Zinc metal complex as a sensor for simultaneous detection of fluoride and HSO4- ions

Article abstract of DOI:10.1039/c5dt01063b

A Schiff base based tripodal receptor was synthesized and complexed with a zinc metal ion (n17) using a very easy single step process. The resulting complex was fully characterized by CHN and single crystal XRD. The real time application of the complex in

Full text of DOI:10.1039/c5dt01063b

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ZINC METAL COMPLEX AS SENSOR FOR
SIMULTANEOUS DETECTION OF FLUORIDE
AND HSO4 IONS
Cite this: DOI: 10.1039/x0xx00000x
-
Jasminder Singha, Manisha Yadavb, Ajnesh Singha, Narinder Singha*
Received 00th January 2012,
Accepted 00th January 2012
Schiff base based tripodal receptor was synthesized and was complexed with zinc metal ion
DOI: 10.1039/x0xx00000x
(
n17) using very easy single step process. The resulting complex was fully characterized by CHN
www.rsc.org/
and single crystal XRD. The real time application of the complex in aqueous media was devised
by preparing its ONP and their sensor activity was tested with various anions by observing
changes in fluorescence profile of n17. It was observed that ONP of n17 responded excellently
for fluoride and sulfate producing two different signals, with a detection limits of 4.84 × 10-12
M
and 5.67 × 10-9 M respectively, without having any interference from each other. The real time
application of the sensor was also tested using various samples collected from various daily
utility items and found to respond exceptionally well.
complexes in an aqueous solvent, for the obvious reason that
the water competes strongly for the hydrogen bonding sites16.
The selectivity of a chemo-sensor for an anionic species is
related to its discrepant ability to interact with the receptor site
through intermolecular hydrogen bonding (HB).
Introduction
Anionic receptors are an important research area1 because of the
considerable importance of anions in nature, as agricultural
fertilizers and industrial raw materials and their corresponding
environmental concerns2-7. The importance of anions can be
estimated from the fact that more than 70% of substrates and
cofactors involved in biological processes carry a net negative
charge8-10. Anions are profoundly involved in catalysis
reactions involving Carboxypeptidase, RNase, ATP synthases,
DNA polymerase, Citrate synthase etc11.Extremely high levels
of sulphates are toxic as it increases the acidity of
the atmosphere and form acid rain. So, anions are also of
important environmental concerns. Therefore, in recent times,
supra-molecular chemists have devoted considerable effort to
design systems capable of recognizing, sensing and transporting
negatively charged species. However, the detection of anionic
species is still a challenging task compared to cationic
determination. The reason behind this lies on the following: 1.
Anionic species donot have uniform shapes like cations12, 2. in
case of anionic species, electrostatic interactions13 are less
effective, 3. pH window14 is narrower( this is an important issue
in aqueous environment). Anion recognition in water is an
extremely challenging task for a number of reasons, the main
reason being that anions are strongly hydrated and any
complexation process that involves anion dehydration will have
to pay a large energy price by an overall increase in the
entropy15. Therefore, it is particularly difficult to develop an
anion recognition system that forms hydrogen bonded
The simultaneous detection of 2 anions is a rarely reported
case in the literature so far. In view of this, it is promising to
visualize the use of such a system in a range of sensing
applications as well as in other situations, such as anion
transport and purification17. Metal complex-based carriers can
have unique anion selectivity based on characteristic
coordination chemistry18. Therefore, recently metal complexes
have been used as anionic sensors as they have vacant binding
sites to bind specific anions or have pendant arms containing
anion receptor units. Transition metal complexes have their
own specific colors due to different electronic structures and
coordinating directly to anions results in alterations in their
electronic structures and hence color changes. These changes
can be measured quantitatively and qualitatively by different
spectroscopic techniques like UV-Visible and fluorimetry. In
the presented work, a poly-nuclear zinc complex was
developed. Zinc can function as active site of hydrolytic
enzymes, where it is ligated by hard donors (N or O). It has
long been recognized as an important co-factor in biological
molecules, either as a structural template in protein folding or
as a Lewis acid catalyst that can readily adopt the coordination
numbers 4, 5, or 619-21. The metal zinc was selected for the
complexation because of its importance in biological systems.
