Simultaneous measurement of hydrogen carbonate and acetate anions using biologically active receptor based on azo derivatives of naphthalene

Article abstract of DOI:10.1016/j.saa.2019.117925

A novel receptor based on azo-derivatives of 1-naphthylamine (2-((E)-((4-chloro-3-(trifluoromethyl)phenyl)imino)methyl)-4-((E)-naphthalene-1-yldiazenyl)phenol(2) abbreviated CTNP was successfully designed and synthesized. Its sensing properties were studied deeply. Systematic studies of CTNP with HCO₃ ^? and AcO^? anions in DMSO disclosed that there is hydrogen-bonding between CTNP and incoming anions. Significant changes in the visible region of the spectrum, as well as a drastic color change of CTNP from pale yellow to red, observed due to interaction as mentioned earlier. The stoichiometry of [CTNP: HCO₃ ^? or AcO^?] complexes and association constants determined through Job's method and Benesi-Hildebrand (B-H) plot, respectively. Taking into account the analysis results, CTNP performs the selective recognition of sub-millimolar concentrations of HCO₃ ^? and AcO^? efficiently. The antifungal activity of the receptor was tested against Aspergillus brasiliensis and Aspergillus niger. CTNP exhibited excellent antifungal activity against both strains. CTNP also represented antibacterial activity against Gram-positive bacteria: Staphylococcus epidermidis. It was cleared that designed receptor can be applied under physiological conditions for a long duration.

Full text of DOI:10.1016/j.saa.2019.117925

Journal Pre-proof
Simultaneous measurement of hydrogen carbonate and acetate
anions using biologically active receptor based on azo derivatives
of naphthalene
Fatemeh Parchegani, Masoumeh Orojloo, Mojgan Zendehdel,
Saeid Amani
PII:
S1386-1425(19)31316-2
https://doi.org/10.1016/j.saa.2019.117925
SAA 117925
DOI:
Reference:
Spectrochimica Acta Part A: Molecular and Biomolecular
Spectroscopy
To appear in:
Received date: 22 September 2019
Revised date:
1 December 2019
6 December 2019
Accepted
date:
Please cite this article as: F. Parchegani, M. Orojloo, M. Zendehdel, et al., Simultaneous
measurement of hydrogen carbonate and acetate anions using biologically active receptor
based on azo derivatives of naphthalene, Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy(2019), https://doi.org/10.1016/j.saa.2019.117925
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Simultaneous measurement of hydrogen carbonate and acetate anions
using biologically active receptor based on azo derivatives of naphthalene
Fatemeh Parchegania, Masoumeh Orojlooa,Mojgan Zendehdela and Saeid
Amania*
aChemistry Department, Faculty of Sciences, Arak University, Dr. Beheshti
Ave., Arak 38156-88349, Iran
*Corresponding author:
E-mail: s-amani@araku.ac.ir; alternative E-mail: amani1331@yahoo.com
Phone office: +98 86 34173415; Fax office: +98 86 34173406
Abstract
A novel receptor based on azo-derivatives of 1-naphthylamine (2-((E)-((4-chloro-3-
(trifluoromethyl)phenyl)imino)methyl)-4-((E)-naphthalene-1-yldiazenyl)phenol(2)
abbreviated CTNP was successfully designed and synthesized. Its sensing properties were
−
studied deeply. Systematic studies ofCTNPwithHCO3 and AcO− anions in DMSO disclosed
that there is hydrogen-bonding between CTNP and incoming anions. Significant changes in
the visible region of the spectrum, as well as a drastic color change of CTNP from pale
yellow to red, observed due to interaction as mentioned earlier. The stoichiometry of [CTNP:
−
HCO3 /or AcO−] complexes and association constants determined through Job's method and
Benesi-Hildebrand (B-H) plot, respectively. Taking into account the analysis results, CTNP
−
performs the selective recognition of sub-millimolar concentrations of HCO3 and AcO−
efficiently. The antifungal activity of the receptor was tested against Aspergillusbrasiliensis
and Aspergillusniger. CTNP exhibited excellent antifungal activity against both strains.
CTNP also represented antibacterial activity against Gram-positive bacteria: staphylococcus
epidermidies. It was cleared that designed receptor can be applied under physiological
conditions for a long duration.
