Investigation of the isomerization effect on diospyrin one-electron reduction potential

Quinone reduction is very important in electrochemistry, biological energy saving and organic reactions. Our knowledge about quinone reduction potentials is so important in understanding the nature of their chemical reactions for designing new electronical materials and evaluating their biological activities. The calculation of reduction potential of quinones by the means of theoretical methods is an appropriate approach for solving experimental measurement problems (1, 2). The one-electron reduction potentials of diospyrin (A) and martinon (B) have been calculated in DMSO at the B3LYP/6-311G++(d,p) level in the present work. The one-electron reduction potentials of quinones ware calculated on the base of following equation: 𝐸𝑁𝐻𝐸 ( 𝑄 ⁄𝑄.−)= 𝐸𝑁𝐻𝐸 ( 𝑃 − 𝐵𝑄 ⁄𝑃 − 𝐵𝑄.−) + Δ𝐺𝑆𝑜𝑙 ∗ 𝐹 (1) Where, ENHE (p-BQ/P-BQ.-) is the reduction potential of para-benzoquinone (P-BQ) in DMSO and F is the Faraday constant (3). The estimated values of reduction potential for A and B are equal to, -0.222 V and -0.397 V, respectively. Isomerization leads to the increase in the reduction potential of related quinone (A).