Spectroscopic and Theoretical Determination of the Electronic Structure of Anisole, Thioanisole, and Methoxy- and Methylthiobenzonitriles:  A Contribution to the Study of Organic Conducting Polymers

and, Maurizio Dal Colle; Distefano, Giuseppe; Jones, Derek; Modelli, Alberto

doi:10.1021/jp000392w

Cited by 14 publications

(14 citation statements)

References 50 publications

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“…To discuss the orientation of the thioether group relative to flanking phenyl rings of 1 to 3 , parent thioanisole is taken as a reference for a planar conformation. Although the equilibrium conformation of neutral thioanisole is still under debate due to divergent experimental results, − there is no doubt about the planarity of its radical cation because it profits from a delocalization of the unpaired electron into the main phenyl π-system.…”

Section: Resultsmentioning

confidence: 99%

Spectroscopic Evidence for Through-Space Arene–Sulfur–Arene Bonding Interaction in m-Terphenyl Thioether Radical Cations

et al. 2015

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Electronic absorption spectra and quantum chemical calculations of the radical cations of m-terphenyl tert-butyl thioethers, where the S-t-Bu bond is forced to be perpendicular to the central phenyl ring, show the occurrence of through-space [π···S···π](+) bonding interactions which lead to a stabilization of the thioether radical cations. In the corresponding methyl derivatives there is a competition between delocalization of the hole that is centered on a p-AO of the S atom into the π-system of the central phenyl ring or through space into the flanking phenyl groups, which leads to a mixture of planar and perpendicular conformations in the radical cation. Adding a second m-terphenyl tert-butyl thioether moiety does not lead to further delocalization; the spin and charge remain in one of the two halves of the radical cation. These findings have interesting implications with regard to the role of methionines as hopping stations in electron transfer through proteins.

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Section: Resultsmentioning

confidence: 99%

Spectroscopic Evidence for Through-Space Arene–Sulfur–Arene Bonding Interaction in m-Terphenyl Thioether Radical Cations

et al. 2015

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“…discussed here. 45,46,61,63,83 We only present the results of calculations relevant to the protonated species. Similar to protonated phenol, 84 there are several protonation sites on neutral anisole and p-fluoroanisole corresponding to different positions of carbon atoms on the benzene rings.…”

Section: Computational Detailsmentioning

confidence: 99%

“…In the present study, protonation effects on the electronic transition energies and photophysical behavior of anisole and p-fluoroanisole will be addressed based on the CC2/MP2 methods. Anisole has been the subject of many experimental [43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60] and theoretical [61][62][63] studies. The high resolution S 1 -S 0 electronic excitation spectrum of anisole has been recorded in a molecular beam experiment by F. Lahmani et al 64 and later by C. G. Eisenhardt et al 48 It has been shown that the band origin of the S 1 -S 0 electronic transition of anisole lies at 36 386 cm À1 (4.512 eV).…”

Section: Introductionmentioning

confidence: 99%

Excited state deactivation pathways of neutral/protonated anisole and p-fluoroanisole: a theoretical study

Omidyan

Rezaei

2014

Phys. Chem. Chem. Phys.

