Adsorption of hydrogen peroxide on functionalized mesoporous silica surfaces

Article abstract of DOI:10.1007/s11224-014-0428-0

MCM-41 and MSU-H mesoporous silicas were successfully functionalized with hydrogen bonds forming organic moieties, which have been proven by elemental analysis. Both moieties, based on oxygen and nitrogen containing groups, were introduced with high efficiency the amount of carbon in all cases exceeded 10 % and the elemental ratios suggest binding to the surface through two or three Si-O-Si bonds. Hydrogen peroxide adsorption was conducted in its aqueous solutions and the amount adsorbed was determined using the ferric thiocyanate method. Results are presented as a function of hydrogen peroxide concentration in aqueous solution from 5 to 30 %. Both functionalized silicas show increased adsorption capacity when compared with that of their unfunctionalized analogues. The surface modified with nitrogen-based organic moiety revealed better adsorption properties as well as higher resistance against oxidation. MSU-H silica, due to its larger pore diameter, provides more space to bind hydrogen peroxide molecules and thus was found to have higher adsorption capacity: it adsorbed up to four times more hydrogen peroxide than MCM-41.

Full text of DOI:10.1007/s11224-014-0428-0

Struct Chem
DOI 10.1007/s11224-014-0428-0
ORIGINAL RESEARCH
Adsorption of hydrogen peroxide on functionalized mesoporous
silica surfaces
•
Dawid Lewandowski Dawid Bajerlein
•
Grzegorz Schroeder
Received: 7 November 2013 / Accepted: 19 March 2014
Ó The Author(s) 2014. This article is published with open access at Springerlink.com
Abstract MCM-41 and MSU-H mesoporous silicas were
successfully functionalized with hydrogen bonds forming
organic moieties, which have been proven by elemental
analysis. Both moieties, based on oxygen and nitrogen
containing groups, were introduced with high efficiency—
the amount of carbon in all cases exceeded 10 % and the
elemental ratios suggest binding to the surface through two
or three Si–O–Si bonds. Hydrogen peroxide adsorption was
conducted in its aqueous solutions and the amount adsor-
bed was determined using the ferric thiocyanate method.
Results are presented as a function of hydrogen peroxide
concentration in aqueous solution from 5 to 30 %. Both
functionalized silicas show increased adsorption capacity
when compared with that of their unfunctionalized ana-
logues. The surface modified with nitrogen-based organic
moiety revealed better adsorption properties as well as
higher resistance against oxidation. MSU-H silica, due to
its larger pore diameter, provides more space to bind
hydrogen peroxide molecules and thus was found to have
higher adsorption capacity: it adsorbed up to four times
more hydrogen peroxide than MCM-41.
atmosphere [1], autodissociation dynamics [2, 3], and
bleaching [4]. It is reasonably stable, readily available,
inexpensive, and generates only water as a by-product [5].
Although its molecule is similar to water, it has not been
much studied in a pure state because of its instability.
However, like water, it forms hydrogen bonds with nitro-
gen- and oxygen-containing compounds [6, 7].
To avoid the stability issues, hydrogen peroxide can be
transformed into a number of complexes with organic
compounds. Urea–hydrogen peroxide complex (UHP) has
already been used in many oxidation processes [8–11] as a
source of anhydrous hydrogen peroxide. It is a stable and
inexpensive solid that has been first prepared by Tanatar [12]
and now is sold by a number of chemical manufacturers. Its
crystals are composed of molecules of urea and hydrogen
peroxide in 1:1 ratio, connected through multiple hydrogen
bonds [13]. Hydrogen peroxide forms also complexes with
melamine [14] and DABCO-di-N-oxide [15]. Some poly-
mer-supported systems containing hydrogen peroxide are
known as well. The most prominent among them is poly-
vinylpyrrolidone-hydrogen peroxide complex (PVP-H2O2),
introduced by Pourali and Ghanei [16] that has already been
successfully used for iodination of aromatic compounds as
well as for oxidation of a,b-enones [17]. It can be easily
prepared from 30 % aqueous solution of hydrogen peroxide
and polyvinylpyrrolidone K-30, it contains up to 23 % of
hydrogen peroxide by weight [18] and is insoluble in organic
solvents [19]. It is stable for several months while stored in a
refrigerator, without losing its weight or activity [16].
