Selective chiral recognition of alanine enantiomers by chiral calix[4]arene coated quartz crystal microbalance sensors

We describe the synthesis of new chiral calix[4]arene derivatives having ( R )-1-phenylethylamine, ( S )-1-phenylethylamine, ( R )-2-phenylglycinol, and ( S )-2-phenylglycinol moieties, and chiral recognition studies for enantiomers of some selected α-amino acid derivatives such as alanine, phenylalanine, serine, and tryptophan using a quartz crystal microbalance (QCM). Initial experiments indicated that the highest selective chiral recognition factor was 1.42 for alanine enantiomers. The sensitivity, limit of detection, and time constant for l -alanine were calculated as 0.028 Hz/μM, 60.9 μM, and 36.2 s, respectively. The results indicated that real-time, sensitive, selective, and effective chiral recognition of alanine enantiomers was achieved with a QCM sensor coated with a chiral calix[4]arene derivative having ( R )-2-phenylglycinol moieties.