The fabrication of nanoscale photonic and electronic devices will rely heavily on bottom up approaches for producing highly organized functional materials. These approaches offer distinct advantages over conventional lithography especially in terms of the spatial precision with which such structures can be built. One of the key barriers to producing operational devices is that of connectivity between the nanoscale and macroscopic world. Interfacial supramolecular chemistry provides this connectivity by combining writeable/addressable surfaces with functional materials. Tremendous progress has been made in the area of interfacial assembly over the past decade. The chemistry for creation of mono- and multilayer assemblies is now well established and increasingly, photoaddressability is being incorporated into such films. Coordination compounds are valuable components in interfacial photonic arrays because they can be "programmed" to perform multiple functions such as surface immobilization, electron transfer and light emission with relative synthetic ease. In particular, coordination compounds, e.g., osmium, ruthenium, rhodium polypyridyl complexes, are attractive as their optical transitions are usually well defined, and in the case of charge transfers, strongly allowed, typically occurring in the visible spectral region. Their luminescence can be used as a probe of the interfacial environment or for creating light addressable functionality within a film. Also, they frequently exhibit reversible electrochemical responses across a number of different oxidation states. Although exploitation of such coordination compounds is not as extensive as organic fluorphores, the number of photoactive interfacial films, incorporating photochemically active coordination compounds is growing significantly. Here, we review some key examples, focusing on how coordination compounds can be exploited to drive layer formation and photophysical and photochemical events at interfaces. (C) 2009 Elsevier B.V. All rights reserved.