Voltammetric and theoretical study of the redox properties of rubrolide analogues.

To understand and predict the relationship between the redox potential and the inhibitory effect of rubrolide analogues upon the photosynthetic electron transport chain, their redox properties were studied. The reduction potential was determined experimentally in DMSO by means of cyclic voltammetry, and theoretically by using B3LYP/6-31G(d,p) and MPWB1K/TZVP computational methods. A good correlation was obtained between the two datasets, MPWB1K/TZVP being the best methodology (correlation coefficient of 0.965 and standard deviation of 0.034, against 0.932 and 0.047 for B3LYP/6-31G(d,p)). A significant relationship was observed between the redox potential of the rubrolide analogues and their ability to interfere with the Hill reaction: the higher the first reduction potential, the more effective the inhibitor. These results will allow for predicting the behavior of novel analogues as inhibitors of the Hill reaction, and directing the synthetic strategy towards more potent inhibitors targeting the photosynthetic electron transport.