Molecular Structure, NMR, HOMO, LUMO, and Vibrational Analysis of O-Anisic Acid and Anisic Acid Based on DFT Calculations

Table 8

Detailed assignment of fundamental vibrations of Anisic acid (AA) by normal mode analysis based on SQM force field calculations.

Sl. no.	Symmetry species 𝐶𝑠	Observed wavenumbers; cm^−1		Calculated wavenumbers; B3LYP/6-31G**; force field cm^−1		IR; intensity	Raman; activity	Characterization of normal modes with PED (%)
		FTIR	Raman	Unscaled	Scaled
1	A′	3435	—	3768	3435	79.523	164.209	υOH (100)
2	A′	—	3085	3232	3085	21.438	120.058	υCH (89)
3	A′	—	3034	3224	3034	7.547	126.718	υCH (99)
4	A′	3029	—	3218	3029	3.520	99.229	υCH (99)
5	A′	3002	—	3209	3002	5.141	52.552	υCH (99)
6	A′	2990	—	3155	2990	2.423	53.071	υCHops (99)
7	A′′	2956	—	3087	2956	45.319	94.074	υCHips (51), υCHss (36), υCHops (12)
8	A′	2941	—	3022	2941	42.847	91.231	υCHss (56), υCHips (44)
9	A′	1688	—	1813	1688	302.139	74.665	υCO (72), bCCO (17),
10	A′	1608	—	1666	1608	216.104	153.242	υCC (62), bCH (22), Rsymd (11)
11	A′	1580	—	1624	1580	34.785	12.359	υCC (66), bCH (14)
12	A′	1518	—	1559	1518	41.495	8.422	bCH (52), υCC (30)
13	A′	1468	—	1516	1468	37.550	10.673	bCHsb (77)
14	A′′	1461	—	1504	1461	14.058	12.183	bCHopb (83)
15	A′	1429	—	1486	1429	5.851	19.586	bCHipb (70), υCC (10), bCH (10)
16	A′	1416	—	1465	1416	14.835	9.149	υCC (39), bCH (35), bCHipb (18)
17	A′	1324	—	1391	1324	31.290	5.311	bCOH (27), υCO (22), bCCO (21), υCC (13)
18	A′	1307	—	1371	1307	8.068	1.444	υCCar (65), bCH (20)
19	A′	1301	—	1331	1301	40.408	7.073	bCH (43), υCC (33)
20	A′	1267	—	1304	1267	245.222	3.723	υCO (37), Rtrigd (20), υCC (16)
21	A′	1181	—	1221	1181	5.734	6.023	bCH (61), υCC (21)
22	A′	1172	—	1209	1172	5.690	5.161	bCHopr (61), bCH (13)
23	A′	—	1137	1189	1137	0.662	4.334	bCHipr (78), bCHopr (14)
24	A′	1131	—	1176	1131	190.946	42.508	bCH (35), υCC (21)
25	A′	1107	—	1139	1107	245.972	63.024	υCCfn (25), Rtrigd (23), bCH (16), υOC (13)
26	A′	—	1100	1114	1100	318.070	20.809	υCO (40), bCOH (22), bCCO (11)
27	A′	1028	—	1069	1028	0.786	11.056	υCC (58), bCH (16)
28	A′	—	1010	1026	1010	29.566	2.343	υOC (51), υCC (28)
29	A′′	929	—	991	929	0.010	0.464	𝜔CH (89)
30	A′′	854	—	966	854	1.379	1.924	𝜔CH (82), ttrigd (12)
31	A′′	846	—	863	846	36.522	1.244	𝜔CH (39), 𝜔CO (32), ttrigd (20)
32	A′	825	—	834	825	24.090	22.373	υCCar (32), Rsymd (27), υOC (22)
33	A′′	774	—	830	774	0.365	4.928	𝜔CH (84)
34	A′′	—	755	775	755	1.082	0.243	ttrigd (51), 𝜔CC (15), 𝜔CH (14), tCO (11)
35	A′	698	—	725	698	35.539	3.075	bCCO (44), υCO (25), bCOH (25)
36	A′′	634	—	710	634	76.887	0.059	tCO (57), 𝜔CH (20), ttrigd (12)
37	A′	617	—	647	617	0.592	6.441	Rasymd (81)
38	A′	550	—	603	550	14.566	0.968	Rsymd (32), υCCfn (13), υCO (11), bCCO (11), bCOC (10)
39	A′′	545	—	601	545	27.876	4.847	𝜔CO (42), tOH (14), 𝜔CH (11), 𝜔CC (11)
40	A′	525	—	511	525	12.735	1.849	bCCO (82)
41	A′	505	—	511	505	50.036	5.698	tOH (24), ttrigd (23), 𝜔CO (19), 𝜔CH (14)
42	A′	440	—	481	440	3.190	2.294	bCO (35), bCOC (29)
43	A′′	—	375	427	375	0.415	0.023	tsym (60), 𝜔CH (19), tasym (17)
44	A′	—	310	335	310	3.569	0.577	Rsymd (48), υCCfn (25)
45	A′′	—	285	304	285	4.416	0.596	𝜔CC (33), tasym (24), tCO (16)
46	A′	—	220	267	220	3.713	2.509	bCOC (29), bCO (17)
47	A′′	—	165	226	165	0.047	0.429	tCH3 (85)
48	A′	—	111	165	111	0.211	0.159	bCC (80)
49	A′′	—	98	132	98	2.323	0.292	Tasym (30), tCOC (30), 𝜔CC (11), 𝜔CH (10), tsym (10)
50	A′′	—	70	78	70	1.302	1.199	tCO (95)
51	A′′	—	60	65	60	0.898	0.216	tCOC (48), tCO (31), tCH3 (12)

R: ring; b: bending; deform: deformation; sym: symmetric; asy: asymmetric; ω: wagging; t: torsion; trig: trigonal; υ: stretching; ips: in-plane stretching; ipb: in-plane bending; ops: out-of-plane stretching; opb: out-of-plane bending; sb: symmetric bending; ipr: in-plane rocking; opr: out-of-plane rocking.
Only contributions larger than 10% are given.