Catalytic applications of β-cyclodextrin/palladium nanoparticle thin film obtained from oil/water interface in the reduction of toxic nitrophenol compounds and the degradation of azo dyes

Article abstract of DOI:10.1039/c8nj06449k

A supramolecular catalyst of Pd/β-cyclodextrin thin film is synthesized via a facile and one-pot procedure at an oil-water interface. Macrocyclic oligosaccharides of cyclodextrins with glucose units have a wide range of applications due to their hydrophobic and chiral interior. Due to the ability of this supramolecular catalyst to form inclusion complexes with small organic molecules, the as-synthesized catalyst was applied for the reduction of toxic nitroaromatic compounds (p, o, m-nitrophenol and 4-Cl-2-nitrophenol) and the degradation of harmful azo dyes (methyl orange and bismarck brown) with considerable results. This investigation illustrates the change of the catalyst properties in the presence of molecular receptors attached to the catalyst surface.

Full text of DOI:10.1039/c8nj06449k

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The role of atropisomers on the photo-reactivity and fatigue of
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Catalytic Applications of β-Cyclodextrin/Palladium Nanoparticles Thin Film
Obtained from Oil/Water Interface in the Reduction of Toxic Nitrophenol
Compounds and Degradation of Azo Dyes
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Azam Zare Asadabadi,b S. Jafar Hoseini,,a,b Mehrangiz Bahramia,b and S. Masoud Nabavizadeha
a Prof. Rashidi Laboratory of Organometallic Chemistry, Department of Chemistry, College of Sciences,
Shiraz University, Shiraz, 7194684795, Iran
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b Department of Chemistry, Faculty of Sciences, Yasouj University, Yasouj 7591874831, Iran
Abstract
The supramolecular catalyst of Pd/β-cyclodextrin thin film is synthesized via a facile and one-pot
procedure at oil-water interface. Macrocyclic oligosaccharides of cyclodextrins with glucose
units exhibit wide range of applications due to their hydrophobic and chiral interior. Due to the
ability of this supramolecular catalyst to form inclusion complexes with small organic molecules,
the as-synthesized catalyst was applied for the reduction of toxic nitroaromatic compounds (p, o,
m- nitrophenol and 4-Cl-2-nitrophenol) and degradation of harmful azo dyes (methyl orange and
bismarck brown) with considerable results. This investigation illustrates the change of the
catalyst properties in the presence of molecular receptors attached to the catalyst surface.
Keywords: Inclusion complex, Oil/water interface, Supramolecular catalyst, Thin film,
Nitrophenol, β-cyclodextrin.
1. Introduction
Along with the rational design of catalytic approaches in industry, supramolecular chemistry
(chemistry beyond the molecule) has attracted significant interest in recent years to improve the

Corresponding author: E-mail: sj.hoseini@shirazu.ac.ir, sjhoseini54@yahoo.com, Fax: +987136460788; Tel:
+987136137117.
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catalysts activity [1]. Cyclodextrins (CDs) are one of the main branches of polysaccharides that
obtain from the starch degradation with various industrial applications since the end of 1980s in
the field of medicine, supramolecular and catalysis chemistry [2,3]. Being biodegradable,
nontoxic, available, producible in large scale amount, easily functionalized, having hydrophobic
central cavity and hydrophilic outer surface and stability against chemical and photochemical
degradation are some of the advantages of CDs that make them a good candidate for the above
applications [4-6]. The special structure of CD molecules enables them to encapsulate small
molecules and form inclusion complexes that control with the host-guest chemistry. Due to the
chemical and physical modification and improvement of the guest molecules, formation of the
inclusion complex is very important in industry [7]. Furthermore, these compounds can be
applied as catalyst for pollution removal of water and air in order to their amazing chemical
reactivity with the accelerated rate. One of the most commonly used noble transition metals
applied in catalysis is palladium. The reaction rate can be increased in the presence of the
nanoparticles (NPs) of Pd due to their high surface to volume ratio [8]. Pd NPs stabilized by
graphene oxide, polymers or CDs have largely been used as catalysts in various applications
[9,10]. In the case of CDs, supramolecular associations dictate a range of properties that is
effective on the aqueous dispersion of Pd NPs, stability and growth in a controlled manner
[11,12]. Pd NPs are applied as heterogeneous catalyst in various environmental problems such as
water pollution [13]. One of the most important need of the day is the reduction of toxic
nitrophenol compounds that obtain from the manufacture of pesticides and dyes to the
corresponding non or less toxic amines which have a key role as an intermediate for antipyretic
drugs (e.g. Paracetamol) [14] and corrosion inhibitors [15]. Different strategies have been
