Full text of DOI:10.1016/j.saa.2018.03.035

Accepted Manuscript
Rapid detection of HSO4− in water: Novel immobilized azo-
azomethine colorimetric anion receptors on solid supports
Saba Mahdavi Hezaveh, Hamid Khanmohammadi, Mojgan
Zendehdel
PII:
S1386-1425(18)30237-3
doi:10.1016/j.saa.2018.03.035
SAA 15907
DOI:
Reference:
Spectrochimica Acta Part A: Molecular and Biomolecular
Spectroscopy
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Received date: 5 December 2017
Revised date:
Accepted
date:
19 February 2018
1
2 March 2018
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ACCEPTED MANUSCRIPT
4
Rapid detection of HSO ˉ in water: Novel immobilized azo-
azomethine colorimetric anion receptors on solid supports

Saba Mahdavi Hezaveh, Hamid Khanmohammadi , Mojgan Zendehdel
Department of Chemistry, Faculty of science, Arak University, Arak 38156-8-8349, Iran
Abstract
The immobilized azo-azomethine receptors on amorphous SiO
and NaY zeolite, S-ZY, have been prepared and applied as solid phase sensors for detection of
HSO ˉ, over other interfering anions, in 100% aqueous media. Remarkably, S-B and S-ZY show
unique and rapid sensitivity towards HSO
2
, S-B, SiO
2
nanoparticles, S-NPs,
4
4
ˉ, which could it easily visualized through naked eye
-4
-1
-4
-1
detection even at 5×10 molL and 4×10 molL , respectively. The fabricated solid phase sensors
were characterized using powder XRD diffraction, TGA-DTA, FE-SEM and also FT-IR
techniques. Moreover, the related molecular anion receptor, HL, has been prepared and used for
naked eye detection of Fˉ and AcOˉ, in dry DMSO. The anions recognition ability of HL was also
1
evaluated using UV–Vis and H NMR spectroscopic methods.
Keywords: Azo-Azomethine; Bisulfate detection; Colorimetric sensor; Schiff base; NaY zeolite.

Corresponding author: h-khanmohammadi@araku.ac.ir ; Tel: +98-86-34173431; Fax: +98-86- 34173406.
1

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1
. Introduction
To date, there are so many reported molecular Schiff-base receptors which are able to detect and
colorimetric sensing of biologically important anions, such as Fˉ, AcOˉ, H PO ˉ, in
2
4
aqueous/semiaqueous media [1-3]. However, some of Schiff base receptors, based on hydrogen-
bonding motifs, have displayed poor selectivity against basic anions in aqueous media [4-6]. The
major bottlenecks of that receptors are insolubility in water and also water intolerance which
restricts their use for real samples analysis in aqueous media [7,8].
Among variety important anions, HSO
biological and industrial areas [9, 10]. For instance, HSO
fertilizers, industrial raw materials and nuclear fuel waste, which eventually get into the
4
ˉ is of particularly interest owing to its established role in
4
ˉ is present in many agricultural
environment [11, 12]. The generated toxic sulfate ions, from dissociation of HSO
irritation of skin, eyes and respiratory paralysis [13].
4
ˉ in water, cause
Therefore, design and synthesis of anion receptors that are able to sense HSO ˉ, in aqueous media,
4
has currently been evolving as a forefront research topic [14, 15]. Up to date, many of molecular
Schiff-bases receptors, as chemosensor have reported which are quite successful for detection of
HSO
to be considerably effective in solution, they can’t applied to the continuous online detection owing
to the intrinsic limitations of HSO ˉ anions in device fabrication. Actually, hydrolysis of -C=N-
bond in the presence of HSO ˉ, and also formation of aldehyde and amine, presented as mechanism
of HSO ˉ anion sensing in water using Schiff base receptors [19, 20].
To date, there have been few reports of solid colorimetric chemosensors for detection of HSO
anion in water [21]. As a new approach, this motivated us to design new receptors based on low-
4
ˉ anions in aqueous/semiaqueous solutions [16-18]. While that existing sensors have proven
4
4
4
4
ˉ
cost molecular azo-azomethines, for rapid detection of HSO ˉ anion in water. However, one major
4
2

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question perturbed us: although the most molecular Schiff bases are water-insoluble, how can we
apply a Schiff base receptor to detect HSO
prepare new covalently immobilized molecular Schiff base receptors on solid supports for
detection of HSO ˉ anion in water.
The molecular Schiff base, HL, was also prepared from the condensation reaction of 2-hydroxy-
-methoxy-5-((4-nitrophenyl)diazenyl)benzaldehyde, 1, with 3-aminopropyl triethoxysilane (3-
4
ˉ anion in water? For this purpose, we design and
4
3
APTES) in EtOH (Scheme 1). Although HL is an excellent receptor for detection and colorimetric
sensing of Fˉ and AcOˉ in DMSO, no significant color change appeared in the presence of the
4
mentioned anions as well as HSO ˉ in water. Then, we prepared new, based on HL, using solid
supports (amorphous SiO , S-B, nano SiO
2
2
, S-NPs, and also NaY Zeolite, S-ZY) for rapid and
high selective detection of anions in water (Scheme 2). Surprisingly, S-B and S-ZY show excellent
,
2ˉ, Clˉ, CNˉ,
sensitivity and selectivity against HSO
NO ˉ, H PO
the detection of HSO
4
ˉ over other anions, such as Fˉ AcOˉ, SO
4
3
2
4
ˉ, in 100% aqueous media. Indeed, S-B and S-ZY would be especially suitable for
4
ˉ anion in water and show significant, discernible and rapid color change,
-4
-1
-4
-1
even with naked eye at 5×10 molL and 4×10 molL , respectively. The structures of all
prepared sensors were also characterized using powder XRD diffraction, TGA-DTA, FE-SEM and
FT-IR technique.
Scheme 1
Scheme 2
2
. Experimental
2
.1. Materials
3

