biostudies-literatureKatsuta SSalt Science Research FoundationJapan Society for the Promotion of Science1373-1379https://www.ebi.ac.uk/biostudies/studies/S-EPMC11208259biostudies-literatureUnknown40(7)A metallacrown-type ionophore, 2,3-pyridinediolate-bridged (3,5-dimethylanisole)ruthenium trinuclear complex, has a high extraction selectivity for Li⁺, but the extraction reaction is very slow. To solve this problem, the effect of temperature on the rapidity and equilibrium of the extraction of Li⁺ and Na⁺ as picrates from water to toluene with the metallacrown was investigated in this study. While the extraction of Li⁺ requires 6 h of shaking for equilibration at 25 °C, the distribution ratio becomes nearly constant after 4 h and 2 h of shaking at 37 °C and 50 °C, respectively. The extraction equilibrium constants (K_ex) and associated thermodynamic parameters determined for Li⁺ and Na⁺ indicate that the extraction reactions are exothermic and enthalpy-driven: ΔH° = - 53 kJ/mol, ΔS° = - 0.03 kJ/(mol K) for Li⁺; ΔH° = - 28 kJ/mol, ΔS° = - 0.03 kJ/(mol K) for Na⁺. Although the extraction ability for Li⁺ and selectivity for Li⁺/Na⁺ decrease with increasing temperature, the values of K_ex and K_ex(Li⁺)/K_ex(Na⁺) are 1.0 × 10⁷ and 1.3 × 10⁴, respectively, even at 50 °C, indicating that both are sufficiently high. In the determination of Li⁺ by extraction spectrophotometry using this metallacrown, extraction at 50 °C for 2 h was employed to speed up the analysis. The method was applied to seawater and serum samples containing a large amount of coexisting ions such as Na⁺ and Mg²⁺, and trace amounts (10^-6-10^-5 mol/L order) of Li⁺ in microvolume samples (sub-mL order) could be successfully determined.Analytical sciences : the international journal of the Japan Society for Analytical ChemistryExtraction spectrophotometry using a lithium-ion selective metallacrown: temperature effect on extraction reaction and application to determination of lithium in serum and seawater.PMC1120825922K0515118K051651605Katsuta SMaeda KfalseExtraction spectrophotometry using a lithium-ion selective metallacrown: temperature effect on extraction reaction and application to determination of lithium in serum and seawater.A metallacrown-type ionophore, 2,3-pyridinediolate-bridged (3,5-dimethylanisole)ruthenium trinuclear complex, has a high extraction selectivity for Li⁺, but the extraction reaction is very slow. To solve this problem, the effect of temperature on the rapidity and equilibrium of the extraction of Li⁺ and Na⁺ as picrates from water to toluene with the metallacrown was investigated in this study. While the extraction of Li⁺ requires 6 h of shaking for equilibration at 25 °C, the distribution ratio becomes nearly constant after 4 h and 2 h of shaking at 37 °C and 50 °C, respectively. The extraction equilibrium constants (K_ex) and associated thermodynamic parameters determined for Li⁺ and Na⁺ indicate that the extraction reactions are exothermic and enthalpy-driven: ΔH° = - 53 kJ/mol, ΔS° = - 0.03 kJ/(mol K) for Li⁺; ΔH° = - 28 kJ/mol, ΔS° = - 0.03 kJ/(mol K) for Na⁺. Although the extraction ability for Li⁺ and selectivity for Li⁺/Na⁺ decrease with increasing temperature, the values of K_ex and K_ex(Li⁺)/K_ex(Na⁺) are 1.0 × 10⁷ and 1.3 × 10⁴, respectively, even at 50 °C, indicating that both are sufficiently high. In the determination of Li⁺ by extraction spectrophotometry using this metallacrown, extraction at 50 °C for 2 h was employed to speed up the analysis. The method was applied to seawater and serum samples containing a large amount of coexisting ions such as Na⁺ and Mg²⁺, and trace amounts (10^-6-10^-5 mol/L order) of Li⁺ in microvolume samples (sub-mL order) could be successfully determined.2024-01-01T00:00:00Z2024 Jul2024-11-21T05:49:09.451Z2024-11-21T05:49:09.451ZS-EPMC112082593865241810.1007/s44211-024-00569-9