804
M. J. Deetz et al. / Tetrahedron 58 (2002) 799±805
machine elements to be assembled and employed in a
coherent manner. Thus, the challenge for researchers is to
align them in ordered arrays on surface or interfaces, so that
their individual molecular outputs can be combined and
ampli®ed to produce a measurable macroscopic output.
134.8, 132.5, 132.4, 132.2, 132.0, 131.5, 131.4, 131.3,
131.2, 131.1, 130.9, 130.1, 129.7, 129.6, 129.3, 127.9,
127.5, 126.2, 126.1, 126.0, 120.9, 120.5, 120.3, 118.8,
114.4, 112.9, 112.3, 70.1, 69.2, 69.0, 68.1, 64.7, 64.7,
38.9, 35.4, 31.2, MS (FAB1) mass calcd for
C106H92N4NaO14 [M1Na]1 1669, found 1669.
4.1.4. Rotaxane [1´4]. Yield 17%. 1H NMR (CDCl3,
300 MHz): d (ppm) 8.53 (d, 2H, J8.4 Hz), 8.41 (d, 2H,
J8.4 Hz), 8.30 (d, 2H, J1.5 Hz), 8.13 (s, 2H), 7.68 (s
(br), 1H), 7.29 (m, 40H), 6.57 (d, 2H, J2.1 Hz), 6.44 (d,
2H, J8.4 Hz), 6.01 (d, 2H, J9.0 Hz) 4.09 (m, 4H), 3.93
(m, 4H), 3.65 (m, 4H), 3.45 (m, 2H), 3.37 (s, 6H), 3.30 (m,
2H), 1.30 (s, 9H). 13C NMR (CDCl3, 75 MHz): d (ppm)
170.9, 168.6, 164.6, 153.9, 148.8, 147.9, 146.6, 146.5,
146.1, 145.5, 139.2, 138.3, 135.0, 135.0, 134.7, 132.8,
132.6, 132.5, 132.2, 131.3, 131.2, 130.8, 129.8, 129.3,
127.8, 127.6, 126.3, 126.2, 121.6, 120.5, 120.2, 119.9,
118.7, 113.5, 112.6, 70.4, 69.5, 69.0, 68.3, 64.8, 38.5,
35.4, 31.3 MS (FAB1) mass calcd for C106H92N4NaO14
[M1Na]1 1669, found 1669.
4. Experimental
4.1. Materials
All salts and NMR solvents were purchased from Aldrich
and, after checking for purity, were used as supplied.
4.1.1. Macrobicycles 1 and 2. The synthesis of cis isomer 1
from dibenzo18-crown-6 has been reported elsewhere in
detail.15 The same procedure was used to make the trans
1
isomer 2. H NMR (300 MHz, CDCl3) d (ppm) 8.31 (bs,
2H), 8.17 (s, 2H), 7.80 (s, 1H), 7.39 (d, 4H, J8.4 Hz), 7.22
(d, 4H, J8.6 Hz), 6.64 (d, 2H, J8.4 Hz), 6.52 (d, 2H,
J8.2 Hz), 6.47 (s, 1H), 4.09±3.79 (m, 16H), 3.34 (s,
6H), 1.39 (s, 9H) ppm. 13C NMR (75 MHz, DMSO-d6) d
(ppm) 170.0, 165.5, 153.5, 148.7, 147.1, 139.3, 138.2,
134.9, 131.1, 129.7, 129.1, 121.2, 119.5, 119.0, 111.7,
111.0, 69.6, 69.6, 67.8, 38.6, 35.2, 31.2. MS (FAB1) exact
mass calculated for C48H51N4O10 [M1H]1 843.3605, found
843.3594. X-Ray crystal data were collected and integrated
using a Bruker Apex system, with graphite monochromated
4.1.5. Rotaxane [2´3]. Yield 6%. 1H NMR (600 MHz,
CDCl3) d (ppm) 8.90 (s, 1H), 8.43 (dd, 2H, J1.7,
7.9 Hz), 8.27 (s, 2H), 8.12 (t, 1H, J7.8 Hz), 8.13 (s, 2H),
7.62 (s, 1H), 7.26±7.11 (m, 42H), 6.46 (d, 4H, J8.8 Hz),
6.43 (dd, 2H, J2.4, 8.4 Hz), 6.40 (d, 2H, J2.4 Hz), 6.30
(d, 2H, J8.4 Hz), 4.00±3.37 (m, 16H), 3.38 (s, 6H), 1.33
(s, 9H) ppm. 13C NMR (125 MHz, CDCl3) (ppm) 169.6,
166.5, 164.7, 153.7, 148.7, 147.9, 146.9, 146.3, 145.7,
139.4, 138.4, 135.7, 134.6, 132.0, 131.6, 131.3, 130.9,
130.7, 129.8, 129.6, 129.5, 127.6, 126.0, 120.4, 119.9,
119.5. 118.5, 112.7, 111.8, 69.6, 69.4, 68.7, 68.1, 64.6,
38.6, 35.2, 31.1. MS (FAB1) mass calculated for
C106H92N4NaO14 [M1Na]1, 1669, found 1669.
