A novel hydrazide-based selective and sensitive optical chemosensor for the detection of Ni2+ ions: Applications in live cell imaging, molecular logic gates and smart phone-based analysis

Article abstract of DOI:10.1039/c9dt02448d

A novel flexible "N", "O"-rich hydrazide-based Schiff base chemoreceptor, 2-(benzamido)-N′-((pyridin-2-yl)methylene)benzohydrazide (L), was designed, synthesised and characterised via¹H-NMR, IR spectroscopy, ESI-MS spectrometry and single-cryst

Full text of DOI:10.1039/c9dt02448d

View Article Online
View Journal
Dalton
Transactions
An international journal of inorganic chemistry
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: A. K. Manna, S.
Chowdhury and G. K. Patra, Dalton Trans., 2019, DOI: 10.1039/C9DT02448D.
Volume 46
Number 10
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
1
4
March 2017
Pages 3073-3412
Dalton
Transactions
An international journal of inorganic chemistry
rsc.li/dalton
Accepted Manuscripts are published online shortly after acceptance,
before technical editing, formatting and proof reading. Using this free
service, authors can make their results available to the community, in
citable form, before we publish the edited article. We will replace this
Accepted Manuscript with the edited and formatted Advance Article as
soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes to the
text and/or graphics, which may alter content. The journal’s standard
Terms & Conditions and the Ethical guidelines still apply. In no event
shall the Royal Society of Chemistry be held responsible for any errors
or omissions in this Accepted Manuscript or any consequences arising
from the use of any information it contains.
ISSN 0306-0012
COMMUNICATION
Douglas W. Stephen et al.
N-Heterocyclic carbene stabilized parent sulfenyl, selenenyl,
and tellurenyl cations (XH , X = S, Se, Te)
+
rsc.li/dalton

Page 1 of 24
Dalton Transactions
View Article Online
Hydrazide based novel selective and sensitive optical che
D
m
OI: 1
o
0.
s
10
e
39
n
/C
s
9
o
DT02448D
r
2
+
for the detection of Ni : Applications in living cell imaging,
molecular logic gate and smart phone
a
b
a
Amit Kumar Manna, ShubhamoyChowdhury and Goutam K. Patra *
aDepartment of Chemistry, Guru GhasidasVishwavidyalaya, Bilaspur (C.G),
India
bDepartment of Chemistry, Gour Banga University, Malda, West Bengal 732
1
03, India
Abstract
A novel flexible “N”, “O” rich hydrazide based Schiff base chemo-receptor 2-(benzamido)-N'-
((pyridin-2-yl)methylene)benzohydrazide (L) has been designed, synthesised and characterised
1
by H-NMR, IR spectroscopy, ESI-MS spectrometry and single crystal XRD analysis. The
2
+
receptor showed colorimetric and fluorometric “turn on” response in presence of only Ni ion
in methanol-tris-HCl buffer medium (10 mM, pH 7.2, 1:1 v/v). The jobs plot analysis revealed
that receptor forms 2:1 complex with Ni2+ ion, further confirmed by ESI-MS analysis. The
2
+
single crystal structure of L-Ni complex (2) has also been isolated. The detection limit was
calculated to 1.8 µM colorimetrically and 1.18 µM fluorometrically, which are far lower than
those recommended by WHO guidelines for drinking water. The experimental results have
further been supported by the DFT studies. The chemosensor L can be applied to the recovery
of contaminated water samples, building of molecular logic gate, smart phone and living cell
imaging.
2
+
Keywords: quinazolinone / Schiff base/ colorimetric sensor / fluorometric sensor / Ni sensor
cell imaging/ logic gate.
*Corresponding Author: Tel.: 91 7587312992,E-mail: patra29in@yahoo.co.in
/

Dalton Transactions
Page 2 of 24
View Article Online
Introduction
DOI: 10.1039/C9DT02448D
In supramolecular chemistry, the design and construction of efficient chemo-receptor which
can precisely detect and quantify heavy transition metal ions, are highly focused in current
research interest, as these ions have significant role in biological, environmental and industrial
processes.1-4 In earlier few years, several traditional analytical techniques like inductively
5
6
7
coupled plasma emission spectroscopy (ICP-ES) , chromatography, potentiometry, atomic
8
9
absorption spectroscopy (AAS) and flow injection amperometry; were mainly used for the
detection of heavy metal ions but most of these techniques involved major drawbacks in terms
of selectivity, sensitivity, time consuming, troublesome sample preparation, skilled personnel
1
0
and also use of expensive and sophisticated instruments. Among the alternative convenient
approaches, optical signalling based chemosensors have been used as promising tools in recent
times, because of their operational advantages, real and onsite analysis, high selectivity and
sensitivity.11-13
Generally, the optical chemosensors for metal ions can be designed by the combination
of binding sites and the signalling units through a covalent linker where the receptors are
selective for specific metal coordinations, which respond as optical signal through signalling
1
4
subunit. The specific ion selectivity depends on the relative stability of the host guest
interaction, hence can be influenced by the cavity size, flexibility of chelator and hardness of
the coordinating atoms; whereas the optical response is due to influence of guest on the
1
5
electronic environment of chromo-fluorophore. As the guest selective binding not always
produce proper signal, thus tailor made synthesis of chemoreceptor with desired functionalities
is necessary to achieve measurable signal through change in emission and/or absorption upon
coordination.
Due to proper geometrical and electronic arrangement, Schiff base (>C=N) organic
framework integrated with a chromophoric and/or fluorophoric unit is one of the most
promising tools for optical based metal ion sensing.16,17 The ligand metal charge transfer
(LMCT) along with intermolecular charge transfer (ICT) and chelation enhancement
fluorescence effect (CHEF) play vital roles in designing Schiff base sensor which can alter the
intensity and wavelength of absorption and emission bands. Moreover fluorescence turn on
process has great advantages in comparison to turn off sensor, as ease of low level
measurement from its dark background which reduce false pulsing and increasing sensitivity.18
Among the transition metal series, Ni2+ is an essential constituent of several metalo-
enzymes like hydrogenases, carbon monoxide dehydrogenases and acireductone dioxygenases

