Photooxidation of triarylphosphines under aerobic conditions in the presence of a gold(iii) complex on cellulose extracted from Carthamus tinctorius immobilized on nanofibrous phosphosilicate

Article abstract of DOI:10.1039/C8RA09721F

Triarylphosphines were converted to the corresponding oxides via photooxidation as a novel method. In this study, cellulose was extracted from the Carthamus tinctorius plant and then oxidized by sodium metaperiodate. A gold complex was supported on this natural cellulose. Then, a gold complex on natural cellulose supported on FPS (FPS/Au(iii)) was synthesized for the reduction of phosphine oxides to corresponding phosphines with remarkable chemoselectivity. The morphology of FPS led to higher catalytic activity. FPS/Au(iii) NPs were thoroughly characterized using TEM, FESEM, FTIR, TGA, and BET.

Full text of DOI:10.1039/C8RA09721F

RSC Advances
View Article Online
View Journal | View Issue
PAPER
Photooxidation of triarylphosphines under aerobic
conditions in the presence of a gold(III) complex on
cellulose extracted from Carthamus tinctorius
immobilized on nanofibrous phosphosilicate
Cite this: RSC Adv., 2019, 9, 1509
ab
and Rahele Zhianiab
*
Seyed Mohsen Sadeghzadeh
Triarylphosphines were converted to the corresponding oxides via photooxidation as a novel method. In
this study, cellulose was extracted from the Carthamus tinctorius plant and then oxidized by sodium
metaperiodate. A gold complex was supported on this natural cellulose. Then, a gold complex on natural
cellulose supported on FPS (FPS/Au(III)) was synthesized for the reduction of phosphine oxides to
corresponding phosphines with remarkable chemoselectivity. The morphology of FPS led to higher
catalytic activity. FPS/Au(III) NPs were thoroughly characterized using TEM, FESEM, FTIR, TGA, and BET.
Received 26th November 2018
Accepted 14th December 2018
DOI: 10.1039/c8ra09721f
rsc.li/rsc-advances
biomimetic modeling and the design of magnetic molecules
have attained much signicance. Schiff bases are also used as
Introduction
corrosion inhibitors, pigments, dyes, polymer stabilizers,
intermediates in organic synthesis, and catalysts.13
Lately, the performance of cellulose has been considered via its
hybridization with various ligands and metal nanoparticles.
These compounds have attracted much interest in different
aspects such as in exible electronics, biocompatible drug
delivery, biosensors, and disposable sensor applications.1,2
Micro-biocomposites are dened as natural compounds with at
least one microscale substance scattered in a matrix, which can
afford micromaterials with usage in industrial chemicals. In
these types of materials, cellulose works as a bio-friendly
substrate and is ubiquitous for novel catalytic applications.3,4
Reproducible natural sources are considered as natural raw
materials for the development of biodegradable plastics and
eco-friendly composites as they can substitute articial poly-
mers, reduce global affiliation on fossil fuel resources and
provide simplied end-of-life access.5–7 Celluloses are the most
abundant natural biopolymers providing exclusive mechanical
stability to microcomposites.8,9 Various aldehydes can trans-
form into polysaccharides with Schiff base ligands and primary
amines in the oxidation of glycolic groups. Usually, for the
conversion of polysaccharides to react with primary amines,
several aldehyde groups are introduced into poly-
saccharides.10,11 Schiff bases build dialdehyde cellulose as
a precious intermediate for cellulose-based substances for drug
deliveries.12 Molybdenum complexes present great potential for
their applications in medicinal chemistry due to their various
antitumor and biological activities. On the other hand,
The oxidation of phosphines to phosphine oxides is an
important subject for industrial reactions, especially in the
reduction of contamination.14 Therefore, the oxidation of
phosphines to phosphine oxides has been an important issue in
chemistry. Given the importance of this issue, many methods
have been extended in these topics.15–29 Despite their signicant
results, phosphine oxidation reactions have some problems. A
catalytic or stoichiometric amount of additives must be added
to initiate or catalyze this reaction.17,22,23 Because of this, a large
amount of toxic material or organic waste is produced. Also, the
formation of by-products cannot be avoided;21,29 this results in
problems with the purication and waste products perhaps
formed in the workup of purication. The issues listed above
show that considerable waste is produced, which is specically
not environmentally friendly. Thus, more efficient reactions
that can be performed under ambient conditions are in urgent
need considering the increasing environmental concerns.
