A New Chiral Binaphthalene‐Based Fluorescence Polymer Sensor for the Highly Enantioselective Recognition of Phenylalaninol

A new (S)-binaphthalene-based polymer (P-1) was synthesized by the polymerization of 5,5'-((2,5-dibutoxy-1,4-phenylene)bis(ethyne-2,1-diyl))bis(2-hydroxy-3-(piperidin-1-ylmethyl) benzaldehyde (M-1) with (S)-2,2'-dimethoxy-(1,1'-binaphthalene)-3,3'-diamine (M-2) through the formation of a Schiff base; the corresponding chiral polymer (P-2) could be obtained by the reduction of polymer P-1 with NaBH4 . Chiral polymer P-1 exhibited a remarkable "turn-on" fluorescence-enhancement response towards (D)-phenylalaninol and excellent enantioselective recognition behavior with enantiomeric fluorescence difference ratios (ef) as high as 8.99. More importantly, chiral polymer P-1 displays a bright blue fluorescence color change upon the addition of (D)-phenylalaninol under a commercially available UV lamp, which can be clearly observed by the naked eye. On the contrary, chiral polymer P-2 showed weaker enantioselective fluorescence ability towards the enantiomers of phenylalaninol.