Phenothiazine-substituted dendrimers (figure ) were chosen, because they are electron rich and redox-active opening for stabilization of the guest-host complexes by charge-transfer interactions between an acceptor -unit on the guest and the phenothiazines on the host. Furthermore the ability to change oxidation state on the dendrimer could give host-guest systems, where the guest was released upon oxidation. We developed previously a fluorescent modular model host-system in order to circumvent the problems associated with quantification of association constants for binding to large dendrimers, which both are capable of binding several guest molecules (up to 32 for a fifth generation poly(propylene imine) dendrimer) as well as showing additional unspecific binding to the interior.