Voltammetric evidences for the interaction of riboflavin with cadmium in aqueous media

Electrochemical Evidences for the Enhancement of Heterogeneous Electron Transfer Rates of Riboflavin in the Presence of Copper

“…It was suggested that riboflavin undergoes a series of proton-coupled electron transfer reactions in dimethyl sulfoxide solutions and is initially reduced by one electron to form the radical anion and the chemical reactions were completely chemically reversible [8][9] . Our previous studies also suggest that riboflavin undergoes a one-electron transfer reaction in aqueous solution and exhibited reversible heterogenous electron transfer with a glassy carbon electrode 10 . It was also found in the same study that the heterogeneous electron transfer rate of riboflavin enhanced at a glassy carbon electrode in the presence of cadmium 10 .…”

“…Our previous studies also suggest that riboflavin undergoes a one-electron transfer reaction in aqueous solution and exhibited reversible heterogenous electron transfer with a glassy carbon electrode 10 . It was also found in the same study that the heterogeneous electron transfer rate of riboflavin enhanced at a glassy carbon electrode in the presence of cadmium 10 . It is well known that metals with suitable ligands are chemically more significant and specific than the metal ions 11 .…”

“…Similar trends of F-values by de Ford and Hume method were found in the literature [20][21] for multi-nuclear complexes. The stepwise stability constants, F 0 [riboflavin] and F 1 [riboflavin] and the overall stability constant, (logβ=11.17) are all in good agreement for the formation of a stable multi-nuclear complex between copper and riboflavin and copper may be co-ordinated to the highest spin density region between nitrogen (12) 10 and oxygen (24) 10 positions of riboflavin. …”

“…The peak separation value is 67.0 mV, which clearly indicated that the redox process is reversible involving single electron transfer. In our previous research 10 , it was reported that CV of riboflavin exhibited a single-step reversible electron-previous process. Curve ii (dotted line) in Figure 1 However, in the presence of riboflavin, the cyclic voltammetric behaviour of copper has been changed dramatically as shown in curve iii in Figure 1.…”

“…To study the comparative heterogeneous electron-transfer rates, the overall rate constants (k f ) of riboflavin 10 , copper and copper-riboflavin system have been compared. To calculate the heterogeneous electron transfer rate coefficient of copper-riboflavin, the variable concentration dependence current-voltage data has been constructed and represented in Figure 2.…”