Page 3 of 24
Dalton Transactions
View Art1ic9l-e Online
and has crucial role in biological processes such as metabolism, respiration and biosynthesis.
DOI: 10.1039/C9DT02448D
2
1
It has huge application for production of useful electronics devices in chemical industry, like
Ni-Cd batteries, electroplating and electroforming.22-23 Stainless steel is one of the alloys of
nickel which is used in the production of tools, machinery and armaments.24 Excessive
2
+
accumulation of Ni than its required limits has negative impact of human physical health and
responsible for respiratory problem, lung cancer, pneumonitis, and allergy, central nervous
disorder.25,26 Thus the detection of Ni ion precisely in biological and environmental level is
one of the challenging tasks in current research interest.
2+
Motivated by the above facts and in continuation of our ongoing research work,27,28 we
have designed and synthesized a novel Schiff base chemosensor N'-(2-hydroxybenzylidene)-2-
(benzamido) benzohydrazide (L), by the coupling of synthesized amine, 3-amino-2-phenyl-
4
(3H)-quinazolinone (1) with 2-pyridene carboxaldehyde. The background strategy behind the
designing of chemoreceptor is mainly based on three ideas. At first, the flexibility of the
chemosensor would permit coordination of suitable metal cations. Secondly presence of
multiple chromophoric moiety >C=O and >C=N may produce proper visible signal. Finally,
multiple –CONH- moieties can increase water solubility of the proposed receptor (L). The
proposed chemosensor (L) can selectively detect Ni2+ ion both colorimetrically and
fluoremetrically in aqueous medium. The recognisation process was further confirmed by the
DFT studies and isolation of single crystal of the metal complex. Moreover the chemosensor
has successful application in real sample analysis, living cell imaging, smart phone base
analysis and in building of molecular logic gates.
Experimental
Materials and General information
All the required materials used for synthesis were obtained from Sigma-Aldrich and used as
received. The analytical grade solvents used for the overall experiments and freshly prepared
double deionized water was used for dilution purpose and preparing tris HCl buffer (10 µM,
pH=7.2) solution. The metal ion solutions were prepared from their nitrate salts except sulphate
salt of Mn2+ and Fe2+ and potassium tetrachloroplatinate(II) salt for Pt . H NMR and C
2+
1
13
NMR spectra were recorded on a Bruker DRX spectrometer operating at 400MHz in
CDCl solvent and chemical shift were recorded in ppm relative to TMS. Absorption spectra
3
were recorded on a Shimadzu UV 1800 spectrophotometer using 10 mm path length quartz
cuvettes with the wavelength in the range of 200-800 nm. High resolution mass (HRMs)
spectra were recorded on a Waters mass spectrometer using mixed solvent HPLC methanol and

Dalton Transactions
Page 4 of 24
View Article Online
triple distilled water. The pH measurements were done using a digital pH meter (Merck) by
DOI: 10.1039/C9DT02448D
adjusting dilute hydrochloric acid and sodium hydroxide in buffer solution. Solutions of the
−
5
−4
receptor L (1×10 M) and metal salts (1×10 M) were prepared in methanol-tris-HCl buffer
10 mM, pH 7.2) medium (1:1 v/v) and H O respectively.
(
2
X-ray data collection and structural determination
X-ray single crystal data were collected using MoKα (λ = 0.7107 Å) radiation on aBRUKER
APEX II diffractometer equipped with CCD area detector. Data collection, datareduction,
structure solution/refinement were carried out using the software package of SMART APEX.29
The structures were solved by direct methods (SHELXS-97) and standard Fourier techniques,
and refined on F2 using full matrix least squares procedures (SHELXL-97) using the SHELX-97
3
0
31
package incorporated in WinGX. In most of the cases, non-hydrogen atoms were treated
anisotropically. Hydrogen atoms were fixed geometrically at their calculated positions
following riding atom model. Structural information of L and 2 have been deposited at the
Cambridge Crystallographic Data Center (CCDC numbers 1917470 and 1917471 respectively).
Synthesis of N-(2-hydroxybenzylidene)-2-(benzamido)benzohydrazide (L)
The synthetic procedure and single crystal structure of the compound 1 (3-amino-2-phenyl-
4
(3H)-quinazolinone) has already been reported by us elsewhere.32 The Schiff base
chemoreceptor L was synthesized by preparing individual solution of 3-amino-2-phenyl-4(3H)-
quinazolinone (1, 1.185 gm., 5mmol) and 2 pyridine carboxaldehyde (0.535 gm, 5 mmol) in
dehydrated methanol followed by mixing of these two solution in presence of catalytic amount
of glacial acetic acid. The reaction mixture was refluxed for 2h maintaining dry condition. The
colourless clear solution was kept in air for 24h. Crystalline solid separated out was filtered,
0
washed with methanol and dried in air. Yield, 1.46 g, 85 %; m.p.>200 C. Single crystals
suitable for X-ray analysis were obtained from the slow evaporation of methanol solution of L.
Anal. Calc. for C H N O : C, 69.76; H, 4.68; N, 16.27. Found C, 69.68; H, 4.63; N, 16.21%.
2
0
16
4
2
+
-1
EI–MS: m/z 367.13 (M+Na , 100%) (Fig. S1). FTIR/cm (KBr): 3447 (wb), 3360 (w), 3215
(m, -NH), 3062 (m, aromatic CH- str), 1662 (vs, C=O), 1641 (vs, C=N), 1606 (m), 1529 (s),
1
1
253(s), 1024(s), 765 (s), 700 (s) (Fig. S2). H NMR (400 MHz, CDCl , TMS): δ 11.50 (s,
3
1
3
NH), 11.30 (s, 1H, NH), 8.60 (s, 1 H, azomethine), 8.5-6.9 (m, 12H, aromatic) (Fig. S3). C
NMR (CDCl , δ ppm, TMS): 165.68, 161.53, 154.57, 148.22, 147.03, 139.51, 134.45, 133.69,
3
1
31.89, 130.22, 129.23, 127.91, 127.59, 127.02, 126.59, 124.43, 122.83, 120.14 (Fig. S4).
Synthesis of nickel complex (NiL , 2)
2
A methanolic solution (10 mL) of Ni(NO ) ·3H O (0.120 g, 0.5 mmol) was added drop wise
3
2
2
with stirring to the saturated solution of L (0.195 g, 0.5 mmol) in methanol (20 mL). The

