Development of highly selective dual mode chromogenic and fluorogenic chemosensor for Bi3+ ions

Article abstract of DOI:10.1016/j.molstruc.2020.128143

A new dual mode chemosensor 8-methoxy-2-(thiophen-2-yl) quinolone (L) was synthesised for selective and sensitive detection of Bi³⁺ ions. The selective distinct colorimetric response and fluorescence quenching were observed upon interaction of L with Bi³⁺ in CH₃CN:H₂O (85:15, v/v) media. The sensor L could form 2:1 stoichiometric complex with Bi³⁺ with an association constant of 2.2 × 10⁵ M^?2 by using Benesi-Hilderbrand (BH) method. The fluorescence quenching constant estimated to be 9.3 × 10⁸ M^?1 by using Stern-Volmer (SV) plot. The lowest detection limit of Bi³⁺ by colorimetric and fluorimetric were found to be 1.78 μM and 0.057 μM respectively. The sensing mechanism of L with Bi³⁺ was studied using ¹H NMR, ESI-mass analysis and theoretical calculations. Finally, the sensor L was applied for the detection of Bi³⁺ in various water and pharmaceutical drug samples.

Full text of DOI:10.1016/j.molstruc.2020.128143

Journal Pre-proof
Development of highly selective dual mode chromogenic and fluorogenic
3+
chemosensor for Bi ions
S. Saravana Kumar, R. Selva Kumar, S.K. Ashok Kumar
PII:
S0022-2860(20)30468-3
DOI:
https://doi.org/10.1016/j.molstruc.2020.128143
MOLSTR 128143
Reference:
To appear in: Journal of Molecular Structure
Received Date: 19 September 2019
Revised Date: 15 February 2020
Accepted Date: 26 March 2020
Please cite this article as: S. Saravana Kumar, R. Selva Kumar, S.K. Ashok Kumar, Development
3+
of highly selective dual mode chromogenic and fluorogenic chemosensor for Bi ions, Journal of
Molecular Structure (2020), doi: https://doi.org/10.1016/j.molstruc.2020.128143.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition
of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of
record. This version will undergo additional copyediting, typesetting and review before it is published
in its final form, but we are providing this version to give early visibility of the article. Please note that,
during the production process, errors may be discovered which could affect the content, and all legal
disclaimers that apply to the journal pertain.
©
2020 Published by Elsevier B.V.

Credit author statement
S. Saravana Kumar: Development or design of methodology
Selva Kumar R: Creation of models
S.K. Ashok Kumar: Writing- Reviewing and Editing

Graphical Abstract

Development of Highly Selective Dual Mode Chromogenic and Fluorogenic
3+
Chemosensor for Bi Ions
a
a
a
S. Saravana Kumar , Selva Kumar R , and S.K. Ashok Kumar *
a
Department of Chemistry, School of Advanced Sciences, Vellore Institute of Technology,
Vellore-632014, Tamil Nadu, India. E-mail: ashok312002@gmail.com
Abstract
A new dual mode chemosensor 8-methoxy-2-(thiophen-2-yl) quinolone (L) was synthesised for
3+
selective and sensitive detection of Bi ions. The selective distinct colorimetric response and
3
+
fluorescence quenching were observed upon interaction of L with Bi in CH CN:H O (85:15,
3
2
3
+
v/v) media. The sensor L could form 2:1 stoichiometric complex with Bi with an association
5
-2
constant of 2.2×10 M by using Benesi-Hilderbrand (BH) method. The fluorescence quenching
8
-1
constant estimated to be 9.3×10 M by using Stern-Volmer (SV) plot. The lowest detection
3
+
limit of Bi by colorimetric and fluorimetric were found to be 1.78 μM and 0.057 µM
3+
1
respectively. The sensing mechanism of L with Bi was studied using H NMR, ESI-mass
3
+
analysis and theoretical calculations. Finally, the sensor L was applied for the detection of Bi in
various water and pharmaceutical drug samples.
Keywords: Colorimetry, Fluorometry, Bismuth, Quenching, Quinoline, DFT.
1
. Introduction
Bismuth is one of the heaviest stable elements in the periodic table and it has been used in
medicine since the middle ages [1]. Bismuth compounds are extensively used in many
pharmaceutical preparation such as antibacterial, anti-HIV and radiotherapeutics agents [2].
Also, it is used in the preparation of creams and hair dyes. Nowadays, bismuth and its
compounds have been used in preparation of metallurgical additive and recycling of uranium in
nuclear fuels [3,4]. The potential application of bismuth in material chemistry including the
bismuth doped luminescence material used in the manufacture of LEDs [5,6]. Bismuth sulphide
used in batteries have also attracted great attention in the past few years [7]. Although bismuth is
considered safe for human health, but the accumulation of bismuth in brain and kidney would

