Carbethopendecinium bromide is a biochemical assay reagent that can be used for membrane potential studies[1].
References
[1] Frantiek Kopecky, et al. Inclusion Complexation of Carbethopendecinium Bromide with Some α- and β-Cyclodextrins Studied by Potentiometry with Membrane Electrodes. Collect. Czech. Chem. Commun. 2004, 69, 384-396.