Chloride transporters have been intensely investigated because of their potential medicinal applications. In particular, pH-switchable transporters are highly appealing as potential anticancer agents, because they might be more active in cancer cells than in normal cells. Owing to its increased acidity, our simple 3,6-dinitro substituted carbazole receptor acts as a pH-switchable transporter, with physiologically relevant apparent pKa of 6.4. Read more in our newest paper in special issue of Frontiers in Chemistry, devoted to anion transport: