A Group Theoretical and Quantum Chemical Study of Electronic Absorption and Fluorescence, Vibrational Spectra, and Conformations of Trimethine Cyanine Dye Molecules

Table 5

Singlet-singlet quantum transitions in isomers I and II.

trans-Isomer		cis-Isomer
Type of transition	, nm, ()	Type of transition	, nm, ()
S0 → S1  π → π (33 → 34)	482.7 (1.0418)	π → π (33 → 34)	481.0 (0.8252)
S0 → S2  π → σ (33 → 38)	330.7 (0.0000)	π → σ (33 → 38 33 → 39 32 → 39)	324.0 (0.0011)
S0 → S3  π → σ (33 → 39 32 → 38)	322.1 (0.0064)	π → σ (33 → 38 33 → 39 32 → 38)	321.5 (0.0059)
→    (33 → 35 32 → 34)	287.4 (0.0141)	(33 → 35)	292.6 (0.1068)
S0 → S5  π → σ (33 → 40 32 → 41)	281.2 (0.0000)	π → σ (33 → 40 33 → 41)	279.0 (0.0031)
S0 → S6  3π → σ (3 → 41 32 → 40)	274.3 (0.0000)	π → π (32 → 34)	273.5 (0.0228)
S0 → S7  π → π (33 → 35 32 → 34)	270.5 (0.0121)	π → σ (33 → 41)	272.7 (0.0160)
S0 → S8  π → π (33 → 36)	269.9 (0.0285)	(33 → 36 33 → 37)	266.7 (0.1628)
S0 → S9   (33 → 37)	266.0 (0.3301)	π → π (33 → 37 32 → 36)	266.3 (0.0772)
S0 →   π → π (33 → 42)	238.3 (0.0000)	π → π (31 → 34)	236.0 (0.0139)
S0 →   π → π (31 → 34)	235.9 (0.0123)	π → π (33 → 42)	232.0 (0.0897)