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The chromatographic lipophilicity ( R M0 , ϕ 0 , S ) of eleven new 1,2,4-triazole derivatives has been determined by RP-TLC with methanol-water mobile phases containing sodium salts of the monovalent anions H 2 PO 4 , Cl , I , NO 3 , CF 3 COO , ClO 4 , and PF 6 . Addition of iodide anions to the mobile phase proved a key factor in obtaining lipophilicity indexes which correlated better with the log P G scale for all the solutes investigated. Addition of neutral or strong chaotropic salts (chlorides, hexafluorophosphates), according to the Hofmeister classification, improved the correlations between R M0 and S and between R M0 and ϕ 0 . Experimental log P TLC values were also established on the basis of calibration plots. These values were also correlated with the calculated lipophilicity log P G . Highly significant improvement of this correlation was achieved for mobile phases modified with sodium iodide. The results obtained are discussed in connection with the known physicochemical properties of anions in solution — lyotropic number, Jones-Dole B coefficient, entropy of hydration, surface tension increment, and effective anion polarizability.

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