^a Department of Chemistry “U. Schiff”, University of Florence, Via della Lastruccia 3-13, Sesto F.no (FI), 50019 Italy

^b Department of Chemistry, Lash Miller Chemical Laboratories, 80 St. George Street, Toronto, ON, Canada

^c Department of Medicinal Chemistry, Photopharmacology and Imaging, Groningen Research Institute of Pharmacy, Faculty of Science and Engineering, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands

^d Institute for Organic and Biomolecular Chemistry, Department of Chemistry, University of Göttingen, Tammannstr. 2, 37077 Göttingen, Germany

^e Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC), University of Göttingen, 37075 Göttingen, Germany

^f Department of Chemistry, Ångström Laboratory, Uppsala University, Regementsvägen 10, 752 37 Uppsala, Sweden