Enantioselective molecular sensing of aromatic amines using tetra-(S)-di-2-naphthylprolinol calix[4]arene

Abstract

This paper presents new analytical data, and evidence of the fluorescence quenching mechanism involved in enantioselective signals obtained with the chiral host tetra-(S)-di-2-naphthylprolinol calix[4]arene. Excellent selectivity is obtained with phenylglycinol and norephidrine in methanol, and samples of unknown enantiomeric composition have been determined with an average error of 1.08 and 0.62%, respectively (n = 6), on the basis of a single fluorescence measurement. The absence of any quenching observed with the related amines of phenylalaninol is attributed to a methylene spacer which inhibits efficient interaction between the aryl group of the guest and the naphthyl group of the host. The importance of the phenyl group of the guest in the quenching mechanism is confirmed by the complete absence of any quenching effect with cyclohexylethylamine.

Varying solvent polarity to tune the enantioselective quenching of a calixarene host

“…In previous work it has been shown that calixarenes 9,10,11,12 and more recently fluorescent calixarenes 13,14,15 can discriminate between enantiomers. Here we present how solvent polarity has an effect not only on the extent of enantiomeric discrimination, but also on the wavelength at which discrimination occurs.…”

“…In general, only fluorophores that are polar in nature will display a large sensitivity to solvent polarity, with non-polar molecules such as hydrocarbons showing much less sensitivity to solvent polarity. 8 In previous work it has been shown that calixarenes [9][10][11][12] and more recently fluorescent calixarenes [13][14][15] can discriminate between enantiomers. Here we present how solvent polarity has an effect not only on the extent of enantiomeric discrimination, but also on the wavelength at which discrimination occurs.…”

Application of L‐proline derivatives as chiral shift reagents for enantiomeric recognition of carboxylic acids

“…Several methods1 have been developed for the determination of the enantiomeric composition, including liquid2 and gas chromatography,3 capillary electrophoresis,4 circular dichroism,5 absorbance spectrometry,6 infrared transmission spectrometry,7 X‐ray anomalous scattering,8 and NMR spectroscopy 9–12…”

Chiral mono and diamide derivatives of calix[4]arene for enantiomeric recognition of chiral amines

“…Many of the chiral calix [4]arene derivatives have shown remarkable recognition properties toward achiral cations and anions, 34,35 however, more interestingly, some of them have exhibited significant chiral discrimination abilities for chiral guests such as amines, organic ammonium salts, amino alcohols, and amino acids. [36][37][38] Our recent studies in this field were mainly dedicated to synthesis and complex formation of chiral calix [4]arene derivatives with amino acids 39 and amines 40 in chloroform. Also the extraction abilities and the transport through chloroform liquid membrane 41 of some functionalized calix [4]arene derivatives upon some anions 42 and cations 43 were performed.…”