Растительные ресурсы, 2023, T. 59, № 3, стр. 321-326

Substance – 1 (Scopoletin)

The IR spectrum shows strong absorption bands at ν = 1710 cm^–1, which are assigned to the CO-δ-lactone cycle. In addition, the IR spectrum also shows characteristic absorption bands at 1631, 1613, 1570, and 1520 cm^–1, which can be attributed to the C=C aromatic cycle. The UV spectrum of the compound displays four distinct peaks at λ_max 229, 254, 298, and 346 nm with lgε (logarithm of the molar extinction coefficient) values ranging from 3.72 to 4.20. The strongest absorption is observed at λ_max 229 nm with lg ε 4.20, while the weakest is observed at λ_max 298 nm with lg ε 3.77. The presence of these absorption peaks in the UV spectrum indicates the presence of conjugated π-electron systems in the compound (Table 1).

The ¹³C NMR spectrum shows 10 peaks, each corresponding to a different carbon atom in the molecule. The chemical shifts (δ values) indicate the relative electron density and shielding of each carbon atom. For example, the carbonyl carbon (C=O) at position 1 has the highest chemical shift at 160 ppm, while the aromatic carbons (C=C) at positions 2–6 have chemical shifts in the range of 110–145 ppm.

The ¹H NMR spectrum provides information about the hydrogen atoms in the molecule and their chemical environment. The spectrum shows six peaks, each corresponding to a different type of hydrogen atom in the molecule. The chemical shifts (δ values) indicate the relative electron density and shielding of each hydrogen atom. For example, the hydrogen atom on the carbonyl group at position 1 appears as a singlet (s) at a chemical shift of 10.32 ppm, while the hydrogen atoms on the aromatic rings appear as singlets or doublets (d) at chemical shifts in the range of 6.23–7.91 ppm.

The scopoletin is an organic compound containing an aromatic ring and a lactone ring, which are confirmed by the ¹³C NMR spectrum. The ¹H NMR spectrum confirms the presence of hydrogen atoms in the aromatic and lactone rings, as well as a methyl group (CH₃) at a chemical shift of 3.82 ppm (table 2).

Table 2.

¹H NMR and ¹³CNMR chemical shift values of scopoletin recorded in CDCl₃

13C NMR
1–C	C	160
2–C	CH	149.4
3–C	CH	144.4
4–C	CH	111.6
5–C	CH	145
6–C	CH	110.4
7–C	C	102.7
8–C	C	151
9–C	C	109.5
10–C	C	55.94
1. Scopoletin – C10H8O4

¹ H-NMR (CDCl₃ 300 MHz) δ: 10.32 (s, 1H), 7.91 (d, J = 9.3 Hz, 1H), 7.22 (s, 1H), 6.78 (s, 1H), 6.23 (d, J = 9.3 Hz, 1H), 3.82 (s, 3H).

Substance – 2 (Oxypeucedanin)

In the IR spectrum, several characteristic peaks are observed, including a strong peak at 1703 cm^–1 corresponding to the carbonyl group in a δ-lactone ring, and four peaks in the range of 1554–1618 cm^–1 corresponding to the aromatic C=C bond. These peaks provide information on the functional groups and molecular structure of the compound. In the UV spectrum, four peaks are observed, with maximum absorption occurring at wavelengths of 220, 249, 266, and 306 nm. The lgε values indicate the intensity of absorption at each peak, with higher values indicating greater absorption (Table 3).

In the provided ¹³C NMR spectrum, we observed the chemical shift of 16 carbon atoms in an unknown molecule. The chemical shift is related to the electron density around each carbon atom, which is influenced by the atoms and groups surrounding it. By analyzing the chemical shift values, we can infer the type of carbon atoms and their neighboring functional groups in the molecule.

The ¹³CNMR spectrum reveals the presence of an aromatic ring system in the molecule. Carbon atoms 1–6 show a distinct pattern of chemical shifts between 25  and 94 ppm, consistent with sp2 hybridized carbons in an aromatic ring. Additionally, there are 11 aliphatic hydrocarbons present in the molecule showing chemical shifts between 99 and 161 ppm.

The provided ¹H NMR spectrum of oxypeucedanin, a molecule with the molecular formula C₁₆H₁₆O₆, further confirms the presence of an aromatic ring system. The proton chemical shifts indicate the presence of five aromatic protons, with chemical shifts at 6.3 ppm (H-3) and 8.2 ppm (H-4) appearing as doublets with a coupling constant of 9.65 Hz, and a singlet at 7.3 ppm (H-8). In addition, the proton chemical shifts at 7.0 ppm (H-3') and 7.6 ppm (H-2') suggest the presence of two meta-coupled aromatic protons (table 4).

Table 4.