Photooxidation23–29 provides an efficient way to realize this
reaction, which normally uses oxygen as the oxidant.25–27
Gold catalysis has quickly become a hot topic in Chemistry
in the past decade.30 Gold species are equally impressive as
heterogeneous or homogeneous catalysts,31,32 showing excellent
results in diversied reactions.33,34 Gold complexes have been
employed as a highly efficient catalyst for the formation of C–O,
C–C, C–S, C–N, C–P, and C–F bonds starting from alkenes and
alkynes.35–37 From a viewpoint of reactivity, Au complexes
involving phosphorus ligands are one of the most reactive
classes of Au catalysts. Supporting these ligands on a recyclable
support is one of the most important approaches to improve
aNew Materials Technology and Processing Research Center, Department of Chemistry,
Neyshabur Branch, Islamic Azad University, Neyshabur, Iran. E-mail:
seyedmohsen_sadeghzadeh@yahoo.com
bYoung Researchers and Elite Club, Neyshabur Branch, Islamic Azad University,
Neyshabur, Iran
This journal is © The Royal Society of Chemistry 2019
RSC Adv., 2019, 9, 1509–1516 | 1509

View Article Online
RSC Advances
Paper
their applicability in organic reactions.38 In recent years, it has isolated by centrifugation, washed with deionized water and
been revealed that the use of gold complexes graed on solid acetone, and dried in a drying oven.
supports plays an important role in preventing the aggregation
of Au.39
Extracted cellulose from Carthamus tinctorius
Recently, our research team presented brous phosphosili-
Cellulose obtained from Carthamus tinctorius was treated with
NaClO2 salt at pH ¼ 4.0 at 75 ꢀC for 2 h and ltered. The residue
was then washed with distilled water and ethanol (95%) and
dried in an oven at 50 ꢀC for 13 h. Next, dried residues were
extracted with KOH (10%) at room temperature for 8 h. Aer
ltration, the residue was washed until neutral and then
washed with ethanol (95%) 5 times. Finally, the samples were
cate (FPS) NPs that have special morphology, and their pore
sizes gradually increase from the center to the surface.40 FPS
NPs showed a high specic surface area due to the pores in the
structures, and the approachability of the active sites signi-
cantly increased as a result of the special morphology and
structure. Additionally, the 3D architectures generated hierar-
chical pore structures with macropores, which can also improve
the mass transfer of the reactant. The FPS-based sorbents may
have several advantages over conventional silica-based
sorbents, including (i) high catalyst loading, (ii) minimal
reduction in the surface area aer functionalization and (iii)
greater accessibility of the catalyst sites to enhance the reaction,
due to the brous structure and highly accessible surface area of
FPS. Given our continued interest in nanocatalysis and catalyst
development for organic reactions,41–45 a novel strategy was re-
ported for the preparation of desired nanocomposites by the
modication of cellulose as a natural resource along with
extracting solution of natural plants for cellulose industrial
applications. Herein, oxidized cellulose was extracted from
Carthamus tinctorius, and we investigated a novel immobilized
gold Schiff base complex on natural cellulose and supported on
brous FPS as a catalyst, catalyzing the photooxidation of
phosphines under aerobic conditions. In this study, we found
that under simple photoirradiation, triarylphosphines can be
easily oxidized into corresponding oxides. This reaction uses
oxygen in the air as the oxidant, which is green and abundantly
available. Very importantly, aer complete conversion, stoi-
ꢀ
dried in an oven at 50 C for 20 h.
General procedure for the preparation of cellulose-FPS NPs
First, 2 mmol of FPS in 20 mL of water was mixed together.
Then, into the mixture, 0.75 mL of acetic acid was dispersed by
ultrasonication; 250 mg of cellulose was added at r.t. and stirred
for another 16 h at 70 ꢀC. The products were washed with
ethꢀanol and deionized water and then dried under vacuum at
50 C for 3 h.
Preparation of dialdehyde cellulose
First, 0.27 g of sodium metaperiodate was added to 0.5 g of
cellulose-FPS suspended in 60 mL of distilled water. The
mixture was stirred in the dark at 60 ꢀC for 10 h. Hereinaer, the
remaining NaIO4 was decomposed by adding glycerol. Finally,
the product was washed with deionized water and dried at r.t.
for 12 h.
chiometric amounts of the oxides were afforded without the Preparation of Schiff base supported on dialdehyde cellulose
formation of any by-products, which indicated that no waste
Here, 0.35 g of DAMC was added to 20 mL of ethanol and then,
was generated during the workup step since simply recycling
0.78 g of 9-aminoacridine was added to the mixture. The
the solvent under vacuum is sufficient for purication (Scheme
mixture was heated under reux for 36 h. The product was
1). Herein, we wish to report our recent observations on the
washed with deionized water and ethanol.
catalyst photooxidation of phosphines under aerobic condi-
tions at an ambient temperature.
