Excited State Behaviors of the Dodecamolybdocerate (IV) Anion: (NH4)6H2(CeMo12O42)·9H2O

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• 作者：Yu Wei Lu ; Bineta Keita ; Louis Nadjo ; Gé ; rard Lagarde ; Eric Simoni ; Guangjin Zhang ; Galina A. Tsirlina
• 刊名：Journal of Physical Chemistry B
• 出版年：2006
• 出版时间：August 10, 2006
• 年：2006
• 卷：110
• 期：31
• 页码：15633 - 15639
• 全文大小：222K
• 年卷期：v.110,no.31(August 10, 2006)
• ISSN：1520-5207

文摘

The polyoxometalate (NH₄)₆H₂(CeMo₁₂O₄₂)·9H₂O (abbreviated as Ce^IVMo₁₂) was synthesized, and its Ce(III) form was obtained by exhaustive electrochemical reduction. Both forms are fairly stable in pH 0.0 media.This stability decreases when the pH increases. The Ce(IV) species, in which the central metal is in the f⁰electronic configuration, is found to fluoresce, a feature that is only straightforwardly explained with theCe(III) state. As the results of a series of experiments converge to confirm the stability of Ce^IVMo₁₂ in themedia studied, a suggested rationale is that the emission originates from a higher-energy ligand-to-metalcharge transfer and follows a scheme which is ultimately equivalent to the classical metal-centered fluorescenceof Ce(III). Detailed studies of the influences of pH and ionic strength were carried out and suggest thatprotonated and/or ion-paired assemblies are the fluorescent species. A reproducible increase of the fluorescenceintensity of Ce^IVMo₁₂ as a function of time was also observed.