A new acylhydrazine N'-(1,3 dimethylbutylene)-3-hydroxy-naphthohydrazide based fluorescent sensor for the detection of Ni2+

Article abstract of DOI:10.1016/j.dyepig.2020.108582

In this paper, a novel hydrazide compound (N'-(1,3 dimethylbutylene)-3-hydroxy-naphthohydrazide) (BMH) was synthesized by a simple three-stage reaction and its chemical structure was confirmed by ¹H NMR, ¹³C NMR and FTIR characterization. This compound was used as fluorescent sensor for the detection of Ni²⁺ based on photoluminescence quenching. The fluorescence quenching of BMH upon the addition of Ni²⁺ is due to the formation of coordination complex which was verified by bind model and density functional theory studies. The Ni²⁺ concentration dependent fluorescence quenching efficiency of BMH was examined and the detection conditions were optimized. There is a good linear relationship between the emission intensity quenching (ΔF = F₀–F) and the Ni²⁺ concentration (c) between 80 nM and 2 μM and the detection limit is 60 nM. The simple preparation of the compound BMH and the high sensitivity of the fluorescent sensor hold great promise for the determination of Ni²⁺ in environment.

Full text of DOI:10.1016/j.dyepig.2020.108582

Journal Pre-proof
A new acylhydrazine N'-(1,3 dimethylbutylene)-3-hydroxy-naphthohydrazide based
2+
fluorescent sensor for the detection of Ni
Mengqin Liu, Zipeng Yin, Yuxing Tan, Junhua Li, Hui Peng, Abing Duan, Chunhua
Luo
PII:
S0143-7208(20)30846-9
DOI:
https://doi.org/10.1016/j.dyepig.2020.108582
DYPI 108582
Reference:
To appear in: Dyes and Pigments
Received Date: 4 April 2020
Revised Date: 22 May 2020
Accepted Date: 25 May 2020
Please cite this article as: Liu M, Yin Z, Tan Y, Li J, Peng H, Duan A, Luo C, A new acylhydrazine N'-(1,3
2+
dimethylbutylene)-3-hydroxy-naphthohydrazide based fluorescent sensor for the detection of Ni , Dyes
and Pigments (2020), doi: https://doi.org/10.1016/j.dyepig.2020.108582.
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© 2020 Published by Elsevier Ltd.

CRediT author statement
Mengqin Liu: Conceptualization, Methodology, Supervision, Funding acquisition,
Zipeng Yin: Investigation, Data curation, Writing- Original draft preparation, Yuxing
Tan: Investigation, Junhua Li: Validation, Hui Peng: Writing - Review & Editing,
Abing Duan: Software, Formal analysis, Chunhua Luo: Writing - Review & Editing

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ARTICLE
A new acylhydrazine N'-(1,3 dimethylbutylene)-3-hydroxy-
naphthohydrazide based fluorescent sensor for the detection of
Ni2+
Mengqin Liua,* , Zipeng Yina, Yuxing Tana, Junhua Lia, Hui Peng b, c , Abing Duan d,*, and
Chunhua Luo c,*
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
In this paper, a novel hydrazide compound (N'-(1,3 dimethylbutylene)-3-hydroxy-naphthohydrazide) (BMH) was
1
synthesized by a simple three-stage reaction and its chemical structure was confirmed by H NMR, 13C NMR and FTIR
characterization. This compound was used as fluorescent sensor for the detection of Ni2+ based on photoluminescence
quenching. The fluorescence quenching of BMH upon the addition of Ni2+ is due to the formation of coordination complex
which was verified by bind model and density functional theory studies. The Ni2+ concentration dependent fluorescence
quenching efficiency of BMH was examined and the detection conditions were optimized. There is a good linear
relationship between the emission intensity quenching (ΔF=F0-F) and the Ni2+ concentration (c) between 80 nM and 2 uM
and the detection limit is 60 nM. The simple preparation of the compound BMH and the high sensitivity of the fluorescent
sensor hold great promise for the determination of Ni2+ in environment.
[6, 7], X-ray fluorescence spectrometry [8, 9], anodic stripping
voltammetry [10] and fluorescent spectrometry [11-15] etc.
Among these approaches, fluorescent chemosensor provides
the advantages of easy processability, in situ analysis, high
1. Introduction
Transition metals play a crucial role in both environmental and
biological fields [1, 2]. Among different transition metals, Ni is
an important element in modern manufacture industries [3].
