Photodissociation spectroscopy of (benzene–toluene)+. Charge delocalization in the hetero-dimer ion

Ohashi, Kazuhiko; Nakane, Youko; Inokuchi, Yoshiya; Nakai, Yasuhiro; Nishi, Nobuyuki

doi:10.1016/s0301-0104(98)00313-9

“…7 Similarly, the 10 260 cm Ϫ1 band in the spectrum of T 2 ϩ is attributed to the CR band; the charge delocalization takes place also in T 2 ϩ . 10 For B 1 T 1 ϩ , there is one strong band at 8510 cm Ϫ1 , which can be ascribed to the CR band. On the basis of the overall features of the spectrum in the region from the visible to near-infrared, the probability of finding the charge on the toluene molecule is analyzed to be approximately 64% for B 1 T 1 ϩ .…”

Section: Methodsmentioning

confidence: 95%

“…More recently, we reported the photodissociation spectra of (benzene͒ 1 ͑toluene͒ 1 ϩ and (benzene͒ 1 ͑naphthalene͒ 1 ϩ . 10,16 For both ions, a strong absorption band is observed in the nearinfrared region; these results mean that the CR interaction occurs even in the heterodimer ions with a certain amount of ⌬IE. Neusser et al also presented an energetic scheme for predicting the dissociation pathways of (benzene) 1 (toluene͒ 2 ϩ and (benzene͒ 2 (toluene͒ 1 ϩ ; this scheme explains well the observed fragmentation patterns.…”

Section: Introductionmentioning

confidence: 87%

“…On the basis of the overall features of the spectrum in the region from the visible to near-infrared, the probability of finding the charge on the toluene molecule is analyzed to be approximately 64% for B 1 T 1 ϩ . 10 The spectra of B 1 T 2 ϩ and B 2 T 1 ϩ FIG. 1.…”

Section: Methodsmentioning

confidence: 99%

“…An analogous CR band is observed also for (toluene͒ 2 ϩ and ͑naphthalene͒ 2 ϩ . 10,11 For these ions, the principal intermolecular interaction is the CR interaction between the -electrons of the aromatic molecules. As seen in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…A simple perturbation theory for a nondegenerate system has been used for analyzing heterodimer ions. 10,16 We apply the same procedure for B 2 T 1 ϩ . Figure 7 depicts an energy level diagram of the species related to B 2 T 1 ϩ .…”

mentioning

confidence: 99%

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Positive charge distribution in (benzene)1(toleune)2+ and (benzene)2(toluene)1+ studied by photodissociation spectroscopy

Inokuchi

¹

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Ohashi²,

Sekiya

³

et al. 2002

The Journal of Chemical Physics

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Aromatic Charge Resonance Interaction Probed by Infrared Spectroscopy

Chatterjee

¹

,

Matsumoto

²

,

Dopfer

³

2018

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Charge resonance is as trong attractive intermolecular force in aromatic dimer radical ions.D espite its importance,this fundamental interaction has not been characterized at high resolution by spectroscopyo fi solated dimers.W e employv ibrational infrared spectroscopyo fc old aromatic pyrrole dimer cations to precisely probe the charge distribution by measuring the frequency of the isolated N À Hstretch mode (n NH ). We observe al inear correlation between n NH and the partial charge qo nt he pyrrole molecule in different environments.S ubtle effects of symmetry reduction, such as substitution of functional groups (here pyrrole replaced by Nmethylpyrrole) or asymmetric solvation (here by an inert N 2 ligand), shift the charge distribution towardt he moiety with lower ionization energy.T his general approach provides ap recise experimental probe of the asymmetry of the charge distribution in such aromatic homo-and heterodimer cations.The intermolecular interactions of aromatic p electrons are important for chemical and biological recognition. [1] Radical ions of arenes are involved in chemical reaction mechanisms, charge transport of modern (bio-)organic materials (organic electronics), and radiation damage in DNAand proteins. [2] In addition to p H-bonding,c ation/anion-p,a nd p-p stacking interactions, [3] the charge-resonance (CR) interaction is af undamental and very strong force in charged arene dimers. [4] Forc ations,t his stabilization arises from sharing the positive charge between two identical or different molecules with the same or comparable ionization energies in a p-stacked dimer.I nahomodimer cation (A 2 + ), the positive charge is equally shared between both molecules, while in ah eterodimer (AB + )t he partner with the lower ionization energy (IE) carries more positive charge.I nt he simplest description, the CR interaction in A 2 + causes as plitting between the two electronic states described by Y AE = Y(A + )Y(A) AE Y(A)Y(A + ); the symmetric Y + ground state is stable and the destabilized antisymmetric Y À state is repulsive.The splitting between both electronic states is twice the stabilization energy of the ground state (ca. 50-100 kJ mol À1 ). Thei nteraction is strongest for A 2 + homodim-ers,a nd decreases in AB + as the difference in the IEs of the two molecules increases (DIE = IE A ÀIE B ). This description of the CR interaction in arene dimer ions is similar to the one employed for odd electron chemical bonds in radical ions (hemibonds) [5] and exciton splitting in delocalized electronic excitation in neutral dimers. [6] In the condensed phase, p-stacked dimer cations of aromatic and polycyclic aromatic hydrocarbons were first detected by electron spin resonance [7] and optical absorption spectroscopy of the intense and broad CR transition connecting the two Y AE states. [7d, 8] Thelatter electronic transition occurs in the low-energy part of the optical spectrum (in the red to near-infrared near 1 mm) and provides adirect measure for the CR splitting.Inthe gas phase,the binding e...

