Visualized Discriminant Analysis and Recognition of Multiple Metal Ions with a Single Cellulose-Based Fluorescent Probe

Visualized discriminant analysis and recognition can facilitate embracing the advanced and complicated sensing and detection technologies. Herein, the first visual analysis method based on RGB–CMYK color systems is established for the recognition of multiple metal ions. Such a visual method is accomplished by only a single fluorescent probe CA-TPY, a cellulose derivative containing terpyridine. The color responses (color changes or fluorescence variations) between CA-TPY and metal ions are creatively illustrated with a graphical representation. Seven metal ions (Ag⁺, Fe²⁺, Co²⁺, Fe³⁺, Zn²⁺, Cd²⁺, and Al³⁺) can be easily recognized and distinguished without depending on the sensibility of the naked eye to color change. It is a very humanistic technique for people with color blindness and superior to conventional colorimetric visual methods. The approach reported herein could provide new insights into visualized analysis in chemical sensing far beyond the paper-based applications, including rapid test strips, rewritable paper, water-jet printing, and security patterns.