Steric Size in Conformational Analysis. Steric Compression Analyzed by Circular Dichroism Spectroscopy
作者:Stefan E. Boiadjiev、David A. Lightner
DOI:10.1021/ja002069c
日期:2000.11.22
methyl, ethyl, isopropyl, tert-butyl, phenyl, and benzyl groups has been determined from a sensitive tetrapyrrole model and exciton coupling circular dichroism (CD) measurements. Unlike the classical cyclohexane model, from which the relative steric demand of functional groups has been assessed quantitatively (A-values) and is based on the preference for equatorial vs axial orientations, the bilirubin
甲基、乙基、异丙基、叔丁基、苯基和苄基的相对空间尺寸已通过灵敏的四吡咯模型和激子耦合圆二色性 (CD) 测量确定。与经典的环己烷模型不同,后者定量评估了官能团的相对空间需求(A 值)并基于对赤道方向与轴向方向的偏好,胆红素模型从头对头空间压缩评估取代基大小. 因此,一组敏感的抗手性 α(R/S)-取代的-β'(S)-甲基中胆红素-XIIIα (1−6) 的激子 CD 振幅表明明显的相对空间大小:叔丁基 ∼ 异丙基 > 苯基∼ 乙基 > 苄基 > 甲基。