메뉴 건너뛰기




Volumn 129, Issue 16, 2007, Pages 5012-5022

New insights into the mechanism of triplet radical-pair combinations. The persistent radical effect masks the distinction between in-cage and out-of-cage processes

Author keywords

[No Author keywords available]

Indexed keywords

DERIVATIVES; DIFFUSION; FREE RADICALS; PLASTIC FILMS; RATE CONSTANTS; VISCOSITY;

EID: 34247489197     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja067461q     Document Type: Article
Times cited : (20)

References (108)
  • 21
    • 34247473611 scopus 로고    scopus 로고
    • Except as necessary for clarity, the subscript designating the specific nature of the B radicals is omitted
    • Except as necessary for clarity, the subscript designating the specific nature of the B radicals is omitted.
  • 22
    • 0001672291 scopus 로고
    • See for instance: a
    • See for instance: (a) Buchachenko, A. L. Chem. Rev. 1995, 95, 2507-2528.
    • (1995) Chem. Rev , vol.95 , pp. 2507-2528
    • Buchachenko, A.L.1
  • 45
    • 0035781101 scopus 로고    scopus 로고
    • (c) Fischer, H. Chem. Rev. 2001, 101, 3581-3610.
    • (2001) Chem. Rev , vol.101 , pp. 3581-3610
    • Fischer, H.1
  • 50
    • 3242712357 scopus 로고    scopus 로고
    • See for instance: a
    • See for instance: (a) Studer, A. Chem. Soc. Rev. 2004, 33, 267-273.
    • (2004) Chem. Soc. Rev , vol.33 , pp. 267-273
    • Studer, A.1
  • 51
    • 49249104655 scopus 로고    scopus 로고
    • Advances in Controlled/Living Radical Polymerization
    • Matyjaszewski, K, Ed, American Chemical Society: Washington, DC
    • (b) Fischer, H. In Advances in Controlled/Living Radical Polymerization; Matyjaszewski, K., Ed.; ACS Symposium Series 854; American Chemical Society: Washington, DC, 2003, pp 10-23.
    • (2003) ACS Symposium Series , vol.854 , pp. 10-23
    • Fischer, H.1
  • 52
    • 0032688223 scopus 로고    scopus 로고
    • Methods that are not generally applicable to monomeric systems or easily amenable to closed solutions are available. See for instance: (a) Fischer, H. J. Polym. Sci, Part A: Polym. Chem. 1999, 37, 1885-1901
    • Methods that are not generally applicable to monomeric systems or easily amenable to closed solutions are available. See for instance: (a) Fischer, H. J. Polym. Sci., Part A: Polym. Chem. 1999, 37, 1885-1901.
  • 72
    • 7744220379 scopus 로고    scopus 로고
    • 16 that would result from recombination of the initial acyl/benzylic radical pairs after irradiations in n-hexane or the polyethylene films. (a) Kaanumalle, L. S.; Gibb, C. L. D.; Gibb, B. C.; Ramamurthy, V. J. Am. Chem. Soc. 2004, 126, 14366-13467.
    • 16 that would result from recombination of the initial acyl/benzylic radical pairs after irradiations in n-hexane or the polyethylene films. (a) Kaanumalle, L. S.; Gibb, C. L. D.; Gibb, B. C.; Ramamurthy, V. J. Am. Chem. Soc. 2004, 126, 14366-13467.
  • 77
    • 0002313325 scopus 로고
    • Volman, D. H, Hammond, G. S, Neckers, D. C, Eds, Wiley-Interscience: New York
    • (b) Ramamurthy, V.; Weiss, R. G.; Hammond, G. S. In Advances in Photochemistry; Volman, D. H., Hammond, G. S., Neckers, D. C., Eds.; Wiley-Interscience: New York, 1993; Vol. 18, pp 67-234.
    • (1993) Advances in Photochemistry , vol.18 , pp. 67-234
