Solvent H-bonding and structural effects on the photo-reduction of Co(III) complexes in water/propan-2-ol and water/1,4-dioxane media

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• 作者：Kumarasamy Sivaraj ; Kuppanagounder P. Elango
• 关键词：Photo-reduction ; Solvent effect ; Kamlet&#x2013 ; Taft equation ; Substituent effect
• 刊名：Journal of Molecular Liquids
• 出版年：2010
• 出版时间：30 September 2010
• 年：2010
• 卷：156
• 期：2-3
• 页码：137-140
• 全文大小：286 K

文摘

The photo-reduction of a series of cobalt(III) complexes of the type cis-β-[Co(trien)(4-R-Py)Cl]Cl₂ where trien=triethylenetetraamine and R = H, Me, Et, t-Bu, COMe, and CN has been studied in water/propan-2-ol and water/1,4-dioxane media of varying compositions. The photo-reduction quantum yield (Φ_Co(II)) data were correlated with solvent and structural parameters with an aim to shed some light on the mechanism of the reaction. Correlation of Φ_Co(II) with macroscopic solvent parameters viz. relative permittivity indicates that the reactivity is influenced by both specific and non-specific solute–solvent interactions. Kamlet–Taft solvatochromic comparison method was used to separate and quantify these effects. The observed non-linear concave downwards type Hammett plot is explained by assuming shift in the excited state within the same overall reaction pathway.