Keywords: Hydrogen carbonates anion; Acetate anion; Chemosensor; Biological activity
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1. Introduction
The design and development of anion detection sensors are one of the most important fields
of study in the chemosensor technology. They have several applications [1-4], including in
organo-catalysis, biology, medicine, environment and in separating mixtures of anions in
−
industrial systems [5, 6]. Among those common anions, hydrogen carbonate (HCO3 )and
acetate (AcO−) ions have been paid much attention due to their necessity in the field of
biology [7,8]. Moreover, physiological acid and base homeostasis are necessary for retaining
−
extracellular and intracellular pH.HCO3 is a natural alkaline buffer that adjusts tissue and
blood pH, via the discharge of carbon dioxide (CO2) [9-11]. CO2, which is produced in
eukaryotic cells, in the physiological environment is a conjugate acid according to the
equation 1 [11]:
(1)
−
Carbonic anhydrase (CA) enzymes accelerate the conversion of CO2 and HCO3 with
catalytic rate constant of up to 106 S-1. Control the equilibrium between CO2, H2CO3, and
−
−
HCO3 ions is critical factor of a healthy life. Variations in the HCO3 / CO2 ratio are known
to affect the structure and function of proteins in metabolic reactions [12,13]. Low
extracellular pH in tumors compared to the healthy tissues induces a physiological obstacle
−
that forbids drugs to penetrate cells, soHCO3 is used as auxiliary to the growth of tumor pH.
−
Hence, determining extracellular pH using hyperpolarized 13C labeled HCO3 has many
usages in basic research of biology and clinical trials [14].Separate from the physiological
−
importance of HCO3 , it has a critical role in the bakery and food industry, because it can be
used as a leavening agent, pH buffer, and an effervescent agent. Worthy of note that acetate
due to its involvement in variety of biochemical functions (enzyme activity and antibody
functions) as well as industrial reactions (extend shelf life in foodstuff) is of particular
interest. Sodium salts of acetate have been used to production and purification of synthetic
peptides, prevent microbial growth, and promote sensory attributes. The elevated level of
AcO− in blood plasma resulting from oxidation of ethanol is an important factor to cause
hangovers [15-18].Due to ubiquity and practical applications of bicarbonate and acetate ions,
it is of utmost importance to develop highly sensitive techniques for monitoring anions.
‒
Under laboratory situations, a wide diversity of methods are accessible to quantify the HCO3
and AcO− content including electrochemical, chromatographic techniques, potentiometric,
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electrophoresis, flow injection amperometric, polarography, and simple titrations. Some of
them are extraordinarily sensitive but need both tedious sample preparation, expensive
instrumentation, and multiple experimental steps, which greatly limit their wide applications
[19-21]. Therefore, potential advantages, containing ease of operation, safe and economy
induces the development of artificial molecular receptors with chromogenic subunits that
−
enable convenient monitoring of HCO3 and AcO− anions by the naked eye [22-28].For
‒
practical uses, the development of small molecular receptors that can detect both HCO3 and
AcO− simultaneously is more favorable [29]. Overall, the development of novel receptors
with appropriate functionalities remains a challenging work for chemists. Conventional
colorimetric anion chemosensor scaffolds employing –NH/-OH/-SH donors can act as
anionic binding sites. In all of these subunits, hydrogen bonding is responsible for п-electron
delocalization, which induces the deep red color of the solution immediately [30-32]. Simple
Schiff base frameworks are ideal modes to design chemosensors due to their excellent photo-
physical properties and generally one-step synthesis [31,33]. In contrast, few studies in which
1-Naphthylamine was employed to prepare azobenzene dye as a precursor for the synthesis of
naphthalene based Schiff base are reported in the literature [34,35].With these considerations,
−
a novel molecular receptor, CTNP, for detection of HCO3 /or AcO − contents over other
physiologically relevant anions was designed and synthesized. In this molecular design, the
CF3 moiety as a robust electron-withdrawing group enhanced the polarity of -OH fragment,
and so accelerated the deprotonation of the phenol proton upon the addition of hydrogen
carbonate and acetate ions. As expected, an extremely color change was observed due to the
−
redshift in absorption when treated with HCO3 /or AcO− ions. Sensor CTNP displayed fast
−
response for selectivity recognition of HCO3 /or AcO− in DMSO solution and revealed
excellent biological activity against various fungal and bacterial strains [36,37].
