ISSN:
0360-6376
Schlagwort(e):
Physics
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
Two possible conformations for poly(cis-5-ethyl-D-proline) have been identified and characterized by using combinations of 1H- and 13C-NMR, CD, and ORD spectroscopic techniques. Both forms have helical conformations similar to those of poly(L-proline) characterized by different amide bonds (cis and trans). However, the carbonyl group of the amide in poly(cis-5-ethyl-D-proline) form II (trans) seems to be closer to perpendicular orientation with respect to the helical axis than in poly(L-proline) form II. The pyrrolidine ring conformation of form I (cis) is probably β+γ--puckered, whereas for form II it is probably β+-puckered in nature. The side-chain ethyl groups prefer to adopt anti conformations to the C5—H bond, or prefer to have χ = 180°, regardless which of the two forms poly(cis-5-ethyl-D-proline) may like to assume. The experimental results agree well with our previous theoretical conformational energy calculations.
Zusätzliches Material:
6 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/pol.1983.170210617
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