Experimental and theoretical insights into free radical capturing activity of 1,5-diaminonaphthalene and 1,5-dihydroxynaphthalene

The radical scavenging activity of two naphthalene derivatives, 1,5-diaminonaphthalene (DAN) and 1,5-diaminonaphthalene (DAN) and 1,5-dihydroxynaphthalene (DHN), was investigated through both experimental and density functional theory methods. Experimentally, the antioxidant capacity of these compounds was assessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH center dot) assay and 2,2 '-azinobis(3-ethylbenzothiazoline-6-sulfonate) (ABTS(center dot+)) assay and compared to the standard antioxidant Trolox. DHN demonstrated a superior ability to capture DPPH center dot free radicals, with an IC50DPPH value of 3.62 +/- 0.01 mu M, while DAN was more effective at neutralizing ABTS(center dot+) radical cations, with an IC50ABTS value of 17.36 +/- 0.02 mu M. Theoretically, density functional theory (DFT) calculations using the theory level of omega b97xd/6-311++g(d,p) were employed to determine the thermodynamic parameters of DHN and DAN in the gas phase and ethanol solvent. Furthermore, the mechanisms and kinetics of capturing reaction between both naphthalene derivatives and HOO center dot radical were also investigated. Based on the potential energy surfaces (PES) via hydrogen atom transfer (HAT) and radical adduct formation (RAF) paths, HAT was determined to be the favored mechanism, with the product amount accounting for more than 99% in the gas phase and 92% in ethanol. (c) 2023 Elsevier B.V. All rights reserved.

Automated summary

The radical scavenging activity of two naphthalene derivatives, 1,5-diaminonaphthalene (DAN) and 1,5-diaminonaphthalene (DAN) and 1,5-dihydroxynaphthalene (DHN), was investigated experimentally and theoretically. DHN demonstrated superior ability to capture DPPH center dot free radicals, while DAN was more effective at neutralizing ABTS(center dot+) radical cations. Density functional theory (DFT) calculations were employed to determine the thermodynamic parameters and investigate the mechanisms of capturing reaction between the derivatives and HOO center dot radical.