Synthesis and enantioselective recognition of an (S)-BINOL-based colorimetric chemosensor for mandelate anions

New chiral receptors 1 and 2 based on (S)-BINOL and thiourea units were synthesized. The chiral recognition of receptors for chiral anions were studied by fluorescence, UV–vis, and 1H NMR spectra. The results of the non-linear curve fitting indicated that the receptors and guest anions formed a 1:1 stoichiometric complex. The obvious color change of receptor 2 can be observed by the naked eye when the enantiomers of mandelate anions were added, which demonstrates that receptor 2 may be used as a colorimetric sensor for mandelate anions.

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(S)-Diethyl 2,2′-(1,1′-binaphthyl-2,2′-diylbisloxy)diacetateC28H26O6[α]D20=+35 (c 0.2, CHCl3)Source of chirality: binaphtholAbsolute configuration: S

(S)-2,2′-(1,1′-Binaphthyl-2,2′-diylbis(oxy)diacetohydrazideC24H22N4O4[α]D20=+177.5 (c 0.2, CHCl3)Source of chirality: binaphtholAbsolute configuration: S

(S)-2,2′-(1,1′-Binaphthyl-2,2′-diylbis(oxy))bis(N-(2-aminoethyl)acetamide)C28H30N4O4[α]D20=+145 (c 0.4, CHCl3)Source of chirality: binaphtholAbsolute configuration: S

Bis(p-nitrophenylthioureylene-carbamoyl-methoxy)-2,2′-(S)-1,1′-binaphthaleneC38H30N8O8S2[α]D20=+19.75 (c 0.05, DMSO)Source of chirality: binaphtholAbsolute configuration: S

Bis(p-nitrophenylthioureylene-ethenecarbamoyl-methoxy)-2,2′-(S)-1,1′-binaphthaleneC42H38N8O8S2[α]D20=+39.5 (c 0.05, DMSO)Source of chirality: binaphtholAbsolute configuration: S