Photoswitchable Rotaxanes
3562 3568
(silica gel, cyclohexane/acetone 3:1) thus separating 2 from the symmet-
ric substitution products; oil, 4.45 g (50%).
lowish-green solid (mp 199 2018C, 0.53 g, 47%). 1H NMR (600 MHz,
CD3CN, 333 K, TMS): d=1.27 (d, J(H,H)=7 Hz, 6H; iPr), 1.29 (d,
J(H,H)=7 Hz, 12H; iPr), 1.71, 1.91, 2.03 (brm, 17H; adamantane, 2-H),
2.43 (t, J(H,H)=8 Hz, 2H; 3-H), 2.54 (d, J(H,H)=7 Hz, 2H; CHT, 7-H),
2.92 (sep, J(H,H)=7 Hz, 1H; iPr), 3.27 (sep, J(H,H)=7 Hz, 2H; iPr),
3.67 (m, 2H; 4-H), 3.73 (m, 2H; 9-H), 3.9 (m, 8H; 5-H, 6-H, 7-H, 8-H),
3.99 (t, J(H,H)=6 Hz, 2H; 1-H), 4.31 (brs, 2H; N-Benzyl), 4.60 (brd,
2H; ring B), 5.4 (brd, 2H; ring A), 5.52 (brd, 2H; ring B), 5.68 (d,
J(H,H)=7 Hz, 1H; CHT, 2-H), 5.79, 5.76, 5.75, 5.74, 5.73 (m, 9H; cyclo-
phane, CHT, H-6) 6.3 (brd, 2H; ring A), 6.43 (d, J(H,H)=9 Hz,1H;
CHT, 5-H), 6,68 (d, J(H,H)=8 Hz, 2H; ring C), 6.90 (d, J(H,H)=7 Hz,
1H; CHT, 3-H), 7.14 (s, 2H; iPr-Ph), 7.36 (d, J(H,H)=8 Hz, 2H; ring C),
7.82 (d, J(H,H)=7 Hz, 8H; cyclophane), 7.86 (s, 8H; cyclophane),
8.87 ppm (d, J(H,H)=7 Hz, 8H; cyclophane); MS (ESI): m/z: 864.8815
[MÀ2PF6]+ (calcd for [C97H109F12N5O6P2]: 864.8831), 526.2268
[MÀ3PF6]+ (calcd for [C97H109F6N5O6P]: 528.2673), 359.9592 [MÀ4PF6]+
(calcd for [C97H109N5O6]: 359.9594).
Without further purification 2 (3.76 g, 8.34 mmol) was treated with ada-
mantane-1-carbonyl chloride (1.82 g, 9.17 mmol) in pyridine (9 mL) for
4 h at 758C.The reaction mixture was poured to dilute HCl (15 mL).The
aqueous solution was extracted several times using dichloromethane as
solvent, and the organic phases were washed with a saturated aqueous
solution of NaCl, dried (Na2SO4), and evaporated.The ester 3 (4.64 g,
91%) was oxidized without further purification by using trityl tetra-
fluoroborate (2.51 g, 7.57 mmol) in dichloromethane affording 4, which
was purified by treating the solid with a mixture of ethyl acetate (10 mL)
und methyl-tert-butylester (MTBE) (40 mL).The tropylium salt 4 (3.7 g,
5.3 mmol) dissolved in dichloromethane (30 mL) was added to aniline
(1.79 g, 19.2 mmol). After stirring for 5 h at room temperature the solu-
tion was washed with an aqueous solution of NaHCO3, the organic phase
was dried (Na2SO4), and the solvent was removed under reduced pres-
sure.The isomer 5 was separated from 6 by CC (silica gel, toluene/ethyl
acetate 8:1, oil, 940 mg (25%). 1H NMR (300 MHz, CD3CN, TMS): d=
1.71, 1.85, 1.93 (brm, 17H; adamantane, 1-H), 2.60 (t, J(H,H)=8 Hz,
2H; 3-H), 2.69 (t, J(H,H)=6 Hz, 1H; CHT, 7-H), 3.64 (s, 4H; 6-H, 7-H),
3.77 (m, 4H; 5-H, 8-H), 3.96 (t, J(H,H)=6 Hz, 2H; 1-H), 4.1, 4.05 (m,
4H; 4-H, 9-H), 5.43 (m, 1H; CHT, 6-H), 5.52 (m, 1H; CHT, 1-H), 6.29
(m, 1H; CHT, 5-H), 6.34 (d, J(H,H)=10 Hz, 1H; CHT, 2-H), 6.66 (d,
J(H,H)=8 Hz, 2H; ring C), 6.83 (d, J(H,H)=9 Hz, 2H; A), 6.94 (d,
J(H,H)=9 Hz; ring B), 7.04 (d, J(H,H)=6 Hz, 1H; CHT, 4-H), 7.09 (d,
J(H,H)=9 Hz, 2H; ring A), 7.11 (d, J(H,H)=8 Hz, 2H; ring C),
7.45 ppm (d, J(H,H)=9 Hz, 2H; ring B).
