Pseudorotaxane Self-Assembly on a TiO Nanoparticle
A R T I C L E S
2
1-(2,4-Dinitrophenyl)-4,4′-bipyridinium chloride (5) was obtained
as reported.14
(t, 18H, J ) 7 Hz); 31P NMR (CDCl3-CD3OD) δ 20.19 (s), -143.6
(heptet, J ) 711 Hz); MS (ES) m/z 1382 (8b+, 7%). Anal. Calcd for
C82H85F12N2O12P5: C, 58.85; H, 5.12; N, 1.67. Found: C, 58.12; H,
5.02; N, 1.54.
1-{4-[Tris[4-[4-(diethoxyphosphono)phenyl]phenyl]methyl]phenyl}-
4,4′-bipyridinium Chloride (6‚Cl). Compound 5 (0.18 g 0.5 mmol)
and dry ethanol (10 cm3) were added to 4 (0.35 g, 0.36 mmol), and the
mixture was heated under reflux for 30 h. The solvent was evaporated
under vacuum. The residue was dissolved in chloroform (100 cm3) and
washed with water (50 cm3) to remove excess 5. The organic layer
was dried (MgSO4) and concentrated. The residue was taken up in
acetone and purified by chromatography (methanol-acetic acid) to give
the product 6‚Cl (0.35 g, 85%) as a yellowish glassy solid: 1H NMR
(CD3OD) δ 9.46 (d, 2H, J ) 6 Hz), 8.98 (br s, 2H), 8.74 (d, 2H, J )
6 Hz), 8.26 (d, 2H, J ) 6 Hz), 7.8-7.9 (m, 16H), 7.74 (dd, 6H, J )
8.5, 4 Hz), 7.55 (d, 6H, J ) 8.6 Hz), 4.1-4.3 (m, 12H), 1.36 (t, 18H,
J ) 7 Hz); 31P NMR (CD3OD) δ 20.32.
1-{4-[Tris[4-[4-(dihydrophosphono)phenyl]phenyl]methyl]phenyl}-
1′-{4-[2-(2-phenoxyethoxy)ethoxy]benzyl}-4,4′-bipyridinium Dibro-
mide (9‚2Br). Me3SiBr (0.1 cm3, 0.75 mmol) was added to 8b‚2PF6
(0.033 g, 0.02 mmol) in 1,4-dioxane (2 cm3), and the mixture was heated
at 30 °C for 1 day, after which it was concentrated under vacuum.
Water (0.5 cm3) and 1,4-dioxane (1.5 cm3) were added to the mixture
and then removed under reduced pressure. The crude mixture was
extracted with methanol to give the product (0.026 g, 95%) as a yellow
glass: 1H NMR (CDCl3-CD3OD) δ 9.36 (d, 2H, J ) 6 Hz), 9.20 (d,
2H, J ) 6 Hz), 8.90 (d, 2H, J ) 6 Hz), 8.78 (d, 2H, J ) 6 Hz), 7.8 (m,
6H), 7.6 (m, 10H), 7.5 (m, 8H), 7.4 (m, 6H), 7.18 (t, 2H, 7 Hz), 6.7-
7.0 (m, 5H), 5.81 (s, 2H), 4.1 (m, 4H), 3.8 (m, 4H); 31P NMR
(CDCl3-CD3OD) δ 18.1; MS m/z 1212 (9+, 16%).
The solubility of the 4,4′-bipyridinium monocation 6 depends
strongly upon the counterion of the salt. Since it was found that the
hexafluorophosphates are more soluble in suitable solvents and could
be purified more readily,6 these salts were used in all subsequent
transformations.
Bis(p-phenylene)-34-crown-10 (10) was prepared according to the
procedure reported:27 mp 90 °C (lit.20 mp 88 °C).