2. Experimental
2.1. General information
All chemical reagents, solvents, and anions (as sodium salts) are available at analytical grade
and used without purification. Ultrapure water (18.2 MΩ/cm) was used throughout all of the
experiments. All measurements were performed under aerated condition. The Fourier
transform infrared (FT-IR) spectra of the samples were recorded using Unicom Galaxy Series
IR spectrometer using KBr pellets. The spectra were calibrated using the polystyrene bands at
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3028, 1601, and 1208 cm−1.The UV-Vis absorption spectra were measured using double
beam Optizen 3220 spectrometer.1H-NMR were recorded on Bruker300 and 250 MHz NMR
instruments, using tetramethylsilane (TMS) as the internal standard, and chemical shifts were
recorded in ppm.A solution of CTNP (4.0×10-5 M) was prepared in dry DMSO. The solution
‒
was titrated with continuous additions of stock solutions of HCO3 and AcOˉ anions(1.0×10-4
M). The UV-Vis absorption spectra were measured employing a quartz cell,and the excitation
slits were set at 5 nm. To investigate the practical applications of the designed receptor, the
antimicrobial activity of CTNP was examined against both fungal and bacterial strains using
conventional techniques.
2.2. Synthesis of 2-hydroxy-5-(naphthalene-1-yldiazenyl) benzaldehyde (HNDB)
Following the general method to createazodyes [38], 1-Naphthylamine (20.0 mmol, 2.86 g)
was dissolved in solution of concentrated hydrochloric acid (10 mL) and ultrapure water (5
mL). The homogeneous mixture was heated to 80 ˚C to form a clear solution. A solution of
sodium nitrite(20.0 mmol, 1.4 g) in 10 mL of ultrapure water was added drop wise to the
+
acidic solution of amine during 5 min at 0˚C to convert an –NH2 group to an –N2 (diazo)
group. Then, the diazonium salts solution was poured drop wise to a solution of
salicylaldehyde (20.0 mmol, 2.5 g), as a coupling reagent which is containing sodium
carbonate (70 mmol, 7.4g) and sodium hydroxide (17mmol. 0.7 g) in ultrapure water. The
reaction mixture vigorously stirred at 0˚C for 3 hours. The obtained precipitate was
successively washed with water and air-dried. The product was recrystallized from ethanol
solution to obtain pure HNDB (3.67 g,yield:67%) as a deep brown solid. M.P. 153–155◦C;
1H-NMR (250 MHz, CDCl3) δ (ppm): 11.37 (s, 1H), 10.10 (s, 1H), 8.29 (d, 1H, J=6.9 Hz),
8.33 (s, 2H), 8.02 (d, 1H, J = 8.4 Hz), 7.96 (d, 1H, J=8.4 Hz), 7.85 (d, 1H, J=6.9 Hz), 7.64
(m, 3H) and 7.20 (d, 1H, J=8.7 Hz). FT-IR (KBr,cm-1); υ: 1660 (C=O), 1620 (C=C), 1481
(N=N), 1288 (C–O), 3049-3173 (aromatic C-H). For C17H12N2O2:Anal. Cal.: C, 73.90; N,
10.14; H, 4.38 %. Found: C, 71.99; N, 9.98; H, 4.68 %.
2.3. Synthesis of 2-((E)-((4-chloro-3-(trifluoromethyl)phenyl)imino)methyl)-4-((E)-
naphthalene-1-yldiazenyl)phenol(2)(CTNP)
A solution of 4-chloro-3-(trifluoromethyl)benzylamine (1.0 mmol, 0.195 g) in ethanol was
gradually added to a portion of HNDB (1.0 mmol, 0.276 g) in ethanol under stirring,
meanwhile 0.5 mL triethylamine was added as catalyst. Then the mixture was refluxed for
6hours at 75 ˚C. After evaporating the solvent, precipitate was purified by washing with n-
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hexane and diethyl ether sequentially, affording brown powders of(0.28 g, yield: 62%), M.P.
140–145◦C;1H-NMR (300 MHz, CDCl3) δ (ppm): 13.22 (s, 1H), 8.80 (s, 1H), 8.92 (d, 1H.