Ê
Mo Ka (l0.71073 A) radiation at 170 K. The structure
was solved by direct methods. Hydrogen atoms were placed
at idealized positions and a riding model with ®xed thermal
parameters was used for subsequent re®nements. The asym-
metric unit contains one half of the macrocycle, with one
orientation of the t-butyl methyl groups at 50% occupancy.
The second orientation of the t-butyl methyl groups is
generated through symmetry. The X-ray data has been
deposited with the Cambridge Crystallographic Data Centre
as supplementary publication number CCDC 168432.
Copies of the data can be obtained free of charge on appli-
cation to CCDC at deposit@ccdc.cam.ac.uk.
4.1.6. Rotaxane [2´4]. Yield 3%. 1H NMR (600 MHz,
CDCl3) d (ppm) 8.40 (s, 4H), 8.30 (d, 2H, J1.4 Hz),
8.12 (s, 2H), 7.57 (s, 1H), 7.23±7.12 (m, 40H), 6.51 (d,
4H, J8.8 Hz), 6.42 (dd, 2H, J2.5, 8.4 Hz), 6.39 (d, 2H,
J2.5 Hz), 6.26 (d, 2H, J8.4 Hz), 3.93±3.89 (m, 4H), 3.83
(dt, 2H, J3.1, 9.5 Hz), 3.75 (td, 2H, J2.3, 9.3 Hz), 3.66
(dt, 2H, J2.9, 10.4 Hz), 3.58 (dt, 2H, J2.7, 9.8 Hz), 3.49
(dt, 2H, J2.9, 11.1 Hz), 3.35±3.32 (m, 2H), 3.38 (s, 6H),
1.34 (s, 9H) ppm. 13C NMR (125 MHz, CDCl3) d (ppm)
169.7, 166.9, 164.6, 153.8, 148.6, 148.0, 146.9, 146.4,
145.9, 139.4, 138.1, 134.5, 133.4, 132.0, 131.8, 130.9,
130.7, 129.8, 129.7, 127.7, 126.0, 120.5, 119.7, 119.3,
118.4, 112.1, 111.6, 69.4, 69.3, 68.6, 67.8, 64.7, 38.5,
35.2, 31.0. MS (FAB1) mass calculated for
C106H92N4NaO14 [M1Na]1, 1669, found 1669.
4.1.2. General rotaxane synthesis. Under an atmosphere of
argon, macrobicycle 1 or 2 (0.025 g, 0.029 mmol) and
potassium 4-tritylphenolate (0.022 g, 0.058 mmol) were
stirred in 5:1 THF/DMF (18 mL) for 1 h. The solution
was cooled to ice temperature then solid phthalolyl or
isophthalolyl dichloride (0.006 g, 0.029 mmol) was added
and the solution allowed to warm and stir for four days.
The solvent was evaporated and the residue puri®ed by
column chromatography using silica gel and CH2Cl2/
MeOH (95:5).
4.1.3. Rotaxane [1´3]. Yield 20%. 1H NMR (CDCl3,
600 MHz): d (ppm) 8.92 (s, 1H), 8.64 (d, 1H, J8.0 Hz),
8.55 (d, 1H, J8.0 Hz), 8.24 (s, 2H), 8.17 (s, 2H), 8.12 (t,
1H, J8.0 Hz), 7.72 (s, 1H), 7.23±7.06 (m, 40H), 6.96 (d,
2H, J9.0 Hz), 6.75 (d, 2H, J9.0 Hz) 6.48 (s, dd, 2H,
J8.5, 2.5 Hz), 6.35 (d, 2H, J8.5 Hz), 6.14 (d, 2H,
J8.5 Hz), 4.05±4.03 (m, 4H), 3.80 (m, 6H), 3.68 (m,
2H), 3.52 (m, 2H), 3.42 (m, 2H), 3.35 (s, 6H), 1.34 (s,
9H). 13C NMR (CDCl3, 150 MHz): d (ppm) 170.3, 167.6,
165.8, 164.8, 153.8, 148.5, 148.3, 148.0, 147.6, 147.2,
146.5, 146.5, 145.7, 145.5, 139.4, 138.3, 136.3, 136.2,
4.2. NMR titration experiments
Aliquots of tetrabutylammonium chloride stock solution
were added to a 10 mM solution (3:1 DMSO-d6/CD3CN,
0.75 mL) of receptor in the presence and absence of
potassium tetraphenylborate. The changes in receptor
chemical shift were monitored and used to produce titration
isotherms which were ®tted to a 1:1 binding model using an
iterative computer method that has been described
elsewhere.17