Supramolecular assemblies of glycoconjugated dyes can be tailored with properties that make them attractive for use in biomedical applications. For example, when assemblies of glycoconjugated dyes are displaying carbohydrates on their periphery in a polyvalent manner, these assemblies can be used to study and visualize biological recognition events. Carbohydrates can selectively target cell membrane receptors and the polyvalency of the carbohydrate display on the supramolecular assemblies can strengthen the interaction with cells. In addition, some dyes assemble into fluorescent objects and some dyes can generate singlet oxygen. A combination of these properties results in a type of assemblies that can be used as a diagnostic and therapeutic tool. Fluorescence allows an easy, non-invasive read-out and is especially interesting for the detection and visualization of diseased cells or organs. Although singlet oxygen can be a reason for oxidative stress in healthy cells, it is also able to kill pathogens with low side effects and no resistance development. In this thesis two different molecular systems have been developed and the photophysical properties of their assemblies, also in the context of possible use, have been studied. As a first system glycoconjugated porphyrins have been synthesized. The type and number of carbohydrates on the periphery of the porphyrins have been varied and their influence on the photophysical properties and the size of the assemblies has been investigated. Studies concerning their bactericidal nature have been performed. The second system consisted of thiophthalonitriles whose assemblies showed excellent fluorescent properties. Also in this case the photophysical character of the assemblies has been documented and the most remarkable result has been that the hetero atom in the dye is decisive for the observation of the aggregation-induced emission. The thiophthalonitrile assemblies featuring mannose moieties underwent specific and reversible interactions with protein binding partners and bacteria. Since the peripheral substitution had no influence on the photophysical properties, its binding to other biological receptors can be easily realized, independent from the characteristics of the dye. This opens up numerous possibilities to apply these fluorescent nanoparticles in diagnostic research.