Hydrogen peroxide can also be encapsulated in different
silica xerogel systems to serve as an oxidant in the presence
of metal catalyst [20–22] or without it, with a hydrogen
peroxide content up to 68 % [23].
Keywords MCM-41 Á MSU-H Á Hydrogen peroxide Á
Adsorption
Introduction
Hydrogen peroxide is a very useful oxidizer that has been
employed in many different fields, such as chemistry of
D. Lewandowski (&) Á D. Bajerlein Á G. Schroeder
Department of Chemistry, Adam Mickiewicz University,
Umultowska 89b, 61-614 Poznan, Poland
e-mail: dawid_le@amu.edu.pl
Mesoporous materials developed in the 1990s, show
numerous advantages: large surface area (*1,000 m2/g),
123

Struct Chem
uniform and controllable pore size, large pore volume
(*1 cm3/g), narrow particle size, open pore structures
[24], chemical and biological stability, and possibility of
control of surface functionalization, which makes them
very useful in a wide variety of applications such as
adsorption, catalysis, ion exchange, sensing [25], chroma-
tography [26], delivery carriers, and controlled drug/gene
release [27]. There are three general paths to achieve sur-
face functionalization of mesoporous silica surface [28]:
postsynthetic functionalization (the so-called ‘‘grafting’’)
and two methods involved in the silica preparation pro-
cess—co-condensation and condensation of bridged or-
ganosilica precursors forming periodic mesoporous
organosilicas. The use of grafting method usually preserves
the mesostructure of the starting silica phase, but the dis-
tribution of organic moieties anchored to the silica surface
is solvent dependent [29] and sometimes leads to pores
blockage [30]. Another advantage of this method is that it
can be applied to a diversity of organic molecules, from
small ones like aminopropyltrimethoxysilane [29] or
compounds used in our experiment, to large moieties as
dendrimers [31] and fullerenes [32]. Co-condensation is a
convenient direct method of synthesis when the total
amount of the organic part is supposed to be rather small. It
provides better homogeneity of organic moieties, but can
alter the matrix structure leading sometimes to totally
disordered products [28]. It also allows the use of extrac-
tion as the only method for surfactant removal, as calci-
nation could destroy organic compounds. After pioneering
works of the groups of Mann and co-workers [33] and
MacQuarrie [34], many different organically modified
mesoporous silicas have been prepared by co-condensa-
tion, including those modified with alkyl, thiol, vinyl/allyl
[35], amino, cyano/isocyano [36], alkoxy [37], organo-
phosphine, and aromatic groups [38]. Periodic mesoporous
organosilicas (PMOs) are materials with modified matrices
but preserved organized pore system and narrow pore size
distribution. They were first synthesized in 1999 by three
groups working independently [39–41]. Until now, various
PMOs are known: ethane- [39], ethene- [40], benzene-
[42], bisphenyl-bridged [43], etc. They have found their
application in chromatography [44] and catalysis [45].
The study was conducted to verify the ability of organic
moieties grafted onto the mesoporous silicas of MCM-41
and MSU-H types to adsorb hydrogen peroxide from its
aqueous solutions at different concentrations. Silica was
chosen for the experiment, as it can be easily functional-
ized and has native silanol groups, able to form desired
hydrogen bonds. Furthermore, both types of silica used
differ in the pore diameter and noticeably in the surface
area. We have used the method of postsynthetic modifi-
cation to anchor nitrogen- and oxygen-containing groups
that are able to form hydrogen bonds as grafting method
offers higher coverage efficiency than direct synthesis
methods and do not influence the order of mesoporous
silica structure. Nitrogen-based compound (1-[3-(trieth-
oxysilyl)propyl]urea) with urea-like moiety was chosen to
permit comparison of the ability of hydrogen peroxide
binding of this moiety and pure urea. Oxygen-based com-
pound (N-(3-triethoxysilylpropyl)gluconamide) has many
hydroxyl groups, and it was chosen to verify their influence
on binding hydrogen peroxide.
