Slow Magnetic Relaxation in a Californium Complex

Luis M Aguirre Quintana; Daniel J Lussier; Jennifer N Wacker; Ashima Bajaj; Dominic R Russo; Alexia G Cosby; Alyssa N Gaiser; Joshua J Woods; Appie A Peterson; Wayne W Lukens; Corwin H Booth; Stefan G Minasian; David K Shuh; Jochen Autschbach; Jeffrey R Long; Rebecca J Abergel

doi:10.1021/jacs.4c10065

Slow Magnetic Relaxation in a Californium Complex

J Am Chem Soc. 2024 Nov 20;146(46):31671-31680. doi: 10.1021/jacs.4c10065. Epub 2024 Nov 5.

Authors

Luis M Aguirre Quintana^{1

2

3}, Daniel J Lussier^{1

2}, Jennifer N Wacker¹, Ashima Bajaj⁴, Dominic R Russo^{1

2}, Alexia G Cosby¹, Alyssa N Gaiser¹, Joshua J Woods¹, Appie A Peterson¹, Wayne W Lukens¹, Corwin H Booth¹, Stefan G Minasian¹, David K Shuh¹, Jochen Autschbach⁴, Jeffrey R Long^{1

2

5

6}, Rebecca J Abergel^{1

2

3}

Affiliations

¹ Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
² Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States.
³ Department of Nuclear Engineering, University of California, Berkeley, Berkeley, California 94720, United States.
⁴ Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States.
⁵ Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, United States.
⁶ Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, California 94720, United States.

PMID: 39500515
DOI: 10.1021/jacs.4c10065

Abstract

We report the synthesis and characterization of the macrocyclic californium derivative Na[Cf(H₂O)(DOTA)] (DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate), 1-Cf, which was studied in comparison to its dysprosium counterpart, Na[Dy(H₂O)(DOTA)], 1-Dy. Divergent spectroscopic and magnetic behaviors were observed between 1-Cf and 1-Dy. Based upon spectroscopic measurements, we propose that accessible 5f → 6d transitions (potentially operating in tandem with charge-transfer transitions) are the major contributors to the observed broadband photoluminescence in 1-Cf. Dc magnetic susceptibility data for 1-Cf revealed lower magnetic moments than those previously observed for 1-Dy and expected for an f⁹ free ion, which calculations suggest is the result of greater ligand field effects. Notably, 1-Cf displays slow magnetic relaxation on the time scale of ac susceptibility measurements, making it the first example of a californium-based single-molecule magnet. A side-by-side comparison of the ac susceptibility data reveals magnetic relaxation properties that widely differ between 1-Cf and 1-Dy. This divergent relaxation behavior is attributed mainly to the inherent difference in spin-orbit coupling between Dy³⁺ and Cf³⁺.