In this study, two novel dual-switch fluorescent chemosensors based on rhodamine-peryleneiimide have been designed and synthesized. The dual-switching behaviors of the sensors were based on the structural transformations of rhodamine and an intramolecular photoinduced electron transfer（PET）process from rhodamine to perylenediimide. These probes exhibited excellent sensitivity to protons with enhanced fluorescence emission from 500 nm to 580 nm. The fluorescence changes of probes were reversible within a wide range of p H values from 2.0 to 11.0. Moreover, the sensors exhibited high selectivity, short response time, and long lifetime toward protons. The possible mechanism was investigated by the DFT calculation and-1H NMR. According to the experiment of confocal laser scanning microscopy, these probes could be used to detect the acidic p H variations in living cells.by the Fundamental Research Funds for the National Natural Science Foundation of China （No. 61178057） and for the Central Universities （No. CXLX12_0085）. The characteristic data of compounds were in the Supplementary information.
Three-photon absorption（3PA） of a push-pull chromophore,2-（3-cyano-（3-（4-（dimethylamino）styryl）-5,5-dimethylcyclohex- 2-enylidene）methyl）-5,5-dimethylfuran-2-ylidene） malononitrile（CFM） including TCF group was measured by the nonlinear transmission method using a femto-second Ti：Sapphire oscillator-amplifier laser system.Its three-photon absorption cross-sections at 1300 ran were 36.8×10^-79 cm^6 s^2 in the solution of DMF and 12.3×10^-79 cm^6 s^2 in the solution of CH_2Cl_2,respectively.The large values were got by experiments in this paper,which is a new exploration for these kinds of materials.The molecule has the potential application foreground of 3PA areas and optical power limiting.