This study is the first on hydrogen peroxide adsorption
(not decomposition) on the surface of organically modified
mesoporous silica. It is supposed to be the basis for future
articles covering the presented issue.
Experimental details
Materials
Mesoporous silicas—MCM-41 (2.1–2.7 nm in diameter
and 1,000 m2/g surface area) and MSU-H (*7.1 nm in
diameter and 750 m2/g surface area), 30 % stock solution
of hydrogen peroxide and 3-(triethoxysilyl)propyl isocya-
nate used for the synthesis of 1-[3-(triethoxysilyl)pro-
pyl]urea (1) were all purchased from Sigma-Aldrich, and
N-(3-triethoxysilylpropyl)gluconamide (2) was purchased
from ABCR GmbH & Co. KG. The structures of com-
pounds used are presented in Fig. 1. Water used for the
preparation of diluted hydrogen peroxide solutions had
been degassed and deionized.
Preparation of reagents
Both mesoporous silicas had been prepared for grafting by
activation in boiling mixture of nitric acid and water (1:1)
for a few hours, filtered off, washed by large amount of
water, and dried in 60 °C for several hours.
A portion of 2 g of 3-(triethoxysilyl)propyl isocyanate
was dissolved in 20 ml of acetonitrile and reacted with dry
gaseous ammonia. The substrates reacted vigorously, so the
solution was mixed and the flask was held in a cool water
bath. After 1 h, the reaction was stopped, and both
ammonia and acetonitrile were evacuated under vacuum.
Gelatinous, quickly crystallizing solid, identified as N-[3-
(triethoxysilyl)propyl]urea, was obtained. Figures 2, 3, and
4 present the spectra obtained for the isolated compound.
1H NMR spectrum was taken on an NMR Varian
VNMR-S 400 MHz spectrometer at 298 K with TMS as a
reference. 1H NMR(400 MHz, CDCl3), d: 0.62–0.67
(t, 2H), 1.20–1.25 (t, 9H), 1.57–1.66 (quin, 2H), 3.11–3.17
(q, 2H), 3.79–3.85 (q, 6H), 4.74–4.77 (s, 2H), 5.20–5.28
(s, 1H).
123

Struct Chem
Fig. 1 Molecules grafted on selected mesoporous silicas surface—1 stands for 1-[3-(triethoxysilyl)propyl]urea and
triethoxysilylpropyl)gluconamide
2 is N-(3-
Fig. 2 1H NMR spectrum of
N-[3-(triethoxysilyl)propyl]urea
Fig. 3 ESI MS spectrum of
N-[3-(triethoxysilyl)propyl]urea
ESI MS spectrum was obtained on a Waters/Micromass
ZQ Mass Detector using 10-3 M methanol solution. ESI
analysis parameters were the following: cone voltage—
30 V, capillary voltage—3 kV, ion source temperature—
393 K, desolvation temperature—573 K, and nitrogen was
used as the nebulizing and desolving gas at flow rate of
80 l/min. ESI MS m/z: [M?H]? 265, [M?Na]? 287,
[M?K]? 303.
C–H alkyl stretching, 1668 cm-1 C=O amide stretching,
1593, 1526 cm-1 N–H amide bending.
Preparation of modified silica
The procedure of modifying both silicas with each of
grafting reagents used was as follows: 250 mg of the
grafting reagent was dissolved in 10 ml of toluene, and
then 250 mg of unmodified mesoporous silica was sus-
pended. The mixture was stirred under reflux for 6 h,
cooled to room temperature, filtered off, washed with pure
toluene, and dried in 60 °C for several hours.