developed to remove the organic pollutants [16,17a,b], but applying a facile way with a low cost
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catalyst is a challenge up to now. Recently, many research groups have studied the
transferhydrogenation of nitro compounds due to the importance of this subject. Ai et. al. have
used porous carbon frameworks encapsulated sub-3 nm Pd NPs for chemoselective
hydrogenation of nitroarenes to the corresponding anilines [17c]. Similar investigation was
reported by Hu et. al. using a magnetically separable 2D Rh/Fe3O4/g-C3N4 catalyst [17d]. A
multicomponent nanocatalyst system of Pd-CuFe was fabricated for the transfer hydrogenation
of nitrile compounds by Liu et. al. [17e]. Bao et. al. have reported a novel core-shell structured
nanocatalyst of Fe3O4@SiO2- NH2-FeCu with excellent activity and chemoselectivity for
hydrogenation of nitroarenes to corresponding anilines in the presence of hydrazine hydrate
[17f]. Like the nitrophenol compounds, azo dyes are another source of water pollution that
creates by textile industries [18] and is the result of uneconomic dyeing techniques. Decrease the
penetration of the oxygen and sun light to the water, risk of living for aquatic life and humans
and disturbing the photosynthesis process are some of the terrible hazardous of these
carcinogenic dyes [19]. So, efficient and economically manage of this kind of water pollution is
very important for industries. Ozonation and biological methods are some of the general water
treatments that are multi-step, time consuming and cost-effective [20] which reported by some
research groups using transition metal NPs synthesized in a harsh conditions [21,22]. One of the
facile techniques for the synthesis of transition metal nano catalysts with high catalytic activity
and low metal loading is liquid-liquid interface, the interface between oil and aqueous solutions,
that attracted a great interest due to the self-assembly of NPs at interface [23]. This defect-free
surface can be applied for the synthesis of nanostructures with special morphology due to the
low rate of nucleation and growth of crystals [24-28]. The obtained structures exhibited a wide
range of applications in catalysis and energy conversion [29-31]. With these issues in mind, we
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attempted to synthesize β-CD modified with Pd in the form of a thin film at the interface
between the water and toluene as a supramolecular catalyst for the reduction of toxic nitrophenol
compounds (p, o, m- nitrophenol and 4-Cl-2-nitrophenol) and degradation of harmful azo dyes
(methyl orange and bismarck brown). In situ dye degradation and simultaneously catalyst
formation in the mild reaction condition are some of the advantages of this strategy. This study
exhibits the effect of the presence of molecular receptors attached to the surface of catalyst that
can change the catalytic properties. Nitrophenols transformation is not only advantageous for
pharmaceutical industry, but also in the pollutant-remediation field.
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2. Experimental
2.1. Materials and methods
All of the chemical compounds and solvents were purchased from Merck and Sigma-Aldrich
Companies. NaBH4 was purchased from Panreac. Methyl orange (C14H14N3NaO3S) with λmax of
464 nm and bismarck brown (C18H18N8) with λmax of 460 nm were purchased from Aldrich. The
crystal structure of the as-synthesized thin film was characterized by powder X-ray diffraction
(XRD) patterns using a Bruker AXS (D8 Advance) instrument employing the reflection Bragg-
Brentano geometry with Cu Kα radiation. The energy dispersive analysis of X-ray (EDAX) was
done applying a Philips XL30 instrument with an accelerating voltage of 20 kV. Transmission
electron microscopy (TEM) image was obtained using a Philips CM-10 TEM microscope
operated at 100 kV. The sputter-coated gold sample was characterized using scanning electron
microscopy (SEM) analysis by a Philips XL30 instrument with an accelerating voltage of 20 kV.
The loading amount of Pd NPs was examined by Inductively Coupled Plasma (ICP) analyzer
(Varian, Vista-Pro). The UV-Vis spectra were carried out using a Lambda 25 spectrophotometer
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(Perkin-Elmer) with a quartz cuvette to control and follow the reaction progress. Ultrasonication
was done using a Soltec bath ultrasonic model. Atomic force microscopy (AFM) analysis was
done using WITec alpha 300 A (Germany).
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2.2. [PdCl2(cod)] synthesis
[PdCl2 (cod)] (cod = cis,cis-1,5-cyclooctadiene), was synthesized according to reference [32a].
In brief, PdCl2 (0.2 g) was dissolved in concentrated HCl (0.5-1 mL) and heated. After cooling to
room temperature, ethanol was added (15 mL) followed by filtration and washed with ethanol (2
mL). cod (300 µL) was added to this stirred solution. The solution turned yellow from brown
immediately. The obtained product was filtrated after 10 min and washed with diethyl ether (3-9
mL).
