Herein we describe the results of a combined theoretical and spectroscopic investigation into the design of a simple molecular system intended to act as a memory storage bank. The main operating principle revolves around the two-electron reduction of an aryl disulfide bond. Addition of the first electron leads to elongation of the S–S bond but it breaks only if there is accompanying protonation. Adding a second electron causes S–S bond cleavage, with or without protonation. The structural changes have been assessed by way of quantum chemical calculations and molecular dynamics simulations. Electrochemical studies show that the two-electron reduced product can be re-oxidised at mildly anodic potentials and the cycle can be repeated many times. Both theory and experiment point towards pronounced potential inversion whereby the second reduction potential lies at a significantly more positive potential than that for the first step. Computer simulations of the cyclic voltammograms give rise to numerical values for the reduction potentials that are in quite good agreement with the computed values and also allow determination of the electrochemical rate constants and transfer coefficients. Accurate simulation of the experimental data can be realised only if one proton accompanies the second reduction step. The possibility to design an effective molecular-scale memory device around this system is discussed briefly.
在本文中,我们介绍了对一个简单分子系统的设计进行理论和光谱学综合研究的结果,该系统旨在充当记忆存储库。其主要工作原理围绕芳基二
硫键的双电子还原。第一个电子的加入会导致 S-S 键的延长,但只有在伴随质子化的情况下,S-S 键才会断裂。无论质子化与否,加入第二个电子都会导致 S-S 键断裂。量子
化学计算和分子动力学模拟对结构变化进行了评估。电
化学研究表明,双电子还原产物可以在轻度阳极电位下被再次氧化,而且这个循环可以重复多次。理论和实验都指向明显的电位反转,即第二次还原的电位比第一步的电位正得多。循环伏安图的计算机模拟得出的还原电位数值与计算值相当吻合,还能确定电
化学速率常数和传递系数。只有在第二个还原步骤中伴随一个质子时,才能实现对实验数据的精确模拟。本文简要讨论了围绕该系统设计有效的分子级存储器件的可能性。