General procedure for the preparation of FPS/Au(III) NPs
In a stirred solution of 0.15 mmol of NaAuCl4 in 50 mL of DMF,
1 g of FPS/ligand was added and reuxed under argon for 12 h.
The obtained solid was washed with 25 mL of THF and 25 mL of
acetone. Further, the product was Soxhlet-extracted with
Experimental
General procedure for the preparation of FPS
In a stirred solution of 30 mL of cyclohexane and 1.5 mL of 1-
pentanol, 2.0 g of tetraethyl orthosilicate (TEOS) and 3.7 g of
tripolyphosphate were dissolved. A solution of 1 g of CPB and
0.5 g of urea in 30 mL of water was added to the top mixture. The
obtained mixture was continually stirred for 45 min at r.t. and
dichloromethane (CH2Cl2) for 24 h to remove unreacted
NaAuCl4 and organic impurities. The resulting product was
dried using vacuum at 75 C to furnish FPS/Au(III) NPs.
ꢀ
General procedure for photooxidations
ꢀ
then placed in a reactor and heated at 120 C for 5 h. FPS was
Here, 8 mg of FPS/Au(III) NPs, 1 mmol of triarylphosphine and
10 mL of dimethyl carbonate were added to a dry quartz reac-
tion ask, which was equipped with a magnetic stirrer. The
mixture was irradiated by a compact uorescent lamp (CFL) (20
W) at r.t. under an air atmosphere. Next, the photoreaction was
completed as monitored by TLC. The solvent was directly recy-
cled under vacuum to afford triarylphosphine oxides as a solid.
Scheme 1 Aerobic photooxidation of triarylphosphines.
1510 | RSC Adv., 2019, 9, 1509–1516
This journal is © The Royal Society of Chemistry 2019

View Article Online
Paper
RSC Advances
(Fig. 1a and c). The study of TEM and FESEM revealed that FPS/
Au(III) has dendrimeric bers (thicknesses of 10–12 nm)
arranged in three dimensions to form walls, which can allow
easy access to the available high level. From FESEM and TEM
images of FPS/Au(III) NPs, it can be seen that no signicant
change was observed aer the modication of the morphology
of NPs (Fig. 1b and d). Fig. 2 shows the TGA analysis of FPS/
Au(III) NPs: the elimination of the physisorbed and chemisorbed
solvent on the surface of the FPS/Au(III) material causes weight
loss below 150 ꢀC. Also, weight loss in the range of 250–450 ꢀC is
about 11.5 wt%, which is related to the organic group
derivatives.
The N2 adsorption–desorption isotherms of FPS/Au(III) NPs
showed characteristic type IV curves (Fig. 3). The BET surface
area for FPS, the total pore volume and the BJH pore diameter
were determined to be 34 m2 gꢁ1, 0.24 cm3 gꢁ1, and 2.43 nm,
respectively; also, the corresponding parameters of FPS/Au(III)
NPs decreased to 30 m2 gꢁ1, 0.20 cm3 gꢁ1, and 2.21 nm. The
nitrogen sorption analysis of FPS/Au(III) NPs also conrmed
a regular and uniform mesostructure with decrease in surface
area, pore diameter and pore volume in comparison with the
observations of pristine FPS. The corresponding pore volumes
Results and discussion
The rst stage in designing FPS/Au(III) NPs was the functional-
ization of FPS with cellulose groups, which could then act as
pseudo chelators or ligands to control metal leaching during
the reaction. In the next step, the aldehyde group of natural
oxidized cellulose reacted with the amine group of 9-amino-
acridine through the Schiff base ligand. The immobilized Schiff
base ligand was then allowed to react with an appropriate
concentration of ammonium heptamolybdate to provide a gold
complex. Finally, FPS/Au(III) NPs were characterized by different
methods such as TEM, FESEM, FTIR, TGA, and BET (Scheme 2).
The structure and morphology of FPS/Au(III) NPs were
studied with TEM and FESEM (Fig. 1). The FPS sample
comprised wall-like domains, and the sizes of walls were stable
Scheme 2 Schematic illustration of the synthesis of FPS/Au(III) NPs.
Fig. 2 TGA diagram of FPS/Au(III) NPs.
