Fluorescent photoinduced electron transfer (PET) sensing of anions using charge neutral chemosensorsElectronic supplementary data (ESI) available: 1H, 13C NMR for 1a–c and UV-Vis and NMR titration results for 1a are available as electronic supplementary information (ESI). See http://www.rsc.org/suppdata/cc/b1/b107608f/