A R T I C L E S
Huang et al.
Table 2. Selected Distances and Angles for 3b·1·3b and 3a·1·3a
parameters
3b·1·3b
3a·1·3a
face-to-face π-stacking centroid-centroid distances (Å)
4.25, 4.32
8.3, 5.7
6.95
7.8
4.29
3.97, 3.50
4.4, 10.3
6.81
7.0
4.30
face-to-face π-stacking ring plane/ring plane inclinations (deg)
centroid-centroid distance (Å) between two phenylene rings of the cryptand
dihedral angle (deg) between two phenylene rings of the cryptand
centroid-centroid distance (Å) between two pyridinium rings of 1
dihedral angle (deg) between two pyridinium rings of 1
0
0
centroid-centroid distance (Å) between two phenylene rings of two cryptand molecules on the same side
8.97
6.89
Table 3. Hydrogen-Bond Parameters for 3a·1·3a
3b·1·3b from the large cryptand. However, there are some
differences resulting from the change in the cavity size of the
host. Because of the smaller size of the cavity of 3a, the guest
1 protrudes out from the cavity to form a pseudorotaxane-like
[3]complex2,6 (Figure 4c,f). Also, because of the smaller ring
size, no bridging water molecules are found in 3a·1·3a.
Therefore, there are no bridging O-H‚‚‚O hydrogen bonds in
3a·1·3a. Every pyridinium proton of 1 is involved in direct
hydrogen bonding to ethyleneoxy oxygen atoms of host 3a
molecules. In 3b·1·3b, four â-protons of 1 share two oxygen
atoms in hydrogen bonding, while in 3a·1·3a, four â-protons of
1 form hydrogen bonds with four different oxygen atoms of
the smaller host. The centroid-centroid distance between
adjacent phenylene rings of the two cryptand molecules
decreases from 8.97 to 6.89 Å from 3b·1·3b to 3a·1·3a. The
two cryptand molecules of 3a·1·3a are connected by two
hydrogen bonds with a C‚‚‚O distance of 3.31 Å, an H‚‚‚O
distance of 2.37 Å, and a C-H‚‚‚O angle of 158° (L in Figure
4c,d). These interactions between complexed hosts stabilize the
trimolecular complex in a manner not common in multimo-
lecular complexes.15,20
parameters
H
I
J
K
L
M
C‚‚‚O distances (Å)
H‚‚‚O distances (Å)
3.25
2.26
3.40
2.50
150
3.07
2.27
136
3.48
2.63
142
3.31
2.37
158
3.35
2.47
147
C-H‚‚‚O angles (deg) 169
conformation of the guest, 1. From 3b·1 to 3b·1·3b, the dihedral
angle between the two pyridinium rings of 1 changes from 5.8°
to 0°, while in the crystal structure of 1 itself, the corresponding
value is 0°.15 In 3b·1·3b, the guest 1 does not extend from the
cavity of the two 3b molecules, so strictly speaking it is not a
pseudorotaxane (Figure 4a,e).
D. Solid-State Structure of a New 2:1 Inclusion Complex
of Small Cryptand 3a with Paraquat (1). In contrast to the
1:1 stoichiometry observed in solution and gaseous states, single
crystals of the complex between the smaller cryptand 3a and 1
were of 2:1 stoichiometry as shown by its crystal structure
(Figure 4c,d, Tables 2 and 3).16 The 2:1 complex 3a·1·3a has
stabilization forces (hydrogen-bonding and face-to-face π-stack-
ing interactions) similar to the homologous 2:1 complex
(11) Crystals of 3b·1·3b were grown by slow evaporation of an acetone (undried)
solution; care was taken to keep the crystals wet, because they were
destroyed when dried. Data were collected to θ ) 29°. The structure was
solved by direct methods using SIR12 and refined by full-matrix least
squares, using the Enraf-Nonius MolEN programs.13 Non-hydrogen atoms
were treated anisotropically, except those of the disordered solvent
molecules. Hydrogen atoms were placed in calculated positions, except
those on the water molecules and the paraquat methyl groups, which were
placed from difference maps. Acetone H atoms and those of water molecule
O3w were not located. Crystal data: prism, orange, 0.85 × 0.68 × 0.22
mm3, (C36H54O15)2:C12H14N2 (PF6)2:(H2O)6:(C3H6O)3, FW 2212.2, triclinic,
space group P-1, a ) 13.298(2) Å, b ) 13.641(1) Å, c ) 15.622(1) Å;
R ) 94.485(7)°, â ) 101.04(1)°, γ ) 99.14(1)°; V ) 2728(1) Å3, Z ) 1,
Dc ) 1.346 g cm-3, T ) 120K, µ ) 1.4 cm-1. Convergence was achieved
with R ) 0.077, Rw ) 0.086, and maximum residual density 0.77 e·Å-3
for 6871 data having I > 3σ(I).
Conclusions
It has again been demonstrated that the formation of the
cryptand structure is an efficient method to improve complex-
ations with paraquat derivatives.2 Two unique 2:1 complexes
were found. 3a·1·3a is unique not only because the guest is
encapsulated in the cavities of two cryptand molecules, but also
because it is stabilized by the interactions between the two host
molecules. 3b·1·3b represents the first case in cryptand-based
complexes that different stoichiometries result from the same
host-guest pair.
