Ion-pair extraction behavior of divalent metal cations using neutral di-Schiff base ligands derived from 1,2-cyclohexanediamine and o-phenylenediamine |
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Authors: | Oshima Syunichi Hirayama Naoki Kubono Koji Kokusen Hisao Honjo Takaharu |
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Institution: | a Division of Basic Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa 920-1192, Japan b Faculty of Science, Department of Chemistry, Kanazawa University, Kanazawa 920-1192, Japan c Division of Natural Science, Osaka Kyoiku University, Kashiwara 582-8582, Japan d Department of Environmental Engineering, Kanazawa Institute of Technology, Nonoichi, Ishikawa 921-8501, Japan |
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Abstract: | Di-Schiff base ligand, N,N'-bis(2-pyridylmethylidene)-trans-1,2-diiminocyclohexane (trans-BPIC), having sufficient hydrophobicity acts as neutral bidentate ligand in ion-pair extraction of divalent metal cations into nitrobenzene with picrate anion. In present study, the effect of steric restriction by chemical structure around imine-N donor atoms in trans-BPIC analogs on their complexation with divalent metal cations in ion-pair extraction was investigated by using N,N'-bis(2-pyridylmethylidene)-cis-1,2-diiminocyclohexane (cis-BPIC) and N,N'-bis(2-pyridylmethylidene)-o-diiminobenezene (BPIB). The former was used to observe the effect by geometrical restriction and the latter was by conjugate restriction. In BPIB-NaPic system, the higher extractability was obtained than those in cis- and trans-BPIC systems, and this result seems to be led by the increase of steric distortion originated from conformational restriction. Namely, it is considered that the extractability can be controlled by steric restriction on the complexation. |
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Keywords: | Ion-pair extraction Divalent transition metal cations Extraction selectivity Steric restriction |
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