The oxidation and reduction mechanisms of substituted 4,7-di(pyrrolidin-1-yl)-1,10-phenanthrolines were investigated in non-aqueous environment by means of cyclic voltammetry. Reduction of these derivatives leads to the formation of radical anion and subsequent reductive cleavage of pyrrolidine-1-yl moiety in overall ECE reduction processes. The regenerating formation of 1,10-phenanthroline was observed. IR spectroelectrochemistry and HPLC-MS/MS analysis were applied to support this result. The presence of pyrrolidine-1-yl moiety significantly thermodynamically facilitates the reduction of the 1,10-phenanthroline structure. Concerning oxidation, the primarily formed cation radical on nitrogen of the pyrrolidine moiety is further oxidized and undergoes a coupled nucleophilic addition of water and hydroxylated compound is formed as the oxidation product. Additionally, further opening of pyrrolidine ring and oxidative cleavage of alkyl are other proposed reactions. The results presented in this work pave the way for novel chelating agents with electrochemically controlled polarity. Furthermore, reductive regeneration of individual components of the molecular assemblies described in this work opens new directions in electrochemical technologies for the environmental protection.
The effects of 4,7-di(pyrrolidin-1-yl) substituents on the reduction and oxidation mechanisms of 1,10-phenanthrolines: New perspectives in tailoring of phenantroline derivatives
Degano I.;
2021-01-01
Abstract
The oxidation and reduction mechanisms of substituted 4,7-di(pyrrolidin-1-yl)-1,10-phenanthrolines were investigated in non-aqueous environment by means of cyclic voltammetry. Reduction of these derivatives leads to the formation of radical anion and subsequent reductive cleavage of pyrrolidine-1-yl moiety in overall ECE reduction processes. The regenerating formation of 1,10-phenanthroline was observed. IR spectroelectrochemistry and HPLC-MS/MS analysis were applied to support this result. The presence of pyrrolidine-1-yl moiety significantly thermodynamically facilitates the reduction of the 1,10-phenanthroline structure. Concerning oxidation, the primarily formed cation radical on nitrogen of the pyrrolidine moiety is further oxidized and undergoes a coupled nucleophilic addition of water and hydroxylated compound is formed as the oxidation product. Additionally, further opening of pyrrolidine ring and oxidative cleavage of alkyl are other proposed reactions. The results presented in this work pave the way for novel chelating agents with electrochemically controlled polarity. Furthermore, reductive regeneration of individual components of the molecular assemblies described in this work opens new directions in electrochemical technologies for the environmental protection.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
