Multifunctional molecular-assemblies and hybrid organic - inorganic materials are examined from the viewpoint of structural freedom of organic molecules. The spin and electronic states of molecular- assemblies are designed in terms of electrical conductivity, magnetism, and ferroelectricity. For example, the designs of flip-flop motions and dipole inversions in the crystals realized the ferroelectric properties. The hybrid assemblies with the supramolecular rotators and magnetic anions formed the multifunctional ferroelectric - ferromagnetic materials. Diverse molecular assemblies from single crystal, plastic crystal, liquid crystal, gel, to Langmuir-Blodgett film are our research targets. The researches will be essential for future molecular electronics.