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Volumn 128, Issue 35, 2006, Pages 11720-11726

Visible light excitation of CdSe nanocrystals triggers the release of coumarin from cinnamate surface ligands

Author keywords

[No Author keywords available]

Indexed keywords

ABSORPTION SPECTROSCOPY; CADMIUM COMPOUNDS; ELECTRIC EXCITATION; ISOMERIZATION; PHOTOCHEMICAL REACTIONS; PHOTOLYSIS; VISIBILITY;

EID: 33748355384     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja063562c     Document Type: Article
Times cited : (38)

References (71)
  • 37
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    • This same ligand has been used to coat gold nanocrystals: Zheng, M.; Li, Z.; Huang, X. Langmuir 2004, 20, 4226.
    • (2004) Langmuir , vol.20 , pp. 4226
    • Zheng, M.1    Li, Z.2    Huang, X.3
  • 39
    • 11144356714 scopus 로고    scopus 로고
    • -1 at 560 nm.
    • (2004) Chem. Mater. , vol.16 , pp. 560
  • 40
    • 33748341102 scopus 로고    scopus 로고
    • note
    • 1H NMR spectrum in the presence of an internal standard and by measuring a UV-visible absorption spectrum. The number of ligands present on the dry nanocrystals, as calculated by these two techniques, matched within 10-20%.
  • 52
    • 33748363720 scopus 로고    scopus 로고
    • note
    • Minor differences in rates of decomposition were attributed to the spectral intensities of the mercury lamp that was used.
  • 53
    • 0001201552 scopus 로고
    • A similar explanation has been reported for the high tendency of excited CdS microcrystals, covered with viologen-functionalized thiols, to donate electrons to solution acceptors: Torimoto, T.; Maeda, K.; Maenaka, J.; Yoneyama, H. J. Phys. Chem. 1994, 98, 13658.
    • (1994) J. Phys. Chem. , vol.98 , pp. 13658
    • Torimoto, T.1    Maeda, K.2    Maenaka, J.3    Yoneyama, H.4
  • 56
    • 0141570903 scopus 로고    scopus 로고
    • A related substance, phenylenediamine, is known to be a scavenger of photogenerated CdSe holes: Sharma, S. N.; Pillai, Z. S.; Kamat, P. V. J. Phys. Chem. B 2003, 107, 10088.
    • (2003) J. Phys. Chem. B , vol.107 , pp. 10088
    • Sharma, S.N.1    Pillai, Z.S.2    Kamat, P.V.3
  • 57
    • 33748365444 scopus 로고    scopus 로고
    • note
    • The fluorescence counts for coumarin could only be used qualitatively since we found that part of the coumarin emission was quenched by the NC (not shown).
  • 58
    • 33748352772 scopus 로고
    • It has been known that the superoxide anion has reasonable stability in DMF (Boon, P. J.; Olm, M. T.; Symons, M. C. R. J. Chem. Soc., Faraday Trans. 1988, 84, 3341) The authors do mention that part of the superoxide anion adds to the carbonyl group of DMF, but this species is presumably also strongly basic.
    • (1988) J. Chem. Soc., Faraday Trans. , vol.84 , pp. 3341
    • Boon, P.J.1    Olm, M.T.2    Symons, M.C.R.3
  • 59
    • 33748368514 scopus 로고    scopus 로고
    • note
    • We found similar results with 72 Å NC covered with ligand 2. Thus, coumarin was efficiently formed from these NC using 620 nm light. However, the tendency for the thiol ligands to detach upon dissolution was dramatically higher for these NC than for the 31 Å NC. Therefore, 72 Å NC are of limited use and are not explicitedly discussed in this paper.
  • 66
    • 33748354700 scopus 로고    scopus 로고
    • note
    • - as supporting electrolyte. Platinum itself was shown not to induce isomerization of the cinnamate by coordination chemistry.
  • 67
    • 33748365859 scopus 로고    scopus 로고
    • note
    • Interestingly, electrolysis of 8 at +0.9 V was accompanied by vast decomposition of the radical cation, thereby excluding any mechanisms that involve the radical cation in explaining the coumarin formation from the NC.
  • 68
    • 33748360519 scopus 로고    scopus 로고
    • note
    • At wavelengths < 440 nm, the same proposed mechanisms will hold true but now isomerization can also occur by direct absorption of the light by the surface cinnamates. The latter pathway was predictable and not of high interest.
  • 71
    • 33748347524 scopus 로고    scopus 로고
    • note
    • The rate of coumarin formation from cinnamates in solution can be increased as much as 1000-10 000-fold by simply switching from DMF to water or ethanol instead. This is a result of acid-catalysis of the lactonization step.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.