2.3. Synthetic procedure for the supramolecular catalyst of Pd/β-CD thin film
To prepare a supramolecular catalyst of Pd/β-CD thin film between the water and toluene
interface, the following procedure is done: β-CD (0.02 g) was dissolved in distilled water (25
mL) and sonicated for 5 min. [PdCl2(cod)] (0.0071 g) was dissolved in toluene (25 mL) followed
by sonication for 5 min. The colorless aqueous solution of β-CD was transferred to the 100 mL
beaker and the yellow toluene mixture was added. After the stabilization of two phases (by
passing a few minutes), the aqueous solution of NaBH4 (5 mL, 0.1 M) was added dropwisely
using a syringe. The yellow toluene phase became pale and the thin layer formed at the interfaces
simultaneously. The produced film was remained in this situation for 24 h to complete the
nucleation, growth and self-assembly processes as illustrates in Figure 1.
2.4. General procedure for nitrophenol reduction
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The obtained thin film produced from sec. 2.3 was applied as a catalyst for the reduction of toxic
nitroaromatic compounds. In the first step, the catalyst was removed from the reaction medium
using a dropper to remove the top toluene layer. Ethanol (10 mL) was added to the catalyst
mixture followed by centrifugation. In a quartz cuvette, the aqueous solution of NaBH4 (15 mM,
0.7 mL) was added to the aqueous solution of p-nitrophenol (0.2 mM, 1.7 mL). The color change
from light yellow to deep yellow was obvious in this step. In the next step, the thin film catalyst
was added using a syringe (The loading of a metal in the thin film was measured using ICP). To
monitor the reaction progress, UV-Vis spectrometer was used. The reaction mixture became
colorless when the reduction completed. Similar procedure was continued for o,m- nitrophenol
and 4-Cl-2-nitrophenol (Figure 2).
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2.5. Insitu dye degradation and catalyst formation
For this insitu catalyst formation and dye degradation, the following procedure was done at room
temperature: In a quartz cuvette (3 mL), aqueous solution of methyl orange and β-CD (1.25 mL)
was used as the bottom aqueous phase (orange color) which stand in contact with the toluene-
[PdCl2(cod)] solution as a top organic phase (1.25 mL) (yellow color). NaBH4 aqueous solution
(250 µL, 0.001 M) was added as a reducing agent to form a thin film. Catalyst formation was
begun simultaneously with methyl orange degradation. The reaction progress was studied using
Lambda 25, Perkin‐Elmer UV-Vis spectrophotometer. When the reaction completed, the top and
bottom phases became colorless with a thin black layer of Pd/β-CD catalyst between the water
and toluene phases. Similar procedure was continued for bismarck brown azo dye (brown color).
3. Results and discussion
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3.1. Mechanism of catalyst formation
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Supramolecular catalyst of Pd/β-CD thin film was prepared via a facile procedure as shown in
Figure 1. [PdCl2(cod)] complex was dissolved in toluene and β-CD compound was dissolved in
distilled water and transferred to a beaker after sonication (Figure 1a,e). [PdCl2(cod)] from the
top phase and β-CD from the bottom phase were moved toward the interface. The driving force
for this movement is the tendency to reduce the energy which is occurred at the interface. At this
time, the (cod) ligand was folded to form a boat conformation and placed itself in the β-CD
cavity and produced an inclusion complex (Figure 1b). NaBH4 was added dropwisely and
formed Pd(0) NPs (Figure 1c,d,f). Depending on the reaction conditions, the product may be
with the morphology in Figure 1c or 1d. If the reduction take place fast, [PdCl2(cod)] will reduce
in the cavity of β-CD and form Pd(0) NPs (Figure 1c), but if the reduction takes place in a low
rate, the morphology will change to Figure 1d. In this study, we have a liquid-liquid interface
strategy which is famous for the low rate of nucleation and growth. So, the produced NPs can
self-assemble at the interface and finally, we have a thin film of Pd/β-CD with morphology like
Figure 1d at toluene-water interface. Also, the wide separation of NPs in TEM image is another
reason that confirms the most probable existence of Figure 1d. Figure 1g shows the top view of
the as-synthesized thin film with the surface area of 16.6 cm2.
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The obtained thin film (Figure 1d,f) was removed from the reaction mixture and applied for
the reduction of toxic nitrophenol compounds to useful aminophenols and degradation of
carcinogenic dyes by formation of inclusion complexes [32b] with these toxic compounds
(Figure 2).
