. 2021 Jan 22;69(4):1272–1282. doi: 10.1021/acs.jafc.0c06827

Table 1. Wavelength of Maximum Absorbance, λ_max (nm), Together with the Corresponding Value for the Oscillator Strength, f, of the Most Populated Cy Color Species That Could Exist in Acid–Base Equilibria and Mole Fraction Distribution, x_i, of Colored Species at the Different pH Values Tested.

	mole fraction,^ax_i			UV–vis spectra
Cy species	pH 5	pH 6	pH 7	λ_max (nm)	f
cation	0.5/0.0098	0.12/0.0010	0/0.0001	524.13	0.8284
neutral N4′^b	0.5/0.0310	0.75/0.0312	0.5/0.0307	544.19	1.2722
neutral N5^c				629.47	0.2975
neutral N7				567.15	0.6907
anion A54′	0/0.0002	0.12/0.0020	0.5/0.0194	624.08	0.7905
anion A74′	0/0.0002	0.12/0.0020	0.5/0.0194	621.07	1.1172

In italics, mole fraction is expressed in times one, obtained in this work, where hydration constant, K_h, (pK_h = 3.01) has been included (see text).

Among the neutral forms, N4′ is by far the most predominant.

λ with maximum absorbance, λ_max, does not correspond to the longest one. λ_max occurs at 442.2 (f: 0.6173).

Table 1. Wavelength of Maximum Absorbance, λmax (nm), Together with the Corresponding Value for the Oscillator Strength, f, of the Most Populated Cy Color Species That Could Exist in Acid–Base Equilibria and Mole Fraction Distribution, xi, of Colored Species at the Different pH Values Tested.

Table 1. Wavelength of Maximum Absorbance, λ_max (nm), Together with the Corresponding Value for the Oscillator Strength, f, of the Most Populated Cy Color Species That Could Exist in Acid–Base Equilibria and Mole Fraction Distribution, x_i, of Colored Species at the Different pH Values Tested.