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

Table 7

Detailed assignment of fundamental vibrations of O-Anisic acid (OAA) 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′	3390	—	3771	3390	72.652	155.385	𝜐OH (100)
2	A′	—	3098	3273	3098	16.124	99.564	𝜐CH (99)
3	A′	—	3083	3233	3083	1.700	135.114	𝜐CH (99)
4	A′	3069	—	3207	3069	10.674	70.382	𝜐CH (99)
5	A′	—	3020	3186	3024	17.253	137.201	𝜐CH (99)
6	A′	3018	—	3157	3018	38.987	58.202	𝜐CH3 (99)
7	A′′	3003	—	3085	3003	5.946	78.409	𝜐CH3 (99)
8	A′	—	2983	3020	2983	52.626	120.657	𝜐CH3 (99)
9	A′	1670	—	1822	1670	358.567	54.628	𝜐CO (53), 𝜐CC (14), bCCO (14), bCOH (12)
10	A′	1600	—	1656	1600	15.061	16.343	𝜐CC (60), bCH (20), Rasymd (10)
11	A′	1579	—	1630	1579	61.364	48.880	𝜐CC (69), bCH (19)
12	A′	1494	—	1539	1494	58.214	10.686	bCH (48), 𝜐CC (37)
13	A′	1466	—	1513	1466	6.534	6.058	bCH3 (43), bCH (25), 𝜐CC (16)
14	A′	—	1439	1506	1439	22.318	5.639	bCH (39), bCH3 (37), 𝜐CC (17)
15	A′′	1435	—	1500	1435	36.525	10.814	bCH3 (88)
16	A′	1411	—	1475	1411	11.849	19.713	bCH3 (74)
17	A′			1382	1367	4.497	1.268	bCOH (35), 𝜐CO (32), bCCO (13), 𝜐CC (11)
18	A′	—	1312	1350	1312	2.182	8.877	𝜐CC (67)
19	A′	1288	—	1320	1288	63.194	1.648	bCH (33), Rtrigd (20), 𝜐CO (13), 𝜐CC (12)
20	A′	—	1287	1302	1287	19.694	0.449	Rtrigd (26), 𝜐CC (25), bCH (20), 𝜐CO (12)
21	A′	—	1184	1210	1184	228.252	32.980	𝜐CC (31), bCH (19), bCH3 (17), 𝜐CO (17)
22	A′	1182	—	1201	1182	162.989	27.136	bCH (42), 𝜐CC (34), bCH3 (10)
23	A′	1170	—	1193	1170	1.576	4.576	bCH3 (57), bCH (24)
24	A′	—	1173	1173	1153	7.419	1.097	υCC (31), bCH (29), bCH3 (25)
25	A′	1140	—	1168	1140	0.662	4.253	bCH3 (96)
26	A′	1049	—	1087	1050	107.304	7.809	𝜐CO (29), 𝜐CC (27), Rtrigd (12)
27	A′	-	1062	1077	1060	104.848	21.650	𝜐CC (41), 𝜐CO (22), bCH (12)
28	A′′	960	-	1060	960	0.609	0.057	𝜔CH (91)
29	A′	—	974	989	974	207.871	0.836	𝜐OC (62), 𝜐CC (12), 𝜐CO (11)
30	A′′	937	—	965	935	1.244	1.294	𝜔CH (91)
31	A′′	—	865	869	865	3.148	3.432	𝜔CH (64), ttrigd (19)
32	A′	—	795	830	795	12.200	4.238	𝜐CO (29), Rsymd (21), 𝜐OC (15), 𝜐CC (15)
33	A′′	761	—	795	761	1.002	0.207	tCO (32), ttrigd (28), 𝜔CH (23), 𝜔CC (11)
34	A′′	—	755	770	755	41.473	1.456	𝜔CH (51), ttrigd (27), 𝜔CO (14)
35	A′′	695	—	747	698	64.512	0.469	ttrigd (52), 𝜔CH (23), tCO (15)
36	A′	—	698	712	695	10.016	17.946	𝜐CC (33), 𝜐CO (23), bCCO (21)
37	A′	—	602	639	602	13.503	2.683	Rasymd (36), bCCO (15) 𝜐CC (12), Rsymd (11)
38	A′′	—	595	594	595	74.804	8.168	tOH (79)
39	A′	—	565	588	565	21.902	1.740	bCCO (28), 𝜐CC (17), bCO (15), Rsymd (14), bCCO (13)
40	A′	540	—	548	540	5.598	4.848	bCCO (40), bCC (16), 𝜐CC (13), Rasymd (10)
41	A′′	480	—	540	480	0.946	0.860	𝜔CO (40), 𝜔CH (16), ttrigd (14), tsym (14)
42	A′′	—	401	435	401	3.585	0.792	tsym (14), 𝜔CC (15)
43	A′	—	380	388	380	4.805	4.133	bCO (64), bCCO (16)
44	A′	—	303	383	303	1.180	4.980	Rsymd (59), bCOC (17), 𝜐CC (15)
45	A′′	—	280	283	280	0.092	0.016	tCH3 (79)
46	A′	—	240	280	240	0.927	0.935	bCOC (40), bCC (30), bCCO (18)
47	A′′	—	180	229	180	0.018	2.096	𝜔CC (30), tCO (20), tsym (18) tasym (11) 𝜔CH (10)
48	A′	—	170	190	170	3.092	0.715	bCC (42), bCOC (29), bCO (12)
49	A′′	—	115	119	115	4.502	0.508	tCOC (47), tsym (15), tCH3 (12)
50	A′′	—	110	96	96	0.922	3.779	tsym (35), tCO (25) tCOC (21), tCH3 (13)
51	A′′	—	—	17	30	1.260	0.037	tCO (99)

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.