Triphenylimidazole Based Fluorescent Probes For Cu²⁺

Metal cations play important roles in environment and organisms. Therefore, it is very significant to develop novel methods for the highly selective, sensitive and rapid detection of metal cations in environmental and organisms. The fluorescent probes by virtue of low cost and high sensitivity can selectively recognize metal cations. Thus the design and synthesis of novel sensitive and selective fluorescent probes have attracted increasing interest for researchers.In this paper,we have designed and synthesized two fluorescent probes for Cu²⁺, and studied the Cu²⁺ sensing performance using UV-vis absorption and fluorescence spectroscopies. The specific contents are as follows:（1） A triphenylimidazole based “coordination” chemosensor（TPIH） for Cu²⁺ determination. This chemosensor was synthesized with the triphenylimidazole as the fluorophore and Schiff base moieties as the specific interaction sites for Cu²⁺. The probe（TPIH） exhibited a strong absorption band at 442 nm in a DMSO/ HEPES（9/1, v/v） mixed solvent as well as a strong emission band at 547 nm. Upon the addition of Cu²⁺, the probe displayed strong fluorescence quenching. Besides, a good linearity between the fluorescence intensity at 547 nm and the concentration of Cu²⁺ from 1.5×10-6 to 4.5×10-5 M was established and the detection limit was reached 8.7 n M, No interference from other common cations. The probe displayed highly sensitivity, selectivity and reversibility.（2） A triphenylimidazole-based chemodosimeter（TPIAD） for Cu²⁺ detection. The maximum absorbance of TPIAD bule-shifted from 470 to 383 nm, and induced a fluorescent color change from colorless to green yellow upon addition of Cu²⁺, which could be observed by the naked eye. TPIAD displayed high sensitivity and selectivity toward Cu²⁺ over other metal ions with detectable fluorescent signals. The probe in the Me OH/HEPES（4/1, v/v） mixed solvent（5.0 μM） exhibited a detection limit of 14.4 n M. The mechanism for decetion of Cu²⁺ was confirmed by the UV-vis spectra, Job’s experiment, MALDI-TOF mass spectrum and 1H NMR spectrum.