Table 3.

Assignments of ¹³C-¹H correlation signals in the HSQC spectrum of lignin samples [26, 27]

Signals	δC/δH	Assignments
MeO	55.4/3.72	C-H in methoxyls
A γ	59.5–59.7/3.40–3.63	Cγ-Hγ in β-O-4′ substructures (A)
A α	71.6/4.88	Cα-Hα in β-O-4′ substructures linked to a S unit (A)
Aβ(G), Aβ(S)	82.8–85.7/4.13–4.46	Cβ-Hβ in β-O-4′ substructures linked to a G unit (A) Cβ-Hβ in β-O-4′ substructures linked to a S unit (A)
S2, 6	103.8/6.69	C2,6-H2,6 in etherified syringyl units (S)
S′2, 6	106.4/7.31	C2, 6-H2, 6 in oxidized (Cα= O) phenolic syringyl units (S′)
G5	115.1/6.72	C5-H5 in guaiacyl units (G)
G2	111.0/7.02	C2-H2 in guaiacyl units (G)
G6	119.0/6.77	C6-H6 in guaiacyl units (G)
FA2	110.8/7.35	C2-H2 in FA
FA6	123.1/7.16	C6-H6 in FA
FA7	144.4/7.42	C7-H7 in FA
H2, 6 pCA	127.5/7.23 129.8/7.52 143.9/7.51	C2, 6-H2, 6 in H units (H) C2, 6-H2, 6, p-coumaroylated substructures (pCA) Cα-Hα, p-coumaroylated substructures (pCA)
	115.0/6.24	Cβ-Hβ, p-coumaroylated substructures (pCA)

G: guaiacyl unit; S: syringyl unit; H: p-hydroxyphenyl unit; pCA: p-coumaric acid; FA: ferulic acid