Page 5 of 24
Dalton Transactions
View Article Online
resulting mixture was continuously stirred for 1 hr. at room temperature and then filtered.
DOI: 10.1039/C9DT02448D
Yield, 68%. Anal. Calc. for C H N NiO : C, 64.45; H, 4.06; N, 15.03%. Found C, 64.36; H,
4
0
30
8
4
+
2+
-1
3
3
1
.99; N, 14.93%. EI–MS: m/z 744.21 (2L-2H +Ni ) (Fig. S5). FTIR/cm (KBr): 3542 (-NH)
431 (-NH), 2920 (w, aromatic CH- str), 1616(br.) (vs, C=O and C=N), 1421 (s), 1382 (s),
332 (s), 1045 (w), 676 (m), 511 (s) (Fig. S6). Slow evaporation of the methanol solution of 2
yielded dark red crystalline solid (suitable for X-ray analysis).
Preparation of Stock solution for photo physical measurement
-3
Receptor Lsolution was prepared initially at the concentration level of 1 × 10 M in 10 ml in
methanol-tris HCl buffer medium (10mM, pH 7.2) solution (1:1 v/v), then diluted to the
desired concentration. Also the stock solution of guest ions were prepared separately from their
2
+
2+
nitrate salts (except sulphate salt of Mn and Fe and potassium tetrachloroplatinate(II) salt
2
+
-3
for Pt ) at a concentration of 1 x 10 M in 10 mL double-deionised water and further diluted
to their desired concentration. After mixing L with each of the metal ions for a few seconds,
absorption and fluorescence spectra were obtained at room temperature.
Computational details
3
3
The program package GAUSSIAN-09 Revision C.01 was employed for all calculations. The
gas phase geometries of the compound was fully optimized symmetry restrictions in singlet
3
4
ground state with the gradient-corrected DFT level coupled with B3LYP. Basis set LanL2DZ
was used for the whole molecules L and NiL (2). The HOMOs and LUMOs of molecular ions
2
were calculated with the same basis set and functional.
Cell imaging study
Human cervical cancer cell, HeLa was selected throughout the study. It was cultured in DMEM
(Dulbecco’s modified eagles medium) and supplemented with 10% Fetal Bovine Serum (FBS),
and a 1% antibiotic mixture containing PSN (Gibco BRL) at 37°C in a humidified incubator
with 5% CO . For cell imaging study the cells were seeded in a 35 mm culture dish with a
2
5
seeding density of 3×10 cells per dish. Cells were grown to 80–90% confluence, harvested
with 0.025% trypsin (Gibco BRL) and 0.52 mM EDTA (Gibco BRL) in phosphate-buffered
saline (PBS) andallowed to re-equilibrate for 24h before any treatment. All experiments were
conducted in DMEM containing 10% FBS and 1% PSN antibiotic. Cells were washed with
PBS and then incubated with DMEM-containing 20 μM chemosensor L [20 μM in DMEM,
DMSO:water = 1: 9 (v/v), pH 7.2 in PBS buffer] for 1h at 37°C. It was left for another
incubation by adding 40 μM of nickel nitrate salt and then fluorescence images were taken by a
fluorescence microscope (Model: LEICA DMLS) with an objective lens of 20×magnification
with excitation of 350-360 nm and emission 470 nm.

Dalton Transactions
Page 6 of 24
View Article Online
Results and discussion
DOI: 10.1039/C9DT02448D
Synthesis and structure of L
2
+
In comparison to most of the N, O rich Schiff base receptor for Ni ion chemosensor L has
been prepared more easily and economically by coupling 3-amino-2-phenyl-4(3H)-
quinazolinone (1) with pyridine 2 carboxaldehyde with high yield (over 80%, Scheme 1) in a
single pot.
Scheme 1 Synthetic procedure of the probe L.
We expected that presence of the peptide bonds and pyridine moiety would increase
water solubility and coordination ability. The receptor L is highly soluble in 1:3 methanol-
water mixture, but all the sensing studies have been carried out in methanol-trisHCl buffer
medium (10 mM, pH 7.2) solution (1:1 v/v), as the solution is stable in this medium for more
than two weeks. The chemical structure of L was confirmed by some solution phase
1
measurements like H-NMR, ESI-mass spectra and also with solid state measurements like IR
spectroscopic studies, elemental analysis and single crystal XRD analysis.
Spectroscopic studies of L towards different metal ions
The metal selective response of chemosensor L was preliminary investigated by absorption
spectral measurement in methanol-tris-HCl buffer (1:1 v/v, 10 mM, pH 7.2) solution at room
temperature. As shown in Fig. 1a the free receptor L displays main absorption band at 310 nm
due to S -S transition. Upon monitoring of 2 equiv. of different metal ions (40 µM in each
0
1
3
+
2+
2+
2+
2+
2+
2+
2+
3+
+
3+
2+
case) like Fe , Cu , Co , Ni , Zn , Cd , Hg , Mn , Cr , Ag , Al and Fe to a fixed
amount of L (20 µM) solution, a red shifted absorption band appeared at 375 nm only in case
2
+
2+
of Ni ion. As a result, colour of the solution changes from colourless to yellow. Except Cu
ion, the other tested metal ions can cause negligible change on absorption spectra of L.
2
+
Although a pale yellow colorization is observed at that concentration level of Cu ion (40 µM)
but no sharp absorption spectra obtained suitable for colorimetric sensing study, even in
addition of excessive amount. Considering physiological application, the selective responses of
2
+
the receptor L towards Ni ion was also investigated by competitive experiments in the same

Page 7 of 24
Dalton Transactions
View Article Online
experimental condition. The co-existence of equivalent amount of common interfering cations
DOI: 10.1039/C9DT02448D
with Ni2+ ions (40 µM Ni with 40 µM other metal ions) individually, cannot disturb the
2+
2
+
2+
absorbance band around 375 nm. Although Pd and Pt ions belongs to the same group in the
periodic table, they do not influence the absorption and emission spectra of L as well as L-Ni2+
2
+
complex. The L-Ni peak remained almost constant even up to 5 fold higher concentration of
background cations (100 µM) with respect to receptor concentration, confirmed by neither
generation of extra peak nor vanishing the original peak (Fig. 1b). Thus the receptor L
2
+
exhibited specific selectivity towards Ni ion which might make it suitable for precise
detection in complex mixtures.
Fig. 1 (a) Absorption spectra of L (20 µM) changes in presence of 2 equiv. of different metal
2
+
ions(40 µM in each case). Inset: colour change of L(20 µM)on addition of 2 equiv. of Ni (40
2
+
µM) (b) Competitive experiment of L(20 µM) towards Ni (40 µM)in presence 2 equiv. other
metal ions (40 µM).
2
+
Next, to determine the sensitive response of L towards Ni ion, absorption titration
experiment was performed in methanol-tris-HCl buffer (1:1 v/v, 10 mM, pH 7.2) mixture. In
absence of guest, probe L showed two absorption bands at 286 nm and 310 nm corresponding
to π-π* transition of multiple aromatic ring and n-π* transition of >C=O and >C=N group
respectively. Upon gradual addition of Ni2+ ion to the solution of L (20 µM), a systematic
development of new absorption band appeared at 375 nm with a simultaneous decrease of the
absorption band at 310 nm. The appearance of well-defined isosbestic point at 353 nm due to
2
+
existence of dynamic equilibrium between L and L+Ni complex and 1.8 equiv. (36 µM) of
guest was enough to reach the plateau around 375 nm (Fig.2a).