Ni based compounds are widely used in the production of
batteries, stainless steels and advanced electronic materials. Ni
is also an essential element involving in biological activities
such as respiration, metabolism and biosynthesis. To keep the
Ni balance is very crucial because the presence of excess Ni
can cause serious health problem such as pneumonitis, asthma
and central nerves system disorder, whereas lack of Ni can be
harmful to eukaryotic and prokaryotic organisms [4].
Consequently, to qualitative and quantitative determination of
Ni is important for both healthy and environmental issues.
There have been various methods for the detection of Ni,
including EDTA titration [5], atomic absorption spectrometry
sensitivity and selectivity.
Recently, various fluorescent chemosensors based on
napthalimides, rhodamine, coumarin and anthroquinone have
been developed and used for the detection of metal ions [3,
16, 17]. As a reporter, the chemosensor should have strong
affinity and good binding selectivity towards the target to
avoid environmental interference. Acylhydrazone is a special
Schiff base that has been used to design fluorescent sensor, in
which the acylhydrazone acts as recognition group.
Acylhydrazone is usually prepared by the reaction of
acylhydrazine with ketones or aldehydes. Due to the presence
of carbonyl group which contains hard basic coordination
atom
O and imine group which contains soft basic
coordination atom N in the molecular structure of these
substances, they can coordinate with many metal ions to form
coordination complexes. In addition, there exist two kinds of
tautomers of acylhydrazine, namely enol and ketone. On one
hand, the deprotonated enol can form covalent bond with
transition metal ion and, on the other hand, the ketone can
coordinate with transition metal ion through the lone pair
electrons and the empty d orbitals of the metal ion. Therefore,
acylhydrazone based compounds provide various coordination
models with transition metal ions and are very promising for
preparing chemosensor for detecting transition metals. Tang
et al. developed a acylhydrazone based fluorescent sensor QP
for the detection of Al3+ and the detection limit is 4.79 ×10-8 M
a.Key Laboratory of Functional Metal-Organic Compounds of Hunan Province,
Hengyang Normal University, Hengyang 421008, PR China. E-mail:
liumengqin2013@163.com
b.Collaborative Innovation Centre of Extreme Optics, Shanxi University, Taiyuan,
Shanxi, 030006, China.
c. Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics,
East China Normal University, Shanghai, 200241, China. E-mail:
chluo@ee.ecnu.edu.cn
d.College of Environmental Science &Technology, Hunan University, Changsha,
410082, China. E-mail: duanabing@hnu.edu.cn
† Footnotes relaꢀng to the ꢀtle and/or authors should appear here.
Electronic Supplementary Information (ESI) available: [details of any
supplementary information available should be included here]. See
DOI: 10.1039/x0xx00000x
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[18]. Yang synthesized a series of novel acylhydrazone Schiff NMR (500 MHz, DMSO, δ): 11.89 (s, 1H), 10.21 (s, 1H), 8.47 (s,
base functional fluorescent probes and used these probes to 1H), 7.83 (d, J = 8.1 Hz, 1H), 7.73 (d, J = 8.2 Hz, 1H), 7.49 (t, J =
analyze HClO in water samples and living cells [19].
7.4 Hz, 1H), 7.33 (t, J = 7.4 Hz, 1H), 7.28 (s, 1H), 4.80 (s, 2H). 13
C
In this work, an acylhydrazone based molecule N '- (1, 3 NMR (126 MHz, DMSO, δ): 167.48, 155.51, 136.29, 129.46,
dimethyl phosphite butyl) - 3 - hydroxy - naphthalene acyl 129.13, 128.55, 127.10, 126.25, 124.08, 118.54, 111.06. HRMS
+
hydrazine (BMH) was synthesized and its structure was (ESI) m/z calculated for C11H11N2O2 (MH)+ 203.08150, found
1
characterized by H NMR, 13C NMR and FTIR. The fluorescence 203.08134
decrease in response to the addition of different transition
2.4. Synthesis of N'-(1,3 dimethylbutylene)-3-hydroxy-
meatal ions was examined. It was observed that BMH showed
naphthohydrazide
highly selective fluorescence quenching with the present of
Ni2+ over other competing metal ions and can be used as
20 ml 4-methyl-2-pentanone and 2.022 g (10 mmol) 3-
hydroxy-2-naphthohydrazide were added to the round bottom
flask, then heated and refluxed for 5 hours. The reaction
fluorescent sensor for determination of Ni element. To the
best of our knowledge, BMH is the first reported
acylhydrazone based fluorescent sensor used for the analysis
of Ni2+.