(12) Burla, M. C.; Camalli, M.; Cascarano, G.; Giacovazzo, C.; Polidori, G.;
Spagna R.; Viterbo, D. J. Appl. Crystallogr. 1989, 22, 389-393.
(13) Fair, C. K. “MolEN, An InteractiVe System for Crystal Structure Analysis”;
Enraf-Nonius, Delft, The Netherlands, 1990.
Experimental Section
(14) (a) Allwood, B. L.; Spencer, N.; Shahriari-Zavareh, H.; Stoddart, J. F.;
Williams, D. J. J. Chem. Soc., Chem. Commun. 1987, 1058-1061. (b)
Asakawa, M.; Ashton, P. R.; Ballardini, R.; Balzani, V.; Belohradsky, M.;
Gandolfi, M. T.; Kocian, O.; Prodi, L.; Raymo, F. M.; Stoddart, J. F.;
Venturi, M. J. Am. Chem. Soc. 1997, 119, 302-310. (c) Asakawa, M.;
Ashton, P. R.; Boyd, S. E.; Brown, C. L.; Gillard, R. E.; Kocian, O.; Raymo,
F. M.; Stoddart, J. F.; Tolley, M. S.; White, A. J. P.; Williams, D. J. J.
Org. Chem. 1997, 62, 26-37 and references therein.
General Procedures. Dimethylformamide (DMF) was distilled
under reduced pressure. Other chemicals were reagent grade and used
as received. All solvents were HPLC or GC grade. The NMR spectra
were recorded on a Varian Unity or Inova Instrument. Low-resolution
electron impact mass spectrometry (LREIMS) was carried out on a
(15) Huang, F.; Slebodnick, C.; Golen, J. A.; Rheingold, A. L.; Gibson, H. W.
Unpublished results.
(17) Oxford Diffraction; Wroclaw: Poland, 2002.
(16) Crystals of 3a·1·3a were grown by vapor diffusion of pentane into an acetone
solution of 1.00 mM 3a and 5.00 mM 1. The data collection routine, unit
cell refinement, data processing, and the face-indexed numerical absorption
correction were carried out with the program CrysAlis.17 Data were collected
from θ ) 2.828° to θ ) 29.386°. Crystal data: prism, yellow, 0.50 × 0.18
× 0.10 mm3, C72H98O24N2P2F12:(C3H6O), FW 1723.57, triclinic, space group
P-1, a ) 10.831(2) Å, b ) 13.165(2) Å, c ) 14.474(3) Å; R ) 93.030-
(14)°, â ) 93.740(15)°, γ ) 105.361(15)°; V ) 1980.6(6) Å3, Z ) 1, Dc
) 1.445 g cm-3, T ) 100 K, µ ) 1.62 cm-1, 40888 measured reflections,
10001 independent reflections, 533 parameters, F(000) ) 906.000, R1 )
0.1014, wR2 ) 0.1159 (all data), R1 ) 0.0470, wR2 ) 0.0766 [I > 2σ(I)],
maximum residual density 0.78 e·Å-3, and goodness-of-fit (F2) ) 0.9627.
The structure was solved by SIR9218 and refined by Crystals.19 Non-
hydrogen atoms were treated anisotropically, and hydrogen atoms were
placed in calculated positions. 4019 reflections were used in refinements
by full-matrix least-squares on F2.
(18) Altomare, A.; Cascarano, G.; Giacovazzo, C.; Guagliardi, A. J. Appl.
Crystallogr. 1993, 26, 343-350.
(19) Watkin, D. J.; Prout, C. K.; Carruthers, J. R.; Betteridge, P. W.; Cooper,
R. I. CRYSTALS; Chemical Crystallography Laboratory, University of
Oxford: Oxford, 2000; issue 11.
(20) (a) Ashton, P. R.; Langford, S. J.; Spencer, N.; Stoddart, J. F.; White, A.
J. P.; Williams, D. J. J. Chem. Soc., Chem. Commun. 1996, 1387-1388.
(b) Ashton, P. R.; Glink, P. T.; Martinez-Diaz, M.-V.; Stoddart, J. F.; White,
A. J. P.; Williams, D. J. Angew. Chem., Int. Ed. Engl. 1996, 35, 1930-
1933. (c) Ashton, P. R.; Ballardini, R.; Balzani, V.; Baxter, I.; Credi, A.;
Fyfe, M. C. T.; Gandolfi, M. T.; Go´mez-Lo´pez, M.; Mart´ınez-D´ıaz, M.-
V.; Piersanti, A.; Spencer, N.; Stoddart, J. F.; Venturi, M.; White, A. J. P.;
Williams, D. J. J. Am. Chem. Soc. 1998, 120, 11932-11942. (d) Ballardini,
R.; Balzani, V.; Clemente-Leo´n, M.; Credi, A.; Gandolfi, M. T.; Ishow,
E.; Perkins, J.; Stoddart, J. F.; Tseng, H.-R.; Wenger, S. J. Am. Chem.
Soc. 2002, 124, 12786-12795.
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9370 J. AM. CHEM. SOC. VOL. 125, NO. 31, 2003