S. A. Ahmed et al. / Tetrahedron 60 (2004) 6029–6036
6035
to a three-necked flask. Powdered NaOH (360 mg, 9 mmol)
was added to the mixture, and the reaction mixture was
stirred for 1 h at room temperature. Acetic acid (540 mg,
9 mmol) was added to the reaction mixture. The reaction
mixture was poured into water, and the product was
extracted with chloroform. Purification of the product
obtained after solvent evaporation was conducted with gel
permeation chromatography to afford the compound in 12%
yield as purple-red viscous oil: 1H NMR (CDCl3, 400 MHz)
d 1.34 (3H, s, CH3), 1.35 (3H, s, CH3), 3.4–3.9 (17H, m,
OCH2), 4.3–4.4 (2H, m, PyCH2), 5.09 (2H, s, PhCH2), 5.76
(1H, d, J¼10.4 Hz, CHv), 6.41 (1H, d, J¼8.0 Hz, ArH),
6.62 (1H, d, J¼10.0 Hz, CHv), 6.90 (1H, t, J¼7.4 Hz,
ArH), 7.06 (1H, t, J¼7.6 Hz, ArH), 7.16 (1H, d, J¼7.2 Hz,
ArH), 7.82 (1H, s, ArH), 7.94 (1H, d, J¼7.6 Hz, ArH),
7.9–8.3 (9H, m, ArH); IR (neat, cm21): 3019 (CH2), 1219
(OCH2), 743 (CvC); m/z 740 (Mþ). Anal. Calcd for
C45H44N2O8: C 72.96, H 5.99, N 3.78, Found: C 72.89, H
5.79, N 3.81.
intensity of merocyanine (IF–M(lex¼lP)) is explained with
instrumental function coefficient (k), incident light intensity
(ILO(lP)), absorbance (A(lP)), fluorescence quantum yield
(F), FRET efficiency (E), and the fraction of light intensity
absorbed by the pyrene moiety to the total light intensity
absorbed at lP (P).
IF2Mðlex ¼ lPÞ ¼ kILOðlPÞð1 2 102Aðl ÞÞðPE þ 1 2 PÞF
P
P is defined with light intensity absorbed by the pyrene
moiety (ILR – P(lP)) and by the merocyanine moiety
(ILR–M(lP)), which are explained with absorbances for the
pyrene moiety (AP(lP)) and for the merocyanine moiety
(AM(lP)),
ILR2PðlPÞ
P ¼
ILR2PðlPÞ þ ILR2MðlPÞ
1 2 102A ðl Þ
P
P
¼
1 2 102A ðl Þ þ 1 2 102A
MðlPÞ
P
P
As the light intensity is corrected to be constant regardless
of wavelength in the instrument for fluorescence spectra
measurement, the FRET efficiency E is explained with P,
IF–M(lex¼lM), IF–M(lex¼lP), A(lM), and A(lP).
4.3. Spectral measurement
Spectral measurement was carried out using acetonitrile as
the solvent at room temperature. The UV–Vis spectra were
taken after allowing a measuring solution to stand overnight
under dark condition. For UV–Vis spectra measurement,
both concentrations for 1 and alkaline-earth metal per-
chlorates were 1£1024 mol dm23 in Figure 1, and those in
Figure 4 were 5£1025 mol dm23. In the case of fluor-
escence emission and excitation spectra measurement,
concentrations for 1, 2, and alkaline-earth metal per-
chlorates were 5£1026 mol dm23, and all measurement
was carried out under argon atmosphere at room
temperature.
!
M
1
IF2Mðlex ¼ lPÞð1 2 102Aðl ÞÞ
E ¼
2 1 þ P
IF2Mðlex ¼ lMÞð1 2 10Aðl ÞÞ
P
P
The absorbances for the pyrene and merocyanine moieties at
345 nm, AP(lP) and AM(lP), were estimated as 0.1075 and
0.06, respectively, while the absorbance at 530 nm was
0.0959. Therefore, the E was calculated at 0.12.
Acknowledgements
For FRET efficiency evaluation,14 both concentrations for 2
and Sr2þ were 5£1025 mol dm23. Merocyanine was excited
at 530 and 345 nm individually, and the former corresponds
to the absorption band of merocyanine, lM, and the latter is
the absorption band of pyrene overlapping with that of
merocyanine, lP. Fluorescence intensity of merocyanine
was evaluated at 615 nm. In general, the relationship among
absorbance (A(l)), transmitted light intensity (IL(l)),
original incident light intensity (ILO(l)), the fraction of
light intensity absorbed by sample to ILO(l) (ILR(l)) is
presented as follows:
We are very much indebted to Japan Society for Promotion
of Science (JSPS) for the financial support of this work by a
Grant-in-Aid for JSPS fellows. One of the authors (K. K.)
acknowledges a Grant-in-Aid-for Scientific Research (B)
(No. 15350043) from the Ministry of Education, Culture,
Sports, Science, and Technology, Japan. We also would like
to thank Ms. Sachiko Namba for her experimental support.
References and notes
ILðlÞ
2AðlÞ ¼ log
ILOðlÞ
1. Organic Photochromic and Thermochromic Compounds,
Crano, J. C., Guglielmetti, R. J., Eds.; Kluwer Academic/
Plenum: New York/London, 1999; Vols. 1 and 2.
ILOðlÞ 2 ILðlÞ
ILRðlÞ ¼ 1 2 102AðlÞ
¼
2. Principles of Fluorescence Spectroscopy; Lakowicz, J. R.,
Ed.; Kluwer Academic/Plenum: New York/London, 1999.
3. (a) Tamai, N.; Yamazaki, T.; Yamazaki, I. J. Phys. Chem.
1991, 95, 3988–3993. (b) Wojtyk, J. T. C.; Kazmaier, P. M.;
Buncel, E. Chem. Commun. 1998, 1703–1704. (c) Filley, J.;
Ibrahim, M. A.; Nimlos, M. R.; Watt, A. S.; Blake, D. M.
J. Photochem. Photobiol., A: Chem. 1998, 117, 193–198.
ILOðlÞ
When only merocyanine moiety is excited at lM, fluor-
escence intensity of merocyanine (IF – M(lex¼lM)) is
explained with instrumental function coefficient (k), inci-
dent light intensity (ILO(lM)), absorbance (A(lM)), and
fluorescence quantum yield (F).
¨
(d) Chibisov, A. K.; Gorner, H. Chem. Phys. 1998, 237,
M
IF–Mðlex ¼ lMÞ ¼ kILOðlMÞð1 2 102Aðl ÞÞF
On the other hand, when both pyrene and merocyanine
moieties are excited at lP, and FRET from the pyrene
moiety to the merocyanine moiety takes place, fluorescence
425–442. (e) Bahr, J. L.; Kodis, G.; de la Garza, L.; Lin, S.;
Moore, A. L.; Moore, T. A.; Gust, D. J. Am. Chem. Soc. 2001,
123, 7124–7133. (f) Rosario, R.; Gust, D.; Hayes, M.; Jahnke,
F.; Springer, J.; Garcia, A. A. Langmuir 2002, 18, 8062–8069.
(g) Kimura, K.; Nakamura, M.; Sakamoto, H.; Uda, R. M.;