solution was cooled to 20
℃ and filtered. The solid was
washed with methanol and vacuum dried to give the light
yellow crystal (27.034 g, yield = 79.22%). Melting point: 146–
℃
. 1H NMR (500 MHz, MeOD, δ): 8.67 (d, J = 15.9 Hz, 1H),
2. Experimental
147
7.87 (d, J = 8.2 Hz, 1H), 7.67 (d, J = 8.3 Hz, 1H), 7.48 (t, J = 7.3
Hz, 1H), 7.34 (t, J = 7.5 Hz, 1H), 7.27 (d, J = 5.5 Hz, 1H), 4.96 (s,
2H), 3.31 (d, 2H), 2.29 (s, J = 7.5 Hz, 1H), 2.10 (s, 1H), 2.00 (s,
1H), 1.04-0.95 (m, 6H).13C NMR (125 MHz, DMSO, δ): 163.09,
160.17, 152.53, 136.49, 132.61, 128.70, 128.20, 127.82,
125.46, 123.84, 119.25, 110.47, 47.55, 25.97, 21.64, 14.91. IR
2.1. Materials and instruments
Cadmium sulfate (AR), Bismuth nitrate (AR), Magnesium
nitrate (AR), Lead nitrate (AR), Zinc sulfate (AR), Nickel nitrate
(AR), Cobalt nitrate (AR), Copper sulfate (AR), Sodium
hydroxide (AR), Nitric acid (68% by weight, aqueous solution),
ethanol (95%), DMF (AR) and DMSO (AR) are purchased from
(KBr): 3400
～2400, 1650, 1550, 1510, 1470, 1360, 1230, 1170,
1
commercially available resources and used as received. H
1140, 1120, 1050, 950, 900, 880, 770, 740, 670, 600, 550, 480
+
NMR and 13C NMR characterization were performed on a
Bruker advance 300 MHz spectrometer. UV-vis and
fluorescence spectra were recorded on UV-2501pc
spectrophotometer and Rf-5301pc fluorescence spectrometer
(Shimazu) respectively.
cm-1. HRMS (ESI) m/z calculated for C17H21N2O2 (MH)+
285.15975, found 285.15915.
2.5. Preparation of stock solution of BMH
The stock solution of BMH was prepared by dissolving 0.0284 g
BMH in DMF and the result solution was transferred to a 50
mL volumetric flask. The volume of the solution was settled to
50 mL and the obtained solution was transferred to a reagent
bottle and kept in refrigerator for further use.
2.2. Synthesis of ethyl 3-hydroxy-2-naphthoate
To a round bottom flask were added 5 g 3-hydroxy-2-
naphthalic acid and 16 mL ethanol. The reaction mixture was
refluxed for 6 h. After the completion of the reaction, the
reaction mixture was cooled down to room temperature and
washed with distilled water. The organic layer was recovered
and washed with saturated sodium bicarbonate followed by
drying with anhydrous MgSO4. The MgSO4 was removed by
filtration and the filtrate was dried under reduced pressure.
The resulted solid was purified by silica chromatography with
petroleum ether and ethyl acetate (10:1, v/v) as eluent to give
2.6. Preparation of stock solutions of transition metal ions
0.1454 g Ni(NO3)2 was added into ultra-pure water and the
obtained solution was transferred into 250 mL volumetric
flask. The volume was settled to 250 mL and kept in
refrigerator for later use. Stock solutions of other metal ions
(Cu2+
、 、 、 、 、
Pb2+ Co2+ Zn2+ Cd2+ Bi3+) were prepared with the
same method as nickel nitrate. The metal nitrate or sulfate
salts were used as the metal ions resource and ultra-pure
water with electrical conductivity of 18.25 MΩ·cm-1 was used
as solvent.
the compound ethyl 3-hydroxy-2-naphthoate (4.1229 g, yield =
1
. H NMR (500 MHz, CDCl3,
70.60%). Melting point: 83–84
℃
δ): 10.58 (s, 1H), 8.49 (s, 1H), 7.81 (d, J = 8.3 Hz, 1H), 7.69 (d, J
= 8.4 Hz, 1H), 7.51 (t, J = 7.6 Hz, 1H), 7.36 – 7.30 (m, 2H), 4.49
(q, J = 7.1 Hz, 2H), 1.50 (t, J = 7.1 Hz, 3H).13C NMR (126 MHz,
CDCl3, δ): 169.91, 156.44, 137.87, 132.32, 129.20, 129.06,
127.02, 126.28, 123.86, 114.43, 111.62, 61.80, 14.25. HRMS
(ESI) m/z calculated for C13H12O3Na+(MNa)+ 239.06787, found
239.06760.