It is the only metal which appears in all enzyme classes
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including carbonic anhydrase and carboxypeptidase, which are coordination of central zinc metal atom (Zn2) is satisfied by six
essential for the processes of carbon dioxide (CO2) regulation bridged phenolate oxygen atoms. It is also interesting to note
and digestion of proteins, respectively22-24. Zinc is stored and that all the phenolate oxygen atoms are acting as bridged ligand
transferred in metallothioneins that are responsible for the between Zn (II) metal centres. The zinc atoms, Zn (1) and Zn
absorption of zinc .However, inadequate or excessive zinc (3) have slightly distorted octahedral coordinations.
intake can be harmful and excess zinc particularly impairs
copper absorption because metallothionein absorbs both
metals25. To be an effective anion receptor, the metal complex
had the combination of strong hydrogen bonding (O–H or N–
H) moieties and positively charged groups such as Zn+2. This
receptor simultaneously26 detected multiple anions in the
aqueous medium.
Results and Discussions
Synthesis of the sensor
The tripodal ligand (H3L1) was primed by the reaction of 2-
Hydroxy-5-nitrobenzaldehyde with Tris (2-aminoethyl) amine
in methanol, with refluxing of one and half hour with zinc
perchlorate as catalyst. H3L1 thus formed was copiously
1
characterized with H NMR, 13C NMR (Figure S1 & S2) and
CHN analysis. H3L1 was further used for complexation with
zinc metal ion using zinc acetate in acetonitrile, carried out at
increased temperature on water bath for about 2 hrs. Solid
separated out was collected and washed with small volume of
acetonitrile; the separated brownish yellow product was
recrystallized in HPLC grade acetonitrile by slow evaporation
method and verified the structure using single crystal XRD
data.
Figure 1: ORTEP diagram of compound n17 with 40% probability thermal
ellipsoids and the atom-numbering scheme (hydrogen atoms and solvent
molecules are removed for clarity).
The maximum deviation from the regular octahedral geometry
is 15.86o and 16.72o in cis-N-Zn-N [N(4)-Zn(1)-N(2)=105.86o,
N(11)-Zn(3)-N(13) = 106.76o ] angles while in trans N/O-Zn-
N/O angles, maximum deviation is of 22.39o and 24.29o
[(N(13)-Zn(3)-O(13)=155.71o,
N(4)-Zn(1)-O(4)=157.61(6)]
respectively in Zn(1) and Zn (2). In case of central Zn (2) atom,
the extent of distortion is less as compared to other two Zn (II)
atoms. The average Zn-N, Zn-O distances and O/N-Zn-O/N
bond angles around Zn(II) octahedrons are comparable to other
similar reported Zn(II) complexes.34 The selected bond lengths
and bond angles are given in supporting information as Table 2.
When crystal packing is viewed down a –axis, the complex
moieties are arranged in form of set of two complex moieties
packed like bricks in a wall (as shown in Figure 2). The
different moieties are held together by weak C-H…N and C-
H…O interactions (hydrogen bonding interactions are given in
supporting information as Table 3). Most of oxygen atoms of
the nitro groups are involved in hydrogen bonding interactions
with neighbouring moieties. The solvent molecules of
crystallization (acetonitrile) are providing more robustness to
the crystal structure by hydrogen bonding and C-H…
interactions (C55-H55C…Cg=3.061Å and angle C55-
H55C…Cg=127.24o where Cg is centroid of ring defined by
atoms C1-C6) with metal complex moieties. To further support
the interaction of zinc metal ion with the receptor, IR studies
were carried out. It is clearly visible from the IR spectra of
receptor and complex of metal ion with receptor that zinc metal
ion interacts with –C=N of the complex leading to shift in the
schiff’s base peak from 1627 cm-1 to 1608 cm-1 (Figure S3).
