The realization of complex functions such as selective recognition and conversion, conversion of light into chemical energy, chemical signal processing and transmittance depend on reactions and property changes of individual molecules that are amplified within an ensemble to macroscopic effects. Often hierarchically organized molecular ensembles play a key role and form building blocks on different length scales. Examples are found in living systems. The realization of similar functions in artificial systems requires the coupling of supramolecular systems to conventional device structures. The lecture will present approaches towards the design of such coupled systems that play a central role for the further development of nanotechnology. Based on the properties of simple systems, routes for preparation, characterization and understanding of more complex interfacial structures will be discussed. The principles will be examplified by conversion of light to chemical energy, electrochemical energy storage and chemical and biochemical sensors.