Design And Syntheses Of Rhodamine-based PH Fluorescence Probe

Intracellular pH is an important factor in cell biology and plays a critical role in many cellular events. Abnormal cellular pH values are known to be linked with inappropriate cellular functions, which are associated with many diseases including cancer, Alzheimer’s disease, and others. Thus, investigation of intracellular pH values and their fluctuation using high resolution microscopy would provide indispensable information to further understand the physiological and pathological processes involved in this process. Fluorescent probes have their obvious advantages in terms of non-invasive, sensitivity, selectivity, subnanometer spatial resolution, more convenient operation in many applications.Rhodamine fluorophores have been used extensively to measure intracellular pH values because of their high extinction coefficients, good photostability, high fluorescence quantum yield, and elongated wavelengths of their absorption and emission to the visible region.In this paper, eleven rhodamine-based pH fluorescence probes based on control the two facters of the mechanism of rhodamine off-on process are designed and synthesesed, which are steric interference of N on spiro and inductive effect of N on spiro. The structures of the compouds were confirmed by IR, MS,1HNMR,13CNMR and X-ray crystallography. The recongnition performance to pH is studied by ultraviolet spectrometer and fluorescence spectra. The results of the study indicated that all of the eleven rhodamine-based pH fluorescence probes could give UV and Flu response to specific pH value. The probes have good selectivity, high fluorescence quantum efficiency and good reversibility. The regional responses of the probes are under7, but the regional response of probe7and9are near neutral pH.