IR spectrum was obtained on a Bruker FT-IR IFS 66/s
spectrometer using 1.2 mg of the compound mixed with
200 mg of KBr and formed into
a
pellet. IR:
3670–3440 cm-1 N–H amide stretching, 2975–2885 cm-1
123

Struct Chem
Fig. 4 IR spectrum of N-[3-(triethoxysilyl)propyl]urea
Hydrogen peroxide adsorption analysis
A series of hydrogen peroxide solutions with concen-
trations increasing from 5 to 30 % and pure, deionized,
and degassed water were prepared for both unmodified
and modified silica systems. Each system was composed
of 35 mg of a selected silica suspended in 6 ml of
hydrogen peroxide solution in a phial and stirred with a
magnetic stirrer at room temperature for 24 h. Then, the
phial contents were filtered off, washed with decent
amount of water, and dried in 50 °C for 2 h to avoid
hydrogen peroxide decomposition. The amount of
hydrogen peroxide adsorbed was determined using the
ferric thiocyanate method [46]. Before absorbance
measurement on an UV–Vis Agilent 8453 Spectropho-
tometer, the silica suspensions were centrifuged to avoid
Fig. 5 Amount of hydrogen peroxide adsorbed on each functionalized
silica as a function of hydrogenperoxide concentration in aqueous solution
disturbances caused by silica particles, and only clear
solution from over the precipitate was taken for
measurement.
Table 1 Comparison of
grafting efficiency for all
obtained systems
Grafting compound
Mesoporous
silica type
Mass percentages of selected elements
Mass ratios
C:H:N
Carbon
(%)
Hydrogen
(%)
Nitrogen
(%)
1-[3-(Triethoxysilyl)
propyl]urea
MCM-41
MSU-H
MCM-41
MSU-H
11.70
11.74
12.31
12.27
15.68
15.71
16.17
16.21
0.030
0.043
0.089
0.093
3.044
3.065
3.160
3.190
3.786
3.954
3.498
3.534
0.832
0.879
1.215
1.242
4.371
4.276
6.310
6.250
1.925
1.969
1.939
1.877
0.034
0.043
0.044
0.012
2.68:0.70:1
2.75:0.72:1
1.95:0.50:1
1.96:0.51:1
8.14:1.97:1
7.98:2.01:1
8.34:1.80:1
8.64:1.88:1
0,88:24.54:1
1.00:20.44:1
2.02:27.61:1
7.75:103.50:1
N-(3-Triethoxysilylpropyl)
gluconamide
Pure MCM-41
Pure MSU-H
123

Struct Chem
Fig. 6 Cross-section of MSU-H silica, functionalized with N-(3-triethoxysilylpropyl)gluconamide, explaining the possible organization of
grafted molecules and hydrogen peroxide adsorbed in the pores. Channel diameter and size of the molecules match
Results and discussion
added with grafted molecules in the amount depending on
the total amount of the given compound grafted, hydrolysis
of its alkoxy-groups, and the amount of Si–O–Si links
formed.
Elemental analysis
Elemental analysis for carbon, hydrogen, and nitrogen
content allowed determination of the amounts of grafting
reagents that had reacted with the silica surface. Results are
presented in Table 1.
The unbound 1-[3-(triethoxysilyl)propyl]urea of the
molecular formula C10H24N2O4Si and the carbon:nitrogen
ratio equal to 4.29:1 can be linked through one (with one
ethoxy-group removed), two, or three Si–O–Si links with
carbon:nitrogen ratios equal to 3.43:1, 2.57:1, and 1.71:1,
respectively. The carbon:nitrogen ratios obtained for this
compound suggest binding through two Si–O–Si links,
when grafted on MCM-41, and through two or three (two
links:three links ratio is 0.29:0.71) links, when grafted on
MSU-H silica. Similar analysis conducted for binding of
N-(3-triethoxysilylpropyl)gluconamide led to the following
results: unbound compound of the molecular formula
C15H33NO9Si and the carbon:nitrogen ratio equal to
The presence of carbon in pure silicas can be a residue
of surfactant used in the manufacturing process. Nitrogen
observed in pure silica can be either adsorbed from the air
or a surfactant residue, and hydrogen is a component of
silanol groups densely covering the surface. The number of
Si–O–Si bonds linking the grafted molecules to the surface
could be easily calculated from the carbon:nitrogen ratio as
hydrogen balance was more difficult to calculate. Hydro-
gen was removed from the surface silanol groups and
123

Struct Chem
12.86:1 can be linked through one, two, or all three links
with carbon:nitrogen ratios equal to 11.14:1, 9.43:1, and
7.71:1, respectively. The carbon:nitrogen ratios for this
compound suggest binding to the surface of both silicas
through two or three Si–O–Si links (for MCM-41 two
links:three links ratio is 0.21:0.79 and for MSU-H
0.45:0.55).