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All of the reagents and solvents involved in synthesis were of analytically grade and used as
received without further purification. 3-Aminopropyl triethoxysilane (3-APTES), 4-Nitroaniline,
Tetraethylorthosilicate (TEOS) and 2-Hydroxy-3-Methoxybenzaldehyde (O-Vanillin) obtained
from Aldrich and Merck. Amorphous SiO
received. NaY Zeolite obtained from SPAG (Tehran, I. R. IRAN).
.2. Instrumentation
2
(mesh 60) was obtained from Merck and used as
2
1H NMR spectra recorded on a Bruker Avance 300 MHz spectrometer. FT-IR spectra recorded as
pressed KBr discs, using Unicom Galaxy Series FT-IR 5000 spectrophotometer in the region of
-1
4
00-4000 cm . Melting points determined on Electrothermal 9200 apparatus. C. H. N. analyses
were performed on a Vario EL III elemental analyzer. Electronic spectra carried out using Optizen
220 UV-Vis in the range 200-700 nm. X-ray diffraction patterns of the prepared samples recorded
using a Philips PW1730 X-ray diffractometer with Cu Kα radiation (0.15418 nm) operated at 30
3
◦
−1
kV and 15 mA at a scan speed of 1 min and 2θ range of 0–80◦.
2
2
.3. Synthesis
.3.1. Azo-coupled O-vanillin precursor, 1
Azo-coupled O-vanillin precursor was prepared according to the modified literature procedure 22].
O-Vanillin (10 mmol) dissolved in water (20 mL) containing (10 mmol) of sodium hydroxide and
(40 mmol) of sodium carbonate during the period of 30 min at 0 ºC. The resulted solution added,
slowly, to a solution of diazonium chloride (10 mmol) in water at 0–5 ºC. The reaction mixture
stirred for one h at 0 ºC and then allowed to warm slowly to room temperature. The product was
collected by filtration and washed with 100 mL of NaCl solution (10%) under vacuum. The
o
1
obtained solid dried in air. Yield: 2.77 g (92%), m.p. 209-211 C. H NMR (d -DMSO, 300 MHz,
6
4

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ppm): δ 3.97 (s, 3H), 7.69 (s, 1H), 7.92 (s, 1H), 8.02 (d, 2H, J=8.41 Hz), 8.39 (d, 2H, J=8.4 Hz),
-1
1
0.37 (s, 1H), 10.52 (br, 1H). IR (KBr, cm ); 1655 (CHO), 1613 (C=C), 1586 (phenol ring), 1516
(
NO
2
), 1340 (NO
2
) 1458 (N=N), 1269 (C-O), 1130, 960 and 756. EI-Ms: MW (C14
H
11
N
3
5
O )=
+
3
01.25, experimental m/z (M )=301.07.
2
.3.2. 2-methoxy-4-(-(4-nitroohenyl)diazenyl)-6-(-(3-triethoxysilyl)propylimino)methyl)phenol,
HL
A solution of 3-APTES (4 mmol) in dry ethanol (10 mL) added to a stirring solution of azo-coupled
precursors, 1, in dry ethanol (20 mL) at 60 ºC. The mixture heated over 24 h at 80 ºC under N
2
-1
atmosphere and then filtered whilst hot. Dark red solid, m. p. >290 ºC. IR (KBr, cm ); 2932 (C–
H), 1647 (C=N), 1609, 1547 (phenol ring), 1516 (NO
2
), 1454 (N=N), 1337 (NO ), 1259 (C–O),
2
1
1
132, 1101 and 856. H NMR (d
6
-DMSO, ppm): δ 0.68 (br, 2H), 1.05 (t, 9H), 1.73 (br, 2H), 3.70
(m, 8H), 4.30 (s, 3H), 7.26 (s, 1H), 7.75 (m, 2H), 8.11 (m, 2H), 8.28(br, 1H), 10.07 (s, 1H).
-1
-1
λ
max(nm) (ε (M cm )): 280 (18875) and 455 (33700) in THF. EI-Ms: MW (C23
H
32
N
4
7
O Si)=
+
5
04.61, experimental m/z (M )=504.20.
2
.3.3. Preparation of SiO
2
NPs
SiO
2
NPs prepared by using modified Stöber method [23] which involves hydrolysis of TEOS and
polyethylene glycol in the presence of ammonia in ethanol as follow: Polyethylengelycol (5 g)
added to a solution of ethanol (20 mL) and double distilled water (100 mL) in 250 mL round
bottom boiling flask. The flask put into the ultrasonic bath at ambient temperature for 30 min.
After this, NH
0 ºC in an oil bath under N
washed with ethanol and double distilled water. The product dried in vacuum oven at 100 ºC for
4 h.
3
(12.5 mL) and TEOS (10 mL) added to the mentioned flask. The mixture kept at
9
2
atmosphere over a period of 24 h. The obtained gel centrifuged and
2
5