2.7. Fluorescence and UV-vis absorption analysis
For fluorescence selectivity study, 50
solution and 100
L 0.1×10-3 M metal ion (Cu2+
Zn2+ Cd2+ Bi3+) were added into 9.85 mL DMF and the
µ
L 0.2×10-3 M BMH
Pb2+ Co2+
、
µ
、
、
、
、
fluorescence spectrum of each sample was measure using a
excitation wavelength of 300 nm. For UV-vis absorption
measurement, 300 µL NaOH solution (pH = 10.5), 50 µ
L 2×10-3
2.3. Synthesis of 3-hydroxy-2-naphthohydrazide
1 g ethyl 3-hydroxy-2-naphthoate, 0.224 ml hydrazine hydrate
and 6 ml ethanol were added into a 50 ml round bottom flask
and the mixture was refluxed for 4 h. After cooling, the
product was filtered and washed with ethanol to give the final
product (0.8g, yield = 84.8%). Melting point: 209-211 ℃. 1H
M BMH solution were added into 9.6 mL DMF. Then 50 µL
1×10-3 M metal ion solution was added into the above solution
and used for UV-vis measurement. A reference solution was
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prepared by mixing 300
µ
L NaOH solution (pH = 10.5), 50
µ
L
3.2. Optical properties of BMH towards metal ions
ultra-pure water and 9.65 mL DMF.
The UV-vis absorption of BMH and BMH with the presence of
different transition metal ions were recorded and shown in
Fig. 1a. The BMH spectrum shows a strong absorption peak at
266 nm and another broad absorption with the peak position
located at 413 nm. The absorption spectrum of BMH changes
with the addition of different metal ions. It can be seen that
Pb2+ and Bi3+ do not clearly affect the absorption profile of
BMH. However, other metal ions such as Ni2+, Cu2+, Co2+, Zn2+
and Cd2+ cause the decrease of the absorption intensities at
266 and 413 nm and the appearance of new absorption peak
at around 307 nm. It should be pointed out that the addition
of Ni2+ leads to the most significant change of the absorption
spectrum and completely disappearance of the absorption
peak at 413 nm. The variation of the absorption feature should
be due to the coordination interaction between the BMH
molecule and the metal ion.
2.8. Determination of Ni2+ by BMH fluorescence probe
To a 10 mL cuvette were added successively with 9.6 mL DMF,
300 L NaOH solution (pH = 10.5), 50
L 0.2×10-3 M BMH
solution and 50
L 0.1×10-3 M Ni(NO3)2. Another solution with
µ
µ
µ
the addition of ultra-pure water instead of the Ni(NO3)2
solution was used as reference sample. The PL spectra was
measured immediately after the sample preparation at room
temperature with an excitation wavelength of 300 nm. The PL
intensity without and with the addition of the Ni2+ were
recorded as F0 and F respectively.
2.9. Computational details
The density functional theory (DFT) calculations were
performed using Gaussian 16, Revision B.01 [20].The geometry
optimizations were conducted using the M06-2X functional
[21, 22], 6-311G(d,p) basis set. Energies reported are free
energies in eV.
0.5
0.4
0.3
0.2
0.1
0.0
600
450
300
150
0
BMH
BMH
(a)
(b)
3+
3+
Bi
Bi
2+
Cd
2+
Cd
2+
Co
2+
2+
Co
2+
Cu
Cu
2+
3. Results and discussion
Ni
2+
Ni
Zn
Pb
2+
Zn
2+
2+
2+
Pb
3.1. Synthesis and characterization of N'-(1,3 dimethylbutylene)-3-
hydroxy-naphthohydrazide (BMH)
300 350 400 450 500
Wavelength (nm)
450
500
550
600
650
Wavelength(nm)
The BMH was synthesized in a three-step procedure as shown
in Scheme 1. In brief, 3-Hydroxy-2-naphthalic acid was
esterification with ethanol and the resulted product was
reacted with hydrazine hydrate to give the 3-hydroxy-2-
Fig. 1. UV-vis absorption with the inserted UV-vis absorption between
375 475 nm (a) and photoluminescence spectra (b) of pure BMH in
DMF and BMH with the addition of different metal ions.