Dalton Transactions
Page 8 of 24
View Article Online
DOI: 10.1039/C9DT02448D
2
+
Fig. 2(a) UV-vis titration of L (20 µM) with Ni (upto 40 µM) in CH OH-tris buffer. Inset:
3
Plot of intensity vs. analyte concentration. (b) Detection limits of L with Ni2+ by ratiometric
measurements.
The ratiometric calibration curve was plotted from the titration experiments, by varying
2
+
absorption intensity ratio (I /I ) with increasing amount of Ni ion. Here, a sigmoidal curve
3
75 310
was obtained with linearity range upto 20 µM (Fig. 2b). The detection limits was found to
.8 µM using the formula, DL = 3σ/m which belongs to lower level of the WHO guideline for
1
drinking water and also a number of the previously reported Ni2+ sensors. The value of
standard deviation σ is obtained from the plot of absorbance intensity versus [L] and slope m is
2
+
obtained from ratiometric calibration curve (I /I ) vs [Ni ] plot.
3
75 310
Host-guest binding stoichiometry can be determined from conventional Jobs plot
analysis, where maximum intensity obtained at 0.7 mole fraction of L due to 2:1 host-guest
complex formation(Fig. S7). Further, the 2:1 complex formation was supported by the mass
spectra and elemental analysis of the isolated complex 2 (vide supra). The base peak obtained
2
+
+
at m/z = 744.21, corresponds to 2L+Ni -2H (Fig. S5). Considering 2:1 host-guest binding, the
2
+
association constant towards Ni was also calculated from Benesi-Hildebrand (B-H) linear
3
-1/2
fitting plot and the value obtained is 1.45x10 M (Fig. 3a); which are highly in agreement to
2
+
the previously reported L+Ni complexes.

Page 9 of 24
Dalton Transactions
View Article Online
DOI: 10.1039/C9DT02448D
2+
Fig. 3(a) Association constant from Benesi-Hildebrand plot; (b) pH effect of L and L–Ni at
75 nm.
3
pH effect
Host-guest binding affinity also dependant on the pH of the working media as it can modify the
structure and coordination ability of pH sensitive groups (>C=O, >C=N, and -NH). To validate
the pH dependency on complexation, a series of L solution (20 µM) with pH range 3 to 12
have been prepared using HCl and NaOH in buffer medium and absorption studies were
2
+
+
monitored in presence of Ni ion (40 µM) (Fig. 3b). At very acidic condition (> pH 4) H ion
acts as a competitor of metal binding, also a chance of imine >C=N bond breaking, which
inhibits co-ordination ability and lowers the absorption intensity. The absorbance intensity of
free receptor as well as its metal complex progressively increases to neutral-basic medium
indicating that efficient electrostatic interaction present between deprotonated L and analyte
2
+
ion. Thus the receptor L can effectively sense Ni ion with a wide pH range 5-12 also validate
for physiological environment.
Reversibility and Logic gate
The reversibility of chemosensor L has been investigated by using common metal chelator
disodium ethylene diamine tetra acetic acid (Na EDTA). The absorption bands around 375 nm
2
along with yellow colour of host-guest complex immediately vanished with the appearance of
2
+
original absorption band of L observed, when L+Ni complex treated with 1 equiv. strong
2
+
chelator Na EDTA (Fig. 4a). Repeated addition of Ni ion, the colour and spectral change
2
2
+
almost recovered. The switching behaviour between L and L+Ni complexes were systematic
even after 5 cycles with the alternative addition of chelator and analytes. Thus INHIBIT logic
2
+
gate can be constructed by using Ni and Na EDTA as a chemical input whereas output signal
2

Dalton Transactions
Page 10 of 24
View Article Online
based on absorbance intensity at 375 nm denoted by binary code “0” and “1”. The logical
DOI: 10.1039/C9DT02448D
behaviour and the corresponding truth table has been summarised in Fig. 4b.
2
+
Fig. 4 (a) Reversibility study of L-Ni complexes with Na EDTA; (b) INHIBIT Logic gate
2
and truth table.
Fluorescence experiment
The metal selective response of the receptor L in excited state was also investigated by
fluorescence measurement (Fig.5a) in methanol-tris-HCl buffer (10 mM, pH 7.2) mixture. Due
to excited energy loss of fluorophore by photo induced electron transfer (PET) and imine
isomerisation via non-radiative pathway, the free receptor L showed weak emission band at
4
50 nm when exposed to UV light for excitation at 350 nm. Sequential addition of 2 equiv. of
3
+
2+
2+
2+
2+
2+
2+
2+
different metal ions (40 µM in each case) like Fe , Cu , Co , Ni , Zn , Cd , Hg , Mn ,
3
+
+
3+
2+
2+
2+
Cr , Ag , Al , Mn and Fe individually to the standard solution of L (20 µM), only Ni ion
caused significant red shifted emission enhancement. Among the other metal ions, most of
them showed either negligible change in emission band or quenching behaviour even upto 5
2
+
fold higher level of Ni concentration. The metal ion form tight complex via imine side and
retard both PET and >C=N isomerisation, caused strong chelation enhancement fluorescence
(
CHEF) process.35
Sensitivity has also been determined from fluorescence titration measurement. When
the Ni2+ ion concentration gradually increased, the weak emission band of free receptor at
50 nm enhanced vertically with slightly red shifted in every step, and finally got saturated
4
2
+
upon 2 equiv. of Ni ion (40 µM) (Fig. 5b). Simultaneously, the colour change of the solution
also visible in UV lamp from light blue to greenish blue. The emission intensity at 465 nm
2
+
showed linear relationship with amount of Ni ion and the detection limit was calculated to