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2
.3.4. General procedure for preparation of amino-modified solid supports
All amino-modified solid supports prepared with similar procedure. The solid support (1 g) added
to a solution of 3-APTES (1 mmol) in anhydrous toluene (100 mL). After ultrasonication, for 30
min, the mixture refluxed for 24 h under N atmosphere. The product separated by centrifugation
2
at 2000 rpm for 10 min. The collected solid washed several times with EtOH by repetitive
dispersion and precipitation cycles to rinse away raw material.
2
.3.5. Preparation of functionalized amorphous SiO
The functionalized amorphous SiO sensor prepared based on previous publications of similar
materials with minor modifications [24]. In brief, 0.1 mmol of 1 in dry EtOH (50 mL) added to
amino-modified amorphous SiO support (1 g) in dry EtOH (20 mL) and the mixture incubated
under stirring for 24 h at 80 °C under N atmosphere. The obtained mixture washed by repeated
2
sensor, S-B
2
2
2
centrifugation (2000 rpm) and resuspension three times with chloroform and ethanol to get rid of
unbound azo precursor.
2
.3.6. Preparation of functionalized SiO
The functionalized SiO nanoparticles sensor prepared based on method for preparation of S-B.
Herein, varying amounts (0.1, 0.3 and 0.5 mmol) of 1 were used for reaction with amino-modified
SiO NPs support (1 g) in dry EtOH (20 mL), separately. In each case, the mixture incubated under
stirring for 24 h at 80 °C under N atmosphere. The obtained mixture washed by repeated
2
nanoparticles sensor, S-NPs
2
2
2
centrifugation (2000 rpm) and resuspension three times with chloroform and ethanol to get rid of
unbound azo precursor.
2
.3.7. Preparation of functionalized NaY Zeolite sensor, S-ZY
6

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The functionalized NaY Zeolite sensor prepared via reaction of 1 (0.5 mmol) with amino-modified
NaY Zeolite support [25] (1 g) in dry EtOH (20 mL). The mixture incubated under stirring for 24
h at 80 °C under N atmosphere. The obtained mixture washed by repeated centrifugation (2000
2
rpm) and resuspension three times with chloroform and ethanol to get rid of unbound azo
precursor.
3
. Results and Discussion
3
.1. Characterization of molecular receptor
The molecular azo-azomethine receptor, HL, synthesized via condensation reaction of azo-
coupled O-vanillin precursor, 1, and 3-aminopropyl triethoxysilane in EtOH (Scheme 1). The HL
characterized by Mass, IR and NMR spectroscopic methods. The total absence of υ(C=O)
-1
absorption band of 1 in the IR spectrum at 1655 cm together with the appearance of a new
-1
absorption band at 1647 cm indicate that the new azo-azomethine, HL, formed. Also, the infrared
-1
spectrum of HL exhibits strong bands at 1337 and 1516 cm assigned to the NO group [26]. In
2
1
the H NMR spectra of 1, the CH=O proton exhibit a singlet resonance at 10.37 ppm. The presence
of a broad signal at ca. 11.50 ppm assigned to the OH proton, as confirmed by deuterium exchange
1
when D
2
O added to d
6
-DMSO solution of 1. In the H NMR spectrum of HL, the CH=N proton
1
exhibit a resonance at 10.07 ppm. Also, the H NMR spectrum show the signals at 
H
0.68-3.80
ppm assigned to the 3-aminopropyl triethoxysilane moiety in molecule (Supplementary materials).
The electronic absorption spectrum of HL, recorded in DMSO at room temperature, display
mainly two intense bands. The first UV band located at ca. 280 nm can assigned to the moderate
energy (π→π*) transition of the aromatic rings while the second band at ca. 450 nm is due to low
energy (π→π*) transition involving the π-electrons and also the charge transfer transitions
involving whole molecule of the receptor [27].
7

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3
.1.2. Anion recognition properties of HL
Initially, the sensing ability of HL towards various anions was investigated qualitatively by visual
examination of the anion-induced color changes of the receptor in dry DMSO. As exemplified in
Fig. 1 (a), upon the addition of 10 equiv. of various anions, as tetrabutylammonium (TBA) salt, to
-5
-1
a solution of HL in DMSO (5×10 molL ), only a vivid colour change observed drastically from
light orange to deep blue and red in the presence of Fˉ and AcOˉ, respectively. Conversely, the
addition of other surveyed anions failed to cause any conspicuous color change which reflects the
capability of molecular HL to detect Fˉ and AcOˉ anions in dry DMSO. However, anion
recognition ability of molecular HL failed when a few drops of water added to the DMSO solution.
To provide fundamental insights into the suitability of HL, the anions recognition behaviour of
HL explored using UV-Vis spectroscopy upon the addition of 10 equiv. of different anions to HL
-5
-1
solution in DMSO (5×10 molL ), Fig. 1 (b). Most significantly, upon the addition of various
anions, only Fˉ and AcOˉ were able to have a profound effect on the electronic spectrum of HL.
Figure 1
The effect of interference of other anions was also evaluated. The result shows that the fluoride
and acetate ions, individually, could detected by naked eyes without interference from other anions
(Supplementary materials).
Moreover, to get quantitative insights into HL-F interaction, sensing mechanism and also study of
absorption spectra changes, the spectrophotometric titration experiment carried out. For this
purpose, absorption spectra changes probed after gradually addition of different concentrations of
-5
-1
Fˉ (0.2–9 equiv.) to a solution of HL (5×10 molL ) in dry DMSO. As shown in Fig. 2 (a), the
addition of Fˉ caused to gradually decreases intensities of the bands at ca. 280 nm and ca. 450 nm
and simultaneously formation of new band at ca. 600 nm, attributed to the charge transfer (CT)
8

