340960-84-1Relevant academic research and scientific papers
Diminished helical character in para-substituted cis-transoidal polyphenylacetylenes due to intramolecular cyclization
Percec, Virgil,Rudick, Jonathan G.,Aqad, Emad
, p. 7205 - 7206 (2007/10/03)
The cis-transoidal PPA helix undergoes irreversible structural changes related to 6π electrocyclization of 1,3-cis-5-hexatriene sequences in the polymer backbone. The dynamics of the helical conformation is evaluated by optical rotation or circular dichroism (CD) spectra at various temperatures. Helical cis- and trans-poly(alkylacetylenes) exhibit different CD spectra in solutions. In the solution, 1,3-cis-5-hexatriene sequences in PPA and its substituted analogues undergo electrocyclization to form cyclohaxadiene repeat units. The results show that literature data on helical PPA are only qualitative as no complete structural analysis was reported in any previous studies.
