Table 6.

(a,b) Thermodynamic and energy parameters of HB and HC acids in various states of ionization in the gas phase (298 K).

(a)
Phenolic Acid	BDE, kcal/mol	IPe, eV	IPo, eV	EHOMO, eV	ELUMO, eV	χ, eV
p-OH Benzoic
z = 0	86.55	8.62	6.86	−6.866	−1.576	4.221
z = −1	72.95	3.42	1.63	−1.627	1.884	−0.129
z = −2	–	−1.11	−2.76	3.757	5.421	−4.089
Vanillic
z = 0	85.76	8.04	6.41	−6.413	−1.527	3.970
z = −1	74.83	3.43	1.68	−1.679	1.873	−0.097
z = −2	–	−1.05	−2.55	2.554	4.587	−3.570
Siringic
z = 0	81.65	7.66	6.12	−6.121	−1.485	3.803
z = −1	73.21	3.40	1.69	−1.691	1.906	−0.107
z = −2	–	−1.01	−2.36	2.363	4.478	−3.421
Gallic
z = 0, C1	82.35	8.06	6.41	−6.405	−1.645	4.025
z = 0, C6	82.86	8.06	6.41	−6.405	−1.645	4.025
z = 0, C5	77.97	8.06	6.41	−6.405	−1.645	4.025
z = −1, C1	75.70	3.57	1.83	−1.827	1.933	−0.053
z = −1, C6	73.26	3.57	1.83	−1.827	1.933	−0.053
z = −1, C5	69.97	3.57	1.83	−1.827	1.933	−0.053
z = −2, C1	–	−0.68	−2.56	2.580	4.923	−3.571
z = −2, C6	–	−0.74	−2.65	2.651	5.064	−3.858
z = −2, C5	–	−0.93	−2.58	2.580	4.293	3.751
cis-Caffeic
z = 0	87.06	8.12	6.41	−6.413	−2.119	4.266
z = −1	77.73	3.44	1.74	−1.736	1.831	−0.047
z = −2	–	−0.44	−2.18	2.175	4.775	−3.475
trans-Caffeic
z = 0	82.54	8.00	6.43	−6.435	−2.150	4.292
z = −1	67.80	3.33	1.58	−1.581	1.429	0.076
z = −2	–	−0.52	−1.97	1.968	4.873	−3.420
cis-Ferulic
z = 0	77.46	7.53	6.65	−6.646	−2.105	4.376
z = −1	76.03	3.44	1.79	−1.787	1.673	0.051
z = −2	–	−0.54	−2.02	2.022	4.210	−3.117
trans-Ferulic
z = 0	82.14	7.66	6.14	−6.144	−2.100	4.122
z = −1	82.64	3.85	1.54	−1.537	1.615	−0.038
z = −2	–	−0.44	−1.82	1.822	4.172	−2.997
cis-Sinapic
z = 0	78.92	7.27	6.35	−6.347	−2.089	4.218
z = −1	70.20	3.61	1.89	−1.890	−1.816	0.037
z = −2	–	−0.80	−1.88	1.885	4.144	−3.014
trans-Sinapic
z = 0	78.57	7.38	5.94	−5.940	−2.082	4.011
z = −1	69.25	3.58	1.64	−1.635	1.541	0.047
z = −2	–	−0.38	−1.68	–	4.085	−2.882
(b)
Phenolic Acid	η, eV	ω × 103, eV	EHOMO–ELUMO, eV	ETE, kJ/mol	PA, kJ/mol	PDE, kJ/mol
p-OH Benzoic
z = 0	2.645	842	5.290	–	–	838.5
z = −1	1.755	1.179	3.511	−106.87	1720.5	1283.3
z = −2	1.131	1569	2.664	–	–	–
Vanillic
z = 0	2.443	806	4.887	–	–	891.5
z = −1	1.776	0.658	3.552	−101.69	1723.1	1290.9
z = −2	1.017	1567	2.033	–	–	–
Siringic
z = 0	2.318	780	4.636	–	–	910.0
z = −1	1.798	0.800	3.597	−97.85	1260.4	834.9
z = −2	1.058	1383	2.116	–	–	–
Gallic
z = 0, C1	2.380	851	4.760	–	–	875.3
z = 0, C6	2.380	851	4.760	–	–	877.4
z = 0, C5	2.380	851	4.760	–	–	856.9
z = −1, C1	1.880	0.188	3.760	−65.99	1691.1	1281.0
z = −1, C6	1.880	0.188	3.760	−71.05	1686.0	1270.8
z = −1, C5	1.880	0.188	3.760	−89.97	1691.1	1257.0
z = −2, C1	1.172	1501	2.343	–	–	–
z = −2, C6	1.207	1541	2.414	–	–	–
z = −2, C5	1.171	1501	2.343	–	–	–
cis-Caffeic
z = 0	2.147	1060	4.294	–	–	–
z = −1	1.783	0.156	3.567	−42.30	1675.9	889.4
z = −2	1.300	1161	2.600	–	–	1301.3
trans-Caffeic
z = 0	2.143	10.75	4.285	–	–	–
z = −1	1.505	0.481	3.010	−49.82	1641.8	881.7
z = −2	1.452	1007	2.905	–	–	1270.6
cis-Ferulic
z = 0	2.270	1054	4.541	–	–	–
z = −1	1.730	0.232	3.460	−42.27	1656.2	906.1
z = −2	1.094	1109	2.188	–	–	1141.3
trans-Ferulic
z = 0	2.022	1050	4.044	–	–	–
z = −1	1.576	0.119	3.152	−42.45	1696.6	913.4
z = −2	1.175	955	2.350	–	–	1283.0
cis-Sinapic
z = 0	2.129	1044	4.258	–	–	–
z = −1	1.853	0.091	3.706	−77.64	1679.7	936.9
z = −2	1.130	1006	2.259	–	–	1253.5
trans-Sinapic
z = 0	1.929	1043	3.858	–	–	925.2
z = −1	1.588	0.071	3.176	−37.04	1635.2	1253.1
z = −2	1.203	863	2.405	–	–	–