Fig. 1 TEM images of FPS NPs (a) and FPS/Au(III) NPs (b); FESEM images
of FPS NPs (c) and FPS/Au(III) NPs (d).
Fig. 3 Adsorption–desorption isotherms of FPS/Au(III) NPs.
RSC Adv., 2019, 9, 1509–1516 | 1511
This journal is © The Royal Society of Chemistry 2019

View Article Online
RSC Advances
Paper
were drastically reduced with the functionalization of ligand/
In the rst step, a series of conventional solvents were tested
Au(III)–P. This can be attributed to increased loading with the (Table 2, entries 1–18). In all the tested solvents, a stoichio-
sensing probe, which occupies a large volume inside the bers metric yield of the desired tris(4-methoxyphenyl)phosphine
(Fig. 3 and Table 1).
oxide was provided. The biggest difference is that dimethyl
FTIR spectra proved the presence of surface silanol, hydroxyl carbonate (DMC) increased the rate of the oxidation process,
and phosphate groups as well as anchored complex [HAuCl4] in which may be due to the higher energy transfer efficiency and
(a) FPS and (b) FPS/Au NPs (Fig. 4). For FPS, the broad absorp- faster single-electron transfer speed (Table 2, entry 8). There-
tion bands at 1092 cmꢁ1 and 3649 cmꢁ1 were attributed to Si– fore, DMC exhibited the best performance among the solvents.
O–Si asymmetric stretching and OH, respectively. Two peaks at Next, the effect of temperature on the reaction was investigated.
793 cmꢁ1 and 469 cmꢁ1 were assigned to Si–O–Si symmetric Increasing the temperature to 80 C did not increase the yield.
ꢀ
stretching and bending vibrations, respectively. The pure FPS Hence, it was found that the best result was obtained at room
sample showed a typical broad peak at around 3399 cmꢁ1 temperature for the desired transformation. The catalyst
associated with the presence of hydroxyl groups, and the quantity is another important issue in the photooxidation of
intensity of this peak increased, which could be due to the triarylphosphine, which should be examined. The reaction was
presence of the immobilized phosphate group on the frame- performed in the presence of 4 mg, 6 mg, 8 mg, and 10 mg of
work of FPS. Also, the phosphate of FPS showed a peak at FPS/Au(II) NPs at r.t. for 2 h (Table 2, entry 25). As expected,
around 1483 cmꢁ1 due to TPP.46 The main peak in the spectrum using FPS/Au(II) NPs as a catalyst resulted in distinctive change
of FPS is the additional peak appearing at 1232 cmꢁ1, which can in product performance. The reaction utilizing 4 mg of catalyst
be assigned to the –P]O stretching vibration, indicatiꢁn1g the offered 52% yield, whereas 81% yield was obtained aer using
presence of a phosphate group.47,48 The band at 963 cm and 6 mg of catalyst aer 2 h. Product performance increased to
the shoulder at 1108 cmꢁ1 were due to the TO and LO modes of 99% when 8 mg of catalyst was used. The inuence of time on
the asymmetric stretching of Si–O–P bonds, respectively.49,50 the photooxidation of triarylphosphine is summarized in Table
The bands at about 724 and 795 cmꢁ1 were assigned to the 1. It is clear that the product performance increased to 99% for
asymmetric stretching of the bridging oxygen atoms bonded to 1 h, but an increase in the time did not result in improvement in
a phosphorus atom.51 These peaks suggested the successful the product yield. Hence, the desirable time for the photooxi-
reaction between TEOS and TPP (Fig. 4a), clearly indicating the dation of triarylphosphine is 1 h. We also examined the reaction
graing of organic groups on the surface of FPS. The organic in the presence of visible light at different intensities. FPS/Au(II)
groups-FPS composite showed bands at around 1091, 793 and NPs were screened under lights of different intensities (8, 15, 20,
462 cmꢁ1. A strong and broad absorption band at 3000– 22 and 32 W), and the other parameters were maintained
3550 cmꢁ1 was related to the –OH and –NH stretching vibra- constant to acquire the respective yields, i.e., 43%, 80%, 99%,
tions. The peaks appearing at 3100 cmꢁ1 and 2930 cmꢁ1 are due 99%, and 99% (Table 2, entries 28–31). The outcomes suggest
to the stretching of the C–H aromatic group and the C–H that the photooxidation of triarylphosphine increases gradually
aliphatic group (Fig. 4b).
as the light intensity increases from 8 to 20 W and stays
constant at 20 W. The use of CFL of 22 and 32 W did not have
any noticeable effect on the yield or reaction time.