～
naphthohydrazide, which was condensation with 4-methyl-2- The PL spectra of BMH in DMF without and with the addition
pentanone to yield the final product N'-(1,3 of metal ions were investigated. Fig 1b shows that BMH
dimethylbutylene)-3-hydroxy-naphthohydrazide (BMH). The presents a strong emission peak at 503 nm under the
chemical structure of BMH was characterized by H NMR, 13C excitation of 300 nm UV light. With the addition of Bi3+, the
1
1
NMR, FTIR and mass spectroscopy. H NMR characterization emission peak shifts slightly to short wavelength, which is
indicates that the aromatic protons appear between 8.67
～
probably due to the changes of test environment such as
7.27 ppm whereas the signals observed between 4.96 0.95 instrumentation and test conditions . On the contrary, the
～
ppm are assigned to the aliphatic protons (Fig. S1). 13C NMR addition of Zn2+ and Cd2+ results in the significant red-shift of
spectrum shows that the peaks at 163.09 and 160.17 ppm can the emission peak to 554 and 544 nm, respectively,
be assigned to the C-N and C=N group, respectively (Fig. S2). accompanied by the decrease of the PL intensity. The red-
The FTIR spectrum (Fig. S3) exhibits a broad band between shifts of the PL peak with the addition of Zn2+ and Cd2+ could
3400
～2400 which can be ascribed to the stretching vibrations be explained by the energy transfer from the BMH molecule to
of O-H and N-H and the characteristic FTIR absorption bands the metal ion after the formation of coordination complex,
can be assigned as follow: 1650 cm-1 (C=O), 1510 cm-1 (C=N), leading to decreased energy of the exciton. The presence of
1550 cm-1 and 1230 cm-1 (N-H). The high resolution mass other metal ions such as Pb2+, Cu2+ and Co2+ causes the sharp
(HRMS) data is consistent with the expected molecular weight decrease of the PL intensity of the BMH. As can be seen, the
for BMH (MH+: 285.15915).
introduction of Ni2+ leads to the completely quenching of the
PL intensity. Therefore, fluorescence determination of Ni2+ by
BMH sensor was established based on the PL quenching of
BMH in response to the Ni2+ addition.
3.3.Optimization of determination conditions
3.3.1. Solvent selection
The effect of different solvent on the detection of Ni2+ was
examined and four solvents were chosen. The emission
spectra of BMH in DMF, DMSO, ethanol (95%) and water show
that the PL intensity (F0) is smaller in ethanol and water than
in DMF and DMSO. This may be due to the less deprotonation
Scheme 1. The synthetic route for the product N'-(1,3
dimethylbutylene)-3-hydroxy-naphthohydrazide
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of BMH in proton solvents. Upon the addition of Ni2+, the PL Fig. 3. The pH value dependent PL intensity of BMH and BMH with the
intensity (F) of BMH decrease in these solvents. In comparison, presence of 1 equiv. of Ni2+ in DMF-H2O solution.
the decrease of PL intensity of BMH in DMF solution is the
most significant and nearly totally quenching of the emission 3.4. Binding mode study
was observed. This indicates that DMF benefits the The binding model between BMH and Ni2+ was studied by
coordination of BMH with Ni2+. Consequently, DMF was fluorescence titration. Fluorescence titration of the Ni2+ (5
µM
chosen as solvent for the analysis of Ni2+. The PL data obtained in DMF) by different amounts of BMH shows that the PL
from Fig. 2 were listed in Table S1.
intensity keep almost constant when the molar ratio of BMH
to Ni2+ is below 2. This can be explained by the completely
consumption of the ligand BMH due to the formation of
coordination complex. Further enhancement of the BMH
amount results in the linear increase of the PL intensity as
shown in the inset of Fig. 4a and this fluorescence
enhancement is due to the presence of uncoordinated BMH.
These results suggest that the sensing behavior of BMH toward
Ni2+ is based on an approximately 2:1 binding mode between
BMH and Ni2+. The chemical structure of the coordination
complex BMH-Ni2+ can be described in Fig. 4b.
