Background: Abnormal Cu(II) ions levels may affect many biological
functions, and it is of great importance to detect Cu(II) ions in organisms.
Methods: Herein, we report a near-infrared (NIR) fluorescent probe
EtRh-N-NH for the detection of Cu(II). In the probe structure, a
rhodamine core was used, and a hydrazine group was employed as the responsive
site. Results & Conlusions: EtRh-N-NH displayed sensitive,
specific and fast response upon Cu(II) with excellent linear relationship between
the concentration and fluorescence emission intensity in 0–1 M range. The
releasing EtRh-COOH exhibited 762 nm of emission wavelength with a 75 nm
of Stokes shift.