Photophysical insights and guidelines for blue “turn-on” fluorescent probes for the direct detection of nitric oxide (NO • ) in biological systems

Abstract

Synthesis and photophysical properties of a family of five blue fluorescent “turn-on” probes for the direct detection of nitric oxide (NO • ) is reported. The probes CB1-5 feature a substituted 7-hydroxy coumarin chromophore coupled to 2-methyl-8-aminoquinoline, which act as tridentate ligand for Cu(II) and active site for monitoring NO • using a replacement strategy. The UV/vis absorption and fluorescence emission characteristics of the probes are significantly influenced by the substitution pattern on the coumarin ring, as well as by solvent polarity and pH. Time-dependent density functional theory (TD-DFT) calculations for CB4 and CB5 showed that the absorptions are due to π-π* transition..