Abstract The electrochemical behaviour of 4,7-dichloro-1,10-phenanthrolines was studied in non-aqueous solution using cyclic voltammetry, controlled potential electrolysis, in-situ UV–Vis and IR spectroelectrochemistry, and HPLC-DAD (HPLC with diode array detector) and HPLC-MS/MS techniques. The substitution of phenanthrolines at position C2 and C5 with methyl groups, chlorine and/or fluorine atoms influences the redox properties and the potential gap between the oxidation and reduction potentials. Reduction leads to the formation of a radical anion and the subsequent cleavage of halide from the molecule. Compounds containing also chlorine or fluorine atoms at position C5 were found to be the most easily reduced. The oxidation of 4,7-dichloro-1,10-phenanthrolines proceeds primarily on the conjugated aromatic rings of phenanthroline forming a short living radical cation at the first oxidation wave and a dication at the second oxidation wave. The changes of the absorption spectra during IR spectroelectrochemistry suggested the formation of an unstable species, whose dimeric structure was hypothesized. Frontier molecular orbitals calculations and theoretical calculations of IR spectra support the findings.

中文翻译：

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红外光谱电化学作为阐明氯取代 1,10-菲咯啉还原机理的有效技术

摘要 4,7-二氯-1,10-菲咯啉在非水溶液中的电化学行为使用循环伏安法、控制电位电解、原位紫外-可见和红外光谱电化学以及 HPLC-DAD（带二极管阵列的 HPLC检测器）和 HPLC-MS/MS 技术。用甲基、氯和/或氟原子取代 C2 和 C5 位的菲咯啉会影响氧化还原特性以及氧化和还原电位之间的潜在差距。还原导致自由基阴离子的形成和卤化物从分子的随后裂解。发现在 C5 位还含有氯或氟原子的化合物最容易被还原。4,7-dichloro-1的氧化，10-菲咯啉主要在菲咯啉的共轭芳环上进行，在第一次氧化波中形成一个短的活性自由基阳离子，在第二次氧化波中形成一个双阳离子。红外光谱电化学过程中吸收光谱的变化表明形成了一种不稳定的物质，推测其二聚体结构。红外光谱的前沿分子轨道计算和理论计算支持了这些发现。