1-Ethyl-1′-(diethylphosphono)ethyl-4,4′-bipyridinium bromide
(11‚2Br) and 1-ethyl-1′-phosphonoethyl-4,4′-bipyridinium bromide
(12‚2Br) were prepared as previously reported.21
1-{4-[Tris[4-[4-(diethoxyphosphono)phenyl]phenyl]methyl]phenyl}-
4,4′-bipyridinium Hexafluorophosphate (6‚PF6). An aqueous solution
of NH4PF6 (2 M, 1 cm3) was added to a solution of 6‚Cl (0.100 g,
0.085 mmol) in chloroform (50 cm3). The mixture was shaken for 1
min, and the organic layer was dried (Na2SO4) and concentrated to
give 6‚PF6 (0.100 g, 93%) as a yellow solid: mp 210-220 °C
1-(2-Phosphonoethyl)pyridinium Bromide (13‚Br). Pyridine (3
cm3) was added to diethyl 2-bromoethylphosphonate (0.98 g, 4 mmol)
in acetonitrile (20 cm3), and the mixture was heated at 70° C for 20 h.
The mixture was concentrated under reduced pressure, dissolved in
water (20 cm3), and washed with dichloromethane (2 × 20 cm3). The
aqueous layer was concentrated and the residue was dissolved in HCl
(6 mol dm-3, 20 cm3). The mixture was heated under reflux for 20 h
and evaporated under reduced pressure to give 13‚Br (0.73 g, 65%) as
1
(decomp); H NMR (CD3OD) δ 8.84 (d, 2H, J ) 6 Hz), 8.66 (d, 2H,
J ) 5 Hz), 8.29 (d, 2H, J ) 6 Hz), 7.7-7.9 (m, 6H), 7.6 (m, 12H),
7.50 (d, 6H, J ) 8.5 Hz), 7.33 (d, 6H, J ) 8.6 Hz), 4.0-4.2 (m, 12H),
1.25 (t, 18H, J ) 7 Hz)); 31P NMR (CD3OD) δ 19.74 (s), -143.46
(heptet, J ) 711 Hz); MS m/z 1111 (6+, 100%). Anal. Calcd for
C65H66F6N2O9P4: C, 62.10; H, 5.29; N, 2.23. Found: C, 61.90; H, 5.17;
N, 2.11.
1
a white solid: mp 152 °C; H NMR (CD3OD) δ 9.09 (d, 2H, J ) 6
Hz), 8.67 (t, 1H, J ) 7 Hz), 8.16 (m, 2H), 4.92 (q, 2H, J ) 7 Hz), 4.8
(s, 2H), 2.6 (m, 2H); 31P NMR (CD3OD) δ 25.2 (s). Anal. Calcd for
C7H11BrNO3P: C, 31.37; H, 4.14; N, 5.23; Br, 29.81. Found: C, 31.19;
H, 3.97; N, 5.16; Br, 29.81.
1-{4-[Tris[4-[4-(diethoxyphosphono)phenyl]phenyl]methyl]phenyl}-
1′-ethyl-4,4′ -bipyridinium Bis(hexafluorophosphate) (8a‚2PF6).
Acetonitrile (1 cm3) and ethyl bromide 7a (0.6 g, 5 mmol) were added
to 6‚PF6 (0.025 g, 0.02 mmol), and the mixture was heated at 80 °C in
a sealed tube for 24 h. The mixture was concentrated and the product
was purified by chromatography [methanol-nitromethane-aqueous
NH4PF6 (2 mol dm-3) in the ratio 80:19:1 by volume] to give 8a‚2PF6
(0.027 g, 95%) as a yellow solid: mp 210-220 °C (decomposition);
1H NMR (CD3OD) δ 9.07 (d, 2H, J ) 7 Hz), 8.95 (d, 2H, J ) 6.4
Hz), 8.55 (d, 2H, J ) 7 Hz), 8.43 (d, 2H, J ) 6.4 Hz), 7.6-7.9 (m,
16H), 7.53 (d, 6H, J ) 8.5 Hz), 7.35 (d, 6H, J ) 8.5 Hz), 4.63 (q, 2H,
J ) 7.2 Hz), 4.0-4.2 (m, 12H), 1.63 (t, 3H, J ) 7.2 Hz), 1.26 (t, 18H,
J ) 7 Hz); 31P NMR (CD3OD) δ 20.24(s), -143.68 (heptet); MS m/z
1-(2-Phosphonoethyl)perdeuteriopyridinium Bromide (14‚Br).