Page 11 of 24
Dalton Transactions
View Article Online
1
.18 µM (Fig. S8). This value is slightly different from result obtained by absorption spectra as
DOI: 10.1039/C9DT02448D
2
+
the difference in sensitivity of both the spectrometer. In the interfering effect, 2 equiv. Cu ion
2
+
can quench the emission intensity of L- Ni complex, but still measurable in the existence of
2
+
2+
2+
Ni ion in the mixed solution (Fig. S9). The other metal ions including Pd and Pt do not
2
+
exhibit any interference for the detection of Ni ion. Thus the chemosensor L is highly
2
+
selective and sensitive fluorometric sensor for Ni .
Fig. 5(a) Fluorescence spectra of L (20 µM) in presence of 2 equiv. different metal ions (40
2
+
µM each) and (b) fluorescence titration of L (20 µM) with Ni (upto 40 µM) in methanol-tris
HCl buffer (1:1) mixture. Inset: colour change in UV lamp.
DFT studies on fluorescence properties
2
+
The probe L displays a simple approach for the selective detection of Ni with enhancement of
fluorescence along with red shift (15 nm), because of the CHEF (chelation-enhanced
2
+
fluorescence) as well as ICT (internal charge transfer) processes after interaction with Ni . The
energy gap between the highest occupied molecular orbital (HOMO) and lowest unoccupied
molecular orbital (LUMO) of L and NiL (2) are 3.96 eV and 2.68 eV respectively. The NiL
2
2
complex 2 compared to L are established the easy electronic transition and get the additional
stability in 2 (Fig. 6). The contours of the electronic distribution in HOMO and LUMO states
of these molecules suggested significant energy differences 1.28 eV between L and NiL (2).
2
Specifically, both HOMO and LUMO states of the nickel complex, 2 with comparing to L
revealed that the electrons are more delocalized insight into the NiL molecule than the L in
2
agreement with the barrier of photo-induced electron transfer process, which may result in the
enhancement of fluorescence through CHEF.35

Dalton Transactions
Page 12 of 24
View Article Online
DOI: 10.1039/C9DT02448D
Fig. 6 Energy level diagram for the frontier MOs of L (left) and NiL complex (2) (right).
2
1H NMR studies
1
In order to investigate the probable binding interaction between host-guest complex, H-NMR
2
+
spectra of L and 2 have been taken in CDCl (Fig. S10). Presence of Ni , the azomethine
3
proton of the free receptor L shifted towards downfield from δ = 8.62 ppm (in case of L) to δ =
9
.1 ppm (for 2), confirmed that complexation occurred through imine site of L. Also the -NH
2
+
proton of hydrazide moiety of L, at δ = 11.55 ppm disappeared during Ni binding, probably
2
+
due to the dispositive charge of Ni was balanced by two deprotonation of L. Most of the
aromatic protons in 2 were shifted towards downfield due to LMCT process. From the above
mentioned facts the probable binding mechanism has been shown in Scheme 2 and confirmed
by X-ray single crystal analysis of 2 (vide infra).

Page 13 of 24
Dalton Transactions
View Article Online
DOI: 10.1039/C9DT02448D
Scheme 2 Proposed sensing mechanism of L.
X-ray single crystal structures of L and NiL (2)
2
To establish the NiL complexation in solid phase, isolation in single crystal form is also
2
necessary, as it is more acceptable in current research interest. Thus careful efforts have been
2
+
taken to isolate the L-Ni complex in the form of single crystal at the experimental condition.
Mixing of receptor-analyte in a 2:1 molar ratio, a block shaped red crystal was separated out,
which was suitable for single crystal XRD analysis.
Geometry optimizations starting from the X-ray crystal structures of L and 2 (Fig. 7)
led to a global minimum as stationary point. Selected geometry optimized parameters are listed
in Table S1. The general drift observed in the crystal structure data is well reproduced. The
calculated bond lengths as well as bond angles are in good agreement with the experimental
crystal structures data (Table S1). In general, a little deviation of the calculated bond distances
and angles from their respective experimental data is observed. The calculated bond lengths of
L and 2 deviate within range of ±3% from the respective observed crystal data, while the bond
angles are vary within the range of ±4%. Since the optimizations L and NiL (2) are conceived
2
under gas phase model.
The single crystals of the probe2-(benzamido)-N'-((pyridin-2-yl)methylene)
benzohydrazide (L) and its Ni(II) complex (2) were grown by slow evaporation of the
methanol solutions at room temperature. The crystallographic data of L andits nickel complex
(2) are listed in Table 1. L crystallized as monoclinic C2/c space group whereas 2 crystallised
as triclinic P-1 space group. 2 crystallises with one molecule of H O. In this Ni(II) complex 2,
2
Ni(II) ion adopted an octahedral coordination geometry comprising of two ligand L moieties

Dalton Transactions
Page 14 of 24
View Article Online
and one Ni(II) ion. The two cationic charges of Ni(II) ion were internally satisfied by two
DOI: 10.1039/C9DT02448D
deprotonated hydrazide NH of two molecules of L. Moreover, coordination number 6 has been
supplemented by coordinating to two molecules of L, leading to the formation of an inner-
metallic complex of the first order for the bivalent metal ion. The metal to donor bond distance
values (Table S1) supports the low spin conformation for the NiL complex 2.
2
ORTEP view of L and 2 along with the atom numbering scheme is shown in Fig. 7.
Close study of the crystal structure of L revealed no intra- or intermolecular π–π stacking in
contrast to that observed in NiL (2). The centroid-to-centroid separations between two
2
pyridine rings of the ligands in 2 are 3.530 Å and 3.764 Å and get extra stability (Fig. 8).36
Earlier this separation was recommended to be 3.80 Å to bring about considerable interaction.
It is also notable that the offset situation of rings, the separation will be increased.37
Fig.7 ORTEP diagrams of L (left) and NiL (2) (right) showing the atom-labelling scheme and
2
3
0% thermal ellipsoids.