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from interaction between fluoride anion and HL. Correspondingly, one clean isosbestic point
observed at 555 nm. Contrary, similar isosbestic point was not observed for AcOˉ anion
(
Supplementary materials).
Plotting of 1/(A−A ), which A and A
Fˉ, respectively, versus 1/[Fˉ] showed a linear relationship, Fig. 2 (b), indicating HL bound with
Fˉ in 1:1 binding stoichiometry. The binding constant, K , as obtained from Benesi–Hildebrand
0
0
are the absorbance of HL in the presence and absence of
a
4
-1
-6
-1
equation [28] is 1.3×10 M and detection limit of Fˉ is 1.13×10 molL .
Figure 2
1
To further study of the interaction between molecular receptor and fluoride, H NMR titration
experiments conducted by addition the different amounts of tetrabutylammoniumfluoride, TBAF,
to d -DMSO solution of HL (Supplementary materials). It is clear that the OH proton signal of the
6
azo phenol moiety at, 13.87 ppm, thoroughly disappeared when only 0.5 equiv. of Fˉ added into a
solution of HL. This indicates that strong hydrogen bond formed between fluoride anion and active
OH group, as previously reported [29]. Interestingly, a typical HF ˉ signal, at ca. 16.0 ppm,
2
1
observed in H NMR titration experiments at higher concentration of Fˉ, indicating that
deprotonation of HL occurred
Moreover, deprotonation of phenolic OH proton was further supported by titration of HL with
standard solution of tetrabutylammonium hydroxide (TBAOH) in DMSO. Fig. 3 indicates the OHˉ
induced spectral changes of HL. Evidently, the titration profile afforded similar spectral pattern as
observed for other basic anions, AcOˉ corroborating the deprotonation phenomenon [30].
Figure 3
3
.2. Solid state sensors
9

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3
.2.1. Anion recognition properties of the solid sensors
The sensing ability of the prepared sensors, S-B, S-NPs and S-ZY, towards various anions, 5×10-
3
-1
ˉ, Clˉ and SO 2
molL , such as Fˉ, AcOˉ, NO
investigated qualitatively by visual examination of the anion-induced color changes of the
individual sensors in water. Surprisingly, S-B and S-ZY were very sensitive toward HSO ˉ and
3
ˉ, CNˉ, H
2
PO
4
ˉ, HSO
4
4
ˉ, as their sodium salts, has
4
exhibited a fast response time, below than 10 s, to detection of bisulfate over other anions in water,
Fig. 4 (a) and Fig. 4 (b). Thus, when S-B and S-ZY added to water solution containing bisulfate,
the color of solution was proportional to the amount of bisulfate ions. Fig. 5 (a) and Fig.5 (b) show
color scale obtained upon the addition of S-B and S-ZY solid to bisulfate solutions of different
concentration. Actually, in the presence of S-B and S-ZY the lowest concentration of HSO
4
ˉ, in
-4
-1
-4
-1
water, which can be recognize by naked eye found to be 5×10 molL and 4×10 molL ,
respectively. Furthermore to check the practical utility of S-B and S-ZY the possible interferences
by other anions carried out. The result indicated that the mentioned sensors could use for the
detection of HSO
materials).
4
ˉ ion in real samples without any other anion interferences (Supplementary
Figure 4
Figure 5
However, when S-NPs used as sensor a significant color change, from dark red to orange-yellow
in water solution was observed in the presence of HSO ˉ after 12 h, over other anions
Supplementary materials). In the other hand, the behavior of S-B and S-ZY in similar acidic
4
(
+
condition (in the presence of HCl) examined. As expected, upon the addition of H ions in aqueous
solution, containing S-B and S-ZY, an obvious color change, quite similar to HSO
-, observed,
4
Fig. 6.
1
0