500
500
400
300
200
100
0
(b)
(a)
400
300
200
100
0
BMH
BMH
BMH+Ni2+
BMH+Ni2+
450
(c)
500
550
600
450
(d)
500
550
600
Wavelength (nm)
Wavelength (nm)
500
400
300
200
100
0
500
400
300
200
100
0
BMH
500
400
(a)
300
BMH+Ni2+
400 17.5 uM
200
BMH
100
0
300
BMH+Ni2+
0.5 1.0 1.5 2.0 2.5 3.0 3.5
C
:C 2+
BMH Ni
200
100
0
0.6 uM
450
500
550
600
450
500
550
600
Wavelength (nm)
Wavelength (nm)
Fig. 2. PL spectra of BMH without and with the addition of Ni2+ in (a)
DMF, (b) DMSO, (c) ethanol and (d) water
450
500
550
600
650
Wavelength (nm)
3.3.2. pH selection
Fig. 4. The relationship between the PL intensity and the BMH
concentration, inset: the CBMH/CNi2+ dependent fluorescence
intensity (a) and (b) the chemical structure of the coordination
complex BMH-Ni2+.
pH plays an important role in the determination of
environmental heavy metals and can affect the host-guest
binding capability due to the pH sensitive characteristic of
some coordination group such as C=O, C=N and -NH. The effect
of solution pH value in the detection of Ni2+ was investigated in
DMF-H2O mixed solvent system with the addition of HNO3 or
NaOH to adjust the pH value between 3.5 and 9.5. As shown in
Fig. 3, The PL intensity of BMH increases with increasing pH
value. However, the PL intensity of BMH-Ni2+ first declines with
3.5. DFT study
To further clarify the binding property between BMH and Ni2+,
density functional theory (DFT) calculations were performed
using the B3LYP/6-311G level(Gaussian 16). The structure of
the BMH-Ni2+ complex was optimized and the N-Ni bond
the increase of pH value between pH 3.5
～8.5 then increase
length is 1.95
Å, the O-Ni bond length is 2.76 Å and the
with the increasing pH value above pH 8.5. The decrease of the
PL intensity for the complex under neutral and mild basic
conditions is probably due to the efficient electrostatic
interaction between the deprotonated BMH and the Ni2+. The
largest difference of the emission intensity is obtained around
pH 8.5. Therefore, pH 8.5 is chosen for the analysis of Ni2+.The
pH relative F0, F and ΔF values are listed in Table S2.
dihedral angel of C-O-Ni- N is 26.8 degree as shown in Figure
5a. The energy gap between the HOMO (-7.23 eV) and LUMO
(-0.61 eV) of BMH was calculated to be 6.62 eV whereas the
energy gap between the HOMO (-3.84 eV) and LUMO (-0.77
eV) for the complex BMH-Ni2+ was 3.07 eV (Fig 5b). It is clear
that after nickel cation complexation, the energy gap of BMH-
Ni2+ is significantly lower than BMH by 3.55 eV. The decrease
energy gap of BMH-Ni2+ facilitates the electronic transition.
These results indicate that the coordination of BMH with Ni2+
has a very strong influence on the orbital energies and
contributes to the fluorescence quenching effect.
1000
BMH
(a)
2+
800
BMH+ 0.5 equiv. of Ni
600
400
200
0
3
4
5
6
7
8
9
10
pH
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to 2 µM, the fluorescence decreased to 46% of its initial value.
In addition, the fluorescence intensity quenching (Δ F = F0 - F)
of BMH was linearly related to the Ni2+ concentration between
0.08
192.6756 c (
coefficient R is 0.9985. The detection limit is 0.06
～
2
µ
M (Fig. 6b). The linear regression equation is:
M) + 0.49255 and the corresponding correlation
M,
ΔF =
µ
µ
calculated in accordance to the equation D = 3σ/K, where σ is
the standard deviation of the blank solution and K is the slope
of the calibration curve. It is much lower than the limit of Ni2+
in drinking water provided by the WHO and other reported
Ni2+ sensors [23-25]. The results obtained in this work were
compared with literature reported sensors for the detection of
Ni2+ as summarized in Table 1, which demonstrates that the
BMH based fluorescent sensor is an appropriate platform for
the detection of Ni2+.
800
(b)
(a)
375
300
225
150
75
Fig. 5. (a) Geometric structure of BMH-Ni2+ and (b) Frontier molecular
△
0
F = 192.6756 C + 0.49255
600
400
200
0
r= 0.99854
orbital diagrams of BMH (left) and BMH-Ni2+ (right)
2 uM
3.6. Linear relationship and detection limit
0
0.0 0.4 0.8 1.2 1.6 2.0
Under the optimum experimental conditions, the linear
relationship was investigated. The experiment was carried out
450
500
550
600
2+
CNi /CBMH
Wavelength(nm)
by adding Ni2+ solution with various concentrations (0.08
～2
Fig. 6. (a) Fluorescence spectra changes of BMH in DMF (1
µM, pH =
µ
M) to the solution of BMH (1 µM) in DMF-H2O (pH= 8.5) and
the variation of fluorescence intensity related to the Ni2+
concentration is shown in Fig. 6a. With the increase of Ni2+
concentration, the fluorescence intensity of BMH at 503 nm
gradually declined. When the concentration of Ni2+ increased
8.5) after addition of 0
～2 µ
M Ni2+ and (b) The calibration curve
between the fluorescence quenching (
Ni2+/BMH.
