Perylene Radical Research Articles

ENDOR of perylene radicals adsorbed on alumina and silica-alumina powders: II. The matrix effects

Nuclei in the environment (matrix) of perylene cation radicals formed on activated alumina and silica-alumina powders exposed to solutions of perylene in benzene solvent were probed with electron nuclear double-resonance (ENDOR) spectroscopy. Both normal and fully deuterated perylene and benzene were studied. Depending on the nature of the sample and experimental conditions, signals were detected from protons, deuterons, and aluminum-27 in the environment of the radical. A strong proton matrix signal was observed in spectra of alumina-adsorbed radicals in all preparations, indicating the presence of protons on the surface. In contrast, spectra of radicals adsorbed on silica-alumina exhibited much weaker proton matrix signals under all conditions. A deuterium matrix signal was observed with both alumina and silica-alumina surfaces (although weakly on the latter) when deuterated solvent was present. Aluminum-27 signals were seen only from samples on the alumina surface. Active site models consistent with the results are discussed. The results suggest that the radicals, although themselves similar, occupy sites of significantly different environment.

ChemInform Abstract: ENDOR of Perylene Radicals Adsorbed on Alumina and Silica‐Alumina Powders. Part 1. The Ring Protons.

ChemInformVolume 18, Issue 52 Physical Organic Chemistry ChemInform Abstract: ENDOR of Perylene Radicals Adsorbed on Alumina and Silica-Alumina Powders. Part 1. The Ring Protons. R. B. CLARKSON, R. B. CLARKSON Dep. Chem., Univ. Ala., Birmingham, AL 35294, USASearch for more papers by this authorR. L. BELFORD, R. L. BELFORD Dep. Chem., Univ. Ala., Birmingham, AL 35294, USASearch for more papers by this authorK. S. ROTHENBERGER, K. S. ROTHENBERGER Dep. Chem., Univ. Ala., Birmingham, AL 35294, USASearch for more papers by this authorH. C. CROOKHAM, H. C. CROOKHAM Dep. Chem., Univ. Ala., Birmingham, AL 35294, USASearch for more papers by this author R. B. CLARKSON, R. B. CLARKSON Dep. Chem., Univ. Ala., Birmingham, AL 35294, USASearch for more papers by this authorR. L. BELFORD, R. L. BELFORD Dep. Chem., Univ. Ala., Birmingham, AL 35294, USASearch for more papers by this authorK. S. ROTHENBERGER, K. S. ROTHENBERGER Dep. Chem., Univ. Ala., Birmingham, AL 35294, USASearch for more papers by this authorH. C. CROOKHAM, H. C. CROOKHAM Dep. Chem., Univ. Ala., Birmingham, AL 35294, USASearch for more papers by this author First published: December 29, 1987 https://doi.org/10.1002/chin.198752055AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume18, Issue52December 29, 1987 RelatedInformation

ENDOR of perylene radicals adsorbed on alumina and silica-alumina powders. I. The ring protons

Complex electron-nuclear double-resonance (ENDOR) spectra were obtained from the radicals formed on activated alumina and silica-alumina powders exposed to solutions of perylene in benzene. Use of deuterated solvent to suppress spectral contributions from proton matrix effects enabled more detailed analysis of resonances associated with hyperfine interactions of ring protons of the perylene radical ion. A model of isotropic Zeeman interactions (g) and very anisotropic hyperfine splittings (A) is supported by multifrequency EPR measurements and ENDOR simulations devised for this work. All three proton hyperfine interactions of the perylene radical ion were resolved and the absolute values of the principal elements of the hyperfine coupling matrices were obtained. The fact that these values for radicals formed on alumina and silica-alumina were nearly identical implies that the same radical species forms on both surfaces. These findings are discussed and the radical is assigned as the cation.

Electron spin echo spectroscopy: A tool to probe structural properties of coals

Electron spin echo (e.s.e.) spectroscopy has been used in these laboratories to investigate proton hyperfine interactions in whole coal, separated coal macerals, synthetic lignites and model materials comprising perylene radical ions adsorbed on alumina and silica-alumina catalysts. The e.s.e. technique provides information that is complementary to electron nuclear double resonance in studying such interactions in coal. Coupling constants measured so far in evacuated samples of Illinois No. 6 agree well with models for condensed ring aromatic structures. Analysis of the proton matrix interactions are best fitted by r = 0.75 ± 0.05 nm, A iso = 0 and n = 40 protons. Matrix interactions from 13C nuclei also are seen. Coupling constants observed in a vitrain component separated from Illinois No. 6 coal are similar to those seen in the whole coal; the fact that the maceral does not exhibit all of the interactions found in whole coal suggests molecular structures to be specific to individual maceral types. Differences in the g-values of macerals may provide a direct, non-destructive route to the analysis of maceral-specific structure.

Electronic absorption spectrum of perylene radical cation trapped in boric acid film

A detailed spectroscopic analysis of the electronic absorption spectrum of the perylene radical cation, produced in a boric acid film by photo-oxidation is reported. To interpret the experimental spectrum, the electronic energy levels and oscillator strengths have been calculated using the Pariser—Parr molecular orbital method with limited configuration interaction. The effect of variation of solute concentration and irradiation time of the films has also been studied. It is found that the agreement between experimental and theoretical results in excellent.

