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Volumn 114, Issue 44, 2010, Pages 19035-19043

Single-molecule fluorescence of a phthalocyanine in pamam dendrimers reveals intensity-lifetime fluctuations from quenching dynamics

Author keywords

[No Author keywords available]

Indexed keywords

DENDRIMERS; DYNAMICS; ELECTRON TRANSITIONS; EXCITED STATES; MOLECULES;

EID: 78149258553     PISSN: 19327447     EISSN: 19327455     Source Type: Journal    
DOI: 10.1021/jp107412p     Document Type: Article
Times cited : (16)

References (73)
  • 49
    • 78149262504 scopus 로고    scopus 로고
    • No changes are observed in the absorption spectra of phthalocyanine upon association with the dendrimer in the region of the Q-band (transition to S1 state); however, in the region of the Soret band (transition to S2 state), a shift and broadening of this band toward longer wavelengths is observed
    • No changes are observed in the absorption spectra of phthalocyanine upon association with the dendrimer in the region of the Q-band (transition to S1 state); however, in the region of the Soret band (transition to S2 state), a shift and broadening of this band toward longer wavelengths is observed.
  • 50
    • 78149233660 scopus 로고    scopus 로고
    • note
    • The Rehm-Weller expression can be written as I" G 0 = (E D ox - E A red) B + (1 - 1 Iμ B) (S p - S r) - W r + W p - h I1/2 where E D ox and E A red stand for the oxidation and reduction potential of the donor and acceptor, respectively, in a medium of permittivity Iμ B; S p,r are the solvation energies of individual reactant and product ions in vacuum; W r,p are the solvation energies and Coulomb interaction of the ions, and h I1/2 is the excited-state energy. The expressions for S p,r and W r,p can be found in
  • 52
    • 78149267793 scopus 로고    scopus 로고
    • For E D ox, we used a value of 0.97 V (vs. SCE) for the oxidation potential of triethylamine in water taken from
    • For E D ox, we used a value of 0.97 V (vs. SCE) for the oxidation potential of triethylamine in water taken from
  • 54
    • 78149243400 scopus 로고    scopus 로고
    • red, we used a value of -0.5 V (vs. SCE) for the reduction potential of aluminum phthalocyanine in DMSO taken from
    • red, we used a value of -0.5 V (vs. SCE) for the reduction potential of aluminum phthalocyanine in DMSO taken from
  • 55
    • 33751379099 scopus 로고    scopus 로고
    • The excited-state energy of the phthalocyanine is around 1.82 eV
    • Ou, Z.; Shen, J.; Kadish, K. M. Inorg. Chem. 2006, 45, 9569-9579. The excited-state energy of the phthalocyanine is around 1.82 eV
    • (2006) Inorg. Chem. , vol.45 , pp. 9569-9579
    • Ou, Z.1    Shen, J.2    Kadish, K.M.3
  • 60
    • 78149270573 scopus 로고    scopus 로고
    • note
    • The value of V 0 2 = 10 cm-1 is small enough to justify the nonadiabatic approximation in eq 2 but at the same time large enough to quench the excited-state lifetime of the phthalocyanine down to subnanosecond values. The value of I = 1 A-1 is typical for electron tunneling through an aliphatic carbon donor-acceptor bridge and therefore is appropriate for the PAMAM dendrimer systems.
  • 71
    • 78149270313 scopus 로고    scopus 로고
    • Besides fluorescence quenching by electron transfer, other factors can change the intensity of the "ona" level in single-molecule fluorescence traces (rotational dynamics, spectral diffusion, and so forth). Indeed, we observe intensity fluctuations in traces of unquenched single phthalocyanine molecules that have monoexponential decays. This is probably related to rotational dynamics of phthalocyanine in more flexible environments. This effect is more pronounced here, because the excitation light is not circularly polarized, and in-plane rotation is enough to change emission intensity. Spectral diffusion does not seem plausible, because the emission light is collected through a filter with a broad wavelength window
    • Besides fluorescence quenching by electron transfer, other factors can change the intensity of the "ona" level in single-molecule fluorescence traces (rotational dynamics, spectral diffusion, and so forth). Indeed, we observe intensity fluctuations in traces of unquenched single phthalocyanine molecules that have monoexponential decays. This is probably related to rotational dynamics of phthalocyanine in more flexible environments. This effect is more pronounced here, because the excitation light is not circularly polarized, and in-plane rotation is enough to change emission intensity. Spectral diffusion does not seem plausible, because the emission light is collected through a filter with a broad wavelength window.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.