Scheme1: synthesis of the ligand H3L1
Structure Determination of Zn complex of H3L1 (n17) using
single crystal XRD
The structure of complex n17 was unambiguously determined
by single crystal X-ray determination. X-ray structure
determination revealed that the complex n17 crystallizes in the
triclinic crystal system ( ) and the asymmetric unit consists
of one neutral complex [Zn3(C18H24N7O6)2]/ [Zn3(L1)2] and four
acetonitrile molecules as solvent of crystallization, out of these
two are disordered. The molecular structure of n17 is shown in
Figure 1
.
The complex n17 is a trinulear Zn(II) complex where three
Zn(II) metal ions are crystallographically different. All metal
centres are octahedrally surrounded by N and O donor atoms
originating from two tripodal ligands (H3L1). In outer Zn (II)
metal ions octahedral coordination is completed by three sp2
hybridized N atoms and three phenolate O atoms while
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Figure 3: Emission profile of n17 in 1: 99, DMF: water system and in pure DMF
system.
Particle size of n17 was analysed using DLS (Dynamic Light
Scattering) and of nano-aggregates of n17 with a narrow size
distribution of ranging from 15-20 nm (Figure 4a). The particle
size distribution of the prepared nano-aggregates was also
confirmed using transmission electron microscopy (TEM)
(Figure 4b). The emission profile of prepared ONPs were also
tested over a period of 8 days and it was observed that prepared
ONPs show nearly same fluorescence profile, without much
decay in the fluorescence (Figure S5).
Figure 2: Packing diagram of compound n17 along a–axis. Metal canters are
shown with help of green polyhedral
Formation of ONP of Zinc complex of H3L1
Organic compounds suspended in a fine particle size ranging
from 10 nm to 1 M in aqueous medium are termed as organic
nanoparticles35. Various methods of ONP formation has been
developed and explored due to their developing demands in
widespread fields of modern world like electronics, photonics,
conducting materials, sensors, etc. Various physio-chemical
parameters and properties like binding sites, solubility of
compound and environmental factors such as pH, temperature,
and salt strength36 of the organic compound are considered for
development and workability of ONP in various applications.
Single step re-precipitation method developed by Fessi37 due to
its ease, economical and reproducibility is being implemented
for formation of ONP of n17 instead of other two steps
techniques. In re-precipitation approach, organic compound
solution prepared in organic solvent (1mL) is injected slowly to
the bulk of aqueous medium (99 mL) without prior
emulsification. Influence of water on photophysical properties
of the complex was studied using fluorescence spectroscopy.
Emission spectrum of n17 was having a broad peak at 430 nm
with DMF as a solvent, while a solvatochromic change in the
peak was observed as peak shifted bathochromically to around
470 nm, when water (1:99) was taken as solvent (Figure 3).
The ratio was optimized as no ONP were formed in
concentration less than this or settled down in concentration
more than this. Shift in the fluorescence can be attributed to the
reason that two types of aggrgates are formed during
nanoparticle formation ‘J’ type and ‘H’ type. Two chromophore
units when get parallel aligned in aggragtes or nanoparticles
causing formation of two new exciton bands. Transition only to
lower exciton band leads to red shift in the spectra and blue
shift in case of transition to higher exciton band.38
Figure 4: (a) Characterization of ONPs of n17 with DLS and (b) Transmission
electron microscopy (TEM)
Recognition properties
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The anion binding ability of n17 was evaluated by observing
the changes in emission profile of n17 caused by addition (100
M) of tetrabutylammonium salts of various anions (F-, Cl-, Br-
-
-
-
, I-, HSO4 , ClO4 , PO42-, CH3COO-, NO3 , CN-)to prepared
ONPs of n17. It was noticed that most of the anions did not
cause any significant change in the emission spectrum of the
-
n17 except Fluoride and HSO4
(
Figure 5), when excited at a
-
wavelength of 300 nm. The addition of HSO4 caused
hypsochromic shift in the fluorescence spectra of the complex
i.e. fluorescence peak got shifted to 370 nm which was earlier
-
at 470 nm. The changes caused by addition of HSO4 ions can
be detected chromogenically even with the naked eye as it leads
to change from yellow to colourless (Figure 6). The same
behaviour was observed with emission photography (Figure
S4).