ChemInform Abstract: NITRATION OF AROMATICS VIA ELECTRON TRANSFER. IV. ON THE REACTION BETWEEN PERYLENE RADICAL CATION AND NITROGEN DIOXIDE OR NITRITE ION

Chemischer InformationsdienstVolume 16, Issue 41 Preparative Organic Chemistry ChemInform Abstract: NITRATION OF AROMATICS VIA ELECTRON TRANSFER. IV. ON THE REACTION BETWEEN PERYLENE RADICAL CATION AND NITROGEN DIOXIDE OR NITRITE ION L. EBERSON, L. EBERSONSearch for more papers by this authorF. RADNER, F. RADNERSearch for more papers by this author L. EBERSON, L. EBERSONSearch for more papers by this authorF. RADNER, F. RADNERSearch for more papers by this author First published: October 15, 1985 https://doi.org/10.1002/chin.198541121Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume16, Issue41October 15, 1985 RelatedInformation

Organic Metals from Simple Aromatic Hydrocarbons: Perylene Radical Salts

Crystal structures, temperature dependent thermopower and conductivity measurements of several metallic perylene radical salt phases are discussed.

Electron spin resonance study of the interaction of perylene with alumina

ESR spectra obtained from the interaction of perylene with alumina become less well resolved with time. The resolution decays with a rate that is dependent on the concentration of adsorbed radical and to a lesser extent on the activation temperature of the catalyst. Radical concentrations < 10 16 g −1 of catalyst and activation temperatures > 650°C give low rates of decay. Decreasing the temperature at which adsorption of the perylene occurs reduces the decay rate markedly. Under suitable conditions a well-resolved nine-line spectrum can be observed for the perylene cation-radical generated on the surface of pure alumina at ambient temperatures. Molecular oxygen plays a decisive role in this electron-transfer process. Subsequent chemical reaction between the perylene cation-radical and oxygen leads to the formation of new radical species and largely accounts for the decrease in resolution of the ESR spectrum with time. On some sites on the alumina surface, however, the perylene radical is stable for long periods. Present findings have particular importance for current theories of cationradical formation on the alumina surface.

Nitration of Aromatics via Electron Transfer. IV. On the Reaction between Perylene Radical Cation and Nitrogen Dioxide or Nitrite Ion.

Nitration of Aromatics via Electron Transfer. IV. On the Reaction between Perylene Radical Cation and Nitrogen Dioxide or Nitrite Ion.

Highly Conducting Perylene Radical Salts

Abstract Temperature dependent dc and microwave conductivity data together with EPR and optical reflectance measurements on the “mixed” system (pe)2(ASF6)0,75(PF6)0,35 × 0,85 CH2Cl2 are described. The data prove metallic behaviour of this organic solid down to 200 K.

Dimerization Equilibria of Aromatic Radical Cations

AbstractIt is demonstrated that for the system perylene in butyronitril, the dimerization equilibria of radical cations R+ + R ⇌ R+2 (I) and 2R+ ⇌ R++2 (II), occur simultaneously. In order to determine thermodynamic data, the complex system can be divided in simple subsystems by employing the property that one component, the radical cations, is generated electrolytically. Thus from the derivative of the absorbance A with respect to the charge q consumed at q = 0, (dA/dq)q=0, the parameters of equilibrium I are obtained: −ΔH+ = (36 ± 6) kJ/mol, −ΔS+ = 71 ± 8) J/mol · K. The temperature variation of a nearly totally electrolyzed solution enables the determination of the parameters of equilibrium II: −ΔH++ = (45 ± 2) kJ/mol, −ΔS++ = (76 ± 8) J/mol · K. For equilibrium I the influence of the follow‐up reaction of perylene radical cations with traces of water could be described quantitatively (pseudo first‐order rate constant −2 · 10−3 s−1).

Radical ion reactivity—I : Application of the dewar-zimmerman rules to certain reactions of radical anions and cations

The application of the Dewar-Zimmerman rules to the interaction between radical cations, derived from 4n + 2 systems, shows that a nucleophile orbital interacting suprafacially with the ion should correspond to an antiaromatic transition state and hence to a less favored pathway relative to competing ones, e.g. electron transfer. An antarafacial interaction would on the other hand correspond to an aromatic transition state and be energetically favorable. Both types of interaction are generally possible for the same reagent, but since the suprafacial one for geometric reasons ensues and thus predominates in the early stage of the reaction, the net result should be an anomalously low reactivity of radical cations vs attack by nucleophiles. By calibration against known, qualitative reactivity data for perylene radical cation it is strongly indicated that halide ions belong to a class of reagents which do not react nucleophilically with radical cations but instead undergo electron transfer oxidation or do not react at all. This type of reaction is discussed in some detail. and several mechanisms involving radical cation/halide ion combination as a critical step can either be ruled out or considered open for reinvestigation. The same idea can be applied to the reaction between radical anions and electrophiles. Accordingly, the protonation of radical anions derived from 4n+2 aromatic systems is remarkably slow, as compared to that of analogous carbanions.

