A Novel Polymeric Chemosensor: Dual Colorimetric Detection of Metal Ions Through Click Synthesis

A highly colored polystyrene derivative bearing side chain chromophores composed of dialkylanilino donor and cyano-based acceptor groups, prepared by atom-economic click postfunctionalization, displays the dual colorimetric detection behavior of several metal ions based on the specific interactions with different nitrogen atoms. Hard to borderline metal ions, such as Fe3+, Fe2+, and Sn2+, are always recognized by the dialkylanilino nitrogen atom, resulting in a decrease in the charge-transfer (CT) band intensity of the donoracceptor chromophores. On the other hand, the recognition site of a soft metal ion of Ag+ is the cyano nitrogen atom due to the readily formed multivalent coordination, which produces a bathochromic shift of the CT band.