The project was aimed at the synthesis, experimental study and theoretical modeling of new transition metal clusters, mixed transition metal-lanthanoid clusters and 1D, 2D and 3D coordination polymers (CPs) which include these clusters as repeat units. We have focused on systems exhibiting properties promissing for practical applications such as single molecule magnet (SMM) and single chain magnet (SCM) behavior, 2D and 3D magnetic ordering, thermally driven spin-crossover (SCO) and light-induced excited spin state trapping (LIESST) effect. The synthesis and comprehensive characterization of these families of compounds with the aid of complementary magnetic and spectroscopic techniques (primarily the measurements of direct/alternating current (DC/AC) susceptibility, magnetization, heat capacity, X-ray diffractions methods, UV/Vis/NIR, IR, NMR, Mass, Raman, Mössbauer and Inelastic Neutron Scattering (INS) spectroscopies, High-Field Multi-Frequency EPR (HFMF EPR), polarized neutron diffraction, etc) were complemented by the comprehensive theoretical description of their magnetic, relaxation and optical characteristics. The main objective was to reveal the key mechanisms governing those properties of the named compounds which are useful for nanotechnological applications. On this basis we obtained new SMMs and SCMs with unprecedentedly high blocking temperatures, and new SCO materials exhibiting hysteresis at room temperatures. The project was based on a tight cooperation of the following three world-recognized groups of researchers of complementary expertise who are congregated into a consortium: Swiss team headed by Prof. S. Decurtins and two Moldovan teams (experimental team headed by Asoc. Prof. S. Baca, and theoretical team headed by Prof. S. Klokishner).