“…Indole‐based fluorescent sensors have been widely synthesized to detect ions. Bi‐indole was used to combine with 6,7,9,10,17,18,20,21‐Octahydrodibenzo[b,k], diaminomaleonitrile and 1,2,3,4,5,6‐hexaaminobenzene respectively to detect F − with high selectivity. Cyanide could be detect by indole organic salt derivatives and colorimetric detected by three indole‐based fluorescent sensors .…”