ΔF) and the molar ratio of
Table 1. Comparison of analytical performance of different techniques for the determination of Ni2+
Linear
range (µM) limit (nM) coefficient
Detection
Correlation
Method
Sensor
References
0–50
0–80
7.5
0.9608
0.9758
0.99
[26]
[27]
[28]
[29]
[30]
[31]
Interferometric sensor
Fluorescence analysis
Fluorescence analysis
Fluorescence analysis
ECH-CS
NiP
21.6
6000–
0.93×106
CD-imidazole
quantum dots
100000
0.1–50
30
20.4
5
0.9953
0.995
0.992
E-GQDs
Flame
atomic
absorption [TBP] [PO4] IL-based
dispersive liquid
0.02–3.4
0.005–0.3
spectrophotometry
GSH-AgNPR
Colorimetric method
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0.85-10.22 340.8
1.36 – 54.5 392
[32]
[33]
[34]
[35]
Spectrophotometry
dimethylglyoxime
Hydroxynaphthol
Blue
0.74
Spectrophotometry
0.1-100
0.52–5.24
0.08–2
100
325
60
0.987
Fluorescence analysis
BNQDs
0.99794
0.9985
Fluorescence analysis
Fluorescence analysis
BPP
BMH
This work
3.7. Selectivity of BMH towards Ni2+
Pb2+
2
550.5
Co2+
1
552.6
Under the optimum experimental conditions, the selective
response of BMH towards Ni2+ was studied by competitive
experiment. The experiment was carried out by mixing the
aqueous solution of Ni2+ and the BMH solution in DMF. The
3.8. Stability of BMH-Ni2+ sensor
concentration of Ni2+ and BMH were 0.87
µM and 10 µM
The stability of constructed sensor is very important for practical
applications. We measure the BMH sensor stabilities relative to
time and temperature and the corresponding results are shown in
Fig. 7. It is clear that the fluorescence intensity displays no obvious
change within 100 h after the preparation of the sensor (Fig. 7a).
When the temperature increases from 20 to 40 ℃, the fluorescence
intensity decreases from 732 to 700. The variation of fluorescence
intensity in response to temperature is below 5% between 20～40
℃. These results demonstrate the good stability of the BMH sensor
towards Ni2+ detection.
respectively and the fluorescence intensity measured was
577.3. As shown in Table 2, it was found that after the addition
of a number of monovalent or divalent anions or metal ions,
the PL intensity do not change significantly (< 5%). These
results demonstrate that the recognition of Ni2+ by BMH does
not interfere by the competitive ions tested.
Table 2. The fluorescence changes of BMH-Ni2+ upon addition
of the competitive ions
Fig. 7. (a) The change of fluorescence intensity of BMH-Ni2+ with time,
F0 : the initial fluorescent intensity of BMH-Ni2+, F: the fluorescent
Molar
ratio
Molar
ratio
PL
PL
intensity
Ions
Ions
intens
ity
relative
to Ni2+
relative to
Ni2+
K+
7100
7900
564.8
567.6
564.8
567.6
570.4
560
Mg2+
Ca2+
Bi3+
2
575
Na+
31.5
3
571.8
551
intensity of BMH-Ni2+ at different time; (b) The temperature
dependent fluorescence intensity of BMH-Ni2+
-
NO3 7100
3.9. Ni2+ determination by recovery experiment
Cl-
7900
5000
Fe3+
Cr3+
Sr2+
4
566.2
553.5
560
To verify the reliability of this method, recovery experiment
was performed by adding a certain amount of standard Ni2+
solution to the river water collected from Xiangjiang River and
the data obtained are shown in Table 3. It is clearly seen that
the concentrations of Ni2+ measured by the BMH fluorescent
probe are very close to the actual values added into the
samples. This result shows that the BMH fluorescent sensor
can be used for the detection of Ni2+ in real samples.
