. 2020 Dec 1;5(49):31880–31890. doi: 10.1021/acsomega.0c04724

Table 2. Complex-Formation Constants, K_abs and K_em, between Ce³⁺ and Carboxylic Acids Other Than DGA in Aqueous Solutions Obtained from Their Absorption and Emission Spectra, Respectively, with the Relative Uncertainty of K_abs with Respect to K_em^a.

ligand	pH	K_abs/M^–1	K_em/M^–1
CH₃COOH	4.73 (4.56)^b	42.0	40.7	3.10
CH₃CH₂COOH	4.87 (4.67)^b	44.6	44.9	0.67
ClCH₂COOH	2.87 (2.68)^b	8.32	8.63	3.73
CF₃COOH	0.60 (0.0)^b	∼0	∼0
CH₃OCH₂COOH	3.53 (3.57)^b	36.8	40.2	9.24
CH₂(CH₂COOH)₂^c : GLA	3.50	21.9	23.4	6.85
	4.00	48.2	46.1	4.36
	4.50	116	119	2.59

Ionic strength I = 0.1 M at room temperature (∼20 °C).

Note that each solution involving a monocarboxylic acid was set to a particular pH to attain equal rates of protonation and deprotonation, such that each value of the adjusted pH became equivalent to that of pK_a at 20 °C in parentheses.⁵⁴

Acid dissociation constants of GLA: pK_a1^GLA = 4.34, pK_a2 = 5.41 at 20 °C.⁵⁴

Table 2. Complex-Formation Constants, Kabs and Kem, between Ce3+ and Carboxylic Acids Other Than DGA in Aqueous Solutions Obtained from Their Absorption and Emission Spectra, Respectively, with the Relative Uncertainty of Kabs with Respect to Kema.

Table 2. Complex-Formation Constants, K_abs and K_em, between Ce³⁺ and Carboxylic Acids Other Than DGA in Aqueous Solutions Obtained from Their Absorption and Emission Spectra, Respectively, with the Relative Uncertainty of K_abs with Respect to K_em^a.