Table 1 Structural parameters of FPS and FPS/Au(III) NP materials
In addition, a series of comparative tests were conducted. In
a dark environment, no products were formed, showing that the
reaction is photocatalytic. In the absence of FPS/Au(III) NPs or
solvent, the reaction also showed that no product was produced
under visible-light irradiation. We used N2 instead of O2 to
conrm the source of the reduction of phosphine oxides to
preprocess FPS/Au(III) NPs. There was only a trace of the
reduction of phosphine oxides under 1 h irradiation with FPS/
Au(III) NPs as the photocatalyst, indicating that the reduction of
phosphine oxides resulted from O2 rather than decomposition
of ligands (Fig. 5).
determined from nitrogen sorption experiments
Catalysts
SBET (m2 gꢁ1
)
Va (cm3 gꢁ1
)
DBJH (nm)
FPS
FPS/Au(III)
34
30
0.24
0.20
2.43
2.21
For further review of catalyst performance, various control
experiments were conducted, and the information is shown in
Table 3. At rst, a standard reaction performed using FPS
showed that any quantity of the product was not formed aer
2 h (Table 3, entry 1). Also, when FPS/ligand was used as the
catalyst, there was no reaction (Table 3, entry 2). The organic
groups could not give acceptable catalytic activity under opti-
mized conditions. Because these results were disappointing, we
did more research into performance improvements of the
product by adding Au(III). This research proved that the
progression of the reaction is exclusively catalyzed by Au(III)
Fig. 4 FTIR spectra of (a) FPS NPs and (b) FPS/Au NPs.
1512 | RSC Adv., 2019, 9, 1509–1516
This journal is © The Royal Society of Chemistry 2019

View Article Online
Paper
RSC Advances
Table 2 Optimization of the reaction conditions
Temperature
Visible light intensity
(W)
Entry
Solvent
(ꢀC)
Catalyst (mg)
Time (h)
Yielda (%)
1
2
3
4
5
6
7
8
EtOH
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
60
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
8
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
0.5
1
1
1
1
22
22
22
22
22
22
22
22
22
22
22
22
22
22
22
22
22
22
22
22
22
22
22
22
22
22
22
32
20
15
8
79
82
86
43
41
38
14
99
86
45
62
59
36
25
—
—
—
32
—
99
99
99
81
52
—
99
51
99
99
80
43
MeOH
i-PrOH
CH2Cl2
CH3CN
CHCl3
CCl4
DMC
DMA
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
1,4-Dioxane
EtOAc
THF
DMSO
H2O
Toluene
n-Hexane
Cyclohexane
Anisole
Solvent-free
DMC
DMC
DMC
DMC
DMC
DMC
DMC
DMC
DMC
80
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
6
4
—
5
5
5
5
5
DMC
DMC
DMC
5
a
Isolated yield.
species complexed on FPS. The nano-sized particles increased separation. Furthermore, the activity and selectivity of the
the exposed surface area of the active sites of the catalyst, nanocatalyst could be manipulated by tailoring physical and
thereby dramatically enhancing the contact between reactants chemical properties such as morphology, shape, composition
and catalyst and mimicking the homogeneous catalysts. As and size. For evaluating the accurate impact of the presence of
a result, FPS/Au(III) NPs were used in the subsequent investi- FPS in the catalyst, FPS/Au(III) NPs were compared with MCM-
gations because of their high reactivity, high selectivity and easy 41/Au(III), SBA-15/Au(III), and nano-SiO2/Au(III). The yields for the
reduction of phosphine oxides were good when nano-SiO2/
Au(III), MCM-41/Au(III) or SBA-15/Au(III) was used as the catalyst,
whereas the yield for FPS/Au(III) was excellent. The large spaces
between the bers could greatly increase the access of the
surface of FPS. These results indicated that FPS exhibited better
performance than SBA-15, MCM-41, and nano-SiO2 (Table 3,
Table 3 Influence of different catalysts for the reduction of phosphine
oxidesa
Entry
Catalyst
Yielda (%)
1
2
3
4
5
6
FPS
FPS/ligand
FPS/Au(III)
Nano-SiO2/Au(III)
MCM-41/Au(III)
SBA-15/Au(III)
—
—
99
47
65
73
Fig. 5 The amount of the reduction of phosphine oxides as a function
of irradiation time under different conditions.
a
Isolated yield.
