This paper deals with molecular materials resulting from the chemical and electrochemical molecular assemblies of organic and inorganic precursors such as organic donors derived from TTF, organic nitronyl nitroxide radicals, decamethylferrocenium, metal bis(dithiolate), metal bis(dithiolene), polyoxometalates, and hexacyanometalates. Some general aspects on molecular materials as well as constraints to design conducting and magnetic materials were recalled and supported by examples from our own contribution in the field. One of the current trends in molecular materials concerns the preparation and the study of materials combining several physical properties in a synergistic way. In this context materials with conducting and magnetic properties and also materials with spin crossover and antiferromagnetic interactions are presented.