The creation of and manipulation with light affects many areas of applications and is therefore of major current interest. This thesis deals with two areas: the change of molecular properties in photochromic molecules and the influence of the ligand surrounding on luminescent properties. In the first part of this thesis, azobenzene derivatives are described. They provide a group of widely used dyes in goods of daily needs. Scientists are interested in these molecules as they are able to undergo an isomerisation from the E to Z form upon irradiation. This change in conformation can be used to regulate the permeability of ion channels in living cells by light. To achieve this, molecules have to be designed that can reversibly bind to the ion channels. The second part of this work reports on luminescent materials. In general, they play an important role in many areas of daily life, particularly since the development of LED technology. Many of those materials however contain expensive or toxic substances. Researchers are therefore trying to find more abundant alternatives that cause less environmental problems. As manganese(II) is an abundant metal, its compounds are interesting candidates for tuneable emissive dyes in diodes. Another interesting group of compounds for such emissive dyes are zinc(II) complexes. Just as manganese, zinc is an abundant metal, however contrary to manganese(II) it usually features solely fluorescence. However, there are recent reports indicating that in special complexes zinc(II) might facilitate phosphorescence originating from its ligands.