4.1022 mbar) to give a yellow liquid (4.29 g, 13.9 mmol, 86% yield). 1H
to those observed for X2c and attributed, respectively, to the first-
and second-order. It is worth noting that the higher order
disappears while the peak at 0.44 nm attributed to the interchain
distance was maintained.
NMR (200 MHz, CDCl3): 0.62 (2H, t, 2JH,H = 8 Hz), 1.48 (16H, m), 1.70
(2H, tt, 2JH,H = 6 and 7 Hz), 2.63 (2H, dd, 2JH,H = 7 Hz), 3.58 (9H, s). 13
C
NMR (50 MHz, CDCl3): 9.20 (CH2–Si), 24.80 (CH2–SH), 25.01 (CH2–
CH2–Si), 30.21 to 30.65 (–CH2–CH2–CH2–), 34.24 (CH2–CH2–SH), 51.60
(O–CH3). 29Si NMR (40 MHz, CDCl3): 242.30. Anal. calcd. for
C14H32O3SSi: C 54.55, H 10.38, O 15.58, S 10.38, Si 9.10. Found: C
54.38, H 10.24, S 10.42, Si 9.08 (%).1b: 1H NMR (200 MHz, CDCl3): 0.67
(2H, t, 2JH,H = 7 Hz), 1.44 (4H, m), 1.74 (2H, tt, 2JH,H = 7 and 8 Hz), 2.50
The accessibility of the SH functional groups in X3a–b was
investigated by testing their chelating ability towards mercury(II)
ions from aqueous solutions. The solids X3a–b were treated with
an aqueous solution of HgCl2 at room temperature arbitrarily for
12 h. The resulting solids were copiously washed with water to
eliminate the non complexed salts and called HgX3a–b. The ratio
of metal ions per thiol moieties in HgX3a and HgX3b was found to
be around 1/3.5 and 1/2.6, respectively, from elemental analyses
results. Thus, all materials had high mercury adsorption capacity
(respectively, 2.2 and 2.5 mmol of Hg2+ per gram of X3a and X3b).
These values are high in comparison with most of those obtained
for thiol-modified mesoporous silica described in the literature6f
2
(2H, dd, JH,H = 8 Hz), 3.56 (9H, s). 13C NMR (50 MHz, CDCl3): 9.38
(CH2–Si), 23.98 (CH2–SH), 24.89 (CH2–CH2–Si), 30.62 (CH2–CH2–SH),
34.06 (–CH2–CH2–CH2–), 50.90 (O–CH3). 29Si NMR (40 MHz, CDCl3):
243.10. Anal. calcd. for C8H20O3SSi: C 42.86, H 9.93, O 21.43, S 14.29, Si
12.25. Found: C 43.01, H 9.88, S 14.28, Si 12.24 (%).2c: To a solution of
2,29 dithiopyridine (4.87 mmol, 1.07 g) in anhydrous dichloromethane
(15 mL) was added 1c (9.74 mmol, 3.00 g), under argon. The resulting
solution was stirred for 4 days at room temperature. Dichloromethane was
removed under vacuum and petroleum ether (20 mL) was added. After
filtration, the filtrate was evaporated and the obtained crude was distilled
(153 uC at 3.1022 mbar) to give a yellow liquid (2.81 g, 4.58 mmol, 94%
yield). 1H NMR (200 MHz, CDCl3): 0.69 (4H, t, 2JH,H = 8 Hz), 1.37 (32H,
m), 1.74 (4H, tt, 2JH,H = 12 and 10 Hz), 2.72 (4H, dd, 2JH,H = 12 Hz), 3.64
(18H, s). 13C NMR (50 MHz, CDCl3): 9.55 (CH2–Si), 23.00 (CH2–CH2–
Si), 28.95 to 30.10 (–CH2–CH2–CH2–), 33.57 (CH2–CH2–CH2–Si), 39.62
(CH2–S–S), 50.89 (O–CH3). 29Si NMR (40 MHz, CDCl3): 242.30. Anal.
calcd. for C28H62O6S2Si2: C 54.72, H 10.10, O 15.64, S 10.42, Si 9.12.
and similar to those of FMMS materials (2.5 mmol Hg2+ g21
)
described by Liu et al.6a,6b
Finally, the mercapto groups were converted into sulfonic acid
(SO3H) groups by treatment of X3a–c with H2O2 solution
followed by acidification with diluted H2SO4 solution to obtain
X4a–c (Scheme 3). Their solid state 13C CP-MAS NMR spectra
showed the diminution of the resonance at 27.4 ppm, characteristic
of the carbon situated, in the a position from the SH group.
