This doctoral thesis is presented as a compilation of scientific articles, some of which have been published or are under revision in high impact international journals. The core of the thesis is the preparation of new complexes, principally paramagnetic complexes, with the ligand 2-pyridinecarboxaldehyde, which is also known as pyca. Simple, commercially available, and low-cost simple salts are used as the substrates. The electronic properties and structures of these complexes, as well as their behavior in solution and in the solid state, are explored using spectroscopic and analytical techniques, including magnetism, UV-vis absorption, single-crystal and powder X-ray diffraction, relaxivity (for evaluation of their potential as possible contrast agents in magnetic resonance imaging), etc. The chapters and sub-sections of the thesis are listed below, and a summary of the most relevant content is provided.
