An antenna triplet sensitiser for 1-acyl-7-nitroindolines improves the efficiency of carboxylic acid photoreleaseElectronic supplementary information (ESI) available: Synthetic details for starting materials and photolysis protocols for 4 plus the calculated absorption spectrum for 4, spectra of its progressive photolysis and comparisons of calculated and experimental absorption spectra for 4 and 5. See http://www.rsc.org/suppdata/pp/b3/b316251f/