J=7.5 Hz), 8.20 (t, 2H, J=10 Hz), 7.96 (t, 2H, J=10Hz), 7.83 (d, 1H, J=7.5 Hz), 7.55-7.66 (m,
J=5Hz), 7.45 (d, 1H, J=7.5Hz), 7.22 (d, 1H, J=7.5 Hz). FT-IR (KBr,cm-1); υ: 1620 (C=N),
1475 (N=N), 1281 (C-O), 3055 (aromatic C-H).For C24H15N3OF3Cl: Anal. Cal.: C, 63.50; N,
9.26; H, 3.30 %. Found: C, 62.93; N, 9.38; H, 3.42 %.
3. Results and Discussion
3.1. Design and synthesis of CTNP
Our basic idea is to create hydrogen bonding sites for anion recognition through visual color
change. Introducing electron-withdrawing group such as –CF3 to the benzylamine moiety
favors the anion binding by increasing molecular polarization. On the other hand, extending
the azo-based aromatic ring from benzene to naphthalene causes a pronounced bathochromic
shift through lengthening the conjugated п- system [39, 40]. Synthetic procedure for CTNP is
1
outlined in scheme 1. H-NMR and FT-IR spectra confirm the structure. The strong band at
1660 cm-1is attributed to the presence of C=O stretching mode completely disappeared in the
spectrum of HNDB, while appearing a new characteristic azomethine (C=N) band at 1620
cm-1 (Fig.1)verify the reaction between HNDB and benzylamine. On the other hand removing
of the band at 2890 cm-1 in CTNP spectrum was observed due to the remove of C-H aldehyde
group of HNDB. Meanwhile, the N=N band at 1480 cm-1 in HNDB spectrum shifted to 1475
cm-1 in CTNP which confirms the presence of N=N band in the final product.To confirm the
1
Schiff base reaction, H-NMR spectra of HNDB and CTNP are obtained. Vanishing of the
aldehyde C-H resonance at 10.1 ppm of HNDB and appearance of newly formed imine signal
at 8.8 ppm supports the formation of C=N bond (Figures S1and S2) [22].
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Scheme 1:Schematic illustration of the synthetic procedure for CTNP
Fig. 1:FT-IR spectra of (a) HNDB, (b) CTNP
3.2. Electronic absorption spectra
The absorption spectra of CTNP were measured in DMSO at a concentration of 4×10-5M
at room temperature. The absorption spectra of CTNP exhibit a high energy band
centered at 330 nm and a low energy band centered at 380 nm assigned to п → п*
electronic transitions of azo-azomethine and intra-molecular charge transfer transition,
respectively [41]. The selectivity of the CTNP receptor was further examined its
−
preference for HCO3 and ACO−in the presence of interfering anions such as F−, Cl−,
−
−
−
−
−
Br−, I−, N3 , SCN−, NO3 , NO2 , ClO4 , HSO4 delivered as their sodium salts and
dissolved in DMSO/H2O (90:10 %; v/v). As anticipated, a noticeable red shift of the
−
main absorption band of free CTNP from 380 to 480 nm upon the addition of HCO3 and
AcO− anions were observed whereas no other anion induced a significant change in
−
absorption spectra (Fig. 2). More importantly, treatment of CTNP with HCO3 and AcO−
caused noticeable color change of the solution which revealed that naked-eye selective
−
sensing of HCO3 and AcO− became possible (Fig S3). The synthesized ligand (CTNP)
is not soluble in H2O solvent and therefore cannot be studied in H2O. For further
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−
investigation, both the CTNP and anionic salts (HCO3 , AcO−) were dissolved in DMSO:
H2O (90:10 %; v/v) solvent (Fig S4, S5) and once again the CTNP was dissolved in dry
DMSO and the mentioned anions were dissolved in pure H2O. (Fig S6, S7) and UV-Vis
spectra were obtained. These results indicate that the presence of H2O has no effect on
−
the recognition process of HCO3 and AcO− ions. But the detection of target anions in
dry DMSO is more outstanding in both color and absorbance data.
Fig. 2: UV-Vis studies of CTNP (4×10-5 M) in DMSO in the presence of 0.1mM different
anions
−
The sensitivity of CTNP towards HCO3 and AcO− was studied by UV-Vis titration tests
−
(Fig. 3, Fig. 4). Addition of HCO3 and AcO−anions (0.1 mM) to a solution of CTNP (0.04
mM) in DMSO resulted in a reduction in electronic absorption at 385nm following the build-
up of a new absorbance band at 495 and 480 nm, respectively. The presence of well-defined
isosbestic points at 425 nm for both anions indicated the formation of receptor-anion
−
complexes (CTNP:HCO3 /or AcO−) with no build-up of detectable byproducts or
intermediates [42].