Pyridine-d5 (0.336 g, 4 mmol) was added to diethyl 2-bromoethylphos-
phonate (1.22 g, 5 mmol) in acetonitrile (5 cm3), and the mixture was
heated under reflux for 25 h. The mixture was concentrated under
reduced pressure, dissolved in water (20 cm3), and washed with
dichloromethane (2 · 20 cm3). The aqueous layer was concentrated and
the residue was dissolved in HCl (6 mol dm-3, 10 cm3). The mixture
was heated under reflux for 20 h and evaporated under reduced pressure
1
to give 14‚Br (0.88 g, 80%) as a white solid: mp 154 °C; H NMR
(CD3OD) δ 9.09 (trace), 8.67 (trace), 8.16 (trace), 4.92 (q, 2H, J ) 7
Hz), 4.8 (s, 2H, exchangeable signal), 2.6 (m, 2H); 31P NMR (CD3-
OD) δ 22.1 (s). Anal. Calcd for C7H6D5BrNO3P: C, 30.79; H, 5.90;
N, 5.13; Br, 29.26. Found: C, 31.15; H, 5.96; N, 5.16; Br, 29.08.
1139 (8a+
- , 100%). Anal. Calcd for
H, 92%), 570 (8a2+
C67H71F12N2O9P5: C, 56.23; H, 5.00; N, 1.96. Found: C, 55.88; H,
4.75; N, 1.92.
4-[2-(2-Phenoxyethoxy)ethoxy]benzyl Bromide (7b) was obtained
Determination of Association Constants. The method used to
determine Ka was developed by Ray and adapted by Stoddart for
pseudorotaxanes.15,16 It involves measuring the optical absorption
spectrum of different solutions containing equal concentrations of, for
example, the viologen 8b‚2PF6 and the crown ether 10. This method
assumes that the complex formed has a 1:1 stoichioimetry and allows
Ka to be defined as
1
similarly to the procedure reported.13 Colorless solid: mp 58 °C; H
NMR (CD3OD) δ 7.2-7.35 (m, 4H), 6.8-7.0 (d, 5H, J ) 8.5 Hz),
4.42 (s, 2H), 4.08 (t, 4H, J ) 5 Hz), 3.85 (t, 4H, J ) 5 Hz). Anal.
Calcd for C17H19BrO3 C, 58.10; H, 5.45; Br, 22.75. Found C, 57.90;
H, 5.55; Br, 22.87.
1-{4-[Tris[4-[4-(diethoxyphosphono)phenyl]phenyl]methyl]phenyl}-
1′-{4-[2-(2- phenoxyethoxy)ethoxy]benzyl}-4,4′-bipyridinium Bis-
(hexafluorophosphate) (8b‚2PF6). Compound 7b (0.017 g, 0.05 mmol)
and benzonitrile (0.1 cm3) were added to 6‚PF6 (0.025 g, 0.02 mmol),
and the mixture was heated at 30 °C for 1 day. The crude mixture was
purified by chromatography (MeOH/MeNO2/NH4PF6) to give the
product 8b‚2PF6 (0.033 g, 99%) as a bright yellow solid: mp 118 °C;
1H NMR (CDCl3-CD3OD) δ 8.99 (d, 2H, J ) 7 Hz), 8.81 (d, 2H, J )
7 Hz), 8.43 (d, 2H, J ) 7 Hz), 8.31 (d, 2H, J ) 7 Hz), 7.8 (m, 6H), 7.6
(m, 10H), 7.53 (d, 6H, J ) 9 Hz), 7.35 (m, 8H), 7.15 (t, 2H, J ) 7
Hz), 6.75-6.9 (m, 5H), 5.63 (s, 2H), 4.1 (m, 16H), 3.8 (m, 4H), 1.26
[8b‚10‚2PF6]
Ka )
(1)
[8b‚2PF6][10]
(27) Anelli, P. L.; Ashton, P. R.; Ballardini, R.; Balzani, V.; Delgado, M.;
Gandolfi, M. T.; Goodnow, T. T.; Kaifer, A. E.; Philp, D.; Pietraszkiewicz,
M.; Prodi, L.; Reddington, M. V.; Slavin, A. M. Z.; Spencer, N.; Stoddart,
J. F.; Vincenti, C.; Williams, D. J. J. Am. Chem. Soc. 1992, 114, 193-
218.
(28) Rao, S. N.; Fitzmaurice, D. HelV. Chim. Acta 1998, 81 (5), 902.
9
J. AM. CHEM. SOC. VOL. 125, NO. 17, 2003 5159