Table 2. Comparison of infrared band assignments (cm⁻¹) for 1 and L-cysteine hydro­chloride, L-CysH₂·HCl (Dokken et al., 2009 ▸).

1	L-CysH2·HCl	Assignment
776 w	770 w	γ CH2
819 w	839 w	δ COO−
871 mw	868 mw	ν CC, δ COO−
944 w	929 w	ν CN, ν CC
1060 mw	1058 mw	ν CN, ν CC
1127 mw	1141 mw	NH3 +
1203 s	1201 s	ν CO, δ OH (COOH)
1247 mw	1272 w	γ CH2
1317 w	1344 w	δ CH
1415 m	1427 m	δ as CH3, δ CH2
1484 s	1477 sh	–
1574 mw	1571 mw	δ as NH3 +, ν as COO−
1601 sh	1619 w	δ as NH3 +, ν as COO−
1724 vs	1743 vs	ν CO
1968 w	–	–
2641 sh	2645 w	ν CH2
2923 s	2943 sh	ν NH3 +, ν CH2, ν CH3
3011 s	3051 sh	ν NH3 +
3453 m	–	–