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Figure 1. Schematic illustration for the formation of Pd/β-CD at aqueous/ organic interface, (a,e)
dissolving the precursors in H2O (bottom phase) and toluene (top phase), (b) organic and
aqueous phases stand in contact with each other and form an inclusion complex, (c,d,f) formation
of Pd/β-CD NPs thin film at the interface depend upon the reaction process, (d) self-assembly of
NPs at toluene-water interface, (g) top view of the as-synthesized thin film
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Figure 2. Schematic of host-guest recognition for Pd/β-CD thin film in the presence of
nitrophenols or azo dyes as guest molecules
3.2. Catalysts Characterization
The as-prepared Pd-based thin film was characterized first using XRD analysis. This analysis
was done on the glass surface. As is observable in Figure 3a, five main diffractions
corresponding to the [(111), (200), (220), (311) and (222)] planes can be seen in 2θ = 40°, 48°,
68°, 82° and 86° and confirms the presence of Pd(0) with face-centered-cubic (fcc) structure
[29].
The composition of the Pd/β-CD thin film was examined using EDAX (Figure 3b) and
elemental mapping analysis (Figure 4) and confirms the presence of C, O and Pd in the film.
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Figure 3. (a) XRD and (b) EDAX patterns of Pd/β-CD thin film
FT-IR analysis was performed to confirm the presence of β-CD in the Pd/β-CD thin film
catalyst using KBr. Figure 5a shows the FT-IR spectrum of β-CD itself and Figure 5b is related
to the Pd/β-CD thin film. Comparing Figure 5b with 5a shows that all the peaks of β-CD are
present in the FT-IR spectrum of Pd/β-CD thin film but with a little shift. Table 1 shows the
details for the FT-IR spectra [33].
Also, thin film was characterized using FE-SEM analysis. As is shown in Figure 6(a-d), the
product has the connected spherical particle shape.
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Figure 4. EDAX elemental mapping analysis of (a) C, (b) O, (C) Pd and (d) C, O, Pd for Pd/β-
CD thin film
Figure 5. FT-IR spectra of (a) β-CD and (b) Pd/β-CD
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Table 1. Details of FT-IR spectra
Wavenumber [cm-1]
Changes
Functional group
β-CD
Pd/β-CD
∆δ
v[OH]
symmetric and
antisymmetric
v[CH2]
v[C-C]
v[O-H]
bending vibration
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3370
3430
+ 60
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2930
1160
2920
1110
+ 10
+ 50
1040
1040
-----
Figure 6. (a-d) FE-SEM images of Pd/β-CD thin film obtain from toluene-water interface
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To investigate the exact morphology and size of the as-prepared catalyst, TEM analysis was
done. The thin film was sonicated in ethanol for 30 sec. and transferred to a cu-grid. Spherical
particles with 6 nm mean diameter was observed (Figure 7a, b).
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Figure 7. (a) TEM image of Pd/ β-CD thin film and (b) histogram of particles size distribution
Figure 8a shows the AFM image acquired at the edge that the film shared with the substrate to
measure the thickness of the thin film. Figure 8b shows the related height profile which estimates
the thickness to be ∼ 210 nm.
Figure 8. (a) AFM image and (b) the related height profile
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3.3. Catalyst applications
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3.3.1. Reduction of nitrophenol compounds
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The efficiency of the as-prepared catalyst was examined in the reduction of nitrophenol
compounds. The reaction progress was followed using UV-Vis spectrometer. In the case of p-
nitrophenol aqueous solution, it has an absorption peak at 317 nm. After the addition of NaBH4
reducing agent, it shifts to 401 nm (Figure 9b,c) and confirms the formation of p-nitrophenolate
in aqueous solution but it does not show any decrease in the absorption peak. So, the reaction is
not progressed in the presence of NaBH4 even by passing a long time. This observation is similar
in the case of 4-Cl-2-nitrophenol (Figure 9a, b), o-nitrophenol (Figure 9e, f) and m-nitrophenol
(Figure 9 g, h). In the case of o-nitrophenol, as is observable in Figure 9 (e, f), the two peaks
centered at 278 and 351 nm are shifted to 283 and 415 nm, respectively after the addition of
NaBH4.
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Figure 9. UV-Vis spectra of (a) 4-Cl-2-nitrophenol, (c) p-nitrophenol, (e) o-nitrophenol, (g) m-
nitrophenol in water, (b, d, f, h) related nitrophenolate formation by adding NaBH4
In the next step, after the addition of Pd/β-CD NPs thin film as a catalyst, the reduction
reaction was investigated using absorption versus wavelength curves that show a reduction of the
absorption peaks related to the nitrophenolate (Figure 10a, c, e, g).
