Effects of substituents and solvent polarity on ESIPT and antioxidant activity of 2,6-Dihydroxybenzaldehyde

2,6-Dihydroxybenzaldehyde (2,6-DHBA), featuring ortho phenolic hydroxyl groups, exhibits notable antioxidant properties. However, the influence of substituents and solvent polarity on its ESIPT behavior and radical scavenging ability remains unclear. Using DFT and TD-DFT methods, we systematically investigated how electron withdrawing (-CN) and electron donating (−NH 2 ) groups, together with dichloromethane and dimethyl sulfoxide solvents, regulate ESIPT and antioxidant activity. The -CN group promotes ESIPT but weakens antioxidant activity, whereas -NH 2 shows the opposite effect. Lower solvent polarity favors ESIPT. These findings provide theoretical guidance for designing phenolic antioxidants and functionalized ligands.