also result in bismuth-induced neurotoxic side effects [8,9]. The various methods have been
3
+
developed to detect trace level of Bi including, inductively coupled plasma-atomic emission
spectroscopy [10] atomic fluorescence spectroscopy [11,12] electrochemical methods [13-15]
and resonance light scattering [16,17]. These reported methods are selective and sensitive. But
expensive and require lengthy pre-treatment procedures and also needs the use of sophisticated
3
+
instruments. Hence, the spectrophotometric and spectrofluorometric determination of Bi ions
using appropriate sensor is one the simplest and the most accurate method. Here, the need is
3
+
therefore to develop sensors which are easy to synthesise and apply for recognition of Bi in
different matrices. Accordingly, from past few years, chromogenic and fluorogenic sensors have
3
+
been reported for detecting of Bi [18-19]. In some of these reports are constraint to, poor
detection limit, limited working pH range and incomplete characterization of the sensor. In order
to overcome these draw backs, herein reporting chromogenic and fluorogenic nature of ligand L
3
+
for the selective and sensitive detection of Bi in partially aqueous media.
2
. Experimental Section
2
.1 Materials and methods
All metal salts are purchased as nitrate in SD Fine chemicals, India. 8-hydroxy quinoline,
thiophene and n-butyl lithium were purchased from Sigma Aldrich. All solvents were purchased
from Merck chemicals used without further purification.
The absorbance and emission spectra were recorded on a JASCO V-730 spectrophotometer and
JASCO FP-8200 spectrofluorometer respectively. Infrared spectra (IR) were recorded on a
-1
Shimadzu Affinity FT-IR spectrometer in the range of 4000-400 cm . Mass spectra were
recorded on a Perkin-Elmer Clarus 680 GC and Clarus 600 MS. NMR spectra were recorded
1
13
using 400 MHz Advance Bruker NMR spectrometer. H and C NMR chemical shift were
recorded in ppm downfield from TMS.
3
+
The energy minimised ground state geometry of neat ligand L and L-Bi complex were
optimized by density functional theory (DFT) using Gaussian 09 W [20].The Backe three
parameter Lee-Yang-Parr (B3LYP) method with the standard basis set 6-311(d,p) for C, H, O, N
and S atoms and the LANL2DZ basis set with effective core potential for Bi atom [21].

3
+
2
.2 Synthesis and characterization of 8-MQ, L and L-Bi
The synthesis of L follows a two-step reaction, the first step involves the preparation of an
intermediate product 8-methoxy quinoline (8-MoQ) and the second step involves the sequential
reaction of the 8-MoQ with thiophene followed by oxidation in nitrophenol leading to the
formation of final compound L (Scheme 1).
3+
Scheme 1: Reagent and conditions to synthesis L and L-Bi
8
-MoQ: To prepare intermediate product 8-MoQ, previously reported procedure was slightly
modified to get product with good yield [22]. Accordingly, 8-hydroxy quinoline (2.5 g, 17
mmol) was dissolved in acetone in the presence of potassium carbonate (3.5 g, 25.5 mmol) then
added dropwise methyl iodide (2.8 g, 20 mmol)taken in acetone. The reaction mixture was
stirred at room temperature for an overnight. After completing the reaction, the reaction mixture
was filtered through pad of celite and washed with acetone. The solvent was evaporated under
reduced pressure to get an intermediate product with a yield of 92%.
1
Characterisation (C H NO): HNMR (400 MHz, CDCl ) δ 8.93 (d, J = 4.1 Hz, 1H), 8.13 (d, J =
1
0
9
3
8
4
1
.2 Hz, 1H), 7.43 (dd, J = 17.6, 14.7 Hz, 2H), 7.38 (d, J= 8.1 Hz, 1H) 7.06 (d, J = 7.6 Hz, 1H),
13
6
.09 (s, 3H). C NMR (101 MHz, DMSO-d ) δ 150.68, 144.48, 135.46, 131.14, 124.62, 121.96,
+
16.93, 114.79, 102.81, 51.21. GC-MS (M ): Calculated: 159.0684 and Obtained: 159.1338.
L: To an ether solution of thiophene (1.7 g, 20 mmol), 1.6 M solution (1.25 ml) of n-butyl
o
lithium in hexane was added dropwise at -5 C under nitrogen atmosphere. The reaction mixture
o
was stirred for 1 h at -5 C to this an ether solution of 8-methoxyquinoline (3.2 g, 20 mmol) was
added over the period of 1 h. After complete addition, the mixture was stirred for 2 h at room
temperature. Then, the reaction mixture was poured into crushed ice and ether extract of the
aqueous phase was evaporated, leaving a deep red oily liquid. Further, oxidation of this oily

