메뉴 건너뛰기




Volumn 127, Issue 46, 2005, Pages 16054-16064

Charge shift and triplet state formation in the 9-mesityl-10- methylacridinium cation

Author keywords

[No Author keywords available]

Indexed keywords

CHARGE TRANSFER; FLUORESCENCE; LIGHTING; ORGANIC COMPOUNDS; PHOSPHORESCENCE; REACTION KINETICS; THERMOANALYSIS;

EID: 28044466668     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja052967e     Document Type: Article
Times cited : (164)

References (126)
  • 72
    • 28044438227 scopus 로고    scopus 로고
    • note
    • 3 and between the two laboratories.
  • 92
    • 0004253982 scopus 로고
    • Interscience Publishers: New York; Chapter 11
    • (c) Acheson, R. M., Ed. Acridines, 2nd ed.; Interscience Publishers: New York, 1973; Chapter 11.
    • (1973) Acridines, 2nd Ed.
    • Acheson, R.M.1
  • 93
    • 28044441886 scopus 로고    scopus 로고
    • note
    • The compound was subjected to repeated column chromatography, TLC and recrystallization in an effort to minimize the contribution made by the LE fluorescence. Simultaneous analysis was made by time-resolved fluorescence to ensure the absence of a long-lived component in the decay records.
  • 94
    • 28044432805 scopus 로고    scopus 로고
    • note
    • + in mixtures, even when the latter is present at very low concentration.
  • 95
    • 28044466013 scopus 로고    scopus 로고
    • note
    • +, and it was assumed, on the basis of Gaussian analyses, that the CT fluorescence is negligible at 510 nm. The CT "pure" fluorescence spectrum was compiled from the Gaussian bands and the two resolved spectra combined to give the best least-squares match to the observed spectrum.
  • 101
    • 28044464975 scopus 로고    scopus 로고
    • note
    • (a) It should be noted that the apparent fluorescence maximum differs in acetonitrile (λ ≈ 590 nm), benzonitrile (λ ≈ 560 nm), and propylene carbonate (λ ≈ 570 nm) as shown in Figures 1, 5, and 6. This is due to very slight changes in the equilibrium distribution of LE and CT states in the different solvents. Because of the vastly different radiative rates, a trivial increase in the percentage of the LE state moves the emission maximum towards the blue. Detailed spectral curve fitting shows that the solvent has minimal effect on the actual energy levels of these two states. The equilibrium distribution is also changed slightly on addition of electrolytes such as tetra-N-butylammonium hexafluorophosphate.
  • 105
    • 28044463199 scopus 로고    scopus 로고
    • note
    • + under identical conditions, except for a small red shift.
  • 106
    • 28044456564 scopus 로고    scopus 로고
    • note
    • + in Oi-saturated acetonitrile has been reported previously but only in the presence of 9,10-dimethylanthracene (ref 20), where electron transfer might compete with singlet oxygen formation. In view of the high quantum yield for singlet oxygen production found here, together with the reinterpretation of the long-lived intermediate species, the mechanism given for the photooxygenation of anthracene derivatives needs to be reconsidered.
  • 108
    • 28044472573 scopus 로고    scopus 로고
    • note
    • The activated process observed at higher temperatures is not too dissimilar from that reported by Fukuzumi et al. (ref 16), allowing for the different solvents, although the derived parameters are different. The real disparity, however, is that whereas our results indicate the onset of an activationless process at low temperature, Fukuzumi et al. (ref 16) reported Arrhenius-type behavior even in frozen media. We have shown previously (ref 17) that the low-temperature EPR results are better explained in terms of a sacrificial photoreaction involving amine impurities in the solvent.
  • 109
    • 28044464055 scopus 로고    scopus 로고
    • note
    • 2 at room temperature (ref 22). The phosphorescence lifetime recorded at 77 K in ethanol containing 10% v/v iodomethane is 4 ms.
  • 110
    • 28044444360 scopus 로고    scopus 로고
    • note
    • (a) The reduction potential for one-electron oxidation of mesitylene in acetonitrile is reported as 1.88 V (ref 48b) vs SCE or 2.1 V (ref 48c) vs SCE. In our hands, the oxidative peak is highly irreversible due to a following chemical process.
  • 115
    • 28044468022 scopus 로고    scopus 로고
    • note
    • At the highest concentration of anthracene used (5 mM) ca. 15% of the CT singlet state would be quenched, but triplet quenching would be quantitative.
  • 117
    • 28044471397 scopus 로고    scopus 로고
    • note
    • 0 = -0.26 eV). The net effect, therefore. is the production of the anthracene π-radical cation by both routes.
  • 118
    • 28044452242 scopus 로고    scopus 로고
    • note
    • 2+ does not quench the triplet state under these conditions.
  • 121
    • 28044438746 scopus 로고    scopus 로고
    • note
    • (a) The apparent temperature dependence in fluid solution can be traced to small changes in the energy gap, connected with frequency changes in solvent librations.
  • 123
    • 28044466466 scopus 로고    scopus 로고
    • note
    • +. There is no mention of CT fluorescence, although this is well documented for related compounds (refs 22, 23, 34).
  • 125
    • 28044460329 scopus 로고    scopus 로고
    • note
    • Fukuzumi et al. (ref 16) report this quantum yield as being 0.98, on the basis of a comparative method apparently using anthracene as quencher, but this value is inconsistent with the noted effect of iodomethane.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.