The silicas obtained contain large amounts of grafted
compounds on their surface, comparable to those of simple
organic compounds grafted in the previous studies on
functionalization of mesoporous surfaces [47, 48], that
could be estimated from the amount of nitrogen as its
content is not dependent on the binding degree. 1-[3-(Tri-
ethoxysilyl)propyl]urea accounts for 32.11 % of total mass
of modified MCM-41 and 41.71 % of MSU-H, which is
1.37 molecules/nm2 of MCM-41 surface and 3.09 mole-
cules/nm2 of MSU-H surface. N-(3-Triethoxysilylpro-
pyl)gluconamide accounts for 44.51 % of total mass of
modified MCM-41 and 45.32 % of MSU-H, which is
1.51 molecules/nm2 of MCM-41 surface and 2.00 mole-
cules/nm2 of MSU-H. These results show clearly that the
pore size is an important factor, influencing the total
amount of compounds grafted.
Fig. 7 Cross-section of MCM-41 silica, functionalized with N-(3-
triethoxysilylpropyl)gluconamide, explaining the possible organiza-
tion of grafted molecules and hydrogen peroxide adsorbed in the
pores. Channel diameter and size of the molecules match
Hydrogen peroxide adsorption analysis
The graphs presented in Fig. 5 for different mesoporous
silicas show clearly that surface modification influenced
the amounts of hydrogen peroxide adsorbed on its surface,
which after modification increased several times. The
adsorption capacity of silicas modified with 1-[3-(trieth-
oxysilyl)propyl]urea was increasing nonlinearly up to a
hydrogen peroxide concentration of 25 %, and then it
dropped to values similar to those obtained for unmodified
silica, probably because of the destruction of organic
moiety anchored to the silica surface (loss of the ‘‘urea’’
part makes it unable to form hydrogen bonds). The silicas
modified with N-(3-triethoxysilylpropyl)gluconamide have
their maximum adsorption at 5 % concentration of hydro-
gen peroxide, and then it decreases slightly to become
almost equal to the adsorption of unmodified silica at 30 %
hydrogen peroxide concentration. A large number of
hydroxyl groups included in gluconamide moiety are oxi-
dized, even at lower concentrations, and partially lose their
ability to form hydrogen bonds (carbonyl group, without a
hydrogen atom, can only be an electron donor). The
average contents of carbon, hydrogen, and nitrogen for
samples bathed in a 30 % solution of hydrogen peroxide
are, respectively, 7.468, 2.261, and 3.897 %. The car-
bon:nitrogen ratio is much smaller than that for the unox-
idized sample, which proves a major destruction to the
organic part and the loss of ability to bind hydrogen per-
oxide. Small increase in the amount of hydrogen peroxide
adsorbed at 25 and 30 % concentrations in comparison to
that adsorbed from hydrogen peroxide solutions of con-
centrations 20 and 25 % may be caused by adsorption on
the uncovered part of the silica surface.
Also, MSU-H silica was found to adsorb much higher
amounts of hydrogen peroxide, although it has smaller
surface area. The influence of pore diameter on the
amounts of hydrogen peroxide adsorbed is also indicated
by the results obtained for each silica separately. The
maximum amounts of hydrogen peroxide for MCM-41 are
similar because of available space limitations. Grafted
molecules occupy most of the pore volume, so there is not
much space to bind H2O2 and its diffusion may be
impaired. MSU-H provides much more space for both
grafted organic moieties and hydrogen peroxide adsorbed
as can be seen comparing Figs. 6 and 7, and the amount of
H2O2 is only limited by the binding abilities of grafted
molecules.
The amount of hydrogen peroxide adsorbed on
unmodified silica surface almost linearly increases with
increasing hydrogen peroxide concentration. This phe-
nomenon can be explained by formation of hydrogen bonds
between free silanol groups and hydrogen peroxide. In the
experimental conditions, almost all of silanol groups were
ionized as mesoporous silanol groups existed in two forms,
Si-(OH)2 and Si-(OH) with pKa values, respectively, 8.2
and 2.0 [49].
