Magnetoactive coordination compounds demonstrating bi- or multistability between magnetic stable states serve as intriguing examples of molecular switches. Currently, research is concentrated on molecular nanomagnets, particularly single molecule magnets, where the magnetization's slow relaxation of purely molecular origin is observed.
The objective of the presented thesis is to provide readers with a basic comprehension of single molecule magnetism and relaxation processes within Co(II) single molecule magnets. Additionally, the thesis delves into the synthesis, characterization, and magnetic properties of Co(II) coordination compounds featuring tridentate N-donor ligands L, along with their deposition onto surfaces.
Two novel ligands and twenty-one novel Co(II) coordination compounds were prepared and characterised by the means of elemental, spectroscopic, and structural analysis. Specifically, four pentacoordinate complexes [Co(L)A2] (A– stands for corresponding anions), ten hexacoordinate Co(II) compounds [Co(L)(κ1-A)(κ2-A)] or [Co(L)2]A2, six coordination compounds with general formula [Co(L)2][CoA4] incorporating hexacoordinate complex cations [Co(L)2]2+ and tetracoordinate complex anions [CoA4]2– and one dimer complex, consisting of two hexacoordinated Co(II) centres [{(L)ClCo}(μ- Cl)2{CoCl(L)}]. Furthermore, the magnetism of herein prepared compounds was analysed by static and dynamic magnetic measurements. Dynamic magnetic measurements revealed that fifteen compounds (C2 − C6, C9, C12 − C19 and C21) demonstrate noticeable peaks in the out-of-phase AC susceptibility components, whereas the remaining six compounds show these peaks beyond the frequency range of the measured alternating magnetic field. It is worth noting that, compound C2 exhibits the rare zero-field slow relaxation of magnetisation. Remaining compounds are field-induced single molecule magnets exhibiting relaxation parameters similar to already reported Co(II) single molecule magnets. Two Co(II) complexes were successfully deposited onto surfaces using wet lithography techniques.
The thesis is organized into 7 chapters and an Appendix. Chapter 2 provides theoretical foundations on magnetism and molecular magnetism, while Chapter 3 offers a review of Co(II) complexes with relevant ligands. Chapter 4 outlines the objectives, Chapter 5 details methods, Chapter 6 presents results and discussions, and the final chapter summarizes key findings.