Complexes of Al(III) with 3′4′-dihydroxy-flavone:: characterization, theoretical and spectroscopic study
Complexes of Al(III) with 3′4′-dihydroxy-flavone:: characterization, theoretical and spectroscopic study
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DOI：
10.1016/s1386-1425(00)00412-1
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发表时间：
2001-03-01
影响因子：
4.4
通讯作者：
Merlin, JC
中科院分区：
文献类型：
--
作者：
Cornard, JP;Boudet, AC;Merlin, JC
Complex formation between aluminium chloride and 3 '4 ' -dihydroxyflavone (3 '4 ' diOHF) in methanol has been studied by UV-visible and Raman spectroscopies combined with quantum chemical calculations. Job's method of continuous variation and the molar ratio method were applied to ascertain the stoichiometry composition of the chelate in pure methanol.两种方法均显示 1:1 复合物。 Geometry optimizations of free and complexed molecules by AM1 and DFT methods show that structural modifications of the ligand, induced by complexation, are minor, and are localized on the chelating site. 3'4'diOHF 和配合物的实验和理论电子光谱之间的良好一致性证实了结构模型。 The great similarities between Raman spectra of the free and complexed form constitute an another proof of the absence of pronounced electronic and geometric changes, and notably demonstrate that the quinoidal form induced by the deprotonation of the two hydroxyl groups does not participate in the 3 '4 ' diOHF complex structure.虽然在酸性介质中不发生络合，但在碱性介质中形成高化学计量的络合物。在乙酸钠或甲醇钠存在下，在甲醇中观察到 (Al(3'4' diOHF)(2))(-) 和 (Al(3'4' diOHF)(3))(3-) 物质。 (C) 2001 Elsevier Science B.V. 保留所有权利。
Complex formation between aluminium chloride and 3 '4 ' -dihydroxyflavone (3 '4 ' diOHF) in methanol has been studied by UV-visible and Raman spectroscopies combined with quantum chemical calculations. Job's method of continuous variation and the molar ratio method were applied to ascertain the stoichiometry composition of the chelate in pure methanol. A 1:1 complex was indicated by both the methods. Geometry optimizations of free and complexed molecules by AM1 and DFT methods show that structural modifications of the ligand, induced by complexation, are minor, and are localized on the chelating site. The good agreement between experimental and theoretical electronic spectra of both 3 '4 ' diOHF and complex confirm the structural models. The great similarities between Raman spectra of the free and complexed form constitute an another proof of the absence of pronounced electronic and geometric changes, and notably demonstrate that the quinoidal form induced by the deprotonation of the two hydroxyl groups does not participate in the 3 '4 ' diOHF complex structure. Whereas no complexation occurs in acidic medium, complexes of high stoichiometry are formed in alkaline medium. (Al(3 '4 ' diOHF)(2))(-) and (Al(3 '4 ' diOHF)(3))(3-) species are observed in methanol in the presence of sodium acetate or sodium methanoate. (C) 2001 Elsevier Science B.V. All rights reserved.