T. Haino et al. / Tetrahedron Letters 46 (2005) 1411–1414
1413
(Table 2). In toluene, the entropy changes in the intra-
molecular complex formation are all positive, but the
enthalpy changes are also positive. Apparently, the
intramolecular complex formation of these C60-linked
compounds is typical entropy driven and enthalpy
opposed process.
The extensive desolvation from the fullerene moiety of
these compounds plays an important role in the guest
inclusion process. Net positive enthalpy suggested that
the energy gain due to the formation of the intramolec-
ular complex was less than the energy loss due to the
desolvation around the guest moiety (Fig. 4). In chloro-
form on the other hand, both the entropy and enthalpy
changes in the complex formation process gave negative
values in all cases. Thus, this is the typical enthalpy dri-
ven and entropy opposed process. The explanation of
these data can be very similar in the case of the intermo-
lecular complex formation in the same solvent.8 From
these analysis it is now clear that the solvation and des-
olvation of host and guest play a crucial role in the form-
ation of the host–guest type supramolecular complex in
solution.
Figure 3. Plots of the intermolecular complexation ratio of 2 and 3
versus observed absorbance in toluene at 282 K (n), 303 K (h), 320 K
(s), and 345 K (·). The concentrations are [3] = 5.72 · 10À2 mmol/L
and [2] = from left to right: 0.0, 4.40, 8.80, 13.2, 17.6,
22.0 · 10À1 mmol/L.
Table 1. Inclusion ratio (%) of 1–3
Temp (K)
CHCl3
Toluene
1a 1b 1c 2 and 3a 1a 1b 1c 2 and 3a
345
320
303
282
84 71 48 2.6
62 43 26 2.1
80 58 35 3.0
90 68 44 5.9
78 63 40 3.6
66 53 35 4.4
50 41 23 6.4
References and notes
a The complexation ratios of 2 and 3 at same concentration as 1a–c
were determined by UV–vis spectra at the concentrations
(6.20 · 10À5 mol/L in CHCl3, 5.63 · 10À5 mol/L in toluene).
1. (a) Hirsch, A. The Chemistry of the Fullerenes;Thieme:
Stuttgart, 1994;(b) Dresselhaus, M. S.;Dresselhaus, G.;
Eklund, P. C. Science of Fullerenes and Carbon Nanotubes;
Academic: San Diego, 1996;(c) Scho¨n, J. H.;Kloc, C.;
Batlogg, B. Nature 2000, 408, 549;(d) Scho¨n, J. H.;Kloc,
C.;Batlogg, B. Science 2001, 293, 2432.
2. (a) Nakamura, E.;Isobe, H.;Tomita, N.;Sawamura, M.;
Jinno, S.;Okayama, H. Angew. Chem., Int. Ed. 2000, 39,
4254;(b) Bernstein, R.;Prat, F.;Foote, C. S. J. Am. Chem.
Soc. 1999, 121, 464;(c) Wada, Y.;Tsukada, M.;Fujihara,
M.;Matsushige, K.;Ogawa, T.;Haga, M.;Tanaka, S. Jpn.
J. Appl. Phys. 2000, 3835.
3. (a) Andersson, T.;Nilsson, K.;Sundahl, M.;Westman, G.;
Wennerstrom, O. J. Chem. Soc., Chem. Commun. 1992, 604;
(b) Yoshida, Z.;Takekuma, H.;Takekuma, S.;Matsubara,
Y. Angew. Chem., Int. Ed. Engl. 1994, 33, 1597;(c) Atwood,
J. L.;Koutsantnis, G. A.;Raston, C. L. Nature 1994, 368,
229;(d) Suzuki, T.;Nakashima, K.;Shinkai, S. Chem. Lett.
1994, 699;(e) Atwood, J. L.;Barnes, M. J.;Bulkhalter, R.
S.;Junk, P. C.;Steed, J. W.;Raston, C. L. J. Am. Chem.
Table 2. Thermodynamic parameters of intramolecular complex
formation process of 1a–c
CHCl3
Toluene
DH
DS
DH
DS
(kcal molÀ1
)
(cal KÀ1 molÀ1
)
(kcal molÀ1
)
(cal KÀ1 molÀ1
)
1a À8.03
À24.0
À15.7
À13.8
5.16
3.89
3.34
18.4
13.1
9.6
1b À4.87
1c À3.79
In order to know the thermodynamic data of the intra-
molecular complexation process, the vanÕt Hoff plot
analysis was carried out to give the thermodynamic data
(A)
solv
solv
solv
solv
solv
solv
solv
solv
solv
+ m
(B)
solv
solv
solv
solv
solv
solv
solv
solv
solv
solv
solv
solv
+ n
Figure 4. Schematic representation of intramolecular complexation process for 1 in each solvent (A, toluene;B, CHCl ).
3