Rotationally resolved electronic spectroscopy study of the conformational space of 3-methoxyphenol

Full Conformational Landscape of 3‐Methoxyphenol Revealed by Room Temperature mm‐wave Rotational Spectroscopy Supported by Quantum Chemical Calculations

“…In addition, high level of theory DFT and MP2 calculations have been performed to analyse the conformational flexibility of 3‐MP. Unlike previous works,,, our experimental results highlight the rotational signatures of the four stable conformations predicted theoretically. In addition to the GS assignment, rotational transitions in the vibrationally ES have been assigned for two conformers.…”

“…Our calculations may be compared with the previous study of Ref. [5] at the CC2/cc‐pVTZ level of theory and the experimental data in the UV range, in the MW range and in the mm‐wave range (this work). The calculations are in good agreement except for the dipole components.…”

“…The para isomer 4‐Methoxyphenol (commonly called mequinol) was also investigated in the same study and two possible conformers of the molecule, trans and cis, have been identified. Very recently, the conformational space of 3‐Methoxyphenol (3‐MP) has been specifically studied by the same group . For the meta isomer, four stable conformations are expected corresponding to the relative positions of the −OH and −OCH 3 groups in the benzene ring plane.…”

“…In order to identify the stable conformers of 3‐MP and to predict their GS rotational and dipolar constants as accurately as possible, high level of theory quantum chemical calculations were performed using Gaussian 16 . Our strategy consisted in the use of larger basis sets compared to previous ab initio studies ,. Dunning et al .…”

Excited‐State Dipole Moments and Transition Dipole Orientations of Rotamers of 1,2‐, 1,3‐, and 1,4‐Dimethoxybenzene

“…However, inductive (+I or −I) effects and even through‐space effects also influence the electron distribution between the ligand and the chromophore. For the hydroxy and methoxy substituents, it has been found that the adjacent C‐atom to which the lone pairs of the O‐atom points, has the lower electron density . Thus, it is interesting to investigate the dipole moments of different rotamers of disubstituted benzenes, which either can talk to each other electronically ( ortho and para ), or communicate only via inductive effects ( meta ).…”