However, there was an evident and sharp increase in the
fluorescence intensity upon addition of F- ions. The spectral
profile of n17 showed 2 folds of enhancement on addition of
100 M of fluoride ions. It is quite evident from the spectral
Figure 5: Fluorescence emission spectra of the receptor n17 upon addition of a
-
-
-
particular anion (F-, Cl-, Br-, I -, HSO4 , ClO4 , PO42-, CH3COO-, NO3 , CN-) of
tetrabutylammonium salts
-
profile changes caused by HSO4 and F- that the receptor binds
with both in a different manner can be attributed to different
binding sites for both the anions i.e. fluoride ions get
coordinated with in the cavity formed by the complex, leading
to separation in the two aromatic nitro rings causing
cancellation of photo induced electron transfer (PET)39,
eventually resulting in enhancement in the fluorescence
-
intensity at same wavelength. On the other hand HSO4 ions
gets coordinated with the metal ions of the complex leading to
modulation of internal charge transfer40, which in turn leads to
shift in the fluorescence (Figure 5) as well as in UV-Visible
absorption profiles (Figure S6) i.e. n17 had two peaks at 310
and 422 nm respectively. On addition of fluoride only peak at
Figure 6: Chromogenic naked eye detection of HSO4- ions using ONP’s of n17
-
422 nm showed the enhancement, while on adding HSO4 ions
the peak gets shifted to 373 nm. The peak at 422 nm can be
attributed to charge transfer band between –OH and –N=C
groups.41This assignment has been concluded on the basis that
both the parents i.e. aldehyde and amine lack this band and this
band appears only upon –C=N linkage.42 Further, no change in
peak position on addition of fluoride ions confirms the photo
induced electron transfer mechanism, as being an excited state
phenomenon would not be visible in UV-Visible spectrum.43
To explore more about the binding affinity of the complex as a
-
receptor for HSO4 and F-, fluorescence titration was carried out
-
separately for both Fluoride and HSO4 , by subsequent
additions 10 mL of 5 mM solution of the respective anion to a
total volume of 5 mL. The fluorescence intensity of n17
increased gradually with each successive addition of fluoride
-
ions (Figure 7 a), while in case of HSO4 ions, initially there is
slight change in the spectra initially up to 40 mL but later the
fluorescence peak shifts from 470 nm to 370 nm and increases
-
On the contrary, addition of HSO4 ions caused modulation of
internal charge transfer, causing the shift in both fluorescence
and UV-Visible spectra (ICT is a ground state phenomenon).44
-
gradually with each successive addition of HSO4 ions (Figure
8 a). The calibration curves for both the anions were plotted on
the basis of changes observed in spectral profile of n17 on
successive addition of respective anions. It was observed that
calibration plot of fluoride ions showed excellent linear
regression upto 200 nM with r2 value of 0.9946 and a detection
limit of 4.84 × 10-12 M (Figure 7 b).
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Figure 7: (a) Changes in the fluorescence spectrum of n17 after the subsequent
additions of fluoride ion in ONP of
1(b) Calibration plot for successive addition of
Fluoride ion to ONP of n17
Figure 9: Calibration plot of interference studies of (a) fluoride ions in presence
HSO4- ions (b) HSO4- ions in presence of fluoride ions.
-
While calibration plot for HSO4 ions showed a linear
regression range from 35-200 nM with r2 value of 0.9907 and a
detection limit of 5.67 × 10-9 M (Figure 8b).
