✍ Scribed by F. S. Richardson; S. Ferber
No coin nor oath required. For personal study only.
The chiroptical properties of S‐proline conformational isomers are examined on a theoretical model in which electronic wave functions are obtained from semiempirical molecular orbital calculations. The CNDO/S molecular orbital model is used to perform SCF‐MO calculations on ground state electronic structure and excited states are constructed in the virtual orbital‐configuration interaction approximation. Electronic rotatory strengths and dipole strengths are calculated directly from the complete (but approximate) molecular electronic wave functions. Zwitterionic, cationic, and anionic S‐proline structures are studied twotypes of conformational variables are represented in the calculations: (1) pyrrolidine ring conformation; and (2) rotation about the C^α^‐COO^−^ bond. Rotatory strengths are found to be somewhat sensitive to rotational isomerism about the C^α^‐COO^−^ bond, but are found to be rather insensitive to conformational changes within the pyrrolidine ring. The CD spectrum of zwitterionic S‐proline down to ∼160 nm appears to be well accounted for by the theoretically calculated results if conformational preferences with respect to rotation about the C^α^‐COO^−^ bond can be assumed to exist in solution media. Furthermore, spectra‐structure correlations are offered for the anionic and cationic forms of S‐proline in solution.
📜 SIMILAR VOLUMES
## Abstract Amino acid‐based block copolymers containing poly(A‐Pro‐OMe) have been synthesized by RAFT polymerization using the dithioester‐terminated poly(DMA) as a macro‐CTA. An amphiphilic block copolymer composed of polystyrene as a hydrophobic segment and poly(A‐Pro‐OMe) as a hydrophilic segme
Several racemic and optically active S-alkyl derivatives of l-thioglycerol have been synthesized. From 3-S-tetradecyl-3-thio-sn-glycerol the dioleoyl and diacetyl esters were prepared. 1,2-Dioleoyl-3-S-tetradecyl-3-thio-sn-glycerol was converted into the corresponding sulphoxide and sulphone. The eh
CD study of the chiral enamines 4-9 revealed the presence of the azastilbenelike chromophore, and exciton coupling between this chromophore (A) and aromatic chromophore B. Coupled excitons in 5 and 8 suggest M (--) absolute conformation between chromophores A and B. o 1996 Wiley-Liss, Inc. KEY WORD