ISSN:
0360-6376
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The synthesis and optical properties of the polyamides [poly(C3A·C3B) and poly(C3A-C3MB)] derived from asymmetric trans-1,2-cyclopropanedicarboxylic acids (C3A), asymmetric trans-1,2-diaminocyclopropanes (C3B), and asymmetric trans-1,2-bis(methylamino) cyclopropanes (C3MB) were reported in the preceding article. This paper describes the NMR studies and conformations of the polyamides. The NMR studies of the polyamides and their diamide models have suggested that the polyamides have about a 90° torsional angle for NH (or CH3) CH. This angle seems to be reasonable because of less steric interaction, especially for poly(+)C3A(+)C3MB. The N—CH3 of the poly(+)C3A(+)C3MB in sulfuric acid-d2 (D2SO4) is a singlet and is tentatively assigned to trans to the carbonyl oxygen of the amide group. In 2,2,2-trifluoroethanol-d3 (TFE-d3) and chloroform-d (CDCl3) it is also a singlet and is tentatively assigned to cis. The overall results obtained suggest that poly(+)C3A(+)C3MB exists in a compact helical conformation in TFE and TMS, while some conformational transition to a highly extended helical form with opposite handedness is induced by the addition of MSA. Likewise, poly(+)C3A(+)C3B must exist in some ordered conformation in the solvents studied. Possible ordered conformations of the polyamides have been proposed based on the experimental results and some assumptions.
Additional Material:
16 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1981.170190211
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