o
liquid with boiling nitrobenzene for about an 2 h at 110 C yield the desired product which
rapidly crystallized on cooling with an yield of 86% [23,24]. The final product was purified by
1
using column chromatography. Characterisation (C H NOS): H NMR (400 MHz, CDCl ) δ
14
11
3
8
1
.12 (d, J = 8.6 Hz, 1H), 7.82 (d, J = 8.6 Hz, 1H), 7.73 (d, J = 3.6 Hz, 1H), 7.45 (d, J = 5.0 Hz,
H), 7.41 (t, J = 7.9 Hz, 1H), 7.35 (d, J = 8.0 Hz, 1H), 7.15 (t, J = 4.3 Hz, 1H), 7.05 (d, J = 7.5
1
3
Hz, 1H), 4.10 (s, 3H). C NMR (101 MHz, DMSO-d
6
) δ 150.55, 146.62, 140.75, 135.26,
+
1
31.91, 123.60, 123.24, 121.57, 120.97, 114.68, 113.50, 103.82, 51.53. GC-Mass (M ):
Calculated: 241.0561 and obtained: 241.0961.
3
+
L-Bi : To the stirred solution of L (1.2 g, 5mmol) in methanol, bismuth nitrate solution in
methanol (1 g, 2.5mmol) was added and the mixture stirred for overnight under room
temperature. After complete formation of complexation, it appeared as solid product and
contents filtered and washed with diethyl ether to offer the pure complex with a yield of 87%.
1
Characterisation (C28
H
22
N
2
O
2
S
2
Bi): H NMR (400 MHz, DMSO-d
6
) δ 8.32 (d, J = 8.7 Hz, 1H),
8
7
.09 (d, J= 8.6 Hz, 1H), 7.95 (d, J = 3.5 Hz, 1H), 7.69 (d, J = 5.0 Hz, 1H), 7.59 – 7.36 (m, 2H),
.21 (d, J = 4.0 Hz, 2H), 3.99 (s, 3H).ESI Mass (2L+Bi+NO ): Calculated: 758.2805 and
3
obtained: 758.2214.
2
.3. Preparation of Pharmaceutical Samples
The practical applicability was studied by taking bismuth containing pharmaceutical samples
such as Bismatrol tablet and Pepto Bismol syrup in which bismuth is present as bismuth
subsalicylate were purchased from local pharmacy shop. To prepare an initial stock solution of
these drug samples, 1.0 g of drug contain bismuth was dissolved in 1mL of hydrochloric acid and
1
0 mL of deionized water. The solution was heated to near boiling for 30 minutes, then contents
were cooled and filtered. The pH of the solution was adjusted to 6.0 using tris-HCl buffer
solution before diluting the contents of the flask to 100 mL using deionized water. The total
3+
concentration of Bi present in the prepared solution was standardised by using ICP-OES
analysis.
3
. Results and Discussion
The synthesis of desired ligand L was accomplished in high yield by reacting 8-methoxy
quinoline with thiophene substitution (Scheme 1). The compound was systematically

1
13
characterized by FT-IR, NMR ( H, C) and mass analysis. According to Pearson’s HASB
3
+
concept, L is having O, N and S donor centres while Bi is border line acceptor and host-guest
3+
formation between L and Bi is characterized by optical spectroscopy.
3
.1 Colorimetric studies
The sensing ability of L towards various metal ions was studied by three different methods
colorimetric, chromogenic and fluorogenic. The ligand L was interacted with 10 equivalence of
+
+
2+
2+
2+
2+
2+
3+
2+
2+
3+
2+
various metal ions such as Na , K , Ca , Mg , Ni , Co , Mn , Fe , Hg , Zn , Cr , Pb ,
3
+
3+
3+
3+
3+
3+
4+
In , La , Bi , Ce , Eu , Dy and Th in CH CN:H O (85:15, v/v) media. As shown in Fig.
3
2
3
+
1
a, free L exhibits a colourless, upon interaction with Bi , it turns into yellow colour while
other tested metal ions did not show any noticeable change in colour. Also, under UV-light, the
3
+
ligand L shows blue fluorescence upon interaction with Bi . The fluorescence of L was
completely quenched while other metal ions did not affect the fluorescence response of L (Fig.
3
+
1
b). Hence, these observations confirms L can selectively bind with Bi over tested metal ions.
(a)
3
+
+
2+
2+
2+
2+
2+
2+
2+
3+
3+
3+
4+
3+
L
Bi Na Ca Mg Cd Mn Ni Hg Zn Ce Cr La Th Fe
(b)
3
+
+
2+
2+
2+
2+
2+
2+
2+
3+
3+
3+
4+
3+
L
Bi
Na Ca Mg Cd Mn Ni Hg Zn Ce Cr La Th Fe
Fig. 1 The colorimetric performance of L with various metal ions in CH CN:H O (85:15, v/v) (a) under
3
2
normal light (b) under UV light