Recyclability
The recyclability of complex was tested by treating it with 0.1
mM of Na2CO3. The complex on treatment with fluoride and
hydrogen sulphate ions showed a remarkable increase in
fluorescence intensity and shift in fluorescence peak
respectively. After respective treatment of anions a solution of
0.1 mM Na2CO3 was added to the solution under constant
sonication. The resultant mixture after addition of 1 equivalent
of Na2CO3 was tested for its fluorescence intensity. It is quite
evident from the fluorescence obtained that Na2CO3 was able to
remove the anions from the complex generating the original
fluorescence profile. The resulting solution was again exposed
to respective anions producing their respective signals, with no
-
Figure 8: (a) Titration of HSO4 .Changes in the fluorescence spectrum of the much loss in the intensity (Figure 11). The whole process can
-
complex after subsequent additions of HSO4 (0–200 μL) (b) Calibration plot for
be used for recycling of the receptor and ensures its
successive addition of HSO4- ion in ONP of n17
reusability.46
Simultaneous Detection
To explore the use of proposed sensor for simultaneous
-
determination of HSO4 and F- ion in same solution,
experiments were performed. Calibration plot was again plotted
for the same by successive additions of one (0-200 nM) and
keeping the concentration of other constant (100 nM) in ONP
solution of n17, to check their possible interference in each
other’s determination. It was observed that the slope of
-
calibration plot 5.6694 and 0.9628 for HSO4 and F- ion
respectively remains the same (Figure 9 a & 9 b) as was
observed in determination of each anion independently i.e.
5.6882 and 0.9605 (Figure 7 b & 8 b). This concluded that the
Figure 11: Recovery test of n17 upon addition of fluoride ions
sensor can be used for determination of both the anions
The proposed sensor was also compared with the reported
sensors for fluoride and HSO4 ions (Table 1). It is quite
evident from the comparison that the proposed sensor offers a
considerable enhancement in detection limit and allows the
determination of two analytes simultaneously.
simultaneously without any interference from each other in
aqueous samples. The binding constant and stoichiometry of
the complexes was calculated using Lehrer–Chipman
equation.45 Plotted curves (Figure S7 & S8) clearly show a
-
-
stoichiometry of 10:1 for fluoride and 2:1 for HSO4 ions,
having a binding constant of 4.2 × 104 M-1 and 2.5 × 104 M-1
respectively. Such high molecularity can be explained on the
basis that organic nanoparticles have number of exposed sites
for interaction with analyte of interest.
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Table 1: Comparison of proposed sensor with the reported sensors in the
literature
Table 2: Estimated values of fluoride and sulfate ions in various items of
daily utilities, calculated using respective calibration plots.
S.
No.
Authors
Solvent
System
DMSO-Water
Simultaneou
s Studies
F- ions
Detectio
n Limit
50 µg
mL−1
-
Ref.
47
S.
No
1.
2
Sample Name
Estimated
Fluoride (nM)
Estimated
Sulfate (nM)
169.37 ± 0.25
134.04 ± 0.21
220.27 ± 0.33
K. V. Gothelf
et al
L. Weber et
al
M. G.
Davidson et
al
D. Chellappa
et al
Z. Bai et al
N. Singh et al
Bodywash (B1)
Bodywash (B2)
Toothpaste (T1)
-
-
1.
2.
Cyclohexane
& THF
Chloroform
F- ions
F- ions
48
3
215.52 ± 0.2
-
49
4
5
6
7
Toothpaste (T2)
80.24 ± 0.3
190.73 ± 0.18
153.53 ± 0.17
107.98 ± 0.2
46.86 ± 0.2
3.
Dentifrices waste (F1)
Dentifrices waste (F2)
Dentifrices waste (F3)
-
-
-
Acetonitrile-
Water
Water
Water
F- ions
8.52 nM
50
4.
5.
F- ions
580 nM
4.84 pM
& 5.67
nM
51
Propos
ed
Sensor
52
F- ions &
-
6.