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Figure 10. UV-Vis absorption spectra for the reduction of (a) 4-Cl-2-nitrophenol, (c) p-nitrophenol, (e) o-
nitrophenol, (g) m-nitrophenol (0.2 mM) using aqueous solution of NaBH4 (15 mM) in the presence of
Pd/β-CD thin film at 25 °C, (b, d, f, h) Plot of -Ln A versus time for the related nitroaromatic compounds
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Due to the high concentration of NaBH4, the pseudo first-order kinetics can be used to evaluate
the rate constants for the reduction of nitrophenols. Furthermore, the absorptions at λmax versus
time were collected (Figure 10b, d, f, h) to obtain the apparent rate constants. These amounts
were compared with the reported data for other catalysts (Table 2).
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Table 2. Comparing the apparent rate constants in the presence of different catalysts
Entry
Catalyst
Apparent rate Metal loading
Reference
constant (s-1)
7.36 x 10-3
1.09 x 10-2
3.60 x 10-3
3.49 x 10-3
1.02 x 10-3
5.90 x 10-4
2.56 x 10-3
1.87 x 10-3
1.00 x 10-2
2.70 x 10-3
7.90 x 10-3
8.54 x 10-3
1.40 x 10-4
1.98 x 10-3
(µg)a
2.0
2.0
2.0
2.0
3.1
2000
2.1
2.1
2.1
2.1
----
----
----
3.2
1
2
3
4
5
6
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9
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Pd/β-CD thin filmb
Pd/β-CD thin filmc
Pd/β-CD thin filmd
Pd/β-CD thin filme
Pd thin filmc
Pd NPs @ black tea
PtNid
This work
This work
This work
This work
[31a]
[34]
[31a]
[31a]
[31a]
[31a]
[35]
[36]
[36]
PtNib
PtNie
PtNic
Au/PMMAc,f
c,g
SPB-Au75Pd25
SPB-Pdc,g
Pt
[37]
a
b
c
d
Obtain from ICP measurement In the presence of 4-Cl-2-nitrophenol; in the presence of p-nitrophenol; in the
presence of o-nitrophenol; e in the presence of m-nitrophenol, f PMMA: poly(methyl methacrylate), g SPB: spherical
polyelectrolyte brushes
From Table 2, we concluded that Pd/β-CD NPs thin film was more effective catalyst for
nitrophenol reduction than other reported catalysts. This better efficiency is the result of
formation of the inclusion complex in the presence of the unique structure of β-CD. Figure 12
shows the detailed mechanism.
3.3.2. Azo dye degradation
To investigate the catalytic effect of the as-synthesized Pd/β-CD NPs thin film, we selected
methyl orange and bismarck brown azo dyes. In the case of methyl orange toxic dye, the solution
became colorless (-N=N cleavaged) from orange (due to the interaction of azo function and two
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aromatic species) simultaneously with the formation of a thin film. This colorless solution
contains N,N-dimethyl-1,4-phenylenediamine and sodium sulfanilate. The degradation progress
in the presence of catalyst was investigated using UV-Vis spectrometer (Figure 11a,c). In the
case of methyl orange, it has an absorption peak at 464 nm which is reduced and vanished when
the reaction progressed. This is due to the (-N=N-) cleavage and decrease of conjugation.
Increase in the intensity of the absorption peak at 280 nm is related to the formation of hydrazine
derivatives that show in Scheme 1 [38]:
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Scheme 1. Formation of a hydrazine derivative as a side product
Figure 11. UV-Vis absorption spectra for the (a) methyl orange and (c) bismarck brown degradation by NaBH4
(0.001 M) in the presence of Pd/β-CD thin film, time interval = 30 sec; Plot of A versus time for the kinetic study of
the reaction of (b) methyl orange and (d) bismarck brown
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To obtain the apparent rate constants, absorbencies at λmax were collected with time for both
methyl orange and bismarck brown dyes (Figure 11b,d). Also, in this case, similar to nitrophenol
reduction process, the pseudo-first order kinetic could be used due to the high concentration of
NaBH4. Table 3 shows the rate constants for this investigation and compares these values with
some reported data.
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Table 3. Comparing the apparent rate constants in the presence of different catalysts
Entry
Catalyst
Apparent rate constant (s-1)
1.85x10-2
Reference
This work
This work
[38]
1
2
3
4
5
6
7
8
Pd/β-CD thin filma
Pd/β-CD thin filmb
Pt thin filma
3.60x10-2
1.09x10-2
PtAu thin filma
[38]
[39]
[39]
[39]
1.70x10-2
a
1.17x10-4
Pt/TiO2
a
4.00x10-5
Pd/TiO2
a
1.06x10-4
(0.4:0.1)PtPd/TiO2
(0.1:0.4)PtPd/TiO2
a
9.60x10-5
[39]
a in the presence of methyl orange, b in the presence of bismarck brown
As is observable from Table 3, Pd/β-CD thin film shows a better catalytic activity than other
catalysts for dye degradation which is related to the ability of β-CD to form an inclusion
complex. Figure 12 shows the general reaction mechanism.
