Probing the Magnetic Relaxation Dynamics in Low-coordinate Mononuclear Lanthanide Aryloxide Single-Molecule Magnets

Abstract

Interdisciplinary research combining Chemistry and Physics has given countless inventions and remains an essential benefactor of material science studies. Single-molecule magnets (SMMs) is one such discovery proving to be of great interest for future technologies. SMMs are molecules that can retain magnetisation below a certain temperature. These nanoscopic magnets can be utilised in the development of ultra-high-density storage devices and quantum computers (via their Quantum tunnelling of magnetisation property). They were discovered three decades ago but have remained technologically impractical; some recent remarkable advancements have re-ignited the research field with new ideas towards making high-temperature SMMs. The latest design approach of high-performing SMMs requires a single Dy centre surrounded by uniaxial anionic ligands (ideally two coordinate Dy complex). Herein, the role of ligands and the resultant crystal field on the physical properties of SMMs is surveyed, and the characteristic advantages of alkoxide and aryloxide ligands in realising low-coordinate high-performing Ln SMMs is investigated. The synthesis and detailed magnetic studies of families of Ln SMMs of coordination number (CN) 5, [Ln(OMes*)2(THF)2X] (Mes*=2,4,6-tBu-phenyl; Ln = Dy, Y; X = Cl, Br, I), CN6, [Ln(OPh*)2(THF)3X] (Ph*=2,6-CHPh2-4-tBu-phenyl; Ln = Dy, Y; X = Cl, Br), and CN4, [Na(THF)6][Ln(OAd*)2Cl2] (Ad*=2,6-Ad-4-tBu-phenyl; Ln = Dy, Y) and [Na(THF)6][Dy(OMes*)3X] (Mes*=2,4,6-tBu-phenyl; X = Cl, BH4), are presented in Chapters 2, 3 and 4, respectively. These results provide meaningful correlations and proof of concepts about low-coordinate Ln SMMs, such as the halide influence on quantum tunnelling of magnetisation in Chapter 2, the effect of a meridional arrangement of anionic ligands on the crystal field and magnetic properties in octahedral Dy complexes in Chapter 3, and interesting magnetic behaviour of distorted tetrahedral Dy SMMs in Chapter 4.

Date of Award	1 Aug 2021
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Richard Winpenny (Supervisor) & David Mills (Supervisor)