Colloidal inorganic nanocrystals (NCs) are among the most exploited nanomaterials to date due to their extreme versatility. Research on NCs went through much advancement in the last fifteen years, for example in the synthesis, which opened up the possibility to control their size and shape: this includes the ability to combine several materials in the same nano-object, with topological control, which has contributed to expand the functionality of NCs and the range of their applications considerably. An additional step forward was the creation of a wide range of superstructures from the assembly of such NCs, which can be clearly thought of as new types of artificial solids. Progress also came from the study of chemical transformations in nanostructures, most notably via cation exchange, which involves replacement of the sublattice of cations in a crystal with a new sublattice of different cations, while the sublattice of anions remains in place. New exciting directions have been uncovered recently through the development of plasmonic semiconducting nanoparticles and by the possibility to chemically adjust the density of free carriers in them. The present talk will highlight the recent progress by our group in the areas of advanced synthesis, assembly and in the study of chemical transformations in NCs, with focus on semiconducting/plasmonic nanomaterials.