Visual enantiomeric recognition of amino acid derivatives in protic solvents.
Various types of chiral host molecules 2-7 based on a phenolphthalein skeleton and two crown ethers were prepared for use in visual enantiomeric recognition, and we examined their enantioselective coloration in complexation with chiral amino acid derivatives 9-22 in methanol solution. Methyl-substituted host (S,S,S,S)-3 showed particularly prominent enantiomer selectivity for the alanine amide derivatives 11 and 12. A combination of methyl-substituted host (S,S,S,S)-3 with guest (R)-11 or (R)-12 developed a purple color, whereas no color development was observed with (S)-11 or (S)-12. On the other hand, phenyl-substituted host (S,S,S,S)-6 showed deeper coloration with a wide range of (S)-beta-amino alcohols compared to that seen with host (S,S,S,S)-6 and the corresponding (R)-beta-amino alcohols at 0 degrees C. Furthermore, absorbance inversion temperatures (AIT) were observed within the range of 0-50 degrees C in many cases.
Tsubaki
Kazunori
K
Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan. tsubaki@fos.kuicr.kyoto-u.ca.jp
Tanima
Daisuke
D
Nuruzzaman
Mohammad
M
Kusumoto
Tomokazu
T
Fuji
Kaoru
K
Kawabata
Takeo
T
D000596:Amino Acids / Q000032:analysis / Q000737:chemistry*; D043844:Crown Ethers / Q000737:chemistry; D015394:Molecular Structure; D020113:Phenolphthalein / Q000737:chemistry; D012997:Solvents; D013237:Stereoisomerism; D013696:Temperature
D000596:Amino Acids; D043844:Crown Ethers; D012997:Solvents; D020113:Phenolphthalein