3
.2 Chromogenic sensing ability
In order to investigate the specific selectivity of L, the UV-Vis spectrophotometric sensing
behaviour of L was studied in the presence and absence of various metal ions in CH CN:H O
3
2
(85:15, v/v). As shown in Fig. 2a, the free L exhibits two absorbance bands at 286 nm and 334
nm were due to π-π* and n-π* transitions in the quinoline ring system with a molar extinction
4
-1
-1
4
-1
-1
coefficient (ε) of 2.15 ×10 L.M .cm and 1.89 ×10 L.M .cm respectively. Upon interaction
3
+
of L with Bi showed bathochromic shift with a distinct spectral band at 300 nm and 370 nm
4
-1
-1
4
-1
-1
with molar extinction coefficient of 2.15 ×10 L.M .cm and 1.89 ×10 L.M .cm respectively.
Other tested metal ions did not show any noticeable spectral change. This confirms the selective
3
+
binding of ligand L with Bi under tested condition.
3
+
Effect of pH on L and L-Bi by spectrophotometric response was studied in the pH range of 1.0-
1
1.0. The free ligand L showed decrease in absorbance below pH 4.0 while in basic region
3
+
variation was very weak. In the case of L-Bi complex showed maximum absorbance and
remain same in the pH range 4.0-8.0, below pH 4.0 and above pH 8.0, the absorbance was starts
to decrease (Fig. 2b). The decrease in the absorbance at acidic pH could be due to protonation on
binding site restricted the complexation and in the basic pH could be due to the formation of
insoluble Bi(OH)3.
(a)

3 2
Fig. 2 (a) UV-Vis spectral response of L with various metal ions in CH CN:H O (85:15, v/v) (b) Effect of
3+
pH on L and L-Bi
3
+
In order to understand the binding property of
L
with Bi , UV-Vis spectral titration was carried
3
+
out by adding incremental amount of Bi (0 -70
μ
M) to
3 2
L (50μM) in CH CN:H O (85:15, v/v).
3
+
Upon successive addition of Bi into
L, the absorption band at 287nm gradually decreased and a
new absorption band at 370 nm was gradually increased with a formation clear isosbestic points
at 266 nm and 313 nm (Fig. 3a). Further, the UV-Vis spectral change was found to be obey the
Beer-Lambert’s law by showing a linear response at 370 nm against the concentration of
3
+
3+
Bi used. Based on the UV-Vis titration, the binding constant of
L with Bi was estimated by
3
+
using BH method, by plotting the change in absorbance against 1/[Bi ] [25]. The estimated
5
-2
association constant (
K
a
) was found to be 2.2×10 M (Fig. 3b). The binding stoichiometry of
with Bi was determined by using Job’s plot [26]. The plot of absorbance at 370 nm against
mole fraction of under a constant total volume. A maximum absorbance was reached the mole
fraction at 0.7, which indicate a 2:1 stoichiometry of
calibration curve, limit of detection (LOD) and limit of quantification (LOQ) were estimated by
standard IUPAC guidelines found to be 1.73 M and 5.78 M respectively (Fig. 3d) [27].
L
3
+
L
3
+
L
to Bi ratio (Fig. 3c). Using the
μ
μ

(a
3+
Fig. 3 (a) UV-Vis spectral titration of L with Bi (b) B-H plot (c) Job’s plot (d) Calibration curve
3
+
The reversibility of spectral response of
complexing agent Na EDTA. The free did not show any absorbance band at 370 nm upon
interaction with Bi a new peak appeared at 370 nm. Further, addition of EDTA into this
L with Bi was investigated by adding strong
2
L
3
+
,
3
+
3+
solution leads to breaking of L-Bi into
L
and EDTA-Bi complex due to this peak 370 nm
3
+
was vanished, further addition of Bi leads to reappearing of the absorbance band at 370 nm
3
+
(
Fig. 4a). The successive events of forming and breaking in complex of L-Bi with EDTA
3
+
indicates reversible nature. Therefore, L-Bi could be recyclable after treatment with EDTA. To
3
+
evaluate the selectivity of
out by adding competing ions to the solution of
condition. The obtained result reveals that, the absorbance band at 370 nm of L-Bi was not
affected by the presence of competing ions, which indicating that can be used as chromogenic
L with Bi over other metal ions, competing experiments were carried
3+
L
in the presence of Bi under the same
3
+
L
3+
sensor for selective detection of Bi (Fig. 4b,10S).