Br-
2
Al3+ 7.5
Cu2+ 1.5
80
2
553.1
Cd2+
549.6
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ARTICLE
Table 3. Determination of Ni2+ concentration in river water by
[3] Patil A, Salunke-Gawali S. Overview of the chemosensor ligands
used for selective detection of anions and metal ions (Zn2+, Cu2+,
Ni2+, Co2+, Fe2+, Hg2+). Inorg Chim Acta. 2018;482:99-112.
[4] A. Sigel HS, R.K.O Sigel. Nickel and its surprising impact in nature.
John Wiley & Sons Ltd, UK. 2007.
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(mercaptoacetamido)benzenesulfonate as a metal indicator for
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assisted liquid liquid microextraction combined with graphite
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[7] Thubkhun N, Tangtreamjitmun N. Determination of nickel by
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[8] de Almeida ON, Luzardo FHM, Amorim FAC, Velasco FG,
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8.
recovery experiment.
Ni2+ (µM)
Blank
725
Water
0.4
0.6
0.8
PL
intensity
725
0
646.3
610.6
568.8
ΔF
78.7
0.406
114.4
0.594
98.5%
156.2
0.808
101%
CNi2+ (μM)
0
Recovery
ratio
101.5%
Conclusions
In
conclusion,
a
hydrazide
compound
(N'-(1,3
dimethylbutylene)-3-hydroxy-naphthohydrazide) (BMH) has
been successfully synthesized and used as fluorescent sensor
for the determination of Ni2+ based on fluorescence
quenching. Upon the addition of Ni2+, the PL intensity of BMH
was significantly reduced due to the formation of 1:2
coordination complex between Ni2+ and BMH, which was
confirmed by binding model and DFT studies. The limit of
detection is as low as 60 nM and there exist a linear
[9] Zheng H, Jia B, Zhu Z, Tang Z, Hu S. Determination of trace
amounts of Pb, Cd, Ni and Co by wavelength-dispersive X-ray
fluorescence spectrometry after preconcentration with dithizone
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[10] Khadro B, Sikora A, Loir AS, Errachid A, Garrelie F, Donnet C, et
al. Electrochemical performances of
B doped and undoped
diamond-like carbon (DLC) films deposited by femtosecond pulsed
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stripping voltammetric (SWASV) technique. Sens Actuators, B.
2011;155:120-5.
relationship between 0.08
～2µM. The easy preparation of
BMH and the high sensitivity make this fluorescent probe very
promising for determination of Ni2+ in real samples.
[11] Manna AK, Chowdhury S, Patra GK. A novel hydrazide-based
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Ni2+ ions: applications in live cell imaging, molecular logic gates and
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triazole functionalized Fe3O4 @SiO2 nanoparticles as fluorescent
sensors for heavy metal ions. Orient J Chem. 2019;35:1054-61.
[13] Vinoth Kumar GG, Kesavan MP, Sankarganesh M, Sakthipandi
K, Rajesh J, Sivaraman G. A Schiff base receptor as a fluorescence
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New J Chem. 2018;42:2865-73.
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selective detection of aniline and Fe3+ by lanthanide-based
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Conflicts of interest
There are no conflictsof interest to declare.
Acknowledgements
This work was financially supported by National Natural
Science Foundation of China (No. 21505035), Scientific
Research Projects of Education Department of Hunan
Province(No. 19K011, No. 18A336), Hunan Hengyang Science
and Technology Plan Preject (2019jhzx0741), Research Project
of Hengyang Normal University(No. 18XKQ01, GN19K04) and
Environmental Monitoring and Evaluation Center of Hengyang
Normal University (KYJG1803).
detection
2020;178:108347.
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of
tertiary
butylhydroquinone.
Dyes
Pigm.
Notes and references
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Highlights
A
novel
hydrazide
compound
(N'-(1,3
dimethylbutylene)-3-hydroxy-naphthohydrazide) (BMH) was synthesized by a simple
three-stage reaction.
BMH was used as fluorescent sensor for the detection of Ni2+ based on fluorescence
quenching.
The fluorescence quenching was due to the formation of BMH-Ni2+ coordination
complex.
The linear range was between 80 nM and 2 µM and the detection limit was 60 nM.

Declaration of interests
☐ The authors declare that they have no known competing financial interests or personal relationships
that could have appeared to influence the work reported in this paper.
☐The authors declare the following financial interests/personal relationships which may be considered
as potential competing interests:
The authors declare that they have no known competing financial interests or personal relationships that
could have appeared to influence the work reported in this paper.