Oxidation resilient dithizones - Synthesis, cyclic voltammetry and DFT perspectives

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• 作者：Karel G. von Eschwege ; ^{veschwkg@ufs.ac.za}
• 关键词：Electrochemistry ; Computation ; Fluoro ; HOMO ; LUMO
• 刊名：Polyhedron
• 出版年：2012
• 期刊代码：87_02775387
• 类别：ch
• 出版时间：30 May, 2012
• 卷：39
• 期：1
• 页码：99-105
• 文件大小：573 K

摘要

Towards improving the resistance of dithizone against oxidation, a series of halogenated derivatives were synthesized. The synthetic limit at which fluorination permanently alters the properties of dithizone was found in the transition from mono- to difluorophenyl substituted dithizones. Relative to unsubstituted dithizone, the ortho-fluoro- and difluorophenyl derivatives exhibit a decline in molar absorptivity, which increasingly renders it less effective in its traditional application as trace metal analysis reagent. By the use of cyclic voltammetry, oxidation resilience was quantified, with largest positive shift in first oxidation peak potential found for 3-fluorodithizone (279 mV). DFT calculated HOMO and LUMO energies of the dithizone derivatives were related to corresponding oxidation (E_pa,1) and reduction potentials (E_pc,C). Correlations between E_HOMO and E_pa,1, and E_LUMO and E_pc,C yielded R² values of 0.98 and 0.95, respectively. Computed molecular orbital and time dependent DFT oscillator renderings agree closely with experimental observations.