This journal is © The Royal Society of Chemistry 2019
RSC Adv., 2019, 9, 1509–1516 | 1513

View Article Online
RSC Advances
Paper
Table 4 (Contd.)
entries 3–6). These results justied the use of FPS NPs in
subsequent investigations because of their easy separation,
high selectivity and high reactivity (Table 3).
Entry
Phosphines
Product
Yielda (%)
With the above-optimized conditions in hand, the substrate
scope of this photooxidation with a series of triarylphosphines
under optimal conditions was investigated. The results are
11
97
Table
4 Photooxidation of triarylphosphines under optimized
conditions
12
99
Entry
1
Phosphines
Product
Yielda (%)
99
a
Isolated yield.
summarized in Table 4. It was observed that the reactions of both
electron-rich and decient phenylated phosphine derivatives
proceeded in high efficiency, affording the corresponding oxides.
No clear electronic effect on the phenyl ring was observed.
Hot ltration and mercury poisoning tests were performed to
obtain information about the heterogeneity or homogeneity of
the reaction. At rst, the relationship between the progress of
reaction and time reached a maximum aer 20–45 min. Thus,
we chose the reaction time of 45 min for the following experi-
ments. The catalyst was ltered out at above 100 ꢀC aer the
reaction proceeded for 45 min, and the yield of product was
94%, as determined by GC. The obtained ltrate with additional
1.0 mmol of triarylphosphine was continually stirred under the
reaction conditions. Aer 45 min, the conversion was deter-
mined to be 94% (Fig. 6). The same approach was applied to the
mercury test. Aer the rst stage, the yield of the product was
93%. In the second stage, aer mercury (0.3 mL) was added into
the ltrate, the ltrate was stirred for another 45 min under the
reaction conditions. The yield of the product remained at 94%.
These phenomena showed that a small amount of catalytically
active Au(III) species may have leached into the reaction mixture.
However, the contents of Au(III) in catalyst before and aer the
reaction were 4.9% and 4.8%, respectively, as determined by
ICP-MS (Table 5). This indicates that most Au(III) species
leaching into solution are recaptured onto the bers of FPS aer
2
3
98
99
4
5
6
96
99
100
7
97
8
95
98
96
9
10
Fig.
6 Effect of time on the yield of photooxidation of
triarylphosphines.
1514 | RSC Adv., 2019, 9, 1509–1516
This journal is © The Royal Society of Chemistry 2019

View Article Online
Paper
RSC Advances
Table 5 The loading amount of Au(III) in FPS/Au(III) NPs
Entry
Catalyst
wt%
1
2
FPS/Au(III) NPs
FPS/Au(III) NPs aer ten reuses
4.9
4.8
Fig. 8 XPS spectra of fresh FPS/Au(III) NPs (a) and FPS/Au(III) NPs after
ten reuses (b).
Fig. 7 Reuse performance of the catalysts.
completion of the reaction. It is important to note that the
heterogeneous property of FPS/Au(III) NPs facilitates their effi-
cient recovery from the reaction mixture aer the completion of
reaction. The amount of Au(III) in FPS/Au(III) NPs was similar
aer reuse for ten consecutive periods of catalysts. Notably, the
catalyst could be recycled up to ten times with a marginal
decrease in activity (Fig. 7). A major concern is the plausible
presence of trace amounts of other active metals (such as Pd,
Cu, Fe, Ni, Cd, and Co) in any component of the reaction. To
solve this problem, it was necessary to carry out ICP analysis of
the reaction components. It can be seen in Table 6 that the
concentrations of Pd, Cu, Fe, Ni, Cd, and Co were very low,
which eliminated the slightest doubt.
Fig.
9 SEM images of fresh HPG@KCC-1/PPh2/AuNPs (a) and
HPG@KCC-1/PPh2/AuNPs after ten reuses (b).
To further understand the underlying reason for the signif-
icant difference in recyclabilities, XPS and SEM were employed
to characterize fresh and reused FPS/Au(III) NPs. The XPS
spectra are shown in Fig. 8. For fresh FPS/Au(III), the Au 4f5/2 and
Au 4f7/2 binding energies were determined to be 89.4 and
catalyst could still be observed. Structural similarities between
fresh FPS/Au(III) NPs and FPS/Au(III) NPs obtained aer ten
reuses accounted for high power in recyclability.
Conclusions
85.7 eV, respectively. Aer being reused ten times, 89.4 eV (4f5/2
)
and 85.7 eV (4f7/2) binding energies were xed, corresponding to
the Au(III) binding energy. SEM images provided further infor-
mation about FPS/Au(III) NPs. SEM images for fresh FPS/Au(III)
NPs and FPS/Au(III) NPs reused ten times are displayed in Fig. 9.