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‒
Fig. 3: Changes in absorption intensity upon titration of CTNP (0.04 mM) withHCO3
‒
(0.1mM). Inset: absorption spectral changes with the incremental addition of HCO3 at
selected wavelengths
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Fig. 4: Changes in absorption intensity upon titration of CTNP (0.04 mM) with AcO‒
(0.1mM). Inset: absorption spectral changes with the incremental addition of AcO‒ at selected
wavelengths.
A filling of the absorption spectra data based on modified benesi-Hildebrand equation gave
−
association constants of receptor CTNP with HCO3 and AcO− anions of 2.24×104 M-1 and
9.2×104M-1, respectively (Fig S8,S9).To examine the ratio of the receptor interaction with the
−
HCO3 and AcO− anions, Job's continuous variation method was employed. The maximum at
−
a mole fraction of 0.5 with both HCO3 and AcO− verify that the receptor binds to anions in a
−
1:1 [CTNP: HCO3 /or AcO−] ratio (Fig. 5) [43].
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‒
Fig. 5: ob s plot diagram of receptor CTNP with (a) CO3 and (b) AcO‒ anions
Based on the calibration curve with the good linear relationship, the detection limit of CTNP
−
towards anions was found as low as 2.33μM (HCO3 ) and 0.55 μM (AcO−) by 3σ method.
The limit of quantitation amounts of CTNP receptor towards anions was also calculated and
evaluated (Table 1).The values obtained show that LOD quantities were low enough for the
−
detection of sub-millimolar quantities of HCO3 and AcO− ions as found in many chemical
systems [44].
Table 1: Formation obtained from UV-Vis studies upon titration of CTNP receptor with
‒
HCO3 /AcO‒ anions in DMSO
LODa
(mol.L-1)
LOQb
(mol.L-1)
Ka
(mol-1.L)
Isosbestic
CTNP
CTNP
+anion
point
(nm)
Anion
λ
ma (nm)
λma (nm)
2.33 × 10-6
5.54 × 10-7 1.68 × 10-6 9.2 × 104
7 × 10-6
2.24 × 104
‒
380
380
495
480
425
425
HCO3
AcO‒
a LOD: Limit of Detection, b LOQ: Limit of Quantitation
3.3. Competitive binding analysis
‒
The possible interferences of other anions on HCO3 and AcO‒detection were also analyzed
through competitive experiments. The absorbance changes of CTNP receptor (0.04 mM, 3.0
‒
mL) in DMSO were measured in the presence of HCO3 ( 0.1mM, 300 μL) in DMSO: 2O
(90:10 %; v/v) and 0.1 mM other interfering inorganic anions including F−, Cl−, Br−, I−,
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−
−
−
−
−
N3 ,SCN−, NO3 , NO2 , ClO4 , and HSO4 . The results showed no interference with the
−
recognition of HCO3 (Fig. 6). Likewise, the competitive experiments verified that tested
anions showed no intervention with the recognition of AcO− anion in DMSO: H2O (90:10 %;
v/v) (Fig. 7 and Figures S10 and S11) [45,46]. In order to find a suitable way to distinguish
‒
HCO3 and AcO− anions, competitive experiments were performed in the presence of
chloride salts of some transition metals (such as CuCl2, NiCl2 and CoCl2). The color of the
¯
(CTNP/HCO3 ) complex in the presence of Cu2+, Ni2+or Co2+ changes from orange to pale
yellow (Fig. 8). While the color of the (CTNP/ ACO¯) complex does not change at the same
conditions (Fig. 9). Also substantial change in the absorption spectra of CTNP corresponding
to the observed color changes was observed.
Fig. 6: Series1(light blue) represent UV-Vis response of CTNP (0.04 mM) in the presence of
various anions (0.1 mM),Series 2 (navy blue ) represent competitive selectivity of CTNP
‒
towards HCO3 (0.1 mM) in the presence of other anions.
