Quantum Chemical Investigation on the Antioxidant Activity of Neutral and Anionic Forms of Juglone: Metal Chelation and Its Effect on Radical Scavenging Activity

Table 3

Thermodynamic parameters (kJ/mol), atomic charge of the central metal(e) (ligand-metal charge transfer), and the correlation coefficient () all obtained at B3LYP/6-31+G(d,p) level.

	Juglone					Deprotonated juglone
	M(e)	ΔH	ΔG	ΔE		M(e)	ΔH	ΔG	ΔE
Gas
Mg(II)	1.84(0.16)	−674.1	−640.4	−672.2	0.746	1.76(0.24)	−1623.6	−1582.4	−1618.5	0.639
Ca(II)	1.93(0.07)	−416.1	−384.1	−415.1		1.88(0.12)	−1275.3	−1237.6	−1227.2
Fe(II)	1.58(0.42)	−769.6	−735.7	−767.5		1.43(0.57)	−1776.1	−1735.3	−1773.6
Co(II)	1.51(0.49)	−838.9	−805.9	−837.9		1.28(0.72)	−1851.3	−1811.9	−1853.8
Ni(II)	1.31(0.69)	−945.1	−915.7	−945.6		1.17(0.83)	−1966.5	−1926.7	−1963.0
Cu(II)	1.08(0.92)	−1027.0	−996.0	−1027.0		0.97(1.03)	−2038.6	−2001.4	−2036.9
Cu(I)	0.89(0.11)	−244.8	−214.1	−244.7		0.81(0.19)	−772.7	−733.5	−769.0
Zn(II)	1.66(0.34)	−841.5	−808.3	−841.6		1.55(0.45)	−1841.0	−1801.1	−1838.7
Water
Mg(II)	1.93(0.07)	−48.6	−14.1	−46.1	0.853	1.89(0.11)	−209.1	−168.2	−205.2	0.871
Ca(II)	1.98(0.02)	9.4	39.3	10.6		1.96(0.04)	−103.2	−62.4	−99.4
Fe(II)	1.85(0.15)	−51.1	−15.0	−49.5		1.74(0.26)	−239.9	−197.3	−235.5
Co(II)	1.80(0.20)	−94.7	−58.9	−92.2		1.66(0.34)	−262.2	−221.1	−259.8
Ni(II)	1.76(0.24)	−117.9	−81.7	−115.3		1.58(0.42)	−321.6	−280.7	−317.2
Cu(II)	1.49(0.51)	−368.7	−333.4	−366.4		1.37(0.63)	−630.8	−590.2	−627.7
Cu(I)	0.98(0.02)	−92.2	−567.4	−90.0		0.86(0.14)	−222.6	−185.2	−219.5
Zn(II)	1.88(0.12)	−63.1	−27.7	−62.8		1.77(0.23)	−242.4	−203.8	−239.5