123

Struct Chem
9. Hasaninejad A, Zolfigol MA, Chehardoli G, Mokhlesi M (2010)
Molybdatophosphoric acid as an efficient catalyst for the catalytic
and chemoselective oxidation of sulfides to sulfoxides using urea
hydrogen peroxide as a commercially available oxidant. J Serb
Chem Soc 75:307–316
10. Varma RS, Naicker KP (1999) The urea–hydrogen peroxide
complex: solid-state oxidative protocols for hydroxylated alde-
hydes and ketones (Dakin reaction), nitriles, sulfides, and nitro-
gen heterocycles. Org Lett 1:189–192
11. Caron S, Do NM, Sieser JE (2000) A practical, efficient, and
rapid method for the oxidation of electron deficient pyridines
using trifluoroacetic anhydride and hydrogen peroxide–urea
complex. Tetrahedron Lett 41:2299–2302
Conclusions
Two different molecules able to form hydrogen bonds were
successfully grafted on the surface of two different meso-
porous silicas of MCM-41 and MSU-H types. The amounts
of hydrogen peroxide adsorbed on their surface were
measured, and MSU-H sample was found to have a higher
adsorption capacity, as about 2–3 times more hydrogen
peroxide got adsorbed on its surface. Unmodified silica
showed also some adsorption abilities dependent on the
concentration of hydrogen peroxide solution. Functional-
ized surface was not resistant enough and the compounds
deposited underwent oxidation, changing the silicas
adsorption properties in higher hydrogen peroxide con-
centrations. Increased amount of hydroxyl groups intro-
duced with N-(3-triethoxysilylpropyl)gluconamide indeed
has enhanced the adsorption of hydrogen peroxide.
Although the content of hydrogen peroxide bound by the
systems obtained was small in comparison with that of
PVP or urea complexes, results of this study can initiate
further development in this field.
12. Tanatar S (1906) J Russ Phys Chem Soc 40L:376
`
13. Lu C-S, Hughes EW, Giguere PA (1941) The crystal structure of
the urea–hydrogen peroxide addition compound CO(NH2)2 H2O2.
J Am Chem Soc 63:1507–1513
14. Chehardoli G, Zolfigol MA (2009) Melamine hydrogen peroxide
(MHP): novel and efficient reagent for the chemo- and homose-
lective and transition metal-free oxidation of thiols and sulfides.
Phosphorus Sulfur Silicon Relat Elem 185:193–203
15. Zolfigol MA, Salehi P, Mallakpour SE, Torabi M (2003) 1,4-
Diazabicyclo[2.2.2]octane 1,4-bis(oxide)-bis(hydrogen perox-
ide)/MClx as a novel heterogeneous system for the oxidation of
urazoles under mild conditions. Bull Chem Soc Jpn
76:1673–1674
16. Pourali AR, Ghanei M (2006) Direct Iodination of aromatic
compounds with polyvinylpyrrolidone supported hydrogen per-
oxide (PVP-H2O2) and potassium iodide or molecular iodine.
Chin J Chem 24:1077–1079
Acknowledgments The authors would like to thank the National
Science Center of Poland (Grant No. 2011/03/B/ST5/01573) for
financial support.
17. Pourali AR, Ghanei M (2006) Efficient epoxidation of a, b-
enones with polyvinylpyrrolidone supported hydrogen peroxide
(PVP-H2O2). Bull Korean Chem Soc 27:1674–1676
18. Merianos JJ (1991) Anhydrous complexes of PVP and hydrogen
peroxide. US Patent 5,008,093
Open Access This article is distributed under the terms of the
Creative Commons Attribution License which permits any use, dis-
tribution, and reproduction in any medium, provided the original
author(s) and the source are credited.