    • Ramamurthy, V.1    Weiss, R.G.2    Hammond, G.S.3
  • 89
    • 0003010968 scopus 로고
    • Bamford, C. H, Tipper, C. F. H, Compton, R. G, Eds, Elsevier: Amsterdam, The Netherlands
    • (a) Rice, S. A. In Diffusion-Limited Reactions. Comprehensive Chemical Kinetics; Bamford, C. H., Tipper, C. F. H., Compton, R. G., Eds.; Elsevier: Amsterdam, The Netherlands, 1985; Vol. 25, pp 1-400.
    • (1985) Diffusion-Limited Reactions. Comprehensive Chemical Kinetics , vol.25 , pp. 1-400
    • Rice, S.A.1
  • 92
    • 0003542711 scopus 로고    scopus 로고
    • Neogi, P, Ed, Marcel Dekker: New York
    • (a) Neogi, P., Ed. Diffusion in Polymers; Marcel Dekker: New York, 1996.
    • (1996) Diffusion in Polymers
  • 95
    • 34247540142 scopus 로고    scopus 로고
    • The concentration of oxygen (from air) in a PE film is ∼4 × 10-4 M.38a In a low-density PE at room temperature, the diffusion coefficients for toluene (a model which overestimates somewhat the diffusion coefficients of benzyl and p-methylbenzyl32,33) and molecular oxygen are ∼2 × 10-8 cm2/s 38b and ∼4.6 × 10-7 cm2/s, 38c respectively. Assuming a collision radius (ρ′) of 5 Å and kdif, 4πρ′N(D1, D2)/1000, a value of ∼108 L/mol-s is calculated. Then, the rate of collision of molecular oxygen with a benzylic radical is ∼4 × 104 s-1, somewhat slower than (but comparable to) the rate of the in-cage reactions (kr, see Table 1, a) Michaels, A. S, Bixler, H. J. J. Polym. Sci. 1961, L, 393
    • r) (see Table 1). (a) Michaels, A. S.; Bixler, H. J. J. Polym. Sci. 1961, L, 393-412.
  • 98
    • 77956803814 scopus 로고    scopus 로고
    • The actual processes for combination of free radicals from the singlet channel are more complex than what is shown here. The simplified expression of the rate constants as 1/4 kdIJKIJ in eq 16, 20, and 24 of the model in Supporting Information is warranted because singlet → triplet radical-pair intersystem crossing should be much slower than an in-cage combination, and in-cage combinations of alkyl singlet radical-pairs is a barrierless process that can compete favorably with diffusion even in fluid solutions39a,b (and, therefore, certainly in our PE films, a) Strauss, O. P, Lown, J. W, Gunning, H. E. in Comprehensive Chemical Kinetics; Bamford, C. H, Tippen, C, Eds, Elsevier: Amsterdam, The Netherlands, 1973; 5, p 566 and references therein
    • 39a,b (and, therefore, certainly in our PE films). (a) Strauss, O. P.; Lown, J. W.; Gunning, H. E. in Comprehensive Chemical Kinetics; Bamford, C. H., Tippen, C., Eds.; Elsevier: Amsterdam, The Netherlands, 1973; Vol. 5, p 566 and references therein.
  • 100
    • 34247539218 scopus 로고    scopus 로고
    • Fitting of the experimental transient absorption traces was performed using the generalized reduced gradient (GRG2) nonlinear optimization code. Lasdon, L. S, Warren, A. D, Jain, A, Ratner, M. ACM Trans. Math. Software 4; Association for Computing Machinery: New York, 1978; pp. 34-50
    • Fitting of the experimental transient absorption traces was performed using the generalized reduced gradient (GRG2) nonlinear optimization code. Lasdon, L. S.; Warren, A. D.; Jain, A.; Ratner, M. ACM Trans. Math. Software 4; Association for Computing Machinery: New York, 1978; pp. 34-50.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.