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Figure 6
3
.2.2. FT-IR Spectroscopy
The symmetric stretching and bending frequency bands of Al–O–Si framework of zeolite are
-1
appear at ca.791 and 463 cm , respectively [31]. The asymmetric stretching of Al–O–Si chain of
-1
zeolite is appear at ca.1010 cm . The IR spectra of S-ZY before and after functionalized and also
after treatment with HSO ˉ are given in Fig. 7. The FT-IR spectra of S-ZY indicated an intense
band about ca.1015 cm attributable to the asymmetric stretching of Al–O–Si chain of zeolite. The
4
-1
-1
broad band about ca. 3550 cm in is due to stretching vibrations involving OH groups. A
comparison of the infrared spectra of the free zeolite Fig.7 (a) and the Schiff base immobilized
receptors before, Fig.7 (c), and after, Fig.7 (d), reaction with HSO
4
ˉ ion show remarkable
−
1
differences in the region 1600–3000 cm . The reduce intensity of υ(C=N) stretching band, at ca.
-1
1
650 cm , in the IR spectra of the Schiff base immobilized receptors together with appearance of
-
1
new band at ca. 1722 cm , after reaction with HSO
4
ˉ, clearly indicated that the immobilized Schiff-
ˉ, Fig.8. The infrared spectra of free S-B
base receptor was hydrolysed after reaction with HSO
4
-1
and S-NPs shows strong bands at ca. 1160, ca. 1090 and ca. 800 cm which are characteristic
silica network according to the similar literature (Supplementary materials) [32].
Figure 7
Figure 8
3
.2.3. BET analysis
Table 1 shows the BET surface area and pore volumes of, amorphous SiO
The S-B and S-ZY displayed abrupt decrease of surface area as compared to amorphous SiO
NaY, respectively. This, may be, attributed to most non-porous coverage of solid supports surface
2
, S-B, NaY and S-ZY.
, and
2
1
1

ACCEPTED MANUSCRIPT
by the azomethine receptor and can lead to restricted access to the pores for adsorption of N
Fig. 9 and supplementary materials [33].
2
gas,
Table 1
Figure 9
3
.2.4. Thermal analysis
Thermal stability and decomposition behavior of the solid sensors have been studied by TGA from
○
room temperature up to 700 C. The TGA curve of S-B is given in the Fig. 10 (a). The first mass
○
loss until 180 C, about 2.1%, is attributed to desorption of water molecules. The second step of
○
weight loss, about 200-600 C, is due to removal of organic fragment from solid surfaces (5.5%).
The TGA plots for S-NPs and S-ZY is shown in Fig. 10 (b) and Fig. 10 (c), respectively. As seen
from Fig. 10 (b) and Fig. 10 (c), the weight loss of 5.09 % and 9.31 % between the temperature
○
intervals of 25-200 C is attributed to desorption of physical and chemical water molecules present
in the S-NPs and S-ZY, respectively. Above this temperature organic fragment comes out with
○
multiple steps in the temperature range 325–500 C. The second step with 5.27 % and 8.05%
weight loss is assigned to decomposition of Schiff base for S-NPs and S-ZY, respectively. In the
last step of S-ZY TGA curve, Fig. 10 (c), the structure of zeolite is changed.
Figure 10
3
.2.5. Powder XRD analysis
The powder XRD patterns of the solid supports before and after immobilization of Schiff base
ligand are given in Fig. 11(a-c). The XRD patterns of zeolite Y is characterized by many sharp
peaks due to the framework ordering of zeolite [34], Fig. 11 (a). The diffraction patterns
1
2

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functionalized support after binding of Schiff base molecule is similar to that of the native support.
This provided that only little or negligible loss in crystallinity and morphology of S-ZY during the
functionalize procedures has taken place and the percentage of amorphization of zeolite Y is small
[
35]. Interestingly, the change at the intensities of XRD peaks is negligible indicating that the most
added Schiff base ligand inserted into and some of them, in agreement with BET data, were in
outside of the channels of zeolite [36]. Fig. 11 (b) shows the powder XRD patterns of native
amorphous SiO and S-B. The presence of several weak peaks, located in the range of 10–55°,
2
indicated that the phase transformation from amorphous to crystalline phase, in S-B, was take
placed during immobilization process. Fig. 11 (c) represents the powder XRD patterns of nano
particles SiO and S-NPs. The morphology of S-NPs studied using the field emission scanning
2
electron microscopy (FE-SEM) technique. It was observed that the prepared S-NPs nanospheres
are aligned, dense and non-crystalline phase, with a diameter of ca.100 nm, as shown in Fig. 12.
Therefore, the response time of S-NPs towards HSO ˉ
is slower, 12 h, than that of larger size and
4
hollow, S-B and S-ZY, sensors.
Figure 11
Figure 12
4
. Conclusion
New series of molecular and also fabricated sensors on solid-supports have prepared as efficient
chromogenic sensing materials for naked eye detection of anions in aqueous and semiaqueous
media. The molecular azo-azomethine sensor, HL, exhibited discernable color changes upon the
1
3

ACCEPTED MANUSCRIPT
addition of more basic anions, such as Fˉ and AcOˉ, in DMSO. The recognition details of the anion
1
sensing of HL were also assessed using H NMR and UV-Vis spectroscopic methods.
Furthermore, the covalently immobilized HL on solid supports, amorphous SiO
2
, S-B, SiO
2
nanoparticles, S-NPs, and NaY zeolite, S-ZY, were prepared. Remarkably, S-B and S-ZY sensors
show unique and rapid sensitivity towards HSO
4
ˉ, over other interfering anions such as Fˉ, AcOˉ,
NO
3
ˉ, CNˉ, H
2
PO
4
ˉ, Clˉ and SO
4
2ˉ in water. The fabricated solid sensors characterized using
powder XRD diffraction, BET, TGA-DTA, FE-SEM and FT-IR techniques. Hydrolysis of the
immobilized Schiff-base receptor, on the surface of the solid support, is responsible for making S-
B and S-ZY as sensors for detection of HSO ˉ in water.
4
Acknowledgments
We are grateful to the Arak University for financial support of this work.
1
4

