Based on the typical Suzuki coupling reaction and Schiff base reaction, a novel fluorescent molecular PCBW is synthesized and applied as a fluorescence and colorimetric sensor to detect Cu in aqueous solution. The PCBW sensor presents the aggregation-caused quenching (ACQ) effect and at 1 × 10 mol L it emits the strongest turquoise fluorescence in the DMSO-H O system ( = 40%). The sensor exhibits a 'turn-off' fluorescent characteristic by adding Cu , and its fluorescent intensity shows a reliable linear relationship with the Cu concentration in the range of 0-6 × 10 mol L , with a detection limit of 1.19 × 10 mol L . Meanwhile, the PCBW sensor also exhibits the colorimetric sensing from colorless to light yellow. The sensor has good selectivity and anti-interference and its pH application range can be extended from 5 to 10. The intramolecular charge transfer (ICT) is speculated as the main fluorescence mechanism of PCBW. In addition, the sensor presents good reusability and is practicable to detect Cu in diverse aqueous samples.