The right view of Figure 12 is represented the mechanism for the reduction of nitrophenol
molecules (guest) on Pd/β-CD NPs thin film (host). The main driving force for the formation of
this inclusion complex is hydrogen bonding with β-CD hydroxyl groups that is reversible. This
means that the guest molecule can leave the hydrophobic inner cavity of β-CD after completion
of the reaction. The same strategy is happened in the case of azo dyes in the left view of Figure
12. β-CD (host) formed an inclusion complex with azo dyes (guest molecules) on the surface of
Pd NPs thin film. This orientation leads to increase the electron transfer between the azo dye and
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NaBH4 on the metal surface that in turn leads to the reduction of the activation energy. So, the
reaction progressed easier and faster.
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Figure 12. Mechanism for the reduction of nitrophenol (guest) on Pd/β-CD NPs thin film (host)
(right view), Forming an inclusion complex with azo dyes (left view)
Conclusions
In this study, the effect of the presence of molecular receptors attached to the surface of catalyst
is investigated that can change the catalytic properties. This molecular receptor is β-CDs with its
interesting structure, hydrophobic and chiral internal cavity, and the ability to form inclusion
complexes with small molecules. We investigated the synthesis of Pd/β-CD NPs thin film at the
interface between water and toluene. This supramolecular catalyst was applied for the reduction
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of toxic nitroaromatic compounds (p, o, m- nitrophenol and 4-Cl-2-nitrophenol) and degradation
of harmful azo dyes (methyl orange and bismarck brown) with high rate constants which is due
to the ability of β-CD to form an inclusion complexes and controls by the host-guest chemistry.
In situ dye degradation and simultaneously, catalyst formation in one hand and the mild reaction
condition in the other hand are some of the advantages of this strategy. Also, nitrophenols
transformation and its benefit for pharmaceutical industry and also pollutant-remediation field
are advantageous. The metal loading in this catalyst is very low so we can reduce the cost of the
catalyst in this way despite improving the catalyst ability.
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Acknowledgements
We thank Shiraz University (Grant No. 97GRD1M348876) and Yasouj University Research
Council, and the Iranian Nanotechnology Initiative Council for their support.
There are no conflicts to declare.
References:
[1] (a) M. J. Webber and R. Langer, Chem. Soc. Rev., 2017, 46, 6600; (b) M. W. Hosseini and J.
M. Lehn, J. Am. Chem. Soc., 1987, 109, 7047; (c) M. W. Hosseini, Bioorganic Chemistry
Frontiers. Springer-Verlag Berlin Heidelberg; 1993, p. 67.
[2] (a) E. A. Kataev, M. Ramana Reddy, G. Niranjan Reddy, V. Hanuman Reddy, C. Suresh
Reddy and B. V. Subba Reddy, New J. Chem., 2016, 40, 1693; (b) G. Crini, Chem. Rev.,
2014, 114, 10940; (c) A. C. Franzoi, I. C. Vieira, C. W. Scheeren and J. Dupont,
Electroanal., 2010, 22, 1376.
21

New Journal of Chemistry
Page 22 of 26
View Article Online
DOI: 10.1039/C8NJ06449K
1
2
3
4
5
6
7
8
9
[3] (a) C. Folch-Cano, M. Yazdani-Pedram and C. Olea-Azar, Molecules, 2014, 19, 14066; (b)
V. B. Yadav, P. Rai, H. Sagir, A. Kumar and I. R. Siddiqui, New J. Chem., 2018, 42, 628; (c)
C. P. da Silva, A. C. Franzoi, S. C. Fernandes, J. Dupont and I. C. Vieira, Enzyme Microb.
Technol., 2013, 52, 296.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
[4] (a) M. L. Bender and M. Komiyama, Cyclodextrins chemistry. Berlin: Springer Verlag; 1978,
p. 96; (b) H. Sagir, Rahila, P. Rai, P. K. Singh and I. R. Siddiqui, New J. Chem., 2016, 40,
6819.
[5] (a) I. Abulkalam Azath, P. Suresh and K. Pitchumani, New J. Chem., 2012, 36, 2334; (b) D.
Duchêne, Cyclodextrins and their industrial uses. Paris: Éditions de Santé; 1987, p. 447.
[6] E. Bilensoy, Cyclodextrins in pharmaceutics, cosmetics and biomedicine; In current and
future industrial applications. Hoboken: John Wiley & Sons Inc; 2011, p. 440.
[7] (a) J. Szejtli, Chem. Rev., 1998, 98, 1743; (b) M. K. Banjare, K. Behera, M. L. Satnami, S.
Pandey and K. K. Ghosh, New J. Chem., 2018, 42, 14542.
