A Naphthalimide-Based Cd(2+) Fluorescent Probe with Carbamoylmethyl Groups Working as Chelators and PET-Promoters under Neutral Conditions

Chemistry. 2016 Jun 13;22(25):8579-85. doi: 10.1002/chem.201600556. Epub 2016 May 12.


We have developed a novel naphthalimide-based Cd(2+) fluorescent probe (1), featuring almost no background response, high sensitivity and selectivity toward Cd(2+) through its high association constant [K=(2.10±0.423)×10(6) ], and a practical working pH range. Membrane-permeability was conferred on 1 by replacing the imide and amide substituents with n-butyl groups, and hence the derivative (4) has found practical utility on fluorescent imaging of Cd(2+) in HeLa cells. Comparison of fluorescent properties between various compounds derived from 1 has demonstrated that the carbamoylmethyl groups in 1 function not only as Cd(2+) chelators but also as promoters for photoinduced electron transfer (PET) by lowering the basicity of the two tertiary amino groups. As a result, 1 and 4 exhibited highly practical performance as Cd(2+) probes under neutral conditions.

Keywords: cadmium; fluorescence; fluorescent probes; naphthalimide; photoinduced electron transfer.

MeSH terms

  • Cadmium / chemistry*
  • Catalysis
  • Cell Membrane Permeability / drug effects
  • Electron Transport
  • Fluorescent Dyes / chemical synthesis
  • Fluorescent Dyes / chemistry*
  • Fluorescent Dyes / pharmacology
  • HeLa Cells
  • Humans
  • Hydrogen-Ion Concentration
  • Imides / chemistry
  • Light
  • Microscopy, Confocal
  • Naphthalimides / chemistry*


  • Fluorescent Dyes
  • Imides
  • Naphthalimides
  • Cadmium