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The potential energy profiles of neutral and protonated anisole and p-fluoroanisole at different electronic states have been investigated extensively by the RI-MP2 and RI-CC2 methods. The calculations reveal that the relaxation dynamics in protonated anisole and p-fluoroanisole are essentially different from those of the neutral analogues. In neutral anisole/p-fluoroanisole, the (1)πσ* state plays a vital relaxation role along the O-CH3 coordinate, yielding the CH3 radical. For both of these molecules, the calculations indicate conical intersections (CIs) between the ground and excited state potential energy (PE) curves, hindered by a small barrier, and providing non-adiabatic gates for radiation-less deactivation to the ground state. Nevertheless, for the protonated cases, besides the prefulvenic deformation of the benzene ring, it has been predicted that the lowest (1)(σ,n)π* state along the C-O-C bond angle plays an important role in photochemistry and the relaxation dynamics. The S1, S0 PE profiles of protonated anisole along with the former reaction coordinate (out-of-plane deformation) show a barrierless relaxation pathway, which can be responsible for the ultrafast deactivation of excited systems to the ground state via the low-lying S1/S0 conical intersection. Moreover, the later reaction coordinate in protonated species (C-O-C angle from 120°-180°) is consequently accompanied with the bond cleavage of C-OCH3 at the (1)(σ,n)π* state, hindered by a barrier of ∼0.51 eV, and can be responsible for the relaxation of excited systems with significant excess energy (hν≥ 5 eV). Furthermore, according to the RI-CC2 calculated results, different effects on the S1-S0 electronic transition energy of anisole and p-fluoroanisole upon protonation have been predicted. The first electronic transitions of anisole and p-fluoroanisole shift by ∼0.3 and 1.3 eV to the red respectively due to protonation.

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“…In several neutral molecules, information on the relative weight of the two conformers and the rotational energy barrier (i.e., the energy difference between the planar and the perpendicular conformers) has been determined by PES measurements [1][2][3] as well as by theoretical calculations. 3,4 A different situation appears to hold for the corresponding aromatic sulfide radical cations. ESR experiments indicate that the planar conformation is the predominant one, which means that the conjugation between the sulfur and the aromatic π system in the radical cation is much more important than the steric interactions.…”

Section: Introductionmentioning

confidence: 99%

Rotational Barriers, Charges, and Spin Densities in Alkyl Aryl Sulfide Radical Cations: A Density Functional Study

Baciocchi

Gerini

2004

J. Phys. Chem. A

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The structures and the torsional potentials for the rotation around the aryl-SR bond of a series of neutral alkyl aryl sulfides and their corresponding radical cations were studied by applying density functional theory at the B3LYP/6-311G** level. In all radical cations the most stable conformer corresponds to the structure in which the S-alkyl group is in the planar conformation, with sulfur and alkyl atoms coplanar with the aromatic ring. The rotational energy barriers were relatively high, ranging from 12.307 to 19.496 kcal/mol. In all cases substantial geometrical changes with respect to the parent sulfide were observed, the radical cation presenting a quinoidic structure, with quasi-single bonds alternating to quasi-double bonds, and a shorter C Ar -S bond. These results illustrate the importance, in the radical cation, of the conjugation between the sulfur atom and the aromatic π system. Such a conjugation is not so important in the neutral molecules and in fact the energy minimum for alkyl phenyl sulfides is located in correspondence of the perpendicular form, with the exception of thioanisole for which the two effects seem to have a similar role. Calculation of Mulliken spin populations, MK and NPA charges showed that PhSR •+ and 4-NCC 6 H 4 SR •+ are mainly sulfur-centered radical cations, whereas 4-Me 2 NC 6 H 4 SMe •+ and 4-MeOC 6 H 4 SMe •+ are essentially aromatic radical cations with some charge and spin density at the sulfur atom. Ionization energies were also calculated for both the planar and perpendicular forms; for the PhSR series (particularly in the former case), they resulted in good agreement with the experimental ones.

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Spectroscopic and Theoretical Determination of the Electronic Structure of Anisole, Thioanisole, and Methoxy- and Methylthiobenzonitriles: A Contribution to the Study of Organic Conducting Polymers

Cited by 14 publications

References 50 publications

Spectroscopic Evidence for Through-Space Arene–Sulfur–Arene Bonding Interaction in m-Terphenyl Thioether Radical Cations

Spectroscopic Evidence for Through-Space Arene–Sulfur–Arene Bonding Interaction in m-Terphenyl Thioether Radical Cations

Excited state deactivation pathways of neutral/protonated anisole and p-fluoroanisole: a theoretical study

Rotational Barriers, Charges, and Spin Densities in Alkyl Aryl Sulfide Radical Cations: A Density Functional Study

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