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References
1] A.B. Aletti, D.M. Gillen, T. Gunnlaugsson ‘Luminescent/colorimetric probes and (chemo-)
[
sensors for detecting anions based on transition and lanthanide ion receptor/binding complexes’
Coord. Chem. Rev., 354 (2018) 98-120.
[
2] P.A. Gale, C. Caltagirone ‘Anion sensing by small molecules and molecular ensembles’ Chem.
Soc. Rev., 44 (2015) 4212-4227.
3] E.A Katayev, Y.A. Ustynyuk, J.L. Sessler ‘Receptors for tetrahedral oxyanions’ Coord. Chem.
Rev., 250 (2006) 3004-3037.
4] J.L. Sessler, E. Katayev, G.D. Pantos, Y.A. Ustynyuk ‘Synthesis and study of a new
[
[
diamidodipyrromethane macrocycle. An anion receptor with a high sulfate-to-nitrate binding
selectivity’ Chem. Commun., (2004) 1276–1277.
[
5] H. Khanmohammadi, K. Rezaeian, Naked-eye detection of inorganic fluoride in aqueous media
using a new azo-azomethine colorimetric receptor enhanced by electron withdrawing groups, RSC
Advances 4 (2014) 1032-1038.
[
6] L. Wang, J. Ou, G. Fang, D. Cao ‘A fluorescent turn-on probe for detection of HSO ˉ
ion based
4
on hydrolysis of BODIPY-derived Schiff base with chromogenic and fluorogenic dual signals’
Sens. Actuators B 222 (2016) 1184–1192.
[
7] X.F. Shang ‘The anion recognition properties of Schiff base or its reductive system based on
,2-bipyridine derivatives’ Spectrochim. Acta Part A, 72 (2009) 1117–1121.
8] S. Ghosh, M.A. Alam, A. Ganguly, N. Guchhait ‘Amido-Schiff base derivatives as colorimetric
2
[
fluoride sensor: Effect of nitro substitution on the sensitivity and color change’ Spectrochim. Acta
Part A, 149 (2015) 869–874.
1
5

ACCEPTED MANUSCRIPT
[
9] M. Alešković, N. Basarić, N. Došlić, V. Tomišić, K. Mlinarić-Majerski ‘HSO ¯ sensing based
4
on proton transfer in H-bonding complexes’ Supramol. Chem., 26 (2014) 850-855.
10] B.A. Moyer, L.H. Delmau, C.J. Fowler, A. Ruas, D.A. Bostick, J.L. Sessler, E. Katayeu, G.D.
[
Pantos, J.M. Llinares, M.A. Hossain, S.O. Kang, K. Bowman-James, in: R.V. Eldik, K. Bowman-
James (Eds.) ‘Advances in Inorganic Chemistry, Academic Press’ New York, 2007, pp. 175–204.
[
11] T.Y. Joo, N. Singh, G.W. Lee, D.O. Jang, Tetrahedron Lett.‘Benzimidazole-based ratiometric
fluorescent receptor for selective recognition of acetate’ Tetrahedron Lett., 48 (2007) 8846–8850.
12] R. Custelcean, V. Sellin, B.A. Moyer ‘Sulfate separation by selective crystallization of a urea-
functionalized metal–organic framework’ Chem. Commun., 15 (2007) 1541-1543.
13] P.I. Jalava, R.O. Salonen, A.S. Pennanen, M.S. Happo, P. Penttinen, A.I. Halinen, M.
[
[
Sillanpaa, R. Hillamo, M.R. Hirvone ‘Effects of solubility of urban air fineand coarse particles on
cytotoxic and inflammatory responses in RAW 264. 7 macrophage cell line’ Toxicol. Appl.
Pharmacol., 229 (2008) 146–160.
[
14] K. Kaur, V.K. Bhardwaj, N. Kaur, N. Singh ‘Imine linked fluorescent chemosensor for Al3+
−
and resultant complex as a chemosensor for HSO4 anion’ Inorg. Chem. Commun., 18 (2012) 79–
8
2.
15] B-Y. Kim, H-S. Kim, A. Helal ‘A fluorescent chemosensor for sequential recognition of
gallium and hydrogen sulfate ions based on a new phenylthiazole derivative’ Sens. Actuators B
[
2
06 (2015) 430–434.
[
16] P. Li, Y-M. Zhang, Q. Lin, J-Q. Li, T-B. Wei ‘A novel colorimetric HSO ˉ
4
sensor in aqueous
media’ Spectrochim. Acta Part A, 90 (2012) 152–157.
1
6

