Benzo[e]indolium derivatives in aqueous solutions: Reaction with bisulfite and successive interaction with Cu2+ and Hg2+.

A new benzo[ e ]indolium derivative 1 including pyridyl and thienyl groups was synthesized and characterized, which failed to response to Hg 2+ or Cu 2+ in aqueous system. However, it is interesting that when it reacted with bisulfite in HEPES buffer, the in situ generated ensemble as 1 -SO 3 H displayed dramatic absorption and fluorescence changes after adding Cu 2+ or Hg 2+ , which were contrary to the changes of 1 upon the addition of bisulfite ions. By contrast, the other two derivatives 2 and 3 showed the almost similar trends of spectral changes, which were short of ligating atoms N or S. The further investigation of 1 HNMR spectra changes of 1 showed that C−SO 3 H bond may be interrupted because the good binding capacity of Hg 2+ and Cu 2+ with O of C−SO 3 H weaken the binding force of C−SO 3 H, which resulted in the recovery of ethylene with benzo[ e ]indolium block. The DFT calculations results further confirmed it. [ABSTRACT FROM AUTHOR]