19. Ghorbani-Choghamarani
A, Azadi
G
(2011) Poly-
vinylpolypyrrolidone-supported hydrogen peroxide (PVP-H2O2),
silica sulfuric acid and catalytic amounts of ammonium bromide
as green, mild and metal-free oxidizing media for the efficient
oxidation of alcohols and sulfides. JICS 8:1082–1090
References
20. Kochkar H, Figueras F (1997) Synthesis of hydrophobic TiO2–
SiO2 mixed oxides for the epoxidation of cyclohexene. J Catal
171:420–430
21. Barbosa GN, MacLeod TCO, Guedes DFC, Assis MD, Oliveira
HP (2008) Preparation, characterization and catalytic studies of
V2O5–SiO2 xerogel composite. J Sol–Gel Sci Technol 46:99–105
22. Neumann R, Levin-Elad M (1997) Metal oxide (TiO2, MoO3,
WO3) substituted silicate xerogels as catalysts for the oxidation of
hydrocarbons with hydrogen peroxide. J Catal 166:206–217
1. Wayne RP (1991) Chemistry of atmospheres. Clarendon Press,
Oxford
2. Gericke K-H, Klee S, Comes FJ, Dixon RN (1986) Dynamics of
H2O2 photodissociation: OH product state and momentum dis-
tribution characterized by sub-Doppler and polarization spec-
troscopy. J Chem Phys 85:4463–4479
3. Docker MP, Hodgson A, Simons JP (1986) Photodissociation of
H2O2 at 248 nm: translational anisotropy and oh product state
distributions. Chem Phys Lett 128:264–269
´
23. Bednarz S, Rys B, Bogdał D (2012) Application of hydrogen
4. Hart PW, Rudie AW (2012) The bleaching of pulp, 5th edn.
Tappi Press, Norcross
peroxide encapsulated in silica xerogels to oxidation reactions.
Molecules 17:8068–8078
24. Popat A, Liu J, Hu Q, Kennedy M, Peters B, Lu GQM, Qiao SZ
(2012) Adsorption and release of biocides with mesoporous silica
nanoparticles. Nanoscale 4:970–975
25. Vallet-Regi M, Ramila A, Real RPd, Perez-Pariente J (2001) A
new property of MCM-41: drug delivery system. Chem Mater
13:308–311
26. Mal NK, Fujiwara M, Tanaka Y (2003) Photocontrolled revers-
ible release of guest molecules from coumarin-modified meso-
porous silica. Nature 421:350–353
5. Kureshy RI, Khan NH, Abdi SHR, Patel ST, Jasra RV (2001)
Enantioselective epoxidation of non-functionalised alkenes using
a urea–hydrogen peroxide oxidant and a dimeric homochiral
Mn(III)-Schiff base complex catalyst. Tetrahedron Asymmetry
12:433–437
6. Goebel JR, Ault BS, Del Bene JE (2001) Matrix isolation and
ab initio study of 1:1 hydrogen-bonded complexes of H2O2 with
NH3 and N(CH3)3. J Phys Chem A 105:6430–6435
7. Goebel J, Ault BS, Del Bene JE (2000) Matrix isolation and
ab initio study of the hydrogen-bonded complex between H2O2
and (CH3)2O. J Phys Chem A 104:2033–2037
27. He Q, Gao Y, Zhang L, Zhang Z, Gao F, Ji X, Li Y, Shi J (2011)
A pH-responsive mesoporous silica nanoparticles-based multi-
drug delivery system for overcoming multi-drug resistance.
