Fluorescence Sensing of Caffeine in Tea Beverages with 3,5diaminobenzoic Acid A rapid, selective and sensitive method for the detection of caffeine in tea infusion and tea beverages are proposed by using 3,5diaminobenzoic acid as a fluorescent probe. The 3,5diaminobenzoic acid emits strong fluorescence around 410 nm under the excitation of light at 280 nm. Both the molecular electrostatic potential analysis and fluorescent lifetime measurement proved that the existence of caffeine can quench the fluorescence of 3,5diaminobenzoic acid. Under the optimal experimental parameters, the 3,5diaminobenzoic acid was used as a fluorescent probe to detect the caffeine aqueous solution. There exists a good linear relationship between the fluorescence quenching of the fluorescent probe and the concentration of caffeine in the range of 0.1xe2x80x93100 xcexbcM, with recovery within 96.0 to 106.2%, while the limit of detection of caffeine is 0.03 xcexbcM. This method shows a high selectivity for caffeine. The caffeine content in different tea infusions and tea beverages has been determined and compared with the results from HPLC measurement.

Perylene DiimideBased Fluorescent and Colorimetric Sensors for Environmental Detection Perylene tetracarboxylic diimide (PDI) and its derivatives exhibit excellent thermal, chemical and optical stability, strong electron affinity, strong visiblelight absorption and unique fluorescence onoff features. The combination of these features makes PDIs ideal molecular frameworks for development in a broad range of sensors for detecting environmental pollutants such as heavy metal ions (e.g., Cu2, Cd2, Hg2, Pd2, etc.), inorganic anions (e.g., Fxe2x88x92, ClO4xe2x88x92, PO4xe2x88x92, etc.), as well as poisonous organic compounds such as nitriles, amines, nitroaromatics, benzene homologues, etc. In this review, we provide a comprehensive overview of the recent advance in research and development of PDIbased fluorescent sensors, as well as related colorimetric and multimode sensor systems, for environmental detection in aqueous, organic or mixed solutions. The molecular design of PDIs and structural optimization of the sensor system (regarding both sensitivity and selectivity) in response to varying analytes are discussed in detail. At the end, a perspective summary is provided covering both the key challenges and potential solutions for the future development of PDIbased optical sensors.