Two-channel near-infrared fluorescence Ag ion sensing of a new star-shaped dendrimer.

A new near-infrared fluorescence sensor PDI-PD for Ag ions was successfully prepared and its structure characterized by H nuclear magnetic resonance (NMR), C NMR and high-resolution mass spectrometry; matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (HRMS MALDI-TOF). The probe exhibited rapid, sensitive, and selective two-channel fluorescence responses towards Ag ions and protons. The probe has a marked high binding affinity and high sensitivity for Ag , with a detection limit of 1.4 × 10  M. An approximately five-fold enhanced core emission at 784 nm was attributed to fluorescence resonance energy transfer (FRET). The enhanced core emission of the probe with Ag ions based on photo-induced electron transfer and FRET is discussed. In addition, the probe presented a visible colour change. All experimental results demonstrated that PDI-PD is an efficient tool for the selective, sensitive and rapid detection of Ag ions and protons using two-channel fluorescence responses.