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46.9; H, 6.1; Br, 34.7; N, 12.2; C18H28Br2N4 requires C, 46.8; H,
6.2; Br, 34.5; N, 12.1].
1
Diiodide salt 2e. Pale yellow powder. Yield: 94%; H NMR
(300 MHz, CD3OD): δ (ppm)=1.42(8H,bs,CH2CH2(CH2)4CH2CH2),
1.97–1.93 [4H, m, CH2CH2(CH2)4CH2CH2)], 4.31–4.26 [4H, m,
CH2CH2(CH2)4CH2CH2)], 5.44 (2H, dd, J = 9.0 and 2.7 Hz,
cis-CHCH2), 5.93 (2H, dd, J = 15.6 and 2.4 Hz, trans-CHCH2),
7.26 (2H, dd, J = 15.6 and 8.7 Hz, CHCH2), 7.79 (2H, d,
J = 1.2 Hz, 4-H or 5-H), 8.00 (2H, d, J = 1.5 Hz, 4-H or 5-H),
9.44 (2H, s, 2-H); 13C NMR (CD3OD): δ (ppm) = 27.1, 29.8,
30.9, 51.3, 110.0, 120.8, 124.6, 129.9, 136.2. [Found: C, 39.1; H,
5.2; I, 45.8; N, 10.1; C18H28I2N4 requires C, 39.3; H, 5.4; I, 45.1;
N, 10.8].
Scheme 2 Synthesis of bis-vinylimidazolium salts.
heated under stirring for 24 h in an oil bath at 90 °C (for tolu-
ene) or at 50 °C (for chloroform). After cooling down to room
temperature, the mixture was filtered and the residue was
washed several times with diethyl ether. Finally, the solid
product was dried at 40 °C.
Dibromide salt 2a. White powder. Yield: 75%; mp >300 °C;
1H NMR (300 MHz, CD3OD): δ (ppm) = 4.96 (4H, m, CH2CH2),
5.49 (2H, dd, J = 10.4 and 3.0 Hz, cis-CHCH2), 5.98 (2H, dd,
J = 18.9 and 3.6 Hz, trans-CHCH2), 7.31 (2H, dd, J = 10.4
and 18.8 Hz, CHCH2), 7.85 (2H, d, J = 2.2 Hz, 4-H or 5-H),
8.09 (2H, d, J = 2.3 Hz, 4-H or 5-H), 9.54 (2H, s, 2-H). 13C
NMR (CD3OD): δ (ppm) = 50.0, 110.8, 121.4, 124.6, 129.8,
130.9, 137.4. [Found: C, 38.3; H, 4.3; Br, 42.5; N, 14.9;
C12H16Br2N4 requires C, 38.3; H, 4.4; Br, 42.5; N, 14.9].
Diiodide salt 2g. Pale yellow powder. Yield: 88%; mp 232 °C;
1H NMR (300 MHz, CD3OD): δ (ppm) = 5.46 (2H, dd, J = 8.7
and 2.7 Hz, cis-CHCH2), 5.52 (4H, s, CH2Ph), 5.95 (2H, dd,
J = 15.6 and 2.7 Hz, trans-CHCH2), 7.29 (2H, dd, J = 15.6 and
8.7 Hz, CHCH2), 7.60 (4H, s, Ph), 7.77 (2H, d, J = 1.8 Hz, 4-H
or 5-H), 8.05 (2H, d, J = 1.8 Hz, 4-H or 5-H), 9.46 (2H, s, 2-H).
13C NMR (CD3OD): δ (ppm) = 53.9, 110.3, 121.1, 124.4, 129.8,
128.8, 130.9, 136.1. [Found: C, 39.6; H, 3.7; I, 46.5; N, 10.3;
C18H20I2N4 requires C, 39.4; H, 3.5; I, 46.4; N, 10.2].
Diiodide salt 2c. Pale yellow powder. Yield: 95%; mp
160 °C. 1H NMR (300 MHz, CD3OD): δ (ppm) = 2.12–2.07 [4H, m,
CH2(CH2)2CH2)], 4.42 [4H, m, CH2(CH2)2CH2)], 5.46 (2H, dd,
J = 8.7 and 2.7 Hz, cis-CHCH2), 5.97 (2H, dd, J = 15.6 and
2.7 Hz, trans-CHCH2), 7.30 (2H, dd, J = 15.6 and 8.7 Hz,
CHCH2), 7.86 (2H, d, J = 1.5 Hz, 4-H or 5-H), 8.02 (2H, d,
J = 1.5 Hz, 4-H or 5-H), 9.48 (2H, s, 2-H); 13C NMR
(CD3OD): δ (ppm) = 27.7, 50.4, 110.1, 120.9, 124.5, 129.8,
136.5; IR (nujol) max (cm−1): 921, 1154, 1377, 1458, 1550,
2854, 2922. [Found: C, 33.8; H, 4.1; I, 50.9; N, 11.3;
C14H20I2N4 requires C, 33.5; H, 4.5; I, 50.3; N, 11.2].
Synthesis of thiol-functionalised silica
Thiol-functionalised silica was prepared using Sigma–Aldrich
SiO2 (403563) as the silica source. 1.5 g of silica gel was heated
overnight at 150 °C in a vacuum line, in order to remove phys-
ically adsorbed water. Then, the solid was reacted with
3-(mercaptopropyl)-trimethoxysilane (2 mL) in 10 mL toluene.
The mixture was heated under reflux in an argon atmosphere
for 24 h. After cooling to room temperature, the material was
isolated by filtration and washed with methanol (50 mL) and
diethyl ether (50 mL). The solid was dried under reduced pres-
sure to give the final material (1.9 g). The loading of thiol
groups was determined by means of elemental analysis of sul-
phur (1.2 mmol g−1).
Dibromide salt 2d. Pale yellow powder. Yield: 78%; mp
>178 °C; 1HNMR (300 MHz, CD3OD): δ (ppm) = 1.42 (8H, bs, CH2
CH2(CH2)4CH2CH2), 1.97–1.93 [4H, m, CH2CH2(CH2)4CH2CH2)],
4.32–4.28 [4H, m, CH2CH2(CH2)4CH2CH2)], 5.45 (2H, dd, J = 15.9
and 2.7 Hz, cis-CHCH2), 5.96 (2H, dd, J = 15.9 and 2.7 Hz,
trans-CHCH2), 7.29 (2H, dd, J = 15.6 and 8.7 Hz, CHCH2),
7.82 (2H, d, J = 1.8 Hz, 4-H or 5-H), 8.03 (2H, d, J = 1.8 Hz, 4-H
or 5-H), 9.44 (2H, s, 2-H); 13C NMR (CD3OD): δ (ppm) = 27.1,
29.7, 30.9, 51.2, 109.9, 120.7, 124.5, 129.8, 136.5. [Found: C,
Synthesis of mlc-SILP materials 1a–g
The mlc-SILP materials were synthesised using excess bis-
imidazolium salt with respect to the –SH groups: 3.62 mol of salt
per mol of –SH. In a typical synthesis, the thiol-functionalised
This journal is © The Royal Society of Chemistry 2014
Catal. Sci. Technol., 2014, 4, 1598–1607 | 1605