ACCEPTED MANUSCRIPT
[
17] W. Lu, J. Zhou, K. Liu, D. Chen, L. Jiang, Zh. Shen ‘A polymeric film probe with a turn-on
fluorescence response to hydrogen sulfate ions in aqueous media’ J. Mater. Chem. B, 1 (2013)
014–5020.
18] S. Erdemir, B. Tabakci, M. Tabakci ‘highly selective fluorescent sensor based on
5
[
2
+
2−
−
calix[4]arene appendedbenzothiazole units for Cu , S and HSO ions in aqueous solution’ Sens.
4
Actuators B 228 (2016) 109–116.
[
19] V. Kumar, A. Kumar, U. Diwan, K.K. Upadhyay ‘Uncovering the true mechanism of optical
ˉ
detection of HSO
4
in water by Schiff-base receptors– hydrolysis vs. hydrogen bonding’ Chem.
Commun., 48 (2012) 9540–9542.
[
‘
[
20] H.J. Kim, S. Bhuniya, R.K. Mahajan, R. Puri, H. Liu, K. Ch. Ko, J.Y. Lee, J.S. Kim
Fluorescence turn-on sensors for HSO ˉ
21] C. Tan, Q. Wang, L. Ma ‘Fluorescent-based Solid Sensor for HSO ˉ
4
’ Chem. Commun., (2009) 7128–7130.
4
in Water’ Photochem.
Photobiol., 86 ( 2010) 1191–1196.
22] H. Khanmohammadi, M. Erfantalab ‘New 1,2,4-triazole-based azo-azomethine dyes. Part I:
Synthesis, characterization and spectroscopic studies’ Spectrochim. Acta Part A, 86 (2012) 39-43.
23] W. Stöber, A. Fink ‘Controlled growth of monodisperse silica spheres in the micron size
range’ J. Colloid Interface Sci., 26 (1968) 62-69.
24] P. Zucca, E. Sanjust ‘Inorganic Materials as Supports for Covalent Enzyme Immobilization:
Methods and Mechanisms’ Molecules, 19 (2014) 14139-14194
25] M. Zendehdel, F. Zamani, H. Khanmohamadi ‘Immobilized 4-methyl-2,6-diformyl phenol
[
[
[
[
complexes on a zeolite: Characterization and catalytic applications in esterification, DielseAlder
and aldol condensation’ Micropor. Mesopor. Mater., 225 (2016) 552-563
1
7

ACCEPTED MANUSCRIPT
[
26] G. Socrates, in: Infrared and Raman Characteristic Group Frequencies, Third ed., John Wiley
&
Sons Ltd, 2001, pp. 295–320.
27] A.M. Khedr, M. Gaber, R.M. Issa, H, Erten ‘Synthesis and spectral studies of 5-[3-(1,2,4-
triazolyl-azo]-2,4-dihydroxybenzaldehyde (TA) and its Schiff bases with 1,3-diaminopropane
TAAP) and 1,6-diaminohexane (TAAH). Their analytical application for spectrophotometric
microdetermination of cobalt(II). Application in some radiochemical studies’ Dyes Pigments. 67
[
(
(2005) 117-126.
[
28] H.A. Benesi, J.H. Hildebrand, ‘A spectrophotometric investigation of the interaction of iodine
with aromatic hydrocarbons’ J. Am. Chem. Soc., 71 (1949) 2703-2707.
29] M. Boiocchi, L. Del Boca, D.E. Go´mez, L. Fabbrizzi, M. Licchelli and E. Monzani ‘Nature
of urea-fluoride interaction: Incipient and definitive proton transfer’ J. Am. Chem. Soc., 126
[
(2004), 16507-16514.
[
30] C. Jin, M. Zhang, C. Deng, Y. Guan, J. Gong, D. Zhu, Y. Pan, J. Jiang, L. Wang ‘Novel
calix[4]arene-based receptors with bis-squaramide moieties for colorimetric sensing of anions via
two different interaction modes’ Tetrahedron Lett., 54 (2013) 796–801.
[
31] D. Chandra, T. Yokoi, T. Tatsumi, A. Bhaumik ‘Highly luminescent organic−inorganic
hybrid mesoporous silicas containing tunable chemosensor inside the pore wall’ Chem. Mater. 19
(2007) 5347–5354.
[
32] L.T. Zhuravlev ‘The surface chemistry of amorphous silica. Colloids Surf. A: Physicochem.
Eng. Aspects, 173 (2000) 1-38.
33] P. Gogoi, A.K. Dutta, S. Saikia, and R. Borah ‘Heterogenized hybrid catalyst of 1-sulfonic
acid-3-methyl imidazolium ferric chloride over NaY zeolite for one-pot synthesis of 2-amino-
-arylpyrimidine derivatives: A viable approach’ Appl. Catal. A: Gen., 523 (2016) 321–331.
[
4
1
8

