Marcella Bonchio et al.
FULL PAPERS
Conclusions
General Procedure for the Synthesis of Hybrids 1
(CP)7H[g-SiW10O36] or K8[g-SiW10O36]¥12 H2O with a phase
transfer reagent (n-Bu4NBr or Ph4PBr) were suspended in
THF (10 20 mL) in the presence of RSi(OEt)3 derivatives (2
equivs.) and of 12 M HCl (6 equivs.). The solution was stirred
for 15 h and the product was isolated by centrifugation or by
solvent evaporation and washed with water, CH3CN or toluene
and finally with diethyl ether. Products were dried for 10 h un-
der high vacuum to obtain yields in the range 40 70%.
Thus, the suitability of POM-based hybrids for aqueous
photocatalysis is particularly encouraging, and future
work aims at improving the design of these composite
materials with a twofold purpose: (i) to fine-tune the bal-
ance of the hydrophilic-hydrophobic components so as
to provide discrete molecular species which can be char-
acterized in solution and used for mechanistic studies;
(ii) to develop new systems for environmentally benign
photocatalytic synthetic applications.
(n-Bu4N)4{g-SiW10O36[N-(3-silylpropyl)-2-carboxy-3,4-full-
1
eropyrrolidine]2O} (1a-TBA salt): H NMR (DMSO-d6): d¼
0.72 (m, 4H), 0.93 (m, 48H), 1.31 (m, 32H), 1.56 (m, 32H),
2.01 (m, 4H), 3.05 (m, 4H), 3.16 (m, 32H), 3.77 (m, 6H), 4.38
(m, 2H), 5.06 (m, 2H), 5.23 (m, 2H); IR (KBr): n¼2959 (s),
2930 (s), 2871 (m), 1734 (m), 1629 (m), 1461 (m), 1378 (w),
1171 (w), 1099 (m), 1043 (m), 1004 (m), 929 (s), 901 (s), 876
(s), 821 (s), 735 (s), 555 (m), 526 cmÀ1 (s); UV-Vis (l>
350 nm): 433.6 nm (e¼16ꢁ103 MÀ1 cmÀ1), 710 nm (e¼1.0ꢁ
103 MÀ1 cmÀ1); anal. calcd. for C198H168N6O41Si3W10: C 45.64,
H 3.25, N 1.61; found: C 45.61, H 2.34, N 1.35.
(CP)4{g-SiW10O36[N-(3-silylpropyl)-2-carboxy-3,4-fullero-
pyrrolidine]2O} (1a-CP salt): IR (KBr): n¼3126 (w), 3060 (w),
2918 (s), 2850 (s), 1737 (w), 1632 (m), 1506 (w), 1485 (m), 1462
(m), 1373 (w), 1208 (m), 1173 (m), 1094 (m), 948 (s), 875 (br s),
819 (s), 734 (s), 682 (s), 645 (w), 549 (w), 525 cmÀ1 (m); anal.
calcd. for C218H176N6O41Si3W10: C 47.97, H 3.25, N 1.54; found:
C 48.93, H 3.41, N 1.86.
Experimental Section
General Remarks
Commercially available reagents were used as received with-
out further purification. MilliQ-deionized water was used
as solvent. (n-Bu4N)2[Mo6O19],[30] (n-Bu4N)4[W10O32],[31]
Na4W10O32,[32] K8[g-SiW10O36]¥12 H2O,[33] N-(3-triethoxysilyl-
propyl)-2-carboxy-3,4-fulleropyrrolidine,[23] N-methyl-2-(10-
decyltriethoxysilyl)-3,4-fulleropyrrolidine,[24] were prepared
following literature procedures.
(CP)7H[g-SiW10O36] was prepared from the potassium salt
by metathesis exchange with cetylpyridinium chloride (1.2
equivs.). IR (KBr): n¼3126 (w), 3053 (w), 2919 (s), 2850 (s),
1632 (m), 1486 (m), 1465 (m), 1175 (w), 981 (m), 936 (s), 899
(s), 858 (s), 737 (br s), 685 (s), 644 (m), 552 cmÀ1 (m); anal.
calcd. for C147H266N7O36SiW10: C 38.60, H 5.86, N 2.14; found:
C 38.24, H 6.02, N 2.02.
