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Structural Changes Induced by Quinones: High‐Resolution Microwave Study of 1,4‐Naphthoquinone
Author(s) -
Saxena Shefali,
Panchagnula Sanjana,
Sanz M. Eugenia,
Pérez Cristóbal,
Evangelisti Luca,
Pate Brooks H.
Publication year - 2020
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.202000665
Subject(s) - chemistry , quinone , ring (chemistry) , molecule , isotopologue , rotational spectroscopy , nucleophile , moiety , photochemistry , crystallography , computational chemistry , stereochemistry , organic chemistry , catalysis
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 C−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.