A novel method to synthesize N-aryl-1-amino indoles
was established by the photoinduced N–N coupling reaction.
This protocol is by treatment of o-nitrobenzyl alcohols
and indolines in the presence of TEAI and acetic acid with a 24 W
ultraviolet (UV) light-emitting diode (LED) (385–405 nm) irradiation.
The products bearing an aldehyde group can be further transformed
to fluorescent probes based on Rhodamine 6G derivative 11, which shows a high specificity and sensitivity for Fe3+.