Chemistry Reference
In-Depth Information
(a)
(c)
(b)
(d)
1200
1400
1600
1200
1400
1600
Raman shift (cm
-1
)
Raman shift (cm
-1
)
FIGURE 7.10.
A comparison of the 3 ps, 320 nm ps-KTR
3
spectrum of the 4-methoxyphenyl
nitrene (a) and a 10 ps, 342 nm ps-KTR
3
spectrum (b) of the 2-fluorenyl nitrene in pure
acetonitrile solvent to the corresponding spectra obtained in mixed aqueous solvents (c and d,
respectively) is shown. The mixed aqueous solvents had concentrations of water-acetonitrile
(60:40) and water-acetonitrile (50:50), respectively.
Source
: Reprinted with permission from
Ref. 43. Copyright (2004) American Chemical Society.
different aryl nitrenes with water are substantially different. A comparison of the
3 ps, 320 nm ps-KTR
3
spectrum of the 4-methoxyphenyl nitrene and a 10 ps, 342 nm
ps-KTR
3
spectrum of the 2-fluorenyl nitrene in pure acetonitrile solvent to the
spectra (left-hand side) acquired in aqueous acetonitrile (right-hand side) shows that
the 4-methoxyphenyl nitrene overlapping Raman bands in the 1400-1600 cm
1
region are composed of mainly four vibrational bands that can be fitted as a sum as
shown in Figure 7.10 by the dotted line peaks whose sum is the dashed line that fits
well the experimental spectral region between 1300 and 1650 cm
1
in both solvents
while the corresponding 2-fluorenyl nitrene Raman peak in the 1400-1650 cm
1
region is composed mostly of one predominant Raman band at 1558 cm
1
that can
also be fit to a Lorentzian band as shown by the dashed curve in Figure 7.10 (the best-
fit Raman band frequencies and FWHM bandwidths for these Raman peaks
displayed in Figure 7.10 are given in Table 1 of Ref. 43).
Examination of Figure 7.10 (see also Table 1 in Ref. 43) shows that the spectra
acquired for the 2-fluorenyl nitrene are very similar in the two different solvent
systems with no appreciable difference seen in the Raman band frequencies of
1558 cm
1
and very little difference in the bandwidth within experimental error
(from 62 cm
1
FWHM to 64 cm
1
). However, a similar examination for the