HSO4 ions
F- ions &
-
Conclusions
A. Mallick et
al
A. Wu et al
A. Kuwar et
al
Acetonitrile-
Water (5:1)
Methanol
Water
7.
8.
9.
-
HSO4 ions
-
HSO4 ions
1.39 mM
0.25 mM
53
54
A new receptor n17 i.e. Zn complex of tripodal ligand was
formed and characterized using various techniques like H, 13C
-
1
HSO4 ions
-
NMR and mass spectroscopy. The structure of the complex was
determined using single crystal XRD. To use the prepared
complex in real time application ONP of the complex were
prepared and found their use in simultaneous and effective
10.
11.
N. Kaur et al
N. Kaur et al
Water
Water
HSO4 ions
37 mM
1.12 mM
55
56
-
HSO4 ions
Real Sample Analysis
detection of HSO4 and F- ions in the real time samples in
−
Sulphate and fluoride are found in various daily practice
products like body wash, shampoo, toothpaste and various oral
care products and are commercially available in market. Some
such products were identified and tested using the proposed
sensor (Figure 10). Thus obtained results were compared with
the calibration plot for estimation of the concentration of
sulphate and fluoride present in the samples (Table 2). The
proposed sensor performed exceptionally well with all the
samples showing substantial signal enrichment in case of
fluoride and alteration in spectral maxima for sulfate, it was
quite discernible over here that proposed sensor was able to
detect amount of sulfate and fluoride present together in various
commercially available samples.
aqueous media. The results were verified using various
commercial samples from our daily chores and calibration
curve plotted in the experiment is being used for determination
of their concentration and concluded that the proposed sensor
can be used to determine both the anions in same solution with
utmost ease and accuracy without any interference and without
any pre-treatment of the solution.
Experimental
All precursor chemicals for the reaction scheme were purchased
from Aldrich and SD Fine, India. All solvents were dried by
standard methods. Unless otherwise specified, chemicals were
purchased from commercial suppliers and used without further
purification. 1H and 13C NMR spectra were recorded on
Avance-II (Bruker) instrument, which operated at 400 MHz for
1H NMR and 100 MHz for 13C NMR (chemical shifts are
expressed in ppm). The fluorescence measurements were
performed on a Perkin Elmer LS55 Fluorescence. IR spectra of
H3L1 and n17 were recorded using a Bruker Tensor 27
spectrometer with KBr discs. IR spectra is used to confirm the
bonding of metal ion with –C=N of H3L1 to form n17. The
TEM images were recorded with Hitachi (H-7500) instrument
worked at 120 kV. A 400-mesh formvar carbon-coated copper
grid was used for sample preparation. This instrument had the
resolution of 0.36 nm (point to point) with 40-120 kV operating
voltage. The particle size of nano-aggregates was determined
with Dynamic Light Scattering (DLS) using external probe
feature of Metrohm Microtrac Ultra Nanotrac Particle Size
Analyzer.
-
Figure 10: Real sample analysis of fluoride and HSO4 ions in various items of
Synthesis of (H3L1)
daily utility
H3L1 was prepared from Tris(2-aminoethyl)amine (146 mg, 1.0
mmol) was stirred with 5-nitro-2-hydroxy benzlaldehyde
(534.4 mg, 3.2 mmol) in the presence of traces of zinc
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perchlorate as catalyst in methanol27, 28. The color of the Anion Binding Studies
solution changed immediately to yellow and precipitate
The anion binding affinity of the n17 was determined by
observing the changes in the photo-physical properties of ONPs
in the presence of different anions. The binding studies were
performed at 25±1ºC, and the solutions were shaken for a
sufficient time before recording the spectra. The working
concentration of ONPs for all experiments was kept 0.01 M.
