Spray coating thin polymeric sensor films for Au 3+

A novel polymeric sensor of the poly(sodium‐4‐styrenesulfonate) (PSS)‐modified rhodamine B derivative ( Rho ) was synthesized using 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide (EDC)/ N , N ′‐dimethylpyridin‐4‐amine (DMAP) as coupling reagents to obtain PSS‐Rho4 in 21% yield. The characterization and “Off–On” sensing phenomena were established through UV–Vis, fluorescence, NMR, and FTIR techniques. The PSS‐Rho4 showed high selectivity and sensitivity for Au 3+ over other metal ions. Upon the addition of Au 3+ , significant color change and “Off–On” fluorescence were observed due to a cation Au 3+ induced spirolactam ring‐opening process with detection limit down to micromolar values (1.2 μM). In addition, spray coating thin polymeric sensor films were produced onto the surface of material ( PSS‐Rho4 ‐ITO and PSS‐Rho4 ‐filtered paper) providing a fast, portable, and easy‐to‐use molecular device for the detection of Au 3+ in the real system. Reversibility was evaluated by rinsing with EDTA solution under basic condition. We believe that, this approach provides a sensitive and accurate method for the detection of Au 3+ in environmental and biological applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137 , 48273.