854714-00-4Relevant articles and documents
Remaekable effect of subtle structural change of chiral pseudo-18-crown-6 on enantiomer-selectivity in complexation with chiral amino alcohols
Hirose, Keiji,Aksharanandana, Pakatip,Suzuki, Michiko,Wada, Kiyoshi,Naemura, Koichiro,Tobe, Yoshito
, p. 405 - 431 (2007/10/03)
Chiral receptors [(S,S)-1] and [(S,S,S,S)-2] having 1,2-dialkoxy-1-(3,5-dimethylphenyl)ethane and 1,2-dialkoxy-1-(3,5-dimethyl phenyl)cyclohexane as chiral building blocks, respectively, were prepared. Thermodynamic parameters of complexations of these and structurally related receptors [(S,S)-3] and [(S,S,S,S)-4] with 2-amino-l-propanol (5), 2-amino-2-phenylethanol (6), and 3-methylbutan-l-ol (7) in chloroform were determined. It was found that the host-guest systems that have same enantiomer-selectivity at 25°C showed opposite selectivity in the enthalpy term. For example, complexations of both (S,S)-1 and (S,S)-3 with 5 are R-selective at 25°C (ΔΔG = 2.2 and 3.8 kJ mol-1, respectively), whereas in terms of the enthalpy of complexation the former is S-selective (ΔΔH = 22 kJ mol-1) but the latter is R-selective (ΔΔH = 10 kJ mol-1).