(b)
3
+
3+
Fig. 4 (a) Dynamic response of L-Bi complex with EDTA (b) Change in absorbance of L-Bi
in the presence of various interfering ions
3
.3 Fluorogenic Sensing ability of L
To gain an inside into the fluorescence properties of
L
towards various tested metal ions, the
spectral emission response was investigated in CH
the ligand exhibits a strong fluorescence at 435 nm upon excitation at 370 nm. But upon
interaction with Bi , the fluorescence intensity of
metal ions did not alter its emission intensity. The change in fluorescence spectral response of
3 2
CN:H O (85:15, v/v). As shown in Fig. 5a,
L
3
+
L
quenches completely while other tested
L
3
+
3+
with Bi shows
enhanced quenching (CHEQ) effect [28]. Upon excitation, electron transfer from the quinolone
unit to the bismuth moiety of the complex occurred due to which intermolecular * charge
transfer between quinolone units are broken and fluorescence quenching occurs. In order to study
L is highly selective to Bi . This can be explained on the basis of chelation
π-π
3+
the dynamic response of
L with Bi , the fluorescence spectral titration was carried out by adding
3+
3+
incremental addition of Bi to
L
. As shown in Fig. 5b, the incremental addition of Bi lead to a
study decrease in fluorescence intensity at 435 nm. The fluorescence quenching constant was
estimated by applying SV method using spectral titration data [22]. The estimated quenching
8
-1
constant was found to be 9.3×10 M (Fig. 5c). Further, the binding stoichiometry 2:1 ligand to
metal ration complex was verified by spectrofluorometric using Job’s plot (Fig. 5d). The LOD
and LOQ were calculated using the calibration curve obtained and found to be 0.057 µM and
0
.197 µM respectively (Fig. 11S).

(a)
(b)
3+
Fig. 5 Fluorescence response of L with (a) various metal ions (λ =370 nm) (b) Titration of Bi (c) SV
ex
plot (d) Job’s plot
3
+
The reversible binding nature of L-Bi complex was also verified by spectrofluorometric by
using a strong chelating agent of EDTA. The fluorescence can be regenerated by adding EDTA
3
+
3+
further can quench by adding Bi
(Fig. 6a). Further, the selectivity of L towards Bi in the
presence of other competing metal ions was also studied by this method. Results show that the
quenching of emission intensity did not affected by the presence of other tested interfering ions
3
+
(
Fig. 6b
, 12S). This supports the highest selectivity of L towards Bi even in the presence of
other metal ions.

(b)
3+
3+
Fig. 6 (a) Dynamic response of L-Bi complex with EDTA (b) Change in fluorescence of L-Bi in the
presence of various interfering ions.
3
.4 Binding Mechanism
3+
1
The binding mechanism of
L with Bi was studied by using H NMR and ESI mass analysis.
The ligand
L shows the methoxy signal appeared at 4.00 ppm and aromatic protons appeared at
3
+
7
.20 to 8.34 ppm (Fig. 7). An incremental addition of Bi does not affect the proton signals. But
3
+
there is nominal change in intensity was noticed after addition of 0.5 equivalence of Bi . This is
3
+
due to involvement of electron donor atoms such as O, N and S involved in binding with Bi .
Hence, methoxy and other aromatic signals are experienced a very weak shielding effect. This
3
+
3+
confirms formation of host-gest complex of L-Bi . Further, the ESI mass spectra of L-Bi
complex shows two major mass peaks (m/z) at 684.2031 and 758.2214 (Fig. 9S). The mass peak
at 684.2031 corresponds to 2 +Bi and 758.2214 corresponds to 2 +Bi+NO This also again
supports 2:1 stoichiometric complex formation between
L
L
3
3
+
L
and Bi .

1
3+
Fig. 7 H NMR spectral titration L with Bi in DMSO-d
6
3
.5 Theoretical Studies
3
+
In order to understand inside photo-physical properties of
theory calculations were carried out using Gaussian 09 program [29-32]. Based on experimental
findings on 2:1 stoichiometric complex formation. The energy minimized structure of and L-
L and L-Bi , the density functional
L
3
+
Bi complex were optimised by applying hybrid exchange correlation function using standard
basis set 6-311(d,p) for C, H, O, N and S atoms and the LANL2DZ basis set with effective core
3
+
potential for Bi atom. The significant energy minimised structure of
been shown in Fig. 8. The bond length between S---Bi, N---Bi and O---Bi were found to be
.834 Å, 2.429 Å, and 2.474 Å respectively. The interaction energy was calculated according to
L and L-Bi complex have
2
3
+
3+
L
the formula Eint = EL-Bi -2E -EBi and it found to be -664.80 kcal/mol which supports the
3
+
formation stable complex between
L
and Bi .Further, the frontier molecular orbital (FMO)
and L-Bi provides an information on the electronic properties. As shown in Fig.
, in case of , the highest occupied molecular orbital (HOMO) and lowest unoccupied
molecular orbital (LUMO) are located on throughout the molecular system with the energy gap
3
+
analysis of
L
9
L
3
+
of 3.76 eV, which supports the ligand-to ligand charge transfer. Whereas in the case of L-Bi
the HOMO orbital is mainly located on quinolone unit and the LUMO orbitals are mainly

