Comparative Study of Vibrational Spectra of Two Bioactive Natural Products Lupeol and Lupenone Using MM/QM Method

Table 3

Comparison of the observed and calculated vibrational spectra of lupeol with (B3LYP/6-31G: PM3) methods.

B3LYP (Calc)	IR (Int.)	IR (Exp)	Vibrational assignments [P.E.D.]
259	8.573	—	Rock (C–CH3)
317	34.472	—	ω (O–H)
556	5.331	546	τ (C–C–C=C)
941	8.306	—	β (C–C–H)
952	9.997	950 (sh)	Rock (C=CH2) + Rock (C–CH3)
999	14.419	—	Rock CH2
1007	13.866	1005 (sh)	Twist CH3
1089	5.420	1037	Twist CH2
1101	8.428	—	Rock CH2
1137	4.075	1145 (sh)	β (C–C–H)
1229	10.558	1189	β (C–C–H)
1292	7.878	1290 (sh)	β (C–C–H)
1328	20.581	—	β (C–C–H)
1360	4.138	—	β (H–C–H)
1398	11.404	1380	β (C–O–H) + β (C–C–H)
2935	5.811	2946	ν(C–H)
2991	8.277	—	ν(C–H)
3051	10.361	3051 (sh)	ν(C–H)
3721	12.146	3746	ν(O–H)

Abbreviations: ν: stretching; β: bending; S: scissoring; w: wagging; τ: torsion; sh: shoulder.