| Περίληψη: | The present PhD Thesis describes the synthesis, spectroscopic and physical characterization studies, single-crystal X-ray structures and magnetic properties of FeIII/LnIII, CoIII/LnIII, NiII/LnIII, ZnII/LnIII and LnIII dinuclear and polynuclear complexes with 2-pyridyl oximes and aminoalcohols as primary organic ligands, where LnIIIs are trivalent lanthanides and YIII (which is not a lanthanide). Molecular dinuclear and polynuclear (coordination clusters) lanthanide(III) complexes attract the interest of synthetic, physical, theoretical and materials chemists due to their involvement in many fields/areas, e.g. single-molecule and single-ion magnetism, magnetic refrigeration, quantum computing, catalysis (both homogeneous and heterogeneous), optics, metal ion-assisted reactivity of organic compounds, and in the chemistry of multifunctional (or "hybrid") molecular materials. Luminescent Ln(III) complexes are attracting attention because these can be used in photonic applications, such as light-emitting diodes, planar waveguide amplifiers and biochemical luminescent probes. The 4f-4f electronic transitions of LnIII ions, which are responsible for the light emission, are narrow and characteristic of each LnIII, while the emitting excited states are long-lived. To face the problem of the spin- and parity-forbidden nature of 4f-4f transitions, aromatic ligands or other d-transition metal ion moieties can be utilized as sensitizers for efficient LnIII-based emission. In the single-molecule magnetism (SMM) area, some LnIII ions, e.g. TbIII and DyIII, are responsible for many of the recent advances in this interdisciplinary area, leading to longer relaxation times and higher working temperatures. LnIII ions play a special role in Magnetism, thanks to their large magnetic moments and (in many cases) huge magnetic anisotropy. The only disadvantage is their very weak exchange interactions as a result of the efficient shielding of the unpaired electrons in the inner 4f atomic orbitals. This has resulted in limited interest in the use of 4f-metal ions for the preparation of 3D molecule-based magnets. In contrast to this, for the case of SMMs, the fact that the magnetic anisotropy is a major requirement to see this effect, explains well the efforts of many research groups around the world to incorporate LnIII ions in combination with 3d-metal ions in the same dinuclear complex or coordination cluster. Such compounds combine the large, predominantly anisotropic magnetic moments of LnIII ions with the high-spin states of many 3d-metal ions. From a synthetic viewpoint, methods must be found to combine LnIII- and 3d-metal ions within the same molecule. Simple mixing of the components in the presence of an organic ligand, often leads to pure 3d-metal complexes owing to the ligand field stabilization for the latter. Thus the choice of the primary organic ligands is of paramount importance for the assembly of 3d- and 4f-metal ions in the same entity. Thus, exploiting the HSAB approach, ligands are often used which possess distinct coordination compartments/functionality, or "pockets", for preferential bonding of the 3d- and 4f-metal ions.
The Dissertation is divided into 8 parts; most parts consist of several chapters. There is also an Appendix section at the end of the Thesis.
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