Rational designing and testing of materials in order to find better candidates is the focus of molecular engineering. Organic molecules can be modified either by their functional groups or their backbones. Numerous experimental studies have been performed to improve solubility, electrochemical redox properties, and cycling stability by modifying functional groups. For instance, Wedege et al. and Wiberg et al. in separate studies observed that solubility and redox potential is influenced by the position, type, and number of functional groups. Moreover, another study showed that heterocycles, where one carbon is substituted by oxygen, sulfur, and nitrogen, can change charge states and improve reactivity. Nevertheless, the experimental verification of the RFB active molecules is slow, especially if new molecules need to be synthesised, the computational pre-screening is very useful.