show abstract

Aromatic Charge Resonance Interaction Probed by Infrared Spectroscopy

Chatterjee

¹

,

Matsumoto

²

,

Dopfer

³

2018

View full text Add to dashboard Cite

Charge resonance is as trong attractive intermolecular force in aromatic dimer radical ions.D espite its importance,this fundamental interaction has not been characterized at high resolution by spectroscopyo fi solated dimers.W e employv ibrational infrared spectroscopyo fc old aromatic pyrrole dimer cations to precisely probe the charge distribution by measuring the frequency of the isolated N À Hstretch mode (n NH ). We observe al inear correlation between n NH and the partial charge qo nt he pyrrole molecule in different environments.S ubtle effects of symmetry reduction, such as substitution of functional groups (here pyrrole replaced by Nmethylpyrrole) or asymmetric solvation (here by an inert N 2 ligand), shift the charge distribution towardt he moiety with lower ionization energy.T his general approach provides ap recise experimental probe of the asymmetry of the charge distribution in such aromatic homo-and heterodimer cations.The intermolecular interactions of aromatic p electrons are important for chemical and biological recognition. [1] Radical ions of arenes are involved in chemical reaction mechanisms, charge transport of modern (bio-)organic materials (organic electronics), and radiation damage in DNAand proteins. [2] In addition to p H-bonding,c ation/anion-p,a nd p-p stacking interactions, [3] the charge-resonance (CR) interaction is af undamental and very strong force in charged arene dimers. [4] Forc ations,t his stabilization arises from sharing the positive charge between two identical or different molecules with the same or comparable ionization energies in a p-stacked dimer.I nahomodimer cation (A 2 + ), the positive charge is equally shared between both molecules, while in ah eterodimer (AB + )t he partner with the lower ionization energy (IE) carries more positive charge.I nt he simplest description, the CR interaction in A 2 + causes as plitting between the two electronic states described by Y AE = Y(A + )Y(A) AE Y(A)Y(A + ); the symmetric Y + ground state is stable and the destabilized antisymmetric Y À state is repulsive.The splitting between both electronic states is twice the stabilization energy of the ground state (ca. 50-100 kJ mol À1 ). Thei nteraction is strongest for A 2 + homodim-ers,a nd decreases in AB + as the difference in the IEs of the two molecules increases (DIE = IE A ÀIE B ). This description of the CR interaction in arene dimer ions is similar to the one employed for odd electron chemical bonds in radical ions (hemibonds) [5] and exciton splitting in delocalized electronic excitation in neutral dimers. [6] In the condensed phase, p-stacked dimer cations of aromatic and polycyclic aromatic hydrocarbons were first detected by electron spin resonance [7] and optical absorption spectroscopy of the intense and broad CR transition connecting the two Y AE states. [7d, 8] Thelatter electronic transition occurs in the low-energy part of the optical spectrum (in the red to near-infrared near 1 mm) and provides adirect measure for the CR splitting.Inthe gas phase,the binding e...

show abstract

Photodissociation spectroscopy of (benzene–toluene)+. Charge delocalization in the hetero-dimer ion

Cited by 23 publications

References 22 publications

Positive charge distribution in (benzene)1(toleune)2+ and (benzene)2(toluene)1+ studied by photodissociation spectroscopy

Positive charge distribution in (benzene)1(toleune)2+ and (benzene)2(toluene)1+ studied by photodissociation spectroscopy

Aromatic Charge Resonance Interaction Probed by Infrared Spectroscopy

Aromatic Charge Resonance Interaction Probed by Infrared Spectroscopy

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