A novel indicator platform comprises a plurality of 1H-lndol-3-yl indicator compounds that are capable of converting to a signalophore compound in response to an external stimulus. In one class of indicator compounds, the resulting signalophores are 2-benzylideneindoline compounds that are formed by an intermolecular Aldol-type process; in a further class of indicator compounds, the resulting signalophores are 10H-indolo[1,2-a]indole compounds that are formed by an intramolecular Aldol-type process. The indicators can be used in a wide array of applications relating, for example, to biological systems or optical data storage.