[8] (a) F. Yu, D. Chen and J. Ma, New J. Chem., 2018, 42, 2216; (b) D. Astruc, Inorg. Chem.,
2007, 46, 1884.
[9] (a) L. Liang, A. K. Diallo, L. Salmon, J. Ruiz and D. Astruc, Eur. J. Inorg. Chem., 2012, 17,
2950; (b) N. Hussain, A. Borah, G. Darabdhara, P. Gogoi, V. K. Azhagan, M. V. Shelke and
M. R. Das, New J. Chem., 2015, 39, 6631.
[10] (a) R. Shankar, B. Jangir and A. Sharma, New J. Chem., 2017, 41, 8289; (b) J. Liu, J.
Alvarez, W. Ong, E. Román and A. E. Kaifer, Langmuir, 2001, 17, 6762.
[11] (a) C. Hubert, A. Nowicki, A. Roucouxa, D. Landyb, B. Leger, G. Crowyn and E. Monflier,
Chem. Commun., 2009, 1228; (b) F. X. Legrand, M. Menand, M. Sollogoub, S. Tilloy and E.
Monflier, New J. Chem., 2011, 35, 2061.
22

Page 23 of 26
New Journal of Chemistry
View Article Online
DOI: 10.1039/C8NJ06449K
1
2
3
4
5
6
[12] L. Strimbu, J. Liu, A. E. Kaifer, L. Strimbu, J. Liu and A. E. Kaifer, Langmuir, 2003, 19,
483.
7
8
9
[13] Y. Wang, J. Liu, P. Wang, C. J. Werth and T. J. Strathmann, ACS Catal., 2014, 4, 3551.
[14] T. Komatsu and T. Hirose, Appl. Catal. A, 2004, 276, 95.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
[15] C. V. Rode, M. J. Vaidya and R. V. Chaudhari, Org. Process Res. Dev., 1999, 3, 465.
[16] (a) S. Yang, S. Lin, J. Fan, Y. Wang, C. Liu and X. Yan, ChemPlusChem., 2017, 82, 1218;
(b) T. N. V. Krishna, P. Sathishkumar, P. Himasree, D. Punnoose, K. V. G. Raghavendra,
Himanshu, B. Naresh, R. A. Rana and H. J. Kim, Electronics, 2018, 7, 245.
[17] (a) L. Lvova, F. Caroleo, A. Garau, V. Lippolis, L. Giorgi, V. Fusi, N. Zacchheroni, M.
Lombardo, L. Prodi, C. Di Natale and R. Paolesse, Front. Chem., 2018, 6, 1; (b) M. T. Amin,
A. A. Alazba and U. Manzoor, Adv. Mater. Sci. Eng., 2014, 1; (c) Y. Ai, M. He, F. Zhang, Y.
Long, Y. Li, Q. Han, M. Ding, H. B. Sun and Q. Liang, J. Mater. Chem. A, 2018, 6, 16680;
(d) Z. Hu, J. Zhou, Y. Ai, L. Liu, L. Qi, R. Jiang, H. Bao, J. Wang, J. Hu, H. B. Sun and Q.
Liang, J. Catal., 2018, 368, 20; (e) L. Liu, Y. Liu, Y. Ai, J. Li, J. Zhou, Z. Fan, H. Bao, R.
Jiang, Z. Hu, J. Wang, K. Jing, Y. Wang, Q. Liang and H. Sun, iSci., 2018, 8, 61; (f) H. Bao,
Y. Li, L. Liu, Y. Ai, J. Zhou, L. Qi, R. Jiang, Z. Hu, J. Wang, H. Sun and Q. Liang, Chem.
Eur. J., 2018, 24, 14418.
[18] (a) K. S. Wang, C. L. Lin, M. C. Wei, H. H. Liang, H. C. Li, C. H. Chang, Y. T. Fang and S.
H. Chang, J. Hazard. Mater., 2010, 182, 886; (b) S. Scalesa, I. Nicotera, D. D’Angelo, S.
Filice, S. Libertino, C. Simari, K. Dimos and V. Privitera, New J. Chem., 2016, 40, 3654.
[19] M. A. Rauf, M. A. Meetani and S. Hisaindee, Desalination, 2011, 276, 13.
[20] Z. Sun, Y. Chen, Q. Ke, Y. Yang and J. Yuan, J. Photochem. Photobiol., 2002, 149, 169.
[21] Y. Gao, W. Sun, W. Yang and Q. Li, Sci. Rep., 2017, 7, 1.
23

New Journal of Chemistry
Page 24 of 26
View Article Online
DOI: 10.1039/C8NJ06449K
1
2
3
4
5
6
[22] B. S. Karnik, S. H. Davies, M. J. Baumann and S. J. Masten, Environ. Sci. Technol., 2005,
39, 7656.
