Switchable and selective detection of Zn2+ or Cd2+ in living cells based on 3'-O-substituted arrangement of benzoxazole-derived fluorescent probes

Two benzoxazole-derived ESIPT fluorescent sensors E1 and E2 show highly selective detection of Zn2+ and Cd2+, respectively, in aqueous solution and living cells. The selectivity switching from Zn2+ to Cd2+ is attributed to the different binding mode which is dependent on the 3'-O-substituted arrangement.