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 and1 H NMR titrations respectively. The optical switching has been successfully use by constructing reversible paper strips for detecting Al3+ as well as F- /AcO- .