Multifunctional spin crossover (SCO) compounds combine classical SCO properties with additional features (e.g. non-linear optics, bulk magnetic ordering, …), thus opening the possibility for prospective and versatile applications. Besides the usually performed magnetic measurements concerning SCO nanomaterials a more straightforward spin state detection method, which allows a precise tracking even in small clusters, is required. The spin state dependent modulation of photoluminescence (PL) is one approach fulfilling these demands. In addition to the development of SCO-PL systems for feasible applications, investigations on the only partially understood mechanism of this phenomenon still need to be conducted.