Structural Changes Induced by Quinones: High‐Resolution Microwave Study of 1,4‐Naphthoquinone

Abstract

1,4-Naphthoquinone (1,4-NQ) is an important product of naphthalene oxidation, and it appears as a motif in many biologically active compounds. We have investigated the structure of 1,4-NQ using chirped-pulse Fourier transform microwave spectroscopy and quantum chemistry calculations. The rotational spectra of the parent species, and its 13 C and 18 O isotopologues were observed in natural abundance, and their spectroscopic parameters were obtained. This allowed the determination of the substitution r s , mass-weighted r m and semi-experimental r e SE structures of 1,4-NQ. The obtained structural parameters show that the quinone moiety mainly changes the structure of the benzene ring where it is inserted, modifying the CÀ C bonds to having predominantly single or double bond character. Furthermore, the molecular electrostatic surface potential reveals that the quinone ring becomes electron deficient while the benzene ring remains a nucleophile. The most electrophilic areas are the hydrogens attached to the double bond in the quinone ring. Knowledge of the nucleophilic and electrophilic areas in 1,4-NQ will help understanding its behaviour interacting with other molecules and guide modifications to tune its properties.

Theoretical and Experimental Spectroscopic Study on 2-Chloro-3-(substitutedphenylamino)-1,4-naphthoquinone Derivatives

“…19 ROS production leads to an oxidant-antioxidant imbalance or oxidative stress and can lead to irreversible biomolecules damage such as lipids, proteins, ribonucleic acid (RNA), and deoxyribonucleic acid (DNA), followed by cell death. 20,21 Other DNA damage mechanisms associated with quinone derivatives include DNA alkylating reaction and intercalation in the DNA double helix. 22 The quinone redox cycle may be influenced by adding electron-attracting or donating substituents to the quinoid system.…”

Bond Length Alternation and Internal Dynamics in Model Aromatic Substituents of Lignin

“…This chemical phenomenon takes place in (multi)‐substituted benzenes and in benzene rings fused to small saturated rings. Despite its interest, there are not many cases where it has been possible to observe this effect experimentally [30–33] …”

“…Despite its interest, there are not many cases where it has been possible to observe this effect experimentally. [30][31][32][33] As a result, it is interesting to assess in detail the structural changes induced by the addition of functional groups, a methoxy group (S), methyl group (MG) or vinyl group (VG), on the structures and bonding. For this purpose and due to the absence of experimental data on isotopologues, we used calculations at the B3LYP-GD3BJ/def2tzvp level which are the ones that best reproduce the experimental constants.…”

Evaluation of the Toxicity on Lung Cells of By-Products Present in Naphthalene Secondary Organic Aerosols

“…The chemical composition of PAH-derived SOA is quite complex, with hundreds to thousands of compounds being present. To simplify our approach, and to allow a molecular approach to the toxic response of these particles, we investigated the impact of by-products mimicking naphthalene-derived aerosols [7][8][9][10]30].…”

“…Once in the air, naphthalene undergoes atmospheric oxidation, mainly by reacting hydroxyl radicals (•OH), and thereby acts as a precursor of secondary organic aerosols (SOA). These ultrafine particles have a complex chemical composition and therefore possess chemical complexity and yield products such as 1,4-naphthoquinone (1,4-NQ), 2-hydroxy-1,4 naphthoquinone (2-OH-NQ), phthalic acid (PA), phthaldialdehyde (OPA) [7][8][9][10].…”