ACCEPTED MANUSCRIPT
[
34] A.H. Ahmed, A.G. Mostafa ‘Synthesis and identification of zeolite-encapsulated iron (II),
iron (III)-hydrazone complexes’ Mater. Sci. Eng. C – Biol. Sci. 29 (2009) 877-883.
35] S. Mandal, D. Roy, R.V. Chaudhari, and M. Sastry ‘Pt and Pd Nanoparticles Immobilized on
[
Amine-Functionalized Zeolite: Excellent Catalysts for Hydrogenation and Heck Reactions’ Chem.
Mater. 16 (2004) 3714-3724.
[
36] A.M. Newman ‘Focus on solid state chemistry’ Nova Science Publishers Inc., USA. (2007)
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Figure Captions
Scheme 1: Synthesis of molecular receptor HL
Scheme 2: The prepared solid sensors
-5
1-
Figure 1: (a) Color change of HL (5×10 molL in DMSO) upon the addition 10 equiv. of various
anions, as TBA salt, from left to right: Free HL, H
2
PO
4
ˉ, Clˉ, NO
2
ˉ, Fˉ, HSO
4
ˉ, AcOˉ, N
3
ˉ, NO ˉ
3
-5
-1
(
b) UV–Vis absorption spectra of HL (5×10 molL in DMSO) in the presence of 10 equiv. of
the mentioned anions
-5
-1
Figure 2: (a) UV-Vis absorption spectra of HL (5×10 molL ) in dry DMSO upon the addition
ˉ
of TBAF (0.2-9 equiv.) (b) Benesi–Hildebrand plot of HL binding with F anion associated with
absorbance change at 600 nm in DMSO
-5
-1
Figure 3: UV-Vis absorption spectra of HL (5×10 molL ) in dry DMSO upon the addition of
TBAOH
-3
-1
Figure 4: (a) Color changes of S-B and (b) S-ZY in present of various anions, (5×10 molL ) in
water. From left to right: (a) none, Fˉ , AcOˉ, SO 2
2ˉ, Clˉ, H
4
ˉ, CNˉ, Clˉ, NO
3
ˉ, H
2
PO
4
ˉ, HSO ˉ and (b) none,
4
Fˉ, AcOˉ, NO
3
ˉ, HSO
4
ˉ, CNˉ, SO
4
2
PO ˉ.
4
Figure 5: Colorimetric response of H O-suspended of (a) S-ZY and (b) S-B in the presence of
2
-3
-3
-4
-4
-1
HSO ˉ (from left to right 5×10 , 1×10 , 5×10 and 1×10 molL )
4
Figure 6: Colorimetric response of H
O-suspended of (a) S-B and (b) S-ZY in the presence of H+
2
ions.
Figure 7: The IR spectra of (a) free zeolite NaY, (b) amino modified zeolite H
S-ZY and (d) S-ZY when treatment with HSO
Figure 8: Possible complexation mode of solid sensors, S-B and S-ZY, with HSO4ˉ
Figure 9: The N adsorption/desorption isotherms of S-ZY
2
N-Y and (c) free
4
ˉ
2
2
0

ACCEPTED MANUSCRIPT
Figure 10: TGA-DTA analyses curves of (a) S-B, (b) S-NPs and (c) S-ZY
Figure 11: powder XRD spectra of (a) NaY zeolite, (b) S-ZY, (c) Amorphous SiO2, (d) S-B, (e)
SiO
2
Nanoparticles, (f) S-NPs
Figure 12: FE-SEM image of S-NPs
2
1

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Table 1. Textural properties of amorphous SiO
2
, NaY, S-B and S-ZY
2
3
Surface area (m /g)
Pore Volume (cm /g)
Amorphous SiO
2
303.04
248.92
560
0.686
0.503
0.390
0.078
S-B
NaY
S-ZY
9.088
2
2

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NH2
H CO
3
HO
H
N
O
O
+
N
N
Si
H CH CO
3
2
OCH CH3
2
O
H CH CO
3 2
1
H CO
3
HO
H
N
N
NO2
N
Si
OCH CH3
2
H CH CO
3
2
OCH CH3
2
HL
Scheme 1
2
3

ACCEPTED MANUSCRIPT
NO2
1
N
O
N
O
O
O
NH2
O
Dry EtOH
Si
Si
O
H C
3
N
O
OH
H
Sensor
S-B
S-NPs
S-ZY
NaY Zeolite
Solid Support
Amorphous SiO2 Nano SiO2
Scheme 2
2
4

ACCEPTED MANUSCRIPT
none
(a)
1
1
.4
.2
1
HL
ligand
H2PO4-
Cl-
(b)
NO2-
HSO4-
N3-
0
0
0
0
.8
.6
.4
.2
0
NO3-
OAC-
F-
2
50
350
450
550
650
750
nm
Figure 1
2
5

ACCEPTED MANUSCRIPT
1
.8
.6
.4
.2
1
1
1
1
(a)
0
0
0
0
.8
.6
.4
.2
0
2
45
345
445
545
645
745
845
nm
3
2
1
0
.5
y = 9E-05x + 0.7356
R² = 0.9929
3
.5
2
(b)
.5
1
.5
0
0
5000
10000
15000
20000
25000
30000
1
/[F-]
Figure 2
2
6

ACCEPTED MANUSCRIPT
1
1
0
0
0
.5
.2
.9
.6
.3
0
263
363
463
563
663
763
nm
Figure 3
2
7

ACCEPTED MANUSCRIPT
Free (S-B) in water
(a)
Free (S-ZY) in water
(b)
Figure 4
2
8

ACCEPTED MANUSCRIPT
Free (S-ZY) in water
(a)
Free (S-B) in water
(b)
Figure 5
2
9