¹H NMR and ¹³CNMR chemical shift values of oxypeucedanin recorded in CDCl₃

13C NMR
1–C	C	25.00
2–C	CH	27.00
3–C	CH	30.00
4–C	CH	71.00
5–C	CH	74.00
6–C	CH	94.00
7–C	C	99.00
8–C	C	104.00
9–C	C	108.00
10–C	C	111.50
11–C	C	112.00
12–C	C	119.00
13–C	C	133.00
14–C	C	139.00
15–C	C	145.00
16–C	C	161.00
2. Oxypeucedanin –C16H16O6

¹ HNMR: 6,30 (d., J = 9.65 Hz, 1H, H-3), 8.20 (d., J = 9.65 Hz, 1H H-4), 7.30 (s., 1H, H-8), 7.00 (d., J = 2.30 Hz, 1H, H-3'), 7.60 m. h. (d., J = 2.30 Hz, 1H, H-2')

Substance – 3 (Isoimperatorin)

The compound has a δ-lactone cycle and an aromatic cycle as evident from its IR spectrum with absorption peaks at 1729 and 1547 cm^–1 for CO-δ-lactone and 1580 and 1610 cm^–1 for C=C aromatic cycle.

The UV spectrum of isoimperatorin shows absorption peaks at λ_max 222, 250, 259, 268 and 310 nm, indicating the presence of conjugated pi-electron system in the compound (Table 5).

The ¹H NMR spectrum of isoimperatorin shows singlet peaks at 6.30 and 8.15 ppm with a coupling constant of 9.65 Hz and a singlet peak at 7.35 ppm, indicating the presence of aromatic protons. The spectrum also shows doublet peaks at 8.00 and 7.60 ppm with a coupling constant of 2.10 Hz, suggesting the presence of a vicinal pair of protons.

The ¹³C NMR spectrum of isoimperatorin shows 16 carbon signals with the corresponding chemical shift values, which indicate the presence of various types of carbon atoms, such as CH, C, and CO-δ-lactone carbon atoms.

Overall, the given data suggest that isoimperatorin is a compound with a complex structure that contains an aromatic ring, a δ-lactone cycle, and a conjugated pi-electron system (Table 6).

Table 6.  

¹H NMR and ¹³CNMR chemical shift values of isoimperatorin recorded in CDCl₃

13C NMR
1–C	C	18.6
2–C	CH	26.2
3–C	CH	70.2
4–C	CH	94.7
5–C	CH	105.4
6–C	CH	108.0
7–C	C	113.0
8–C	C	114.7
9–C	C	119.5
10–C	C	139.9
11–C	C	140.2
12–C	C	145.3
13–C	C	149.4
14–C	C	153.1
15–C	C	158.5
16–C	C	161.7
3. Isoimperatorin – C16H14O4

¹ H NMR(6.30, 1H, J = 9.65 Hz and 8.15 m. h., 1H, J = 9.65 Hz), sinqlet (7.35 m. h., 1H), dublet (8.00, J = 2.10 Hz, 1H and 7.60 m. h., J = 2.10 Hz, 1H)

Substance – 4 (Columbianetin)

The IR spectrum shows absorption bands at 3408  (OH-group), 1716 (CO-δ-lactone), and 1619 and 1580 cm^–1 (C=C aromatic cycle), indicating the presence of an OH group, a lactone group, and an aromatic ring. The UV spectrum shows absorption peaks at 220 (lg ε 4.08), 252 (lg ε 3.52), 262 (lg ε 3.55), 300 (lg ε 3.83), and 327 nm (lg ε 4.18) (Table 7).

The ¹H NMR spectrum of columbianetin, recorded in DMSO-d6, shows five peaks. The peak at 6.18 ppm corresponds to a proton on carbon 6 (H-6) and is a doublet with a coupling constant (J) of 2 Hz. The peak at 6.14 ppm corresponds to a proton on carbon 8 (H-8) and is a doublet with a coupling constant of 2 Hz. The peak at 7.53 ppm corresponds to a proton on carbon 1' (H-1') and is a doublet with a coupling constant of 8.4 Hz. The peak at 6.89 ppm corresponds to a proton on carbon 4' (H-4') and is a doublet with a coupling constant of 8.8 Hz. The peak at 7.55 ppm corresponds to a proton on carbon 5' (H-5') and is a doublet of doublets with coupling constants of 2.4 and 8.5 Hz.

The ¹³C NMR spectrum of columbianetin, recorded in CDCl₃, shows 14 peaks. The chemical shift values indicate the presence of one carbonyl group (C-2), one lactone group (C-3), and an aromatic ring with six carbons (C-4 to C-9). In addition, there are four methylene carbons (C-10 to C-13) and one methyl carbon (C-14) (Table 8).

Table 8.  

¹H NMR and ¹³CNMR chemical shift values of columbianetin recorded in CDCl₃

13C NMR
1–C	C	160.2
2–C	CH	151.3
3–C	CH	139.2
4–C	CH	134.3
5–C	CH	132.6
6–C	CH	127.8
7–C	C	125.9
8–C	C	118.8
9–C	C	116.2
10–C	C	72.8
11–C	C	71.0
12–C	C	67.3
13–C	C	66.4
14–C	C	20.8
Columbianetin – C14H14O4

¹ H NMR (DMSO-d6, 400 MHz) δH (ppm) = 6.18 (1H, d, J = 2 Hz, H-6), 6.14 (1H, d, J = 2 Hz, H-8), 7.53 (1H, d, J = 8.4 Hz, H-1'), 6.89 (1H, d, J = 8.8 Hz, H-4'), 7.55 (1H, dd, J = 2.4 and 8.5 Hz, H-5')