All reagents and solvent were purchased from commercial source and used without further purification, if not stated. All reactions were carried out on the magnetic stirrers and their reaction process was monitored on thin layer chromatography (TLC). Absorption and fluorescence spectra were taken on a Shimadzu UV-1800 spectrophotometer and a Hitachi F-2700 fluorescence spectrometer, respectively. 1H NMR and 13C NMR measurements
were recorded at 600 and 150 MHz on a Brucker Avance 600-MHz spectrometer. Dimethyl sulfoxide (DMSO-d6) was solvent, and tetramethylsilane (TMS) was used as internal standard. A pH meter (Mettler Toledo, Switzerland) was used to determine the pH values.HRMS (ESI) were taken on a Fourier transform ion cyclotron resonance mass spectrometry (Varian 7.0T).