Benzothiazole croconium colorimetric probe, preparation method and application

The invention relates to a benzothiazole croconium colorimetric probe. A preparation method of the benzothiazole croconium colorimetric probe comprises the steps of preparation of 3-ethyl-2-methyl benzothiazole-3-iodide and preparation of a benzothiazole croconium dye. The benzothiazole croconium colorimetric probe and the preparation method have the advantages that the synthesis process of the benzothiazole croconium dye is simple, the reaction condition is easy to control, the pure product can be obtained through simple aftertreatment, and the benzothiazole croconium dye has the excellent optical property and optical stability; the benzothiazole croconium dye is solid powder, is convenient to store and has the good prospect; by adding EDTA and studying the influence of EDTA on probe recognition, a switch-type iron ion and copper iron sensor is invented.