic relaxation dominated by Orbach mechanism and an effective energy barrier Ueff = 12.3 cm-1 (17.7 K) with a pre-exponential relaxation time, τ0 of 7.3 × 10-6 s. A similar reaction of mononuclear macrocyclic complexes with a higher number of fluoride equivalents results in polymeric {[LnL(μ-F)](NO)} complexes. The X-ray crystal structure of the Nd(III) derivative of this type shows trinuclear units that are additionally linked by single fluoride bridges to form a linear coordination polymer.
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