Biomedical Engineering Reference
In-Depth Information
increases are systematically larger for thiophenolate ligands that
contain more electron-withdrawing groups. Analogous effects on
intensities are also observed in the NIR emissions of Au 140 NCs upon
place exchange of alkanethiolates with thiolates having short
connecting alkanethiolate chains to quaternary ammonium and
ω -carboxylic acid termini.
Figure 9.4 Luminescence spectra of Au 38 (SC2Ph) 24 MPCs in THF (excited
at 450 nm) during ( in situ ) ligand exchange with (A) 4-
chlorothiophenol, (B) 4-bromothiophenol, (C) tiopronin,
(D) N -acetyl--cysteine, and (E) 2-mercaptoethanol. Panel
F presents luminescence spectra (excited at 400 nm) of
Au 140 [S(CH 2 ) 5 CH 3 ] 53 MPCs in CH 2 Cl 2 for increasing lengths of
time (bottom to top) of ligand exchange with TMA, following
isolation and cleanup of the exchange product. Asterisks
indicate artifacts from second- and third-order excitation
leakage, due to wide slits; the sharp minimum at 1165 nm was
due to background solvent/ligand absorption. Reprinted with
permission from Ref. 62. See also Color Insert.
 
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