Aer being reused ten times, the wall-like structure of the
In conclusion, visible light-induced oxidation of triar-
ylphosphine was developed under aerobic conditions. This
reaction provided a cheaper and greener method for the prep-
aration of phosphine oxide derivatives. Considering that this
method is environmentally friendly and that the substrate scope
is broad, this protocol may be widely used in the oxidation of
phosphine derivatives.
Table 6 Chemical composition of the reaction components using ICP
Conflicts of interest
Entry
Element
Weight percent (%)
1
2
3
4
5
6
Pd
Cu
Fe
Ni
Cd
Co
—
<0.01
—
<0.01
—
—
There are no conicts to declare.
Notes and references
1 A. Codou, N. Guigo, L. Heux and N. Sbirrazzuoli, Compos. Sci.
Technol., 2015, 117, 54–61.
This journal is © The Royal Society of Chemistry 2019
RSC Adv., 2019, 9, 1509–1516 | 1515

View Article Online
RSC Advances
Paper
2 H. Liimatainen, M. Visanko, J. A. Sirvio, H. Hormi and 25 K. A. Prokop and D. P. Goldberg, J. Am. Chem. Soc., 2012, 134,
J. Niinimaki, Biomacromolecules, 2012, 13, 1592–1597. 8014–8017.
3 S. Coseri, G. Biliuta, C. Simionescu, K. Stana-Kleinschek and 26 K. Ohkubo, T. Nanjo and S. Fukuzumi, Bull. Chem. Soc. Jpn.,
V. Harabagiu, Carbohydr. Polym., 2013, 93, 207–215. 2006, 79, 1489–1500.
4 T. Shui, S. Feng, G. Chen, A. Li, Z. Yuan, H. Shui, X. Kuboki 27 A. Ding, Y. Wang, R. Rios, J. Sun, H. Li and H. Guo, J. Saudi
and C. Charles, Biomass Bioenergy, 2017, 105, 51–58. Chem. Soc., 2015, 19, 706–709.
5 J. Yongkim and H. Choi, Cellul. Chem. Technol., 2014, 48, 25– 28 Y. Zhang, C. Ye, S. Li, A. Ding, G. Gu and H. Guo, RSC Adv.,
32. 2017, 7, 13240–13243.
6 M. Bansal, G. S. Chauhan, A. Kaushik and A. Sharma, Int. J. 29 A. Ding, S. Li, Y. Chen, R. Jin, C. Ye, J. Hu and H. Guo,
Biol. Macromol., 2016, 91, 887–894.
Tetrahedron Lett., 2018, 59, 3880–3883.
30 L. P. Liu and G. B. Hammond, Chem. Soc. Rev., 2012, 41,
3129–3139.
31 A. S. K. Hashmi, L. Schwarz, J. H. Choi and T. M. Frost,
Angew. Chem., Int. Ed., 2000, 39, 2285–2288.
7 P. Zugenmaier, Pure Appl. Chem., 2006, 78, 1843–1855.
8 E. C. S. Filho, J. C. Melo, M. G. Fonseca and C. Airoldi, J.
Colloid Interface Sci., 2009, 340, 8–15.
9 U. J. Kim and S. Kuga, J. Chromatogr. A, 2001, 919, 29–37.
10 S. M. A. S. Keshk, A. M. Ramadan and S. Bondock, 32 A. S. K. Hashmi and G. J. Hutchings, Angew. Chem., Int. Ed.,
Carbohydr. Polym., 2015, 127, 246–251. 2006, 45, 7896–7936.
11 U. J. Kim, S. Kuga, M. Wada, T. Okano and T. Kondo, 33 W. B. Wang, G. B. Hammond and B. Xu, J. Am. Chem. Soc.,
Biomacromolecules, 2000, 1, 488–492. 2012, 134, 5697.
12 X. Liu, C. Manzur, N. Novoa, S. Celedon and D. Clloarri, 34 L. Guczi, A. Beck and Z. Paszti, Catal. Today, 2012, 181, 26–
Coord. Chem. Rev., 2018, 357, 144–172. 32.
13 J. Lindh, C. Carlsson, M. Strømme and A. Mihranyan, 35 A. S. K. Hashmi, A. M. Schuster, S. Litters, F. Rominger and
Biomacromolecules, 2014, 15, 1928–1932. M. Pernpointner, Chem.–Eur. J., 2011, 17, 5661–5667.