Rotaxane 13: A solution of rotaxane 11 (0.10 g, 0.05 mmol) in MeCN
containing Et4NPF6 (0.1m, 50 mL) was oxidized by a controlled potential
electrolysis (EA =0.9 1.2 V [SCE], HEKA PG285) at a Pt electrode in
the anode region of an H cell until a charge output of 2 FmolÀ1 was con-
sumed.After evaporating and washing with water, the remaining blue
solid was purified by column chromatography (silica gel, acetonitrile
(400 mL), ethyl acetate (200 mL), cyclohexane (100 mL) containing am-
monium hexafluorophosphate (7 g)).Rotaxane 13 (0.10 g, 94%) was ob-
tained as
a
blue solid.Mp.208
8C (decomp); 1H NMR (600 MHz,
CD3CN, TMS): d=1.25 (d, J(H,H)=7 Hz, 18H; iPr), 1.7 (m, 2H; 2-H),
1.8, 2.0, 2.1 (brm, 17H; adamantane, 3-H), 2.43 (t, J(H,H)=8 Hz, 2H; 3-
H), 2.91 (sep, J(H,H)=7 Hz, 1H; iPr), 2.99 (brm, 2H; 4-H), 3.1 (brs,
2H; ring A), 3.16 (sep, J(H,H)=7 Hz, 2H; iPr), 3.95 (brm, 2H; 9-H), 4.0
(brm, 6H; 5-H, 6-H, 7-H, 8-H), 4.05 (t, J(H,H)=7 Hz, 2H; 1-H), 4.48 (d,
J(H,H)=4 Hz, 2H; N-benzyl), 4.80 (brd, 2H; ring A), 5.70, 5.72, 5.75,
5.77 (m, 8H; cyclophane), 5.99 (t, J(H,H)=4 Hz, 1H; NH), 6.31 (br, 2H;
ring B), 6.97 (d, J(H,H)=9 Hz, 2H; ring C), 7.14 (s, 2H; aromatic), 7.4
(brd, 2H; ring B), 7.82 (s, 8H; cyclophane), 7.9 (brs, 8H; cyclophane),
8.00 (d, J(H,H)=9 Hz, 2H; ring C), 8.27 (m, 1H; tropylium, 7-H), 8.31
(t, J(H,H)=10 Hz, 1H; tropylium, 6-H), 8.42 (dd, J(H,H)=12; 2 Hz,
1H; tropylium, 2-H), 8.72 (brm, 1H; tropylium, 5-H), 8.81 (dd, J(H,H)=
12; 2 Hz, 1H; tropylium, 3-H), 8.89 ppm (d, J(H,H)=7 Hz, 8H; cyclo-
phane); UV/Vis (MeCN): lmax (e)=583 (50000), 387 (10800), 262.5 nm
The solution of 5 (1 g, 1.4 mmol) in toluene (150 mL) was heated under
reflux for 11 h.After removing the solvent the isomer 7 resulted as an
oil, which was used for the synthesis of the rotaxane without further puri-
fication. 1H NMR (300 MHz, CD3CN, TMS): d=1.71, 1.85, 1.93 (brm,
17H; adamantane), 2.60 (t, J(H,H)=8 Hz, 2H; 3-H), 2.76 (d, J(H,H)=
8 Hz, 2H; CHT, 7-H), 3.64 (s, 4H; 6-H, 7-H), 3.76 (m, 4H; 5-H, 8-H),
3.96 (t, J(H,H)=6 Hz, 2H; 1-H), 4.04, 4.1 (m, 4H; 4-H, 9-H), 5.6 (m,
1H; CHT, 6-H), 6.39 (d, J(H,H)=10 Hz,1H; CHT, 5-H), 6.34 (d,