FT-IR spectra were recorded with Perkin Elmer 1720X or
1600 instruments; UV-Vis spectra were recorded with Perkin
Elmer Lambda 16 or Lambda 45 spectrophotometers, using
1 mm or 1 cm path length quartz cells; 1H NMR spectra were
recorded with a Bruker AC 250 spectrometer, 183W NMR
and 29Si NMR spectra were obtained at 16.7 and 59.6 MHz, re-
spectively, with Bruker Avance DRX 400 (10-mm tubes) and
DRX 300 spectrometers, and referenced to Na2WO4 (D2O,
2 M) and TMS (CDCl3, 50% v/v) solutions. For photooxidation
experiments, irradiation was performed with a light source
housing (Oriel Instruments), equipped with a 500-W Hg-Xe
arc lamp, 200 500 W power supply, F/1.5 UV grade fused silica
condenser, liquid (water) filter to absorb IR radiations, a sec-
ondary focusing lens to maximize the incident light and cut-
off filter allowing irradiation at l>375 nm. The lamp features
a continuous emission spectrum from 250 nm to the near IR, to
which the discontinuous emission spectrum of Hg, in the UV
field, is overlapped; (see Oriel Instrument The Book of the
Photon tools). HPLC analyses were performed on a Spectra-
system P2000 instrument equipped with a photodiode array de-
tector (Spectrasystem UV6000LP, Thermo Separation Prod-
ucts) or with a UV SPD-6A detector plus CR-3A integrator
(Shimadzu) and using a reverse phase column (Lichrosphere
RP18 Alltech). Chemical oxygen demand (COD) analyses
were performed with the standard Cr(VI)/H2SO4 kit Idrimeter
by Carlo Erba.
(CP)4{g-SiW10O36[N-methyl-2-(10-silyldecyl)-3,4-fullero-
pyrrolidine]2O} (1b-CP salt): IR (KBr): n¼3126 (w), 3059 (w),
2921 (s), 2850 (s), 1631 (m), 1485 (m), 1461 (m), 1373 (w) , 1171
(w), 1093 (m), 1045 (w), 1003 (w), 948 (s), 884 (br s), 819 (s), 731
(br s), 682 (m), 643 (w), 555 (w), 525 cmÀ1 (m); anal. calcd. for
C
230H204N6O37Si3W10: C 49.62, H 3.69, N 1.51; found: C 49.12, H
4.10, N 1.59.
(n-Bu4N)3H{g-SiW10O36[NH2(CH2)3Si]2O} (1c): 1H NMR
(DMSO-d6): d¼0.51 (t, 4H), 0.93 (t, 36H), 1.30 (m, 24H),
1.57 (m, 28H), 2.82 (m, 4H), 3.17 (m, 24H), 7.60 (m, 4H);
183W NMR (DMSO): d¼ À108.5 (4W), À132.5 (2W),
À143.7 (4W); 29Si NMR (DMSO-d6): d¼ À63.6 (2Si), À88.8
(1Si); IR (KBr): n¼2961 (s), 2934 (s), 2872 (s), 1624 (w),
1482 (s), 1467 (m), 1380 (m), 1101 (m), 1041 (m), 1001 (m),
962 (s), 901 (br s), 837 (s), 819 (s), 775 (br s), 547 cmÀ1 (m);
anal. calcd. for C54H124N5O37Si3W10: C 19.31, H 3.72, N 2.09;
found: C 19.16, H 3.68, N 1.85.
(n-Bu4N)3H[g-SiW10O36(PhCH2CH2Si)2O] (1d): 1H NMR
(DMSO-d6): d¼0.76 (m, 4H), 0.93 (t, 36H), 1.30 (m, 24H),
1.56 (m, 24H), 2.63 (m, 4H), 3.16 (m, 24H), 7.16 (m, 10H);
183W NMR (DMSO): d¼ À107.8 (4W), À134.8 (2W),
À141.3 (4W); 29Si NMR (DMSO-d6): d¼ À63.8 (2Si), À88.6
(1Si); IR (KBr): n¼2961 (s), 2934 (m), 2872 (m), 1629 (w),
1482 (s), 1379 (m), 1100 (m), 1042 (m), 1003 (m), 963 (s), 930
(s), 901 (s), 883 (s), 818 (s), 736 (s br), 546 (m), 510 cmÀ1 (m);
anal. calcd. for C64H127N3O37Si3W10: C 22.26, H 3.71, N 1.22;
found: C 21.02, H 3.38, N 1.31.
1
(Ph4P)2H2[g-SiW10O36(n-PrSi)2O] (1e): H NMR (DMSO-
d6): d¼0.41 (t, 4H), 0.90 (m, 6H), 1.33 (m, 4H), 7.78 (m,
40H); 183W NMR (DMSO): d¼ À106.6 (4W), À136.7 (2W),
À142.2 (4W); 29Si NMR (DMSO-d6): d¼ À62.7 (2Si), À88.8
(1Si); IR (KBr): n¼3059 (w), 2952 (w), 2866 (w), 1623 (m),
1584 (m), 1482 (m), 1404 (m), 1437 (s), 1336 (w), 1316 (w),
1189 (w), 1164 (w), 1107 (s), 1044 (m), 997 (m), 963 (s), 900
652
¹ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
Adv. Synth. Catal. 2004, 346, 648 654