[en] The following work is divided into three topics, in which 71 new coordination compounds and 11 new organic compounds are presented. The first project describes the continuation of the investigation of the versatile biquinoxen system, where biquinoxens are similar to the well-known viologens. The biquinoxen system exhibits multifaceted properties such as reversible redox states, luminescence and coordination to metal centres. In this work, the possibility of tuning the emission wavelength of the biquinoxen derivatives was investigated and in the course of this, 7 new compounds with emission wavelengths over a range of 63 nm, from green-yellow to red light, were produced. In addition, the biquinoxen system was used in reactions with transition metal salts. This involves the in-situ generation of a radical ligand species that is stabilised by coordination to Co${}^{II}$, Cu${}^{II}$ and Zn${}^{II}$ ions. The Co${}^{II}$ complexes were already described in my bachelor thesis, but were reproduced here and their supramolecular networks investigated in more detail and compared with the 4 new Cu${}^{II}$ and Zn${}^{II}$ containing complexes. The chapter on the second project describes the exploration of the complexation properties of the H${}_2$opch ((2-hydroxy-3-methoxybenzylidene)pyrazine-2-carbohydrazide) ligand family with lanthanide ions. Firstly, the influence of the different ionic radii of the lanthanides, resulting from the lanthanide contraction, was investigated in reactions with different lanthanide nitrates but with identical reaction conditions. This led to 11 new tetra- to octa-nuclear complexes. Amongst others, a mixed-valent Ce${}_4$ complex and a Gd${}_8$ compound which shows an excellent magnetocaloric effect could be isolated. Furthermore, the ligand was modified to investigate the influence of intra- and especially intermolecular interactions. The focus here was to investigate the effect of halogen interactions which have the advantage of being easily varied in strength, on the resulting optical and magnetic properties. This led to 18 new complexes. The third project deals with the expansion of a radical-lanthanide dimer system which has been under study for several years in the Powell group. Here, the already known complexes were reproduced and their properties in solution investigated. Furthermore, the magnetic properties of previously unexplored lanthanide variations were measured. All four components of the original complex (lanthanide ion, neutral co-ligand, anionic co-ligand and radical ligand) were systematically varied and magnetic measurements performed on the Dy${}^{III}$ analogues. In this investigation, 38 new complexes were prepared, amongst which one compound was identified exhibiting slow relaxation of magnetisation up to a temperature of 30 K and a thermal energy barrier of 475 K. In this systematically varied series of single molecule magnets the relaxation dynamics were investigated and compared in order to establish a strategy on how to improve the single molecule magnetic behaviour of these compounds, in particular by suppressing phonon-based relaxation processes.