3
+
located on Bi metal centre with an energy gap of 2.02 eV which supports the possible charge
transfer from ligand-to-metal (LMCT) during interaction. The decrease in band gap from 3.76
3
+
eV to 2.02 eV supports the lower the excitation energy of L-Bi as compared to L.
3
+
Fig. 8 DFT optimised structure of
L
and L-Bi complex
3+
Fig. 9 Frontier molecular orbital of L and L-Bi complex by DFT/B3LYP method
3
.6 Analytical Applications
3+
The practical utility of present sensor
L was studied to estimate the Bi concentration in
different water samples such as double distilled water, tap water and well water. In which the

3
+
standard amount to Bi was added under the different environmental condition and estimated
3
+
the Bi concentration using spectrophotometry and spectrofluorometric methods. Results are
summarised in the Table 1 which shows a good recovery between added and found
3+
3+
concentration of Bi . In addition, the sensor was applied for the determination of Bi
concentration in different pharmaceutical samples such as Bismatrol tablet and Pepto Bismol
syrup and the results are compared with ICP-OES analysis. As it is observed from Table 1, there
3
+
has a satisfactory agreement between the Bi estimated by
L and those determined with standard
ICP-OES method. The performance of present work was compared with previously reported in
the literature [33-39] (Table 1S.). It reveals that present sensor is highly selective compare to
many other sensors reported.
3+
Based on the observations in the sensing studies of Bi ions with
L
. In logic gate
3
+
implementation, Bi and
Table 2S). The gates operate in fluorescence and absorption modes when Bi . The output
defined as 1 and 0 corresponds to strong and weak fluorescence response. The simplest logic
L were used as inputs while absorption and emission signal as output
3
+
(
3
+
3+
gate NOT was achieved by giving metal ions (Bi ) as input 1 to the
producing an OFF response.
L, in the absence of Bi and
3
+
Table 1. Analysis of Bi in the different water systems and pharmaceutical samples using
L
3+
Bi Found by
Recovery
3
+
Bi Added
mg/L)
(mg /L)
(%)
Samples
(
UV-Vis
FL
UV-Vis
98.9
FL
1
2
1
2
1
2
0
0
0
0
0
0
9.89
19.74
9.76
9.91
99.1
DD water
Tap water
Well water
19.80
9.82
98.7
97.6
97.5
95.4
95.2
96.3
97.8
99.0
98.2
98.0
96.2
96.0
98.5
98.7
19.49
9.54
19.61
9.62
19.04
13.65
8.02
19.19
13.66
8.12
Tablet
Syrup
13.86*
8.2*
*Estimated by ICP-OES analysis

4
. Conclusion
3+
In summary, a new chromogenic and fluorogenic chemosensor
L for selective detection of Bi
have been successfully studied. The good selectivity and high sensitivity were revealed by a
series of UV-Vis and fluorescence spectral measurements. A good linear relationship was
observed between the absorbance and emission intensity with respect to the concentration of
3
+
3+
Bi . In addition, this sensor was proved to be a practical probe for the detection of Bi in
bismuth containing drug samples.
Acknowledgment
Authors are thankful to DST-VIT-FIST for NMR, SIF-VIT for GC-MS. Vellore Institute of
Technology, Vellore for providing SEED Grant other research facilities.
References
[1]
P.J. Sadler, H. Li, H. Sun, Coordination chemistry of metals in medicine: target sites for
bismuth, Coord. Chem. Rev. 185 (1999) 689-709.
[2]
H. Ashkenani, M.A. Taher, Application of a new ion-imprinted polymer for solid-phase
extraction of bismuth from various samples and its determination by ETAAS, Int. J.
Environ. Anal. Chem. 93 (2013) 1132-1145.
[3]
Y. Yamini, M. Chaloosi, H. Ebrahimzadeh, Solid phase extraction and graphite furnace
atomic absorption spectrometric determination of ultra trace amounts of bismuth in water
samples, Talanta. 56 (2002) 797-803.
[
4]
5]
G.G. Briand, N. Burford, Bismuth compounds and preparations with biological or
medicinal relevance, Chem. Rev. 99 (1999) 2601-2658.
[
F. Kang, M. Peng, Q. Zhang, J. Qiu, Abnormal anti-quenching and controllable multi-
3
+
3+
transitions of Bi luminescence by temperature in a yellow-emitting LuVO4: Bi
phosphor for UV-converted white LEDs, Chem. Eur. J. 20 (2014) 11522-11530.
[
6]
7]
H. Zhou, Q. Wang, Y. Jin, Temperature dependence of energy transfer in tunable white
3+
3+
light-emitting phosphor BaY
2 3
Si O10: Bi , Eu for near UV LEDs, J. Mater. Chem. C. 3
(2015) 11151-11162.
[
Z. Zhang, C. Zhou, L. Huang, X. Wang, Y. Qu, Y. Lai, J. Li, Synthesis of bismuth
sulfide/reduced graphene oxide composites and their electrochemical properties for

