This contribution describes the rational step-by-step construction of molecular solids useful for the field of molecular electronics. Chain stiffness as a structural principle leads to the design of the macromolecules which already in a molecularly disperse state show effects expected for 1-dimensional solids. Phthalocyaninatopoly (siloxane)s are described as a typical example. The optical spectra of these polymers are explained based on the theory of 1 - D excitonic interactions. Such polymers can be subjected to the Langmuir-Blodgett-technique. Monolayers of the rod-like macromolecules at the air-water interface are transferred to solid substrates with concurrent orientation of the rod-axes into the dipping direction. Anisotropic multilayers are obtained in which the rods are stacked regularly in layers. When rods of different chemical composition are used a series of different architectures can be achieved, e.g. nanocomposites composed of layers alternating in chemical structure and direction of the rods. Such systems show interesting optical, electrochemical and electrical properties when properly composed. Furthermore, guest molecules can be placed ("doped") into the matrix of the side-chains in which the rod-backbones are embedded. Thus, when ionophores are chosen as guests, ion-sensitive membranes can be achieved. Their application to build ion sensitive FET-devices is described.