Harnessing a pyrimidine based molecular switch to construct reversible test strips for F − /AcO − with respect to Al 3+ : A colorimetric approach

We report novel compound 4-nitro-2-((pyrimidin-2-ylamino) methyl) phenol (1) synthesized by the condensation of 5-nitro salicylaldehyde with 2-amino pyridine. Compound 1 serves as a dual signalling chromogenic receptor for F−/AcO− and Al3 + ions. The chromogenic response of 1 towards the aforementioned analytes is reversible with respect to either Al3 +/X (= F/AcO)− or X(F/AcO)−/Al3 +. The limit of detection of 1 for F− and AcO− are 1.0025 × 10− 7 M and 0.79 × 10− 7 M, respectively. The optical switching has been rationalized on the basis of UV–Vis titrations and 1H NMR titrations respectively. The optical switching has been successfully use by constructing reversible paper strips for detecting Al3 + as well as F−/AcO−.