lithium ion batteries, Electrochim. Acta. 114 (2013) 88-94.
[
[
[
8]
D.J. Lowe, Adverse effects of bismuth subgallate. A further report from the Australian
Drug Evaluation Committee., Med. J. Aust. 2 (1974) 664-666.
9]
P. Lechat, R. Kisch, Influence of conditions of use on the neurotoxicity of bismuth salts
administered per os, Ann. Pharm. Fr., 44 (1988) 437-441.
10] H. Karami, M.F. Mousavi, Y. Yamini, M. Shamsipur, On-line preconcentration and
simultaneous determination of heavy metal ions by inductively coupled plasma-atomic
emission spectrometry, Anal. Chim. Acta. 509 (2004) 89-94.
[
11] A. Ulivo, I. Paolicchi, M. Onor, R. Zamboni, L. Lampugnani, Flame-in-gas-shield
miniature flame hydride atomizers for ultra trace element determination by chemical
vapor generation atomic fluorescence spectrometry, Spectrochim. Acta Part B At.
Spectrosc. 64 (2009) 48-55.
[
[
[
[
[
[
12] M.N.M. Reyes, M.L. Cervera, M. De la Guardia, Determination of total Sb, Se, Te, and Bi
and evaluation of their inorganic species in garlic by hydride-generation–atomic-
fluorescence spectrometry, Anal. Bioanal. Chem. 394 (2009) 1557-1562.
13] F. Fathirad, D. Afzali, A. Mostafavi, T. Shamspur, S. Fozooni, Fabrication of a new
carbon paste electrode modified with multi-walled carbon nanotube for stripping
voltammetric determination of bismuth (III), Electrochim. Acta. 103 (2013) 206-–210.
14] K. Tyszczuk-Rotko, I. Sadok, M. Barczak, M. Jabłońska-Czapla, A new voltammetric
sensor based on thiol-functionalized polysiloxane film modified by lead nanoparticles for
detection of Bi (III) ions, Electrochim. Acta. 208 (2016) 102-108.
15] N.S. Gadhari, B.J. Sanghavi, S.P. Karna, A.K. Srivastava, Potentiometric stripping
analysis of bismuth based on carbon paste electrode modified with cryptand [2.2. 1] and
multiwalled carbon nanotubes, Electrochim. Acta. 56 (2010) 627-635.
16] F. Cui, L. Wang, Y. Cui, Determination of bismuth in pharmaceutical products using
methyltriphenylphosphonium bromide as a molecular probe by resonance light scattering
technique, J. Pharm. Biomed. Anal. 43 (2007) 1033-1038.
17] M.S. Yang, J.H. Jin, X. An, F.L. Cui, Determination of bismuth in pharmaceutical
products by resonance light scattering using quaternary ammonium salts as molecular
probe, J. Anal. Chem. 69 (2014) 942-947.

[
18] M. Arvand, and M. Eskandarnejad, Development of a Highly Sensitive and Selective
Bismuth Optical Sensor Based on (2E,4E)-5-(2,4-Dinitrophenyl Amino)penta-2,4-dienal,
Anal. Letters, 41 (2008) 2877-2892.
[19] T. Alizadeh, N. Hamidi, M. R. Ganjali and P. Nourozi, Development of a highly selective
3
+
and sensitive electrochemical sensor for Bi determination based on nano-structured
bismuth-imprinted polymer modified carbon/carbon nanotube paste electrode, Sensors
Actuators B Chem., 245 (2017) 605-614
[
20] M.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, Gaussian 09, revision D. 01, (2009).
21] L.M. Reith, M. Himmelsbach, W. Schoefberger, G. Knör, Electronic spectra and
photochemical reactivity of bismuth corrole complexes, J. Photochem. Photobiol. A
Chem. 218 (2011) 247-253.
[
[
22] H.M.S. Kumar, R.S. Kunabenchi, J.S. Biradar, N.N. Math, J.S. Kadadevarmath, S.R.
Inamdar, Analysis of fluorescence quenching of new indole derivative by aniline using
Stern–Volmer plots, J. Lumin. 116 (2006) 35-42.
[23] A. Corsini, E.J. Billo, Metal chelates of 2-(2′-thienyl)-8-hydroxyquinoline: anomalous
ratios of formation constants, Can. J. Chem. 47 (1969) 4655-4659.
[
24] A. Jaafari, V. Ouzeau, M. Ely, F. Rodriguez, A. Yassar, J.J. Aaron, P. Benalloul, C.
Barthou, Fine-tuning the optical properties of aluminium and lithium quinolates through
oligothiophene substituents in 2-position, Synth. Met. 147 (2004) 175-182.
[
[
[
[
25] H.A. Benesi, J.H. Hildebrand, A Spectrophotometric Investigation of the Interaction of
Iodine With Aromatic Hydrocarbons, J. Am. Chem. Soc. 71 (1949) 2703-2707.
26] P. Job, Formation and stability of inorganic complexes in solution, Ann. Di Chim. Appl. 9
(1928) 113-203.
27] F. Allegrini, A.C. Olivieri, IUPAC-consistent approach to the limit of detection in partial
least-squares calibration, Anal. Chem. 86 (2014) 7858-7866.
28] S. Zhang, T. Yu, M. Sun, H. Yu, Z. Zhang, S. Wang, H. Jiang, Highly sensitive and
selective fluorescence detection of copper (II) ion based on multi-ligand metal chelation,
Talanta. 126 (2014) 185-190.
[29] C. Berrones-Reyes, B. M. Muñoz-Flores, A. M. Cantón-Diáz, M. A. Treto-Suárez, Páez-
D. Hernández, E. Schott, V.M. Jiménez-Pérez, Quantum chemical elucidation of the