J(H,H)=10 Hz, 1H; CHT, 2-H), 6,65 (d, J(H,H)=9 Hz, 2H; ring C),
6.80 (d, J(H,H)=9 Hz, 2H; ring A), 6.89 (d, J(H,H)=9 Hz; ring B), 6.97
(d, J(H,H)=6 Hz, 1H; CHT, 3-H), 7.07 (d, J(H,H)=9 Hz, 2H; ring A),
7.27 (d, J(H,H)=9 Hz, 2H; ring C), 7.44 ppm (d, J(H,H)=9 Hz, 2H;
ring B).
(66720 molÀ1dm3 cmÀ1);
elemental
analysis
calcd
(%)
for
Pseudorotaxane 10: Compound 7 (0.007 g, 0.0098 mmol) together with 9
C97H108F30N5O6P5 (2163.6509): C 53.80, H 5.03, N 3.24; found: C 53.86, H
5.12, N 3.34.
(0.011 g, 0.010 mmol) was dissolved in CD3CN (1.5 mL) in order to meas-
1
ure HNMR spectra (see Supporting material).
Molecular thread 14: A soultion of compound 12 (0.14 g, 0.15 mmol) in
MeCN containing Et4NPF6 (0.1m, 50 mL) was oxidized by a controlled
potential electrolysis (EA =0.9 1.2 V [SCE], HEKA PG285) at a Pt elec-
trode in the anode region of a H cell until a charge output of 2 FmolÀ1
was consumed.After evaporating and washing with water, the remaining
blue solid was purified by column chromatography (silica gel, acetonitrile
(400 mL), ethyl acetate (200 mL), cyclohexane (100 mL) containing am-
monium hexafluorophosphate (7 g)).Compound 14 (0.13 g, 79%) was
obtained, as it was necessary to record its NMR spectrum in order to cal-
culate the CIS values of 13.Mp..80 8C (decomp); 1H NMR (600 MHz,
CD3CN, TMS): d=1.24 (d, J(H,H)=7 Hz, 18H; iPr), 1.7 (m, 2H; 2-H),
1.8, 2.0, 2.1 (brm, 15H; adamantane), 2.58 (t, J(H,H)=8 Hz, 2H; 3-H),
2.91 (sep, J(H,H)=7 Hz, 1H; iPr), 3.16 (sep, J(H,H)=7 Hz, 2H; iPr),
3.66 (m, 4H; 6-H, 7-H), 3.76 (m, 2H; 5-H), 3.83 (m, 2H; 8-H), 3.95 (t,
J(H,H)=7 Hz, 2H; 1-H), 4.03 (m, 2H; 4-H), 4.48 (d, J(H,H)=4 Hz, 2H;
N-benzyl), 5.91 (t, J(H,H)=4 Hz, 1H; NH), 6.81 (d, J(H,H)=9 Hz, 2H;
ring A), 6.95 (d, J(H,H)=9 Hz, 2H; ring C), 7.14 (s, 2H; iPr-Ph), 7.16 (d,
J(H,H)=9 Hz, 2H; ring B), 7.79 (d, J(H,H)=9 Hz, 2H; ring B), 7.96 (d,
J(H,H)=9 Hz, 2H; ring C), 8.28 (t, J(H,H)=12; 1H; tropylium, 6-H),
8.39 (dd, J(H,H)=12; 2 Hz, 1H; tropylium, 7-H), 8.56 (dd, J(H,H)=12;
2 Hz, 1H; tropylium, 2-H), 8.67 (dd, J(H,H)=12; 2 Hz, 1H; tropylium,
5-H), 8.78 ppm (dd, J(H,H)=12; 2 Hz, tropylium 3-H); UV/Vis (acetoni-
Rotaxane 11: Compound 7 (0.39 g, 0.55 mmol) dissolved in dichloro-
