Triple-Decker Hexaazamacrocyclic Lanthanide(III) Complexes: Structure, Magnetic Properties, and Temperature-Dependent Luminescence
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 <b>[Ln</b><sub><b>3</b></sub><b>L</b><sub><b>3</b></sub><b>(μ</b><sub><b>2</b></sub><b>-F)</b><sub><b>4</b></sub><b>(NO</b><sub><b>3</b></sub><b>)</b><sub><b>2</b></sub><b>](NO</b><sub><b>3</b></sub><b>)</b><sub><b>3</b></sub>. 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-μ<sub>2</sub>-F bridges. The detailed analysis of the photophysical properties of the <b>[Eu</b><sub><b>3</b></sub><b>L</b><sub><b>3</b></sub><b>(μ</b><sub><b>2</b></sub><b>-F)</b><sub><b>4</b></sub><b>(NO</b><sub><b>3</b></sub><b>)</b><sub><b>2</b></sub><b>](NO</b><sub><b>3</b></sub><b>)</b><sub><b>3</b></sub><b>·2H</b><sub><b>2</b></sub><b>O</b> and <b>[Tb</b><sub><b>3</b></sub><b>L</b><sub><b>3</b></sub><b>(μ</b><sub><b>2</b></sub><b>-F)</b><sub><b>4</b></sub><b>(NO</b><sub><b>3</b></sub><b>)</b><sub><b>2</b></sub><b>](NO</b><sub><b>3</b></sub><b>)</b><sub><b>3</b></sub><b>·3H</b><sub><b>2</b></sub><b>O</b> 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 <b>[Eu</b><sub><b>1.5</b></sub><b>Tb</b><sub><b>1.5</b></sub><b>L</b><sub><b>3</b></sub><b>(μ</b><sub><b>2</b></sub><b>-F)</b><sub><b>4</b></sub><b>(NO</b><sub><b>3</b></sub><b>)</b><sub><b>2</b></sub><b>](NO</b><sub><b>3</b></sub><b>)</b><sub><b>3</b></sub><b>·3H</b><sub><b>2</b></sub><b>O</b> are in accordance with the ratiometric luminescent thermometer behavior. Measurements of the direct-current (dc) magnetic susceptibility of the <b>[Dy</b><sub><b>3</b></sub><b>L</b><sub><b>3</b></sub><b>(μ</b><sub><b>2</b></sub><b>-F)</b><sub><b>4</b></sub><b>(NO</b><sub><b>3</b></sub><b>)</b><sub><b>2</b></sub><b>](NO</b><sub><b>3</b></sub><b>)</b><sub><b>3</b></sub><b>·2H</b><sub><b>2</b></sub><b>O</b> 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 <i>U</i><sub>eff</sub> = 12.3 cm<sup>-1</sup> (17.7 K) with a pre-exponential relaxation time, τ<sub>0</sub> of 7.3 × 10<sup>-6</sup> s. A similar reaction of mononuclear macrocyclic complexes with a higher number of fluoride equivalents results in polymeric <b>{[Ln</b><sub><b>3</b></sub><b>L</b><sub><b>3</b></sub><b>(μ</b><sub><b>2</b></sub><b>-F)</b><sub><b>5</b></sub><b>](NO</b><sub><b>3</b></sub><b>)</b><sub><b>4</b></sub><b>}</b><sub><b>n</b></sub> 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.
Authors
- Paula Gawryszewska (ORCID: https://orcid.org/0000-0002-4514-6877)
- Katarzyna Ślepokura (ORCID: https://orcid.org/0000-0001-8330-4218)
- Jerzy Lisowski (ORCID: https://orcid.org/0000-0002-4793-1748)
Institutions
- University of Wrocław (PL)
Publication Details
- Journal
- Inorganic Chemistry
- Published
- 2024-08-09
- DOI
- https://doi.org/10.1021/acs.inorgchem.4c02047
- Citations
- 4
- Primary Topic
- Magnetism in coordination complexes
- Type
- article
- Field-Weighted Citation Impact
- 0.47
Funders
- Uniwersytet Wrocławski