turn-on luminescence mechanism in two new Schiff bases as selective chemosensors of
2
+
Zn : synthesis, theory and bioimaging applications. RSC Advances, 9 (2019) 30778-
0789.
30] M. A. Treto-Suárez, Y. Hidalgo-Rosa, E. E. Schott, X. Zarate and D. Paéz-Hernandéz,
3
[
3
+
Understanding the Selective Sensing Mechanism of Al Cation by a Chemical Sensor
Based on Schiff-base. A Theoretical Approach, The Journal of Physical Chem. A (2019)
6
970-6977.
[
[
[
[
[
31] X. Zarate, A. Rodriguez-Serrano, E. Schott and J. Tatchen, DFT/MRCI assessment of the
2
+
excited-state interplay in a coumarin-schiff Mg fluorescent sensor, J. of Computational
Chem. (2019).
32] M. A. Treto-Suárez, Y. Hidalgo-Rosa, E. Schott, X. Zarate and D. Páez-Hernández,
Radiative decay channel assessment to understand the sensing mechanism of a fluorescent
3
+
turn-on Al chemosensor, Int. J. of Quantum Chem. (2019).
33] I.M. El-Sewify, M.A. Shenashen, A. Shahat, H. Yamaguchi, M.M. Selim, M.M.H. Khalil,
3
+
S.A. El-Safty, Dual colorimetric and fluorometric monitoring of Bi ions in water using
supermicroporous Zr-MOFs chemosensors, J. Lumin. 198 (2018) 438–448.
34] S. Guang, G. Wei, Z. Yan, Y. Zhang, G. Zhao, R. Wu, H. Xu, A novel turn-on fluorescent
2
+
3+
probe for the multi-channel detection of Zn and Bi with different action mechanisms,
Analyst. 143 (2018) 449–457.
35] X. Gao, H. Zhao, X. Zhao, Z. Li, Z. Gao, Y. Wang, H. Huang, Aqueous phase sensing of
bismuth ion using fluorescent metal-organic framework, Sensors Actuators B Chem. 266
(2018) 323–328.
[
[
[
36] S.D. Chanda Kumari, Dibyendu Sain, Selective sensing of bismuth (III) ion by an 8-
hydroxyquinoline based tripodal receptor, Int. J. Res. Soc. Nat. Sci. 1 (2015) 1–9.
37] F.T. Lianwei Yu, Jianfei Tian, Bismuth ions selective fluorescent chemosensor based on
rhodamine-B, Asian J. Chem. 28 (2016) 287–290.
38] E. Zhang, P. Ju, Q. Li, X. Hou, H. Yang, X. Yang, Y. Zou, Y. Zhang, A novel rhodamine
3
+
6
G-based fluorescent and colorimetric probe for Bi : Synthesis, selectivity, sensitivity
and potential applications, Sensors Actuators B Chem. 260 (2018) 204–212.
[39] K. Ramasamy, S. Thambusamy, Dual emission and pH based naphthalimide derivative
3
+
fluorescent sensor for the detection of Bi , Sensors Actuators B Chem. 247 (2017) 632-

6
40.

Highlights
•
The 8-methoxy-2-(thiophen-2-yl) quinoline exhibits colorimetric, chromogenic and
3+
fluorogenic responses with Bi
•
•
•
L showed high selectivity and no interference from other test metal ions
5
-2
The detection limit and the association were 57 nM and 2.2 ×10 M respectively
3
+
1
The binding mechanism of L-Bi complex formation was established by H NMR, ESI-
mass and DFT studies.

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.