Table 5.

Electronic transition, their assignments, the absorption maxima and oscillator strengths of the 2-styrylpyridine and IIIa–IIIc compounds calculated at the B3LYP/6-31G(d)//B3LYP/6-311 + G(d,p) theory level.

	Electronic transition	Absorption maxima (nm (eV))		Oscillator strengths		MO/Character (% Coefficient)	Experimental (nm (eV))
		Gas	PCM	Gas	PCM
2-styrylpyridine	S0–S1	311.6 (3.98)	323.3 (3.83)	0.8922	1.0597	HOMO→LUMO (98%)	311.0 (3.99)
	S0–S2	291.2 (4.26)	288.1 (4.30)	0.0014	0.0014	HOMO-2→LUMO (97%)
	S0–S3	270.9 (4.58)	271.6 (4.57)	0.0030	0.0049	HOMO-1→LUMO (74%) + HOMO→LUMO+2 (25%)
IIIa	S0–S1	309.3 (4.01)	320.9 (3.86)	0.9656	1.1193	HOMO→LUMO (98%)	309.6 (4.01)
	S0–S2	298.4 (4.16)	300.5 (4.13)	0.0010	0.0133	HOMO-1→LUMO (96%)
	S0–S3	295.7 (4.19)	295.2 (4.20)	0.0116	0.0012	HOMO→LUMO + 1 (86%) + HOMO-2→LUMO (12%)
IIIb	S0–S1	312.7 (3.96)	324.1 (3.83)	0.9432	1.0916	HOMO→LUMO (97%)	312.0 (3.98)
	S0–S2	302.7 (4.10)	302.8 (4.10)	0.0010	0.0141	HOMO-1→LUMO (96%)
	S0–S3	297.7 (4.16)	300.3 (4.13)	0.0088	0.0012	HOMO→LUMO + 1 (82%) + HOMO-2→LUMO (14%)
IIIc	S0–S1	307.2 (4.04)	318.3 (3.89)	0.7615	0.9422	HOMO→LUMO (98%)	293.6 (4.23)
	S0–S2	285.4 (4.34)	296.9 (4.18)	0.1545	0.1452	HOMO→LUMO + 1 (71%) + HOMO-3→LUMO (24%)
	S0–S3	309.0 (4.01)	288.1 (4.30)	0.0021	0.0018	HOMO-1→LUMO (93%)