High-efficient colorimetric detection of sulfide and silver ions based on a long-wavelength absorbing carbocyanine dye

The high-efficient detection of specific inorganic ions in H 2 O is extremely important, and monitoring S 2− and Ag + is of great significance because their abnormal levels will lead to many environmental and health problems. Herein we propose a long-wavelength absorbing carbocyanine dye DIDS-Li as a colorimetric probe to detect S 2− and Ag + based on color changes induced by structural changes of DIDS-Li. Sensing results suggest that the S 2− will cause the azure DIDS-Li to become colorless and the Ag + causes DIDS-Li to become bright yellow. This colorimetric probe also shows the good immunity to interference, a wide linear response range, and quantitative accuracy of S 2− and Ag + detections in natural water samples. Meanwhile, we also develop a smartphone analysis method that greatly improves the real-time detection ability of DIDS-Li for S 2− and Ag + . This work elucidates the relationship between carbocyanine dye and inorganic ions which offers a new means for efficient detection of S 2− and Ag + and the new idea for the application of carbocyanine dyes in colorimetric detection.