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Volumn 111, Issue 41, 2007, Pages 14968-14976

Chiroptical responses of D-/L-penicillamine-capped gold clusters under perturbations of temperature change and phase transfer

Author keywords

[No Author keywords available]

Indexed keywords

ABSORPTION SPECTRA; DICHROISM; ELECTROPHORESIS; GOLD; PERTURBATION TECHNIQUES; THERMAL EFFECTS; X RAY SCATTERING;

EID: 35948982535     PISSN: 19327447     EISSN: 19327455     Source Type: Journal    
DOI: 10.1021/jp074830b     Document Type: Article
Times cited : (70)

References (49)
  • 25
    • 35948994406 scopus 로고    scopus 로고
    • We also measured CD spectra at an elevated temperature of 60 0C; however, after cooling the temperature to 20 °C again, the CD signals were decreased (∼60 %) as compared to the initial value. For this reason, the temperature effect was examined within the range of 20-40 °C
    • We also measured CD spectra at an elevated temperature of 60 0C; however, after cooling the temperature to 20 °C again, the CD signals were decreased (∼60 %) as compared to the initial value. For this reason, the temperature effect was examined within the range of 20-40 °C
  • 26
    • 35948989939 scopus 로고    scopus 로고
    • Although our Hitachi U-4100 spectrophotometer cannot access temperature control equipment for the absorption measurements, our spectropolarimeter JASCO J-820 can simultaneously measure the ordinary absorption as well as the CD response at a fixed temperature
    • Although our Hitachi U-4100 spectrophotometer cannot access temperature control equipment for the absorption measurements, our spectropolarimeter JASCO J-820 can simultaneously measure the ordinary absorption as well as the CD response at a fixed temperature.
  • 35
    • 35948995614 scopus 로고    scopus 로고
    • In the phase transfer of carboxylate-modified gold nanoparticles in the presence of TOABr, it has been established that the molar ratio between the surface carboxylate anion and the TOA cation is almost unity, that is, the phase transfer occurs via 1:1 stoichiometric ion-pair formation. Similarly, the phase transfer of Pen-capped gold clusters proceeded in a ∼1:1 stoichiometry of surface penicillamine and TOABr; see the Supporting Information for more detail
    • (c) In the phase transfer of carboxylate-modified gold nanoparticles in the presence of TOABr, it has been established that the molar ratio between the surface carboxylate anion and the TOA cation is almost unity, that is, the phase transfer occurs via 1:1 stoichiometric ion-pair formation. Similarly, the phase transfer of Pen-capped gold clusters proceeded in a ∼1:1 stoichiometry of surface penicillamine and TOABr; see the Supporting Information for more detail.
  • 36
    • 35949002702 scopus 로고    scopus 로고
    • L. However, since the larger cluster compounds have considerably smaller anisotropy factors, the CD signal intensities were too weak to exactly analyze and to compare with those of the aqueous phase samples.
    • L. However, since the larger cluster compounds have considerably smaller anisotropy factors, the CD signal intensities were too weak to exactly analyze and to compare with those of the aqueous phase samples.
  • 39
    • 0037427247 scopus 로고    scopus 로고
    • In regard to the phase transfer of dimercaptosuccinic acid-capped gold clusters (core size, ∼0.8 nm) from water to toluene, a similar solvent effect that causes a slight red shift of the HOMO-LUMO transition peak has been observed without alternating the core size and structure of the clusters (Negishi, Y.; Tsukuda, T. J. Am. Chem. Soc. 2003, 125, 4046), which further supports our observations.
    • (c) In regard to the phase transfer of dimercaptosuccinic acid-capped gold clusters (core size, ∼0.8 nm) from water to toluene, a similar solvent effect that causes a slight red shift of the HOMO-LUMO transition peak has been observed without alternating the core size and structure of the clusters (Negishi, Y.; Tsukuda, T. J. Am. Chem. Soc. 2003, 125, 4046), which further supports our observations.
  • 41
    • 35948989938 scopus 로고    scopus 로고
    • + site. The former case was successful.
    • + site. The former case was successful.
  • 42
    • 35948986221 scopus 로고    scopus 로고
    • If the core of penicillamine-capped gold clusters is originally chiral, their CD signals may be responsible for the superposition of the chiral core and dissymmetric field contributions. Although we cannot fully rule out the possibility of the chiral core conditions, we have proposed that an inherently chiral core arrangement in the gold clusters seems unlikely on the basis of the kinetic/structural considerations in our previous study (ref 6). Because it is evident that a CD change detected in the temperaturedependent measurements comes from a dissymmetric field modification caused by surface ligands, we conclude that the observed optical activity is not due to the chiral core of the clusters.
    • If the core of penicillamine-capped gold clusters is originally chiral, their CD signals may be responsible for the superposition of the chiral core and dissymmetric field contributions. Although we cannot fully rule out the possibility of the chiral core conditions, we have proposed that an inherently chiral core arrangement in the gold clusters seems unlikely on the basis of the kinetic/structural considerations in our previous study (ref 6). Because it is evident that a CD change detected in the temperaturedependent measurements comes from a dissymmetric field modification caused by surface ligands, we conclude that the observed optical activity is not due to the chiral core of the clusters.
  • 44
    • 0141929396 scopus 로고    scopus 로고
    • (a) Raval, R. Nature 2003, 425, 463.
    • (2003) Nature , vol.425 , pp. 463
    • Raval, R.1


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.