Figure 4.

NMR Characterization of Isolated Plant Seed Coat Lignins and in Vitro Synthetic Lignin Polymers (DHPs).

(A) Aromatic subregions of short-range ¹³C-¹H correlation (HSQC) NMR spectra. Volume integrals are given for the lignin aromatic units that are color-coded to match their assignments in the spectrum.

(B) and (C) Partial long-range ¹³C-¹H (HMBC) NMR spectra, showing subregions exhibiting aromatic correlations to benzodioxane α-protons (B) and correlations to β-aryl ether side-chain α-protons (C). Box with x2 or x4 indicates regions that were vertically scaled two- or fourfold.