Simultaneously, a new resonance at 58.8 ppm appeared, which was
assigned to carbon situated in the a position from the SO3H group
(Fig. 1). XPS measurements and conductimetric titration of
materials revealed that 75% of SH groups were transformed into
SO3H groups. The X-ray powder diffraction patterns of X4a–c
showed a broad reflexion with low resolution (see ESI{, 3). That
was probably due to the reduction of the contrast between the
inorganic part and the organic chains due to replacement of SH
groups by SO3H groups.
1
Found: C 54.78, H 10.08, S 10.53, Si 9.16 (%).2b: H NMR (200 MHz,
CDCl3): 0.66 (4H, t, 2JH,H = 10 Hz), 1.43 (8H, m), 1.69 (4H, tt, 2JH,H = 13
et 11 Hz), 2.68 (4H, dd, 2JH,H = 11 Hz), 3.60 (18H, s). 13C NMR (50 MHz,
CDCl3): 9.46 (CH2–Si), 23.03 (CH2–CH2–Si), 29.24 (CH2–CH2–S–), 32.68
(CH2–CH2–CH2–Si), 39.36 (CH2–S–S), 50.88 (O–CH3). 29Si NMR
(40 MHz, CDCl3): 241.80. Anal. calcd. for C16H38O3S2Si2: C 43.05, H
8.52, O 21.52, S 14.35, Si 12.56. Found: C 42.98, H 8.51, S 14.42, Si
12.51(%).
1 S. L. Burkett, S. D. Sim and S. Mann, Chem. Commun., 1996, 1367.
2 C. E. Fowler, S. L. Burkett and S. Mann, Chem. Commun., 1997, 1769.
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In summary, we have described a new method for the formation
of ordered and highly thiol-functionalized silica starting from bis
silylated precursors containing disulfide units in alkylene chains.
The high adsorption affinity of the SH groups towards mercury
ions, renders these materials promising for removal of other heavy
metal ions from aqueous solutions i.e. environmental remediation.
Finally, the SO3H groups could be useful for heterogeneous
catalysts. This study describes a method leading to ordered hybrid
materials by self-assembly thanks to van der Waals interactions.10
It is an innovative route for the structuration and functionaliza-
tion, which leads to materials, different from those obtained
through surfactant-directed assembly.
6 (a) X. Feng, G. E. Fryxell, L.-Q. Wang, A. Y. Kim, J. Liu and
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Chem. Mater., 2003, 15, 2017.
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P. J. Grobet and P. A. Jacobs, J. Catal., 1999, 182, 156; (b) W. M.
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Chem. Commun., 1998, 37; (c) I. Diaz, F. Mohino, J. Pe´rez-Pariente and
E. Sastre, Appl. Catal., 2001, 205, 19.
The authors thank Dr Philippe Dieudonne´ (GDPC, Universite´
Montpellier II, France) for SAXS measurements, the CNRS and
the Universite´ Montpellier II for financial support.
9 A. M. Liu, K. Hidajat, S. Kawi and D. Y. Zhao, Chem. Commun., 2000,
1145.
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Notes and references
{ 1c: To a solution of NaSH (24.40 mmol, 1.36 g) in anhydrous methanol
(35 mL) was added a solution of 11-bromopentyltrimethoxysilane
(16.20 mmol, 5.75 g) in anhydrous methanol (30 mL), under argon. The
resulting solution was stirred for 14 h at room temperature. Methanol was
removed under vacuum and the resulting residue was stirred in pentane
(50 mL). After filtration of NaBr and NaSH, the filtrate was evaporated
under vacuum. The crude product was purified by distillation (113 uC at
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Chem. Commun., 2006, 347–349 | 349