Aluminum(III) induced green luminescence for naked eye detection: Experimental and computational studies

Article abstract of DOI:10.1016/j.ica.2013.11.038

Al(III) has extensive use in modern day life, however excess Al(III) can induce several health hazards, leading to Alzheimer's or Parkinson's diseases. So, easy determination of Al(III) in biological samples is highly relevent. A group of three probes, (4

Full text of DOI:10.1016/j.ica.2013.11.038

Inorganica Chimica Acta 412 (2014) 67–72
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Inorganica Chimica Acta
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Aluminum(III) induced green luminescence for naked eye detection:
Experimental and computational studies
a
a
a
b
Sisir Lohar , Animesh Sahana , Arnab Banerjee , Amarnath Chattopadhyay ,
b
c,
⇑
a,
⇑
Subhra Kanti Mukhopadhyay , Jesús Sanmartín Matalobos , Debasis Das
a
Department of Chemistry, The University of Burdwan, Burdwan 713104, West Bengal, India
Department of Microbiology, The University of Burdwan, Burdwan, West Bengal, India
Departamento de Química Inorgánica, Facultade de Química, Avda. Das Ciencias s/n, 15782 Santiago de Compostela, Spain
b
c
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 2 July 2013
Received in revised form 28 November 2013
Accepted 30 November 2013
Available online 16 December 2013
Al(III) has extensive use in modern day life, however excess Al(III) can induce several health hazards,
leading to Alzheimer’s or Parkinson’s diseases. So, easy determination of Al(III) in biological samples is
highly relevent.
A group of three probes, (4E)-4-(2-hydroxybenzylideneamino)-1,2-dihydro-2,3-
dimethyl-1-phenylpyrazol-5-one (APSAL), 2-((Z)-(quinolin-8-ylimino)methyl) phenol (AQSAL) and
(
(
4E)-4-((2-hydroxynaphthalen-1-yl)methyleneamino)-1,2-dihydro-2,3-dimethyl-1-phenylpyrazol-5-one
HNAP) have been used to dicriminate Al from other biologically relevent and common metal ions at
3
+
Keywords:
Luminescence
Aluminum(III)
Naked eye detection
DFT and TD-DFT studies
physiological pH. Although the synthesis of APSAL and HNAP have been reported earlier, their interaction
3
+
3+
with Al have not been studied earlier. Interestingly, in presence of Al , HNAP generates green lumines-
cence, which has been highly useful for its naked eye detection while the other two generate pale yellow
4
ꢁ1/2
coloration having no luminescence. The binding constant (6.4 ꢀ 10 M
) and lowest detection limit
ꢁ8
3+
3+
(
1.8 ꢀ 10 M) of HNAP for Al are higher than the rest two in the series. The higher Al detection effi-
ciency of HNAP has been rationalised from DFT and TD-DFT studies. The HOMO–LUMO energy gap
3
+
reduces to the maximum extent in HNAP-Al complex compared to free HNAP in the series.
Ó 2013 Elsevier B.V. All rights reserved.
1
. Introduction
structural variations to achieve trace level naked eye detection.
Two of them have been synthesized by condensing salicylaldehyde
with 4-aminoantipyrine (APSAL) [21] and 8-aminoquinoline sepa-
rately (AQSAL) while the third one using 2-hydroxy-1-naphthalde-
hyde and 4-aminoantipyrine (HNAP) [22] Studies on the already
reported probe, obtained by condensing 2-hydroxy-1-naphthalde-
hyde with 8-aminoquinoline (HNAQ) is excluded [23] All three
Metal ion selective sensors have found significant importance in
chemical, biological, and environmental processes [1–3]. Very re-
cently, several fluorescent assays have been successfully developed
for biological applications [4–7]. Aluminum, the third abundant
element in the lithosphere is extensively used in modern life, viz.
food packaging, cookware, drinking water supplies, antiperspi-
rants, deodorants, bleached flour, antacids as well as manufactur-
ing of cars and computers [8–10]. Excess aluminum, however,
can induce several health hazards leading to Alzheimer’s [11]
and Parkinson’s diseases [12]. Therefore, determination of Al in
environmental and biological samples has immense importance
for human health. Recently, several Al3 sensors have been re-
ported [13–17], including some quinoline based sensors [18]. How-
ever, naked eye luminescence detection of Al3 is still rare [19]. We
are actively engaged to develop low cost improved methodology
for easy determination of Al3 using selective fluorescent and col-
orimetric probes [20]. Herein, we have systematically studied three
3
+
probes can selectively discriminate Al from other common and
biologically relevant metal ions. In presence of Al3+, emission
wavelength of APSAL and HNAP undergo blue shift while HNAP
shows green luminescence, useful for naked eye detection. Due
to presence of hydrophilic –OH functionality, all the probes operate
3
+
3
+
in aqueous medium enabling intracellular Al imaging.
+
+
2. Results and discussion
+
The proton has always acted as a significant competitor of the
metal ion, so pH optimization is necessary to figure out the maxi-
mum efficiency of the probe for Al(III). Figs. S1–S3 (Supporting
information, henceforth ESI) clearly demonstrate that pH 7.0 to
3
+
new Al
selective fluorescent probes by engineering their
8
.5 is suitable for the entire study. Emission intensity of APSAL,
⇑
Corresponding authors. Tel.: +91 342 2533913; fax: +91 342 2530452 (D. Das).
E-mail address: ddas100in@yahoo.com (D. Das).
AQSAL and HNAP remain nearly unchanged upon addition of
Al at pH below 4.5. At lower pH, protonation of the hydroxyl
3
+
0
020