3,7-Bis(N-methyl-N-phenylamino)phenothiazinium Salt: Improved Synthesis and Aggregation Behavior in Solution

In this paper, the optimization of the synthesis of 3,7-bis(N-methyl-N-phenylamino)phenothiazinium chloride with a detailed analysis of reaction parameters, i.e. solvent, temperature, amount of amine, as well as addition of a non-nucleophilic base, is presented. Spectroscopic, electrochemical and computational data show that the presence of the two phenyl rings, directly bound on the PTZ+ core, inhibits the aggregation ability of the salt at concentrations up to 10–3 M. Furthermore, the introduction of an aromatic group in phenothiazinium-based molecules appears strategic to introduce other useful functionalities, thus opening new opportunities in the drug design/discovery research field.