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Fig. 7: Series1(light blue) represent UV-Vis response of CTNP (0.04 mM) in the presence of
various anions (0.1 mM), Series 2 (navy blue ) represent competitive selectivity of CTNP
towards AcO‒ (0.1 mM) in the presence of other anions
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-
Fig. 8: Changes in intensity and color of CTNP (0.04 mM) with HCO3 (0.1mM) in the
presence of transition metals.
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Fig. 9: Changes in intensity and color of CTNP (0.04 mM) with AcO− (0.1mM) in the
presence of transition metals.
3.4. Response time and pH dependence studies
−
To determine the stability of complexes CTNP: HCO3 /or AcO−, the time-dependent
−
variations in the absorbance spectra of CTNP upon treatment with HCO3 /or AcO− anions
were investigated. The absorbance intensity at corresponding wavelengths reached maximum
‒
immediately in the presence of a few drops of HCO3 or AcO‒ ions, implying the fast reaction
of CTNP and anions. On the other hand, the absorbance intensities remained constant for
−
several days, indicating that the complexes CTNP: HCO3 and CTNP: AcO− are very stable
ensembles (Fig. 10).
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‒
Fig. 10: Time dependence of receptor CTNP in the presence of HCO3 ion (red bar) and
AcO‒ ion (green bar).
−
The absorbance response to HCO3 /or AcO−anions was also analyzed at various pH values to
estimate the working pH range. At acidic pH, receptor CTNP did not display absorbance
−
response to anions due to the protonation of HCO3 /or AcO− anions. Complexes CTNP:
−
HCO3 /or AcO− showed remarkable absorbance response at neutral and basic pH values since
hydroxide ion concentration of the solution is high. These results confirmed that CTNP could
‒
be used for recognition of HCO3 /or AcO− anions within a pH range of 7.0-10.0 without
being affected by the physiological pH [47] (Fig. 11).
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‒
Fig. 11: Changes in absorption intensityof receptor CTNP in the presence of HCO3 /AcO‒ with pH
variations
3.5. Mechanistic study of CTNP receptor
1
To further strengthen obtained results, H-NMR spectra of the CTNP receptor were recorded
−
in DMSO (Fig. 12 and Fig. S12). During on addition of both HCO3 as well as AcO− anions,
1
significant chemical shifts of proton signals were observed in H-NMR spectra of CTNP.
More importantly, complete deprotonation of the phenyl proton signal at 12.9 ppm due to the
effect of an electron-withdrawing substituent (-CF3) occurred. At the same time, due to the
deprotonation process, comparable upfield chemical shifts of phenyl ring protons and imine –
CH=N proton through the shielding effect of anionic moiety were observed. The results
−
affirm that HCO3 and AcO− ions can acts as a base here and accelerate the deprotonation
process during the interaction with the receptor CTNP [32,48-50].
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Fig. 12: Partial 1H-NMR (300 MHz) spectra changes of (a) CTNP in DMSO and (b) in the
‒
presence of HCO3 (DMSO:D2O)
4. Biological activity of CTNP receptor
4.1. Biological activity
The antimicrobial activity of CTNP was evaluated in vitro against both fungal and bacterial
strains by usual techniques.
4.2. Antifungal study
The antifungal test of CTNP was examined against Aspergillusniger(ATCC 16404) and
Aspergillusbrasiliensis (PTCC 5011) strains by agar well diffusion technique. Active fungal
were grown on Muller Hinton Agar medium in Petri plates. Three wells of 6 mm diameter
were made. After injection of micro-organisms, the CTNP solution (100μL, 300 μg/mL) were
loaded on Petri plates and plates were incubated at 37 ˚C for 24 hours. The diameter zone of
inhibition (mm) was measured and compared with Nystatin as the reference (Table 2). A
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comparative study of the MIC (Minimum inhibitory concentration) and MBC (Minimum
bactericide concentration) magnitudes for CTNP and reference indicated that CTNP
prevented the fungal growth strains both Aspergillusniger and Aspergillusbrasiliensis
[51,52].
4.3. Antibacterial study
The antibacterial test of CTNP was assessed against bacterial strains by disc diffusion
technique. In this technique, blotting paper discs of 8 mm diameter were prepared for the
dipping into different levels of concentration solutions of CTNP at room temperature.
