and Eu1) also displayed cytotoxicity and/or haemolytic properties as well. The varied activity profile that is observed for these slightly altered compounds is encouraging as it indicates a direct relationship between the antimicrobial activity, toxicity, haemolysis and their structure, suggesting that further optimization could lead to better compounds. In the extended panel, Eu1 showed very high levels of activity against all the tested fungal strains with MIC values between 6-98 nM. Promisingly the complex exhibited no cytotoxicity or haemolysis up to 200 µM, resulting in a therapeutic index of 33,333 (Table in SI). In addition to this promising in vitro activity profile, the prominent luminescence of these compounds could be leveraged for fluorescence microscopy studies which could provide information about the mode of action of this compound class.