Phosphorescent pH sensors and switches with substitutionally tunable response range based on photo-induced electron transfer

According to the principle of photo-induced electron transfer (PET), five aminomethyl-bromonaphthalene phosphoroionophores with long lifetimes (to ms) were synthesized, all of them working well in beta-cyclodextrin (beta-CD) aqueous solutions. They form a family of phosphorescent sensors with pH-dependent spectral properties. For all the compounds, the fully protonated form exhibits the highest phosphorescence emission intensity and the proton-free form of the sensor is weakly emissive, due to the designed PET process. The sensors also show the expected pH dependence of phosphorescence quantum yields. Responses of the sensors are tuned by variation of substituent. The pH response ranges for 1-5 were 4.3-6.5, 3.5-10.5, 3.4-10.5, 3.4-10.5 and 3.4-6.1, respectively. Copyright (c) 2005 John Wiley & Sons, Ltd.