Nutrient agar medium was used to activate bacterial culture on Petri plates containing
mentioned paper discs and incubated overnight at 37˚C to monitor growth inhibition of the
bacteria. The diameter zone of inhibition (mm) around the discs were measured and
compared with that of Gentamicine as standard drug (Table 2).The CTNP receptor inhibits
the growth of staphylococcus epidermidies (ATCC 12228) [53,54].
Table 2:Biological activity results of the CTNP receptor in vitro
Micro organism
Diameter of
inhabitation (mm)
Inhabitation
with
MIC MBC
reference
12
13
13
35a
125
2000
2000
250
-
-
Staphylococcus epidermidis
Aspergillusniger
Aspergillusbrasiliensis
27b
30b
a Gentamicin as reference for bacterial strains, b Nystatin as reference for fungal strains
5. Conclusion
A new Schiff base framework is synthesized starting from naphthalene based azo ligand. The
designed structure acts as an efficient receptor for the hydrogen carbonate and acetate ions
with high selectivity over other test anions. The sensor system shows a drastic color change
upon treatment withanions mentioned above, paving the way for visual recognition ofions.
Under conditions of UV-Vis spectral displacement, the excellent binding affinity of receptor
towards anions was observed. The synthesized ligand exhibited good potential as
antibacterial and antifungal property in vitro against Gram-positive bacteria
(staphylococcusepidermidies) and fungal (Aspergillusniger and Aspergillusbrasiliensis)
strains.
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6. Acknowledgment
The authors would especially appreciate the Arak University for providing financial support
of this research.
7. Conflict of interest
The authors declare no conflict of interest.
8. Appendix
Supplementary data to this article can be found online at
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[3] O. Arslan, B. Aydıner, E. Yalcin, B. Babür, N. Seferoglu, Z. Seferoglu, "8-
Hydroxyquinoline based push-pull azo dye: Novel colorimetricchemosensor for anion
detection",J. Mol. Struct. 1149 (2017) 499-509.
[4] Q. e, . I. Vargas- iga, S. H. Kim, S K. Kim, J. Kim, '' Macrocycles as Ion Pair
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Author Contributions Section
Dear Editor of Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
The manuscript entitled “Simultaneous measurement of hydrogen carbonate and acetate anions
using biologically active receptor based on azo derivatives of naphthalene” by Fatemeh Naderi,
Masoumeh Orojloo, Mojgan Zendehdel, and Saeid Amani for publication in the Spectrochimica Acta
Part A: Molecular and Biomolecular Spectroscopy as a research article. This submission is approved
by all authors for publication in this Journal. I confirm that this manuscript is not under consideration
for publication in any other Journal and if accepted, it will not be published elsewhere in the same
form in English or in any other language.
Best Wishes and Kindest Regards
Saeid Amani, Ph.D.
Professor of Inorganic Chemistry, Chemistry Department, Arak University, Dr. Beheshti Ave. Arak
38156-88349, Iran
E-mail: s-amani@araku.ac.ir and alternative E-mail: amani1331@yahoo.com
Phone office: +98 86 34173415; Fax office: +98 86 34173406
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Declaration of Interest Statement
The authors declare no conflict of interest.
Professor Saeid Amani
Chemistry Department, Arak University, Dr. Beheshti Ave.
Arak 381568849, Iran
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Graphical Abstract:
A novel Schiff base receptor based on azo-derivatives of 1-naphthylamine (2-((E)-((4-chloro-
3-(trifluoromethyl)phenyl)imino)methyl)-4-((E)-naphthalene-1-yldiazenyl)phenol(2)
−
abbreviated CTNP was synthesized. Systematic studies of CTNP with HCO3 and AcO−
anions in DMSO disclosed that there is hydrogen-bonding between CTNP and incoming
anions. The antifungal activity of the receptor was tested against Aspergillusbrasiliensis and
Aspergillusniger. CTNP exhibited excellent antifungal activity against both strains. CTNP
also represented antibacterial activity against Gram-positive bacteria: staphylococcus
epidermidies.
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Highlights:
1. A new molecular receptor (CTNP), based on azo-derivatives of 1-naphthylamine
synthesized.
2. CTNP exhibited a colorimetric and optical dual-mode response.
−
3. Excellent detection of HCO3 and ACO − with low detection limit could be obtained
with CTNP receptor.
4. The designed receptor also represented antimicrobial activity in vitro against both
fungal and bacterial strains.
27