Biomaterials 32:7711–7720
8. Boehlow TR, Spilling CD (1996) The regio- and stereo-selective
epoxidation of alkenes with methyl trioxorhenium and urea–
hydrogen peroxide adduct. Tetrahedron Lett 37:2717–2720
123

Struct Chem
28. Hoffmann F, Cornelius M, Morell J, Froba M (2006) Silica-based
mesoporous organic–inorganic hybrid materials. Angew Chem
Int Ed 45:3216–3251
29. Salmio H, Bruhwiler D (2007) Distribution of amino groups on a
mesoporous silica surface after submonolayer deposition of am-
inopropylsilanes from an anhydrous liquid phase. J Phys Chem C
111:923–929
39. Inagaki S, Guan S, Fukushima Y, Ohsuna T, Terasaki O (1999)
Novel mesoporous materials with a uniform distribution of
organic groups and inorganic oxide in their frameworks. J Am
Chem Soc 121:9611–9614
40. Melde BJ, Holland BT, Blanford CF, Stein A (1999) Mesoporous
sieves with unified hybrid inorganic/organic frameworks. Chem
Mater 11:3302–3308
30. Lim MH, Stein A (1999) Comparative studies of grafting and
direct syntheses of inorganic–organic hybrid mesoporous mate-
rials. Chem Mater 11:3285–3295
41. Asefa T, MacLachlan MJ, Coombs N, Ozin GA (1999) Periodic
mesoporous organosilicas with organic groups inside the channel
walls. Nature 402:867–871
31. Acosta EJ, Carr CS, Simanek EE, Shantz DF (2004) Engineering
nanospaces: iterative synthesis of melamine-based dendrimers on
amine-functionalized SBA-15 leading to complex hybrids with
controllable chemistry and porosity. Adv Mater 16:985–989
32. Fukuoka A, Fujishima K, Chiba M, Yamagishi A, Inagaki S,
Fukushima Y, Ichikawa M (2000) Photooxidation of cyclohexene
and benzene with oxygen by fullerenes grafted on mesoporous
FSM-16. Catal Lett 68:241–244
42. Yoshina-Ishii C, Asefa T, Coombs N, MacLachlan MJ, Ozin GA
(1999) Periodic mesoporous organosilicas, PMOs: fusion of
organic and inorganic chemistry ‘inside’ the channel walls of
hexagonal mesoporous silica. Chem Commun 24:2539–2540
43. Kapoor MP, Yang Q, Inagaki S (2002) Self-assembly of
biphenylene-bridged hybrid mesoporous solid with molecular-
scale periodicity in the pore walls.
124:15176–15177
J Am Chem Soc
33. Burkett SL, Sims SD, Mann S (1996) Synthesis of hybrid inor-
ganic–organic mesoporous silica by co-condensation of siloxane
and organosiloxane precursors. Chem Commun 11:1367–1368
34. Macquarrie DJ (1996) Direct preparation of organically modified
MCM-type materials. Preparation and characterisation of ami-
nopropyl-MCM and 2-cyanoethyl-MCM. Chem Commun
16:1961–1962
35. Mercier L, Pinnavaia TJ (2000) Direct synthesis of hybrid
organic-inorganic nanoporous silica by a neutral amine assembly
route: structure-function control by stoichiometric incorporation
of organosiloxane molecules. Chem Mater 12:188–196
36. Huh S, Wiench JW, Yoo J-C, Pruski M, Lin VS-Y (2003)
Organic functionalization and morphology control of mesoporous
silicas via a co-condensation synthesis method. Chem Mater
15:4247–4256
37. Fowler CE, Burkett SL, Mann S (1997) Synthesis and charac-
terization of ordered organo-silica-surfactant mesophases with
functionalized MCM-41-type architecture. Chem Mater
18:1769–1770
38. Cagnol F, Grosso D, Sanchez C (2004) A general one-pot process
leading to highly functionalised ordered mesoporous silica films.
Chem Commun 10:1742–1743
44. Kim D-J, Chung J-S, Ahn W-S, Kang G-W, Cheong W-J (2004)
Morphology control of organic-inorganic hybrid mesoporous
silica by microwave heating. Chem Lett 33:422–423
45. Fukuoka A, Sakamoto Y, Guan S, Inagaki S, Sugimoto N,
Fukushima Y, Hirahara K, Iijima S, Ichikawa M (2001) Novel
templating synthesis of necklace-shaped mono- and bimetallic
nanowires in hybrid organic-inorganic mesoporous material.
J Am Chem Soc 123:3373–3374
46. Boltz DF, Howell JA (1978) Colorimetric determination of
nonmetals, vol 8, 2nd edn. Wiley, New York
47. Chang F-Y, Chao K-J, Cheng H-H, Tan C-S (2009) Adsorption of
CO2 onto amine-grafted mesoporous silicas. Sep Purif Technol
70:87–95
48. Sec¸kin T, Gu¨ltek A, Kartaca S (2003) The grafting of Rhodamine
B onto sol–gel derived mesoporous silicas. Dyes Pigments
56:51–57
49. Rosenholm JM, Czuryszkiewicz T, Kleitz F, Rosenholm JB,
´
Linden M (2007) On the nature of the Brønsted acidic groups on
native and functionalized mesoporous siliceous SBA-15 as
studied by benzylamine adsorption from solution. Langmuir
23:4315–4323
123