Isotope effect on the J–T distortion of partially deuteriated benzene cation radicals: an experimental EPR and theoretical DFT study

Toriyama, Kazumi; Okazaki, Masaharu; Jansson, Magnus; Lund, Anders; Lunell, Sten

doi:10.1039/b315835g

Cited by 6 publications

(6 citation statements)

References 26 publications

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“…Some key structural parameters of these coordination sites in Ru-1 and Ru-3 are selected and shown in Supplementary Table S1 (Supporting Information). These coordination sites are octahedral ones, with geometric distortion caused by Jahn-Teller effect ( Toriyyama et al, 2004 ). Their Ru(II)-N bond length values fit in a restricted region of 2.06 ± 0.03 Å, whereas the ligand bite angles with Ru(II) center localize in a region of 79 ± 2°.…”

Section: Resultsmentioning

confidence: 99%

Comparison Between Binuclear and Mononuclear Ru(II) Complexes: Synthesis, Structure, Photophysics, and Oxygen Sensing Performance

2021

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Owing to their attractive potential in optoelectronic application, luminescent Ru(II) complexes with diamine ligands are harvesting more and more research efforts. These literature efforts, however, are mostly mononuclear ones, with no detailed discussion on the performance comparison between mononuclear and multinuclear Ru(II) complexes. This work synthesized three diamine ligands having two or multiple chelating sites in each ligand, as well as their Ru(II) complexes. The single-crystal structure, electronic structure, and photophysical parameters of these Ru(II) complexes were analyzed and compared. It was found that multinuclear Ru(II) complexes had a pure MLCT (metal-to-ligand charge transfer)–based emissive center, showing longer emission lifetime and higher emission quantum yield, which were desired for oxygen sensing. Then, the oxygen sensing performance of these mononuclear and multinuclear Ru(II) complexes was systematically compared by doping them into polymer fibers via electrospinning method. Improved oxygen sensing performance was observed from binuclear Ru(II)-doped nanofibrous samples, compared with the sensing performance of mononuclear ones, including higher sensitivity, shorter response/recovery time, and better photostability. The causation was attributed to the fact that the emissive state of multinuclear Ru(II) complexes was MLCT-based ones and thus more sensitive to O2 quenching than monocular Ru(II) complexes whose emissive state was a mixture of MLCT and LLCT (ligand-to-ligand charge transfer). In addition, a multinuclear Ru(II) complex had multiple emissive/sensing components, so that its sensing collision probability with O2 was increased, showing better photostability and shorter response/recovery time. The novelty of this work was the linear oxygen sensing curve, which was rarely reported in the previous work.

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Section: Resultsmentioning

confidence: 99%

Comparison Between Binuclear and Mononuclear Ru(II) Complexes: Synthesis, Structure, Photophysics, and Oxygen Sensing Performance

2021

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“…The ESR detection of the static Jahn-Teller distortion in cationic radicals with originally degenerated occupied molecular states has been done already with several examples such as SF 6 + [132], benzene + [133,134], etc . At higher temperatures the hyperfine structure for the benzene cation results in six equivalent protons due to the fast exchange of the three equivalent distorted structures [135].…”

Section: Selected Examplesmentioning

confidence: 99%

“…This phenomenon is called pseudo-rotation. The influence of the isotopic substitution on the Jahn-Teller distortion was demonstrated by means of cations of methane, cyclopropane, and cyclohexane [134]. The respective theoretical background can found in [136].…”

Section: Selected Examplesmentioning

confidence: 99%

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Isotope Effects in ESR Spectroscopy

Stößer

Herrmann

2013

Molecules

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In order to present the relationship between ESR spectroscopy and isotope effects three levels are considered: (i) ESR spectroscopy is described on a general level up to the models for interpretation of the experimental spectra, which go beyond the usually used time and mass independent spin-Hamilton operator, (ii) the main characteristics of the generalized isotope effects are worked out, and finally (iii) the basic, mainly quantum mechanical effects are used to describe the coupling of electron spins with the degrees of freedom, which are accessible under the selected conditions, of the respective paramagnetic object under investigation. The ESR parameters and the respective models are formalized so far, that they include the time and mass depending influences and reflect the specific isotope effects. Relations will be established between the effects in ESR spectra to spin relaxation, to spin exchange, to the magnetic isotope effect, to the Jahn-Teller effects, as well as to the influence of zero-point vibrations. Examples will be presented which demonstrate the influence of isotopes as well as the kind of accessible information. It will be differentiated with respect to isotope effects in paramagnetic centres itself and in the respective matrices up to the technique of ESR imaging. It is shown that the use of isotope effects is indispensable in ESR spectroscopy.

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“…Benzene (Bz) is a simple aromatic hydrocarbon and an important solvent for several organic solutes. The radical cation of the benzene molecule (Bz + ) is J–T active, and it has several other interesting characteristics. − Figure shows a schematic illustration of the types of structural deformation of Bz + and the shifts of orbital energies due to the J–T effect (an expression of the potential energy curve is given in Scheme S1 of the Supporting Information). There are two types of deformation in Bz + : the compressed and elongated forms, which are expressed as Bz + (comp) and Bz + (elong), respectively.…”

Section: Introductionmentioning

confidence: 99%

Jahn–Teller Effect of the Benzene Radical Cation: A Direct ab Initio Molecular Dynamics Study

Tachikawa

2018

J. Phys. Chem. A

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The benzene radical cation (Bz) is a typical model molecule of the Jahn-Teller (J-T) active species. Bz has two structural forms due to the J-T effect. These are the compressed and elongated forms, expressed as Bz(comp) and Bz(elong), respectively. In Bz(comp), the hexagonal structure of the benzene ring is compressed up and down, and in Bz(elong), it is pulled up and down. From electron spin resonance experiments, it was found that Bz takes a compressed form in low-temperature Freon matrices (CFCl and CFClCFCl), whereas the elongated form was found in argon matrices. However, the selectivity of these structural forms is still unclear. In this study, the ionization dynamics of isolated benzene (Bz) and benzene-M complexes (where M denotes counter-molecules, M = NH, HO, CFCl, CH, CHOH, Ar, SH, ammonia dimer, or water dimer) have been investigated by means of the direct ab initio molecular dynamics (AIMD) method in order to shed light on the Bz formation mechanism. The static ab initio calculations showed that Bz(comp) is slightly more energetically stable than Bz(elong), although the energy difference was only 0.1 kcal/mol at the CCSD/6-311++G(d,p) level. The direct AIMD calculations indicated that Bz(comp) was formed from the Bz-M complexes when M was NH, CFCl, or an ammonia dimer, whereas the ionization of Bz-M when M was HO, CH, CHOH, SH or a water dimer formed Bz(elong). In the case of complexes with an argon dimer, Bz(Ar), both forms were obtained from a slight orientation change of Ar on Bz. A selective rule is discussed on the basis of the calculated results.

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Isotope effect on the J–T distortion of partially deuteriated benzene cation radicals: an experimental EPR and theoretical DFT study

Cited by 6 publications

References 26 publications

Comparison Between Binuclear and Mononuclear Ru(II) Complexes: Synthesis, Structure, Photophysics, and Oxygen Sensing Performance

Comparison Between Binuclear and Mononuclear Ru(II) Complexes: Synthesis, Structure, Photophysics, and Oxygen Sensing Performance

Isotope Effects in ESR Spectroscopy

Jahn–Teller Effect of the Benzene Radical Cation: A Direct ab Initio Molecular Dynamics Study

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