Page 15 of 24
Dalton Transactions
View Article Online
DOI: 10.1039/C9DT02448D
Fig. 8 View of NiL .H O (2.H O) showing, intramolecular π–π stacking interactions (magenta
2
2
2
dotted line).
Table 1Crystallographic data and refinement parameters of the probe L and 2.H O
2
Identification Code
Empirical formula
Formula weight
Temperature/K
Crystal system
Space group
a/Å
b/Å
c/Å
α/°
β/°
L
2.H O
2
C H N O
344.38
296.24
monoclinic
C2/c
11.2708(7)
12.1463(9)
25.4971(14)
90
98.351(2)
90
C H N NiO
5
2
0
16
4
2
40 32
8
763.44
294.58
triclinic
P-1
10.445(7)
13.227(9)
14.693(10)
66.869(14)
72.930(16)
82.241(15)
1784(2)
2
γ/°
Volume/Å3
3453.5(4)
8
1.3246
Z
3
ρ g/cm
calc
1.4210
μ/mm-1
F(000)
0.089
1440.6
0.602
793.0
Radiation
Mo Kα (λ = 0.71073)
5.04 to 54.24
12225
Mo Kα (λ = 0.71073)
4.44 to 57.18
54364
2
Θ range for data collection/°
Reflections collected
Independent reflections
3794 (R = 0.0360,
9010 (R = 0.1036,
int
int

Dalton Transactions
Page 16 of 24
View Article Online
DOI: 10.1039/C9DT02448D
Rsigma = 0.0402)
3794/0/235
1.090
Rsigma = 0.0763)
9010/0/490
1.112
Data/restraints/parameters
Goodness-of-fit on F2
Final R indexes [I>=2σ (I)]
Final R indexes [all data]
CCDC number
R = 0.0481, wR = 0.1129 R = 0.0648, wR = 0.1693
1
2
1
2
R = 0.0756, wR = 0.1344 R = 0.1149, wR = 0.2129
1
2
1
2
1917470
1917471
Application of the chemosensor L in real samples
As the industrial waste water was mixed with the normal water resources, the bio accumulation
of Ni2+ ion is mainly initiated through water contamination. Thus efficiency of the
chemosensor L towards waste water sample was checked. The accuracy of the measurement
2
+
was estimated by spiking a known amount of standard Ni solution and its recovery was
calculated using calibration curve (intensity ratio vs. conc.) and Lambert-Beer law (Table 2).
2
+
The recovered concentration Ni ion by the receptor L are well fitted to spiked amount with
satisfactory precision (RSD valueless than 2%) suggesting that the molecular probe L would be
2
+
frequently used to detect Ni ion in environmental samples.
2
+
Table 2 Determination of Ni ion in water samples.
Metal Ion
Spiked amount
μM)
Recovered
amount(μM)
9.96
Recovery %
99.6
RSD % value
(
1
0
Ni2+
1.35
10
10.14
10.23
101.4
1
0
102.3
Smart Phone Based Colour Image
To investigate rapid and convenient colorimetric determination of Ni2+ by the proposed
receptor L, without other laboratory instruments, easy to handle smartphone based studies were
2
+
also carried out. Thus various concentration levels of Ni contaminated sample was prepared in
tap water and standard solution of probe L was added to the sample followed by the image of
each sample was captured in flashlight by a smartphone (Fig. S11). Then the obtained images
were analysed by an embedded application tool RGB grabber shunamicode in smartphone to
2
+
get the value of red green and blue channel level and plotted with concentration of Ni ion
2
+
(
Fig. S12). Among them, the blue to red (B/R) channel intensity ratio as a function of [Ni ]
ion showed most significant variation with good linearity (Fig. 9) obtained upto 25 µM. The
smartphone based detection limit was calculated to 1.52 µM using same equation 3σ/m. The

Page 17 of 24
Dalton Transactions
View Article Online
unknown concentration (X) also calculated using this standard curve (Fig. 9) by smartphone
DOI: 10.1039/C9DT02448D
image capture without any expensive and sophisticated instruments.
Fig. 9 Plot of the ratio of colour channel level.
Cell imaging study
2
+
To validate the affinity of receptor L towards Ni ion inside the intracellular medium, cell
imaging study has been performed by a fluorescence confocal microscope. Proper incubation
0
2+
of human cervical cancer cell, HeLa for 2h at 37 C either by the receptor L or Ni ion,
individually showed only dark background, when continuously irradiated at 350 nm wave
2
+
lengths. Under the similar condition, when the same cell pre-incubated by 40 µM Ni solution
followed by 20 µM probe L, a bluish green fluorescence image was observed (Fig. 10). These
2
+
results clearly indicate that the receptor L can be applicable to detect Ni ion inside the living
system with good cell permeability and minimum interference from background.
Fig. 10 Fluorescence microscopy images of the Hela cells after incubation for 2 h: (a) cells +
2
+
2+
probe L (20 μM), (b) cells + Ni (40 μM) and (c) cells +probe L (20 μM) + Ni (40 μM).

Dalton Transactions
Page 18 of 24
View Article Online
DOI: 10.1039/C9DT02448D
Comparison of L with other reported Schiff-base chemosensors
In continuation of our ongoing effort for providing useful analytical techniques to monitor the
increasing number of analytes of environmental relevance as quickly and as cheaply as possible
and with the highest order of sensitivity, the present paper describes the synthesis of a new
hydrazide based optical probe, (L), which was validated for detection and quantification of
2
+
Ni ions in real samples. The probe L is readily soluble in aqueous methanol (1:1 CH OH-
3
2
+
H O) which produces a detectable color change in presence of Ni ion and has
2
excitation/emission wavelengths very close to the visible region.
To the best of our knowledge, few previously reported Schiff base chemosensors for
2
+
Ni ion were also available. Here, the synthesized probe L was compared with those reported
chemosensors (Table 3). Although most of the other Schiff-base chemosensors showed
somewhat lower detection limit value compared to this proposed sensor, but there were some
limitations like: only colorimetric responds, low pH range and only solution based detection
without isolation of single crystal of the host-guest complex etc. The important features of the
proposed chemosensor L are: not complicated synthetic procedure, high sensitivity, wide pH
range (5-12), reversibility in binding to the analyzed cations, high accuracy and precision,
isolation of host-guest complex in single crystal form, application in contaminated water
sample, living cell imaging and smartphone based analysis. Thus the proposed chemoreceptor
gives a new arena in the field of Schiff base chemosensor.
Table 3 Comparison of L with other reported Schiff-base chemosensors
Chemical structure of the probe
Sensing
method
Binding LOD Isolation in
Ref.
form of
Constant
single
crystal
Colorimetric 2.34 x
0.5
µM
No
No
38
4
-1
N
10 M
N
HO
HO
O
O
O
4
H
Colorimetric 2.9 x 10
0.12
µM
39
N C
-1
M
O O
O
N