methane (1.5 mL) was added to a solution of 9 (0.73 g, 0.66 mmol) in ace-
tonitrile (6 mL).Dichloromethane was then removed under reduced
pressure. 2,4,6-Tris(isopropyl)benzyl bromide (0.163 g, 0.55 mmol) togeth-
er with 2,6-di-tert-butyl-4-methylpyridine (0.113 g, 0.55 mmol) dissolved
in acetonitrile (2 mL) was added to the green solution of the pseudoro-
taxane.The reaction solution was stirred under an argon atmosphere for
48 h at room temperature, the solution was evaporated, and the residue
was extracted with MTBE (75 mL).From the filtrate compound 12
formed as oil (0.23 g. 45%). 1H NMR (300 MHz, CD3CN, 303 K, TMS):
d=1.23 (d, J(H,H)=7 Hz, 18H; iPr), 1.71, 1.85, 1.95 (brm, 17H; ada-
mantane, 2-H), 2.61 (t, J(H,H)=8 Hz, 2H; 3-H), 2.79 (d, J(H,H)=7 Hz,
2H; CHT, 7-H), 2.90 (sep, J(H,H)=7 Hz, 1H; iPr), 3.21 (sep, J(H,H)=
7 Hz, 2H; iPr), 3.65 (m, 4H; 6-H, 7-H), 3.80 (m, 4H; 5-H, 8-H), 3.97 (t,
J(H,H)=6 Hz, 2H; 1-H), 4.06 (m, 2H; 8-H), 4.10 (m, 2H; 5-H), 4.23 (s,
2H; N-benzyl), 5.61 (m, 1H; CHT, 6-H), 6.43 (d, J(H,H)=9 Hz,1H;
CHT, 5-H), 6.54 (d, J(H,H)=9 Hz,1H; CHT, 2-H), 6.73 (d, J(H,H)=
9 Hz, 2H; ring C), 6.83 (d, J(H,H)=9 Hz, 2H; ring A), 6.91 (d, J(H,H)=
9 Hz, 2H; ring B), 6.99 (m, 1H; 3-CHT) 7.08 (d, J(H,H)=9 Hz, 2H; ring
A), 7,10 (s, 2H; iPr-Ph), 7.38 (d, J(H,H)=9 Hz, 2H; ring C), 7.50 ppm
(d, J(H,H)=9 Hz, 2H; ring B).
trile):
lmax
(e)=583
(50000),
387
(10800),
262.5 nm
The solid insoluble in MTBE was purified by column chromatography on
(66720 molÀ1dm3 cmÀ1); MS (ESI): m/z: 918.5673 [C61H76NO6]+ (calcd:
neutral Al2O3 (Fluka) by using
a solvent mixture of acetonitrile
918.5673).
(400 mL), ethyl acetate (200 mL), and cyclohexane (100 mL) containing
ammonium hexafluorophosphate (7 g).The green fraction was concen-
trated under reduced pressure and the resulting solid was washed with
water (350 mL) and MTBE (75 mL).Rotaxane 11 was formed as a yel-
Methoxy-substituted rotaxanes 15: The isomeric mixture of the methoxy
derivatives 15 was obtained by addition of methanol (0.1 mL) to a solu-
tion of 13 (20 mg) in MeCN (2 mL) that contained NaHCO3 (20 mg).
Chem. Eur. J. 2004, 10, 3562 3568
¹ 2004 Wiley-VCH Verlag GmbH & Co.KGaA, Weinheim
3567