14 (a) J.-L. Montchamp, Acc. Chem. Res., 2014, 47, 77–87; (b) 36 M. N. Hopkinson, A. D. Gee and V. Gouverneur, Chem.–Eur.
M. Hashiguchi, K. Nagata, K. Tanaka and Y. Matsuo, Org. J., 2011, 17, 8248–8262.
´
Process Res. Dev., 2012, 16, 643–646; (c) E. M. Sletten and 37 Y. Zhang and C. Zhu, Catal. Commun., 2012, 28, 134–137.
C. R. Bertozzi, Acc. Chem. Res., 2011, 44, 666–676; (d) 38 (a) T. Yamamoto, T. Yamada, Y. Nagata and M. Suginome, J.
C.-J. Li and L. Chen, Chem. Soc. Rev., 2006, 35, 68–82; (e)
J. I. G. Gadogan and R. K. Mackie, Chem. Soc. Rev., 1974, 3,
81–137.
Am. Chem. Soc., 2010, 132, 7899–7901; (b) X. Zhang, P. Li,
Y. Ji, L. Zhang and L. Wang, Synthesis, 2011, 2975–2983.
39 M. S. Sadeghzadeh, RSC Adv., 2015, 5, 68947–68952.
15 R. Dobrovetsky and D. W. Stephan, Angew. Chem., Int. Ed., 40 R. Zhiania, M. Khoobi and S. M. Sadeghzadeh, Microporous
2013, 52, 2516–2519. Mesoporous Mater., 2019, 275, 76–86.
16 A. G. Majouga, E. K. Beloglazkina, A. A. Moiseeva, 41 S. M. Sadeghzadeh, RSC Adv., 2015, 5, 17319–17324.
O. V. Shilova, E. A. Manzheliy, M. A. Lebedeva, 42 S. M. Sadeghzadeh, Appl. Organomet. Chem., 2016, 30, 835–
E. S. Davies, A. N. Khlobystov and N. V. Zyk, Dalton Trans.,
2013, 42, 6290–6293.
17 W. Peng and J. M. Shreeve, J. Fluorine Chem., 2005, 126,
1054–1056.
18 W. Levason, R. Patel and G. Reid, J. Organomet. Chem., 2003,
688, 280–282.
19 B. G. Jacobi, D. S. Laitar, L. Pu, M. F. Wargocki,
842.
43 S. M. Sadeghzadeh, Microporous Mesoporous Mater., 2016,
234, 310–316.
44 M. A. Nasseri and S. M. Sadeghzadeh, J. Iran. Chem. Soc.,
2014, 11, 27–33.
45 S. M. Sadeghzadeh and M. A. Nasseri, Catal. Today, 2013,
217, 80–85.
A. G. DiPasquale, K. C. Fortner, S. M. Schuck and 46 Ph. Massiot, M. A. Centeno, I. Carrizosa and J. A. Odriozola,
S. Brown, Inorg. Chem., 2002, 41, 4815–4823. J. Non-Cryst. Solids, 2001, 292, 158–166.
20 B. R. Travis, B. P. Ciaramitaro and B. Borhan, Eur. J. Org. 47 M. Stan, A. Vasdilescu, S. Moscu and M. Zaharescu, Rev.
Chem., 2002, 3429–3434. Roum. Chim., 1998, 43, 425.
21 L. A. Wozniak and W. J. Stec, Tetrahedron Lett., 1999, 40, 48 H. S. Liu, T. S. Chin and S. W. Yung, Mater. Chem. Phys.,
2637–2640. 1997, 50, 1.
22 Y. Futami, H. Nishino and K. Kurosawa, Bull. Chem. Soc. Jpn., 49 I. N. Chakraborty and R. A. Condrate, Phys. Chem. Glasses,
1989, 62, 3567–3571. 1985, 26, 68–73.
23 L. A. Wickramasinghe and P. R. Sharp, Inorg. Chem., 2014, 50 Y. K. Kim and R. E. Tressler, J. Mater. Sci., 1994, 29, 2531–
53, 1430–1442. 2535.
24 F. Avenier, C. Herrero, W. Leibl, A. Desbois, R. Guillot, 51 G. Lakshminarayana and M. Nogami, Solid State Ionics, 2010,
´
J.-P. M. Mahy and A. Aukauloo, Angew. Chem., Int. Ed.,
2013, 52, 3634–3637.
181, 760–766.
1516 | RSC Adv., 2019, 9, 1509–1516
This journal is © The Royal Society of Chemistry 2019