Page 19 of 24
Dalton Transactions
View Article Online
Colorimetric/
Fluoremetric
No
40
DOI: 10.1039/C9DT02448D
CF3
H
N
N
O
N
O
N
O
NO2
Colorimetric
1.47
µM
No
41
H
N
N
N
O
Colorimetric 1.29 x
0.1
µM
42
43
Cl
N
N
5
-1
1
0 M
OH
Colorimetric/
Fluoremetric
Red crystal
N
N
OH HO
Colorimetric 4.01 x
0.36
µM
No
44
6
-1
1
0 M
S
N
N
OH HO
Cl
Cl
Colorimetric
Red crystal
Present
work
O
N
N
N
H
NH
O
Conclusions
In summary, we have successfully designed and synthesized a quinazolinone derived Schiff
2
+
base chemosensor L for fluorescent colorimetric detection of Ni with high selectivity and
sensitivity over other competitive ions in aqueous medium. A 2:1 stoichiometry between L and
2
+
Ni were supported by Job-plot, ESI-mass spectral analysis and DFT studies. The single crystal
of the probe L and its nickel complex 2 were also isolated. The detection limits reached up to
1
.8 µM and 1.18 µM respectively by colorimetric and fluoremetric measurements, which were

Dalton Transactions
Page 20 of 24
View Article Online
far lower than those recommended by the WHO guidelines for drinking water. The reversible
DOI: 10.1039/C9DT02448D
2
+
response to Ni ion was established by the Na EDTA experiments. Moreover, L could operate
2
in a wide range of pH and can be successfully applied for detection and quantification of Ni2+
in environmental samples, smart phone based analysis, living cell imaging and for building
INHIBIT type of logic gates. On the basis of these results, we believe that receptor L will be a
2
+
remarkablesupplement in the sphere of simple Schiff base sensor for Ni ion.
Acknowledgements
G.K.P would like to thank the Department of Science and Technology (SR/FST/CSI-264/2014)
and Department of Biotechnology, Government of India, New Delhi for financial support.
A.K.M. thanks the CSIR, Government of India, for financial support in the form of research
fellowship.
Supporting Information Summary
CCDC 1917470 and1917471contain the supplementary crystallographic data for the probe
Land the complex 1. The data can be obtained free of charge from the Cambridge
Crytallographic Data Centre, 12 Union Road, Cambridge CB21EZ, UK; Fax: (+44)1223-336-
0
33; or email: deposit@ccdc.cam.ac.uk: Supplementary data containing Tables S1 and Fig. S1-
S12 of this article can be found online at…………………………..
Conflicts of interest
Authors declare no conflicts of interest.
References
1
D. Maity, A.K. Manna, D. Karthigeyan,T.K. Kundu, S.K.Pati and T.Govindaraju, Chem.
Eur. J., 2011, 17, 11152.
2
L. Dong, C. Wu, X. Zeng, L. Mu, S.F. Xue, Z. Tao and J.X.Zhang, Sens.Actuators B. Chem.,
2
010, 145, 433.
C.Y. Li, X.F. Kong, Y.F. Li, C.X. Zou, D. Liu and W. G. Zhu, Dyes &Pigments, 2013, 99,
03.
3
9
4
5
Q. Lin, T.T. Lu, X. Zhu, T.B. Wei, H. Li and Y.M. Zhang, Chem. Sci. 2016,7, 5341.
S. L. C. Ferreira, A. S. Queiroz, M. S. Fernandes and H. C. dos Santos, Spectrochim.ActaB,
2
002, 57, 1939.
6
7
8
A. Ali, H. Shen and X. Yin, Anal. Chim. Acta, 1998, 369, 215.
D. Shan,C. Mousty and S. Cosnier, Anal. Chem., 2004, 76, 178.
M. H. Mashhadizadeh, M. Pesteh, M. Talakesh, I. Sheikhshoaie, M. M. Ardakani and M.A.
Karimi, Spectrochim. Acta B, 2008, 63, 885.

Page 21 of 24
Dalton Transactions
View Article Online
9
S. Dadfarnia, M. A. H. Shabani, F. Tamadon and M. Rezaei, Microchim.Acta, 2007, 158,
DOI: 10.1039/C9DT02448D
1
59.
1
1
1
1
1
1
0 G. K. Patra, R. Chandra, A. Ghorai and K. K. Shrivas, Inorg. Chim.Acta, 2017, 462, 315.
1 X. Zhou, S. Lee, Z. Xu and J. Yoon, Chem. Rev., 2015, 115, 7944.
2 J.J. Lee, Y.W. Choi, G.R. You, S.Y. Lee and C. Kim, Dalton Trans., 2015, 44, 13305.
3 A. Chowdhury, P. Howlader and P.S. Mukherjee, Chem. Eur. J., 2016, 22, 1424.
4 M. M. Ramon, S. Felix, Chem. Rev. 2003, 103, 4419.
5 P. Ghosh, K. Pramanik, S. Paul, P. Malpaharia, S. K. Chandra, S. K. Mukhopadhyay, and P.
Banerjee, ACS Appl. Bio Mater., 2018, 1, 683.
1
6 M.C. García-López, B.M. Munoz-Flores, V.M. Jiménez-Pérez, I. Moggio, E. Arias and R.
C. Navarro, Dyes &Pigm., 2014, 106, 188.
1
1
7 D. Lewing and H. Koppetz, F.E. Hahn, Inorg. Chem., 2015, 54, 7653.
8 J. R. Lakowicz, Fluorescence Sensing: Principles of Fluorescence Spectroscopy.Springer,
Boston, MA, 2006, 623.
1
2
2
2
2
9 B. Zambelli, F. Musiani, S. Benini and S. Ciurli, Acc. Chem. Res., 2011, 44, 520.
0 S.W. Ragsdale, J. Biol. Chem., 2009, 284, 18571.
1 R.J. Maier, Biochem. Soc. Trans., 2005, 33, 83.
2 K.S. Kasprzak, F. W. Sunderman and K. Salnikowa, Mutat. Res.,2003, 533, 67.
3 P.H. Kuck, Mineral Commodity Summaries: Nickel, United States Geological Survey,
2
006.
2
4 J. R. Davis, Uses of Nickel, ASM Specialty Handbook: Nickel, Cobalt, and Their Alloys,
ASM International, 2000, 7.
2
5 W. Lee, K. A. Davis, R. L. Rettmer and R.F. Labbe, Am. J. Clin. Nutr.,1988, 48, 286.
2
2
6 X. Q. Liu, X. Zhou, X. Shu and J. Zhu, Macromolecules, 2009, 42, 7634.
7(a) R. Chandra, A.K. Manna, K. Rout, J. Mondal and G.K. Patra, RSC Adv.,2018,8, 35946; (b) A.
Ghorai, J. Mondal, R. Saha, S. Bhattacharya and G. K. Patra, Anal. Methods, 2016, 8, 2032.
8 (a) J. Mondal, A.K. Manna, K. Rout, S.K. Singh, J.P. Naskar and G.K. Patra, Int. J. Env.
Anal. Chem., 2018, 98, 1160; (b) A.K. Manna, J. Mondal, K. Rout and G.K. Patra, Sens. and
Act. B: Chem, 2018, 275, 350.
2
2
3
3
9 SMART & SAINT Software Reference manuals, version 5.0; Bruker AXS Inc.: Madison,WI,
1
998.
0 T. Gruene, H. W. Hahn, A. V. Luebben, F. Meilleur and G. M. Sheldrick, J. Appl. Cryst.,
014, 47, 462.
1 (a) L.J. Farrugia, WinGX: An Integrated System of Windows Programs for the Solution,
2