For anion binding assay 100 L of tetrabutylammonium salts
(10 M) of 10 different anions were selected namely, F-, Cl-,
separated out in quantitative yield. These precipitates were
filtered, washed with methanol and dried. Yield = 90.2 %
º
(535.37 mg). mp = 197 C. C27H27N7O9: C, 54.64; H, 4.59; N,
16.52. Found: C, 54.58; H, 5.51; N, 16.61.
Synthesis of Zn acetate+ ACN+ H3L1 (n17)
An acetonitrile solution of Zn acetate (27.76 mg, 1.5 eq) was
added to a solution of H3L1 (50mg, 1 eq) in acetonitrile. The
solution was refluxed for two hours during which the color of
the solution changed slightly. After the completion of reaction,
the solution was filtered and kept for crystallization by slow
evaporation. Brownish-yellow colored crystals were obtained
having yield of 92.43% (36.22 mg). The crystal structure was
obtained by single x-ray crystallography.
-
-
Br-, I-, HSO42-, ClO4 , PO42-, CH3COO-, NO3 , CN- in aqueous
medium and changes in the photo-physical properties of ONP
n17 were determined by Fluorescence spectroscopy. Further,
-
simultaneous detection of the 2 anions (F- and HSO4 ) was
carried out so as to determine any interference caused by the 1
ion in the detection of the other anion by adding 100 L of one
ion as interferent anion and doing successive addition of 10 L
as anion being determined. The effect of ionic strength was
explored by recording the spectra at different concentration of
tetrabutylammonium perchlorate (0-100 equivalent). The pH
titrations were accomplished to comprehend the effect of pH on
X-Ray Crystallography
The X-ray diffraction data for n17 were collected on a Bruker
X8 APEX II KAPPA CCD diffractometer at 293 K using
graphite monochromatized Mo-K radiation ( = 0.71073 Å).
The crystals were positioned at 50 mm from the CCD and the
the recognition profile of ONP n17
.
diffraction spots were measured using a counting time of 10 s. Real Sample Analysis
Data reduction and multi-scan absorption were carried out
Real time application of the proposed sensor was tested using
using the APEX II program suite (Bruker, 2007). The structures
were solved by direct methods with the SIR97 program29 and
refined using full-matrix least squares with SHELXL-97.30
Anisotropic thermal parameters were used for all non-H-atoms.
The hydrogen atoms of C–H groups were with isotropic
parameters equivalent to 1.2 times those of the atom to which
they were attached. All other calculations were performed using
the programs WinGX31 and PARST.32 The molecular diagrams
were drawn with DIAMOND.33 Final R-values together with
selected refinement details are given in supporting information
as Table 1.
-
commercially available samples of HSO4 and F- ions i.e. B1
and B2 are the commercially available body wash (0.5g in 100
mL water) having sodium lauryl sulfate as their major
ingredient, T1 and T2 are the two major toothpaste brands
having both sulfate and fluoride in them (0.250 g in 100 mL of
water) in form of sodium fluoride and sodium lauryl sulfate and
F1-3 are taken from dentifrices waste taken from different
dentists, which is quite rich in fluoride content and is used
without further dilution. All samples were taken in aqueous
form.
Notes and References
Preparation of Organic Nanoparticles of n17 (ONP 1)
a
Chemistry Department, Indian Institute of Technology Ropar (IIT
The organic nano particles (ONP) of n17 were prepared by re-
precipitation single step method. Solution of the ligand was
Ropar),Rupnagar, Panjab, India, 140001.
b
Centre for Converging Technologies, University of Rajasthan, Jaipur,
dissolved in 1 mL DMF with various concentrations. The India, 302004.
* nsingh@iitrpr.ac.in
working solution was slowly injected into water (100 mL)
under sonication and size of the ONP formed were analyzed
using DLS probe after every injection. It was observed after
using various concentrations of ligand that concentration
having 0.1mM of complex in 1.0 ml of DMF gave the optimum
sized ONP. Prepared ONP were sonicated again for 10-15
minutes, making sure the temperature of the solution containing
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Table of Contents
Complex of tripodal receptor with zinc metal ion (ONPs) were used for simultaneous determination of F-
-
and HSO4 ions.