The reduction of perylene radical cation by nucleophilic addition

The reduction of perylene radical cation by nucleophilic addition

Solvation Shell Relaxation and Ion-Electron Recombination in Strongly Associated Solvents

The relaxation properties of the region in a solution in which there is strong interaction between the solute and solvent molecules (the cybotactic region) were studied with electron paramagnetic resonance spectroscopy used as the detection system. In the system under investigation, perylene radical cation was used as the solute, and either sulfuric acid or fluorosulfonic acid was used as the solvent. The properties studied were the solvent cage reorientation time and the ion-electron recombination time. Modulated light of a known wavelength distribution was used to irradiate the sample and synchronize a lock-in detector, which was used to detect the light-induced effects, to the light modulation frequency. Signal averaging techniques were used so that accurate values of the output as functions of the sample temperature, irradiation light wavelength, and irradiation light modulation frequency were obtained. Two extreme model systems were used to interpret the light-induced signal data, a reversible and an impulse model. A range of times was specified for the solvent cage reorientation and ion-electron recombination as a function of the sample temperature. In sulfuric acid, the cage reorientation time varies from 1176 μsec at 6°C to 99 μsec at 77°C, while the ion-electron recombination time varies from 649 to 42 μsec. The temperature range studied for fluorosulfonic acid was −36–95°C. In this range, the cage reorientation time varied from 857 to 81 μsec and the ion-electron recombination from 815 to 35 μsec. Over the temperature ranges studied, the intermediate coupling constant for the perylene radical cation increased from 13.7 to 224 mG in sulfuric acid and 19.7 to 345 mG in fluorosulfonic acid.

Protonation of perylene radical anions by alcohols and water in tetrahydrofuran

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTProtonation of perylene radical anions by alcohols and water in tetrahydrofuranG. Levin, C. Sutphen, and M. SzwarcCite this: J. Am. Chem. Soc. 1972, 94, 8, 2652–2656Publication Date (Print):April 1, 1972Publication History Published online1 May 2002Published inissue 1 April 1972https://doi.org/10.1021/ja00763a015RIGHTS & PERMISSIONSArticle Views145Altmetric-Citations27LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (492 KB) Get e-Alerts Get e-Alerts

Electrochemiluminescence of Energy‐Deficient Systems I. Triplet‐Triplet‐Annihilation in Mixed Systems

AbstractIt is shown by means of electrochemical experiments that the chemiluminescent electron‐transfer reaction between perylene radical anions and tri‐p‐tolylamine radical cations and between perylene radical cations and benzil radical anions, respectively, are energy‐deficient, i. e. the reaction enthalpy is smaller than the energy of the lowest excited singlet state of perylene, the fluorescence emission of which is observed. This result implies the formation of perylene molecules in the triplet state in the course of the electron‐transfer reaction with subsequent triplet‐triplet annihilation yielding perylene molecules in the excited singlet state. The triplet mechanism is confirmed by the analysis of the light intensity‐time curves.

Electrochemiluminescence of Energy‐Deficient Systems II. The Role of Excimer Formation in the Pure Perylene System

AbstractThe reaction enthalpy Δ H of the chemiluminescent electron‐transfer reaction between perylene radical cations and anions has been estimated from electrochemical measurements. The comparison of H with the energies of the excited states of perylene leads to the conclusion that excited singlet molecules, the emission of which is observed, cannot be formed directly; rather excited triplets are produced in the electron‐transfer reaction which yield excited singulets via triplet‐triplet annihilation. This mechanism is confirmed by the analysis of the ecl intensity‐time curves. The long‐wavelength component occuring in the ecl spectrum of perylene is ascribed to excimer emission in agreement with the experimental results. These suggest the assumption that the intensity ratio of the long‐wavelength component to the fluorescent component is determined by the fact that perylene triplets—dependent on electrolysis time ‐ are quenched by excess radical ions in the reaction zone; the excimers, however, are not.

Computer Simulation of the ESR Spectra of the Naphthalene, Anthracene, and Perylene Radical Cations in a Polycrystalline Medium

Computer simulation of ESR spectra in polycrystalline environments is extended to the case of free radicals in which the unpaired spin is extensively delocalized. An approximate model is proposed for the anisotropic effects (g tensor, dipolar hyperfine tensor, component shape and width). This model is tested on the spectra of anthracene and perylene radical cations in boric-acid glass [G. Vincow and P. M. Johnson, J. Chem. Phys. 39, 1143 (1963)]. The spectral structure is reproduced by the calculations. A principal application of this simulation procedure is the extraction of values of the Fermi contact hyperfine splittings in cases for which these have not been measured. As an illustration, the powder spectrum of the naphthalene cation radical is considered, yielding | a1H | = 5.4 ± 0.3 G and | a2H | = 1.62 ± 0.3 G. In addition calculations are performed which indicate the sensitivity of the simulated spectra to variations in values of the parameters of the model.