Dalton Transactions
Page 22 of 24
View Article Online
DOI: 10.1039/C9DT02448D
Refinement and Analysis for Single Crystal X-ray Diffraction Data, version 1.80.01;
Department of Chemistry: University of Glasgow, 2003;
(b) L.J. Farrugia, WinGX suite for small-molecule single-crystal crystallography, J. Appl.
Crystallogr., 1999, 32, 837.
3
3
2 A. K. Manna, J. Mondal, K. Rout and G.K. Patra, J. Photochem. Photobiol A: Chem., 2018,
67, 74.
3
3M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman, G.
Scalmani, V. Barone, B. Mennucci,G.A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H.P.
Hratchian, A.F. Izmaylov, J. Bloino, G. Zheng, J.L. Sonnenberg, M.Hada, M. Ehara, K.
Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T.
Vreven, J.A.Montgomery, Jr., J.E. Peralta, F. Ogliaro, M. Bearpark, J.J. Heyd, E. Brothers,
K.N. Kudin, V.N. Staroverov, R. Kobayashi,J. Normand, K. Raghavachari, A. Rendell, J.C.
Burant, S.S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J.M. Millam, M. Klene,J.E. Knox, J.B.
Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R.E. Stratmann, O. Yazyev, A.J.
Austin, R. Cammi, C.Pomelli, J.W. Ochterski, R.L. Martin, K. Morokuma, V.G.
Zakrzewski,G.A. Voth, P. Salvador, J.J. Dannenberg, S. Dapprich,A.D. Daniels, Ö. Farkas,
J.B.Foresman, J.V. Ortiz, J. Cioslowski and D.J. Fox, Gaussian 09, Revision C.01,
GaussianInc.,Wallingford, CT; 2009.
3
3
3
4 (a) A.D. Becke.,J. Chem. Phys., 1993, 98, 5648;
(b) C. Lee, W. Yang and R.G. Parr.,Phys. Rev. Sect. B, 1988, 37, 785.
5 S. Chowdhury, A. Bhattacharya, P. Saha, S. Majumder, E. Suresh and J. P. Naskar, J Coord.
Chem., 2016, 69, 3664.
6 P. Saha, J. P. Naskar, S. Majumder, B. Saha, R. Ganguly, A. Bhattacharya and S.
Chowdhury, J. Chin.Chem. Soc., 2018, 65, 1035.
3
3
3
4
4
7 C. Janiak. J. Chem. Soc., Dalton Trans., 2000, 3885.
8 J. Jiang, C. Gou, J. Luo, C. Yi and X. Liu, Inorg. Chem. Commun. 2012, 15, 12–15.
9 L. Wang, D. Ye and D. Cao, Spectrochim. Acta A, 2012, 90, 40.
0 H. Li, L. Cai, J. Li, Y. Hu, P. Zhou and J. Zhang, Dyes and Pigments, 2011, 91, 309-316.
1 S. Goswami, S. Chakraborty, S. Paul, S. Halder and A.C. Maity, Tetrahedron Lett., 2013, 54,
5
075.
4
2 D. Peralta-Domínguez, M. Rodríguez, G. Ramos-Ortíz, J. Luis Maldonadoa, M.A. Meneses-
Navaa, O. Barbosa-Garcíaa, R. Santillan and N. Farfánc, Sensors Actuators B Chem., 2015,
2
07, 511.

Page 23 of 24
Dalton Transactions
View Article Online
DOI: 10.1039/C9DT02448D
4
4
3 B. Chowdhurya, M. Karar, S. Paul, M. Joshi, A. Roy Choudhury and B. Biswas, Sens. &
Actuators B. Chem. 2018, 276, 560-566.
4 G. G. VinothKumar, K. M. Palsamy, S. Murugesan , K. Sakthipandi, R. Jegathalaprathaban
and S. Gandhi, New J. Chem., 2018, 42, 2865.

Dalton Transactions
Page 24 of 24
View Article Online
Graphical Abstract
DOI: 10.1039/C9DT02448D
Hydrazide based novel selective and sensitive optical chemosensor
2
+
for the detection of Ni : Applications in living cell imaging,
molecular logic gate and smart phone
a
b
a
Amit Kumar Manna, ShubhamoyChowdhury and Goutam K. Patra *
aDepartment of Chemistry, Guru GhasidasVishwavidyalaya, Bilaspur (C.G),
India
bDepartment of Chemistry, Gour Banga University, Malda, West Bengal 732
1
03, India
A novel flexible hydrazide based Schiff base chemo-receptor 2-(benzamido)-N'-((pyridin-2-
yl)methylene)benzohydrazide (L) has been designed, which showed colorimetric and
2
+
fluorometric “turn on” response in presence of only Ni . The chemosensor L can be applied
to the recovery of contaminated water samples, building of molecular logic gate, smart phone
and living cell imaging.