The synthesis of four fluorescent photoinduced electron transfer (PET) chemosensors 1–4 for anions is described. These are all based on a simple design employing charge neutral aliphatic or aromatic thiourea anion receptors connected to an anthracene fluorophore via a methylene spacer. Here the anion recognition occurred through 1: 1 hydrogen bonding between the thiourea protons and the anion, as demonstrated by observing the changes ...