7
8
9
[23] S. G. Booth and R. A. W. Dryfe, J. Phys. Chem. C, 2015, 119, 23295.
[24] C. N. R. Rao and K. P. Kalyanikutty, Acc. Chem. Res., 2008, 41, 489.
[25] C. N. R. Rao, G. U. Kulkarni, V. V. Agrawal, U. K. Gautam, M. Chosh and U. Tumkurkar,
J. Colloid Interface Sci., 2005, 289, 305.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
[26] C. N. R. Rao, H. S. S. R. Matte, R. Voggu and A. Govindaraj, Dalton Trans., 2012, 41,
5089.
[27] S. J. Hoseini, Z. Barzegar, M. Bahrami, M. Roushani and M. Rashidi, J. Organomet. Chem.,
2014, 769, 1.
[28] S. J. Hoseini, N. Mousavi, M. Roushani, L. Mosaddeghi, M. Bahrami and M. Rashidi,
Dalton Trans., 2013, 42, 12364.
[29] S. J. Hoseini, M. Bahrami and M. Dehghani, RSC Adv., 2014, 4, 13796.
[30] Y. Gründer, M. D. Fabian, S. G. Booth, D. Plana, D. J. Fermin, P. I. Hill and R. A. W.
Dryfe, Electrochim. Acta, 2013, 110, 809.
[31] (a) S. J. Hoseini, M. Bahrami, N. Sadri, N. Aramesh, Z. Samadi Fard, H. Rafatbakhsh Iran,
B. Habib Agahi, M. Maddahfar, M. Dehghani, A. Zarei Baba Arabi, N. Heidari, S. F.
Hashemi Fard and Z. Moradi, J. Colloid Interface Sci., 2018, 513, 602; (b) S. J. Hoseini, M.
Bahrami, Z. Samadi Fard, S. F. Hashemi Fard, M. Roushani, B. Habib Agahi, R. Hashemi
Fath and S. Saberi Sarmoor, Int. J. Hydrogen Energy, 2018, 43, 15095.
[32] (a) A. P. Ginsberg, Inorganic Syntheses, Inorganic Syntheses, Inc, New Jersey, 1990; (b) X.
Chen, S. G. Parker, G. Zou, W. Su and Q. Zhang, ACS Nano 2010, 4, 6387.
[33] I. Bratu, F. Veiga, C. Fernandes, A. Hernanz and J. M. Gavira, Spectroscopy, 2004, 18, 459.
24

Page 25 of 26
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View Article Online
DOI: 10.1039/C8NJ06449K
1
2
3
4
5
6
7
8
9
[34] S. Lebaschi, M. Hekmati and H. Veisi, J. Colloid Interface Sci., 2017, 485, 223.
[35] K. Kuroda, T. Ishida and M. Haruta, J. Mol. Catal. A: Chem., 2009, 298, 7.
[36] S. Gu, Y. Lu, J. Kaiser, M. Albrecht and M. Ballauff, Phys. Chem. Chem. Phys., 2015, 17,
28137.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
[37] S. J. Hoseini, M. Rashidi and M. Bahrami, J. Mater. Chem., 2011, 21, 16170.
[38] M. Bahrami and S. J. Hoseini, Appl. Organomet. Chem., 2018, 32, e3920.
[39] F. Zhang, F. Xie, T. Fong, K. Zhang, T. Chen and W. Oh, Synth. React. Inorg. M., 2012, 42,
685.
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Graphical Abstract
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Catalytic Applications of β-Cyclodextrin/Palladium Nanoparticles Thin Film Obtained
from Oil/Water Interface in the Reduction of Toxic Nitrophenol Compounds and
Degradation of Azo Dyes
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Azam Zare Asadabadi,b S. Jafar Hoseini,,a,b Mehrangiz Bahramia,b and S. Masoud Nabavizadeha
a Prof. Rashidi Laboratory of Organometallic Chemistry, Department of Chemistry, College of Sciences, Shiraz
University, Shiraz, 7194684795, Iran
b Department of Chemistry, Faculty of Sciences, Yasouj University, Yasouj 7591874831, Iran
The supramolecular catalyst of Pd/β-cyclodextrin thin film is synthesized via a facile and one-pot
procedure at oil-water interface and applied for the reduction of toxic nitrophenol compounds
and degradation of harmful azo dyes with considerable results. Nitrophenols transformation is
not only advantageous for pharmaceutical industry, but also in the pollutant-remediation field.
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Corresponding author: E-mail: sj.hoseini@shirazu.ac.ir, sjhoseini54@yahoo.com, Fax: +987136460788; Tel:
+987136137117.