A new chromone-based fluorescent probe for ratiometric detection of Pd 2

A new chromone-based fluorescent probe (HMPM) is introduced for the selective detection of Pd 2+ . The designed probe exhibits a ratiometric fluorescence enhancement, which can be attributed to the ESIPT and/or chelation enhancement fluorescence (CHEF) processes. HMPM is efficient enough to detect Pd 2+ solely in the presence of other metal ions in DMSO/H 2 O solution (1 : 1, v/v, pH = 7.2) with a limit of detection as low as 2.9 nM. Furthermore, the complex formation of HMPM with Pd 2+ is confirmed by the single crystal X-ray diffraction method. The changes in electronic structure and absorption spectrum of HMPM upon complexation with Pd 2+ are supported by DFT and TDDFT calculations. Moreover, the probe (HMPM) could be effectively used for the detection of Pd 2+ by a dip-stick method.