Table 1 Fluorescence data in 2MeTHF at 77 K
Compoundsa
Donor l(0–0) ꢂ 1 nm
Accep. l(0–0) ꢂ 1 nm
Db
toF d/ns
kETc/(ns)ꢁ1
c
tF (donor)/ns
9 (6Zn)
7 (12)
7Mg (6Mg)
7Zn (6Zn)
8 (6Zn)
576
623
583
576
576
574
594
644
605
600
603
602
18
21
22
24
27
28
0.47(7)
0.32(4)
0.26(4)
0.24(3)
0.20(2)
0.18(1)
1.92
23.3
12.2
1.92
1.92
1.92
1.6(4)
3.0(5)
3.8(4)
3.7(6)
4.5(5)
5.0(3)
10 (6Zn)
a
b
c
The numbers in parentheses are the reference molecules used to extract toF. The uncertainties are ꢂ2 nm. The uncertainties are indicated in
d
brackets. ꢂ0.3.
(Mg or Zn); substituents, and dimer formation (like the special
pair in the reaction center) in order to maximize efficiency in
k
ET(S1) as needed.
PDH thanks the Natural Sciences and Engineering Research
Council of Canada (NSERC), the Agence National de la
Recherche (ANR) for the grant of a Research Chair of
Excellence, and the Fonds Quebecois pour la Recherche en
´ ´
Sciences Naturelles et Technologie (FQRNT) for funding.
Notes and references
1 (a) P. D. Harvey, C. Stern and R. Guilard, in Handbook of
Porphyrin Science with Applications to Chemistry, Physics, Materials
Science, Engineering, Biology and Medicine, ed. K. M. Kadish,
K. M. Smith and R. Guilard, World Scientific Publishing,
Singapore, 2011, vol. 11, pp. 1–179; (b) P. D. Harvey, in The
Porphyrin Handbook, ed. K. M. Kadish, K. M. Smith and
R. Guilard, Academic Press, San Diego, 2003, vol. 18, ch. 113.
2 T. Forster, Ann. Phys. (Leipzig), 1948, 2, 55.
¨
3 A. Osuka, K. Muruyama, I. Yamasaki and N. Tamai, Chem. Phys.
Lett., 1990, 165, 392.
4 (a) S. Faure, C. Stern, R. Guilard and P. D. Harvey, J. Am. Chem.
Soc., 2004, 126, 1253; (b) S. Faure, C. Stern, E. Espinosa,
R. Guilard and P. D. Harvey, Chem.–Eur. J., 2005, 11, 3469.
5 D. L. Dexter, J. Chem. Phys., 1953, 21, 836.
Fig. 2 Graph of D vs kET(S1) in 2MeTHF at 298 K (top) and 77 K
(bottom). At 298 K, the uncertainties are the same as the box.
6 (a) N. Miyaura and A. Suzuki, Chem. Rev., 1995, 95, 2457;
(b) Cross-coupling reactions: A practical guide, ed. N. Miyaura,
Springer, Berlin, 2002; (c) J. Song, N. Aratani, H. Shinokubo and
A. Osuka, Chem.–Eur. J., 2010, 16, 13320; (d) Y. Nakamura,
S. Y. Jang, T. Tanaka, N. Aratani, J. M. Lim, K. S. Kim,
D. Kim and A. Osuka, Chem.–Eur. J., 2008, 14, 8279;
(e) S. Tokuji, T. Yurino, N. Aratani, H. Shinokubo and
A. Osuka, Chem.–Eur. J., 2009, 15, 12208; (f) N. Aratani and
A. Osuka, Chem. Commun., 2008, 4067; (g) F. Cheng, S. Zhang,
A. Adronov, L. Echegoyen and F. Diederich, Chem.–Eur. J., 2006,
the J integral. For example, in the light harvesting complex
LH2 of the purple photosynthetic bacteria, there is an efficient
S1 energy transfer (1.2 ps)1 from B800 to B850 (composed of
bacteriochlorophylls, and 800 and 850 means the position of
the 0–0 peaks). This 50 nm gap means a better overlap between
the donor fluorescence with the acceptor absorption. Again,
this trend (Fig. 2) cannot go to infinity but it is noteworthy
that the width of the porphyrin fluorescence band is B100 nm
(see Fig. 1). Second, since the J integral also plays an
important role in kET(S1), using squeezed special pairs would
further contribute to this effect since it is known that
compressing the two macrocycles against each other induces
an increase in the bandwidth and couplings.9,10 Moreover,
studies on supramolecular systems, where dynamics at the
time scale of energy transfer have been shown to be important,
have also been reported.11 This work shows for the first time a
dependence between kET(S1) and the position of the 0–0
fluorescence peaks or indirectly the S1–S1 energy gap between
the donor and the acceptor, which is easily explained by the
12, 6062; (h) L.-A. Fendt, M. Stohr, N. Wintjes, M. Enache,
¨
T. A. Jung and F. Diederich, Chem.–Eur. J., 2009, 15, 11139;
(i) G. Bringmann, D. C. G. Gotz, T. A. M. Gulder, T. H. Gehrke,
¨
T. Bruhn, T. Kupfer, K. Radacki, H. Braunschweig, A. Heckmann
and C. Lambert, J. Am. Chem. Soc., 2008, 130, 17812; (j) D. C.
G. Gotz, T. Bruhn, M. Senge and G. Bringmann, J. Org. Chem.,
¨
2009, 74, 8005; (k) L. L. Chng, C. J. Chang and D. G. Nocera,
J. Org. Chem., 2003, 68, 4075; (l) A. G. Hyslop, M. A. Kellett,
P. M. Iovine and M. J. Therien, J. Am. Chem. Soc., 1998,
120, 12676.
7 J. S. Lindsey and J. N. Woodford, Inorg. Chem., 1995, 34, 1063.
8 C. P. Gros, F. Brisach, A. Meristoudi, E. Espinosa, R. Guilard and
P. D. Harvey, Inorg. Chem., 2007, 46, 125.
9 F. Bolze, C. P. Gros, M. Drouin, E. Espinosa, P. D. Harvey and
R. Guilard, J. Organomet. Chem., 2002, 643–644, 89.
10 M. Filatov, F. Laquai, D. Fortin, R. Guilard and P. D. Harvey,
Chem. Commun., 2010, 46, 9176.
11 T. S. Balaban, N. Berova, C. M. Drain, R. Hauschild, X. Huang,
H. Kalt, S. Lebedkin, J.-M. Lehn, F. Nifaitis, G. Pescitelli,
V. I. Prokhorenko, G. Riedel, G. Smeureanu and J. Zeller,
Chem.–Eur. J., 2007, 13, 8411.
Forster theory based on the J integral. These observations also
¨
are found to be consistent with the universal conclusion that
nature chooses her ‘‘ingredients’’ appropriately, including metals
c
This journal is The Royal Society of Chemistry 2011
Chem. Commun., 2011, 47, 8817–8819 8819