Ideal liquid sorbents, such as phenolate zwitterions, represent a novel and promising technology for CO2 capture. To enhance their design and reactivity with CO2, two types of substituents, electron-donating groups (EDGs) and electron-withdrawing groups (EWGs) were investigated. Using Density Functional Theory (DFT) with a large basis set, their effectiveness as reactivity modulators was assessed through energy decomposition analysis, non-covalent interaction, natural bond orbitals (NBO), evaluation of reaction energy barriers and pKa. EDGs, in general, enhance phenolate reactivity and stability, highlighting their potential in the design of advanced zwitterionic sorbents for CO₂ capture. Conversely, EWGs demonstrated mixed effects, providing lower CO2 capture effectiveness but enhancing recyclability of the phenolates. In summary, our findings provide a framework to investigate substituent efficacy and design next-generation carbon capture materials.