Spin System Assignment of Homo-o-Phenylene Ethynylene Oligomers

Citations Over Time

Abstract

We previously reported the synthesis and solution characterization of short o-phenylene ethynylene (oPE) foldamers. Proton correlation techniques are not adequate for NMR assignment in these compounds as the ethynylene linkers interrupt proton connectivity. In order to facilitate structural characterization and more fully harness the power of NMR, it is necessary to know the sequence of spin systems along the molecular backbone. For example, spin system assignment is required to unambiguously assign NOE correlations for structural determination of folded forms in solution. Therefore, we developed a method to assign the aromatic spin systems in these compounds using HMBC experiments. This has been performed for tetrameric (Es4), pentameric (Es5), and hexameric (Es6) oligomers and is expected to prove useful for this class of foldamers in general. The proton assignments obtained by this technique have been useful toward confirming the previous hypotheses of helical folding in oPE systems.

Related Papers

• → Syntheses of Monofunctional Derivatives of m-Phenylene-16-crown-5, Bis(m-phenylene)-32-crown-10, and m-Phenylene-p-phenylene-33-crown-10(1997)29 cited
• → The viscoelastic properties of poly(phenylene ethers). I. Unsubstituted and methyl or phenyl substituted polymers(1971)28 cited
• → Sulphonation of poly(phenylene ether sulphone)s containing hydroquinone residues(1993)26 cited
• → Thermal studies of blends of poly(phenylene sulfide) (PPS) with poly(phenylene sulfide sulfone) (PPSS) and with poly(phenylene sulfide ether) (PPSE)(1995)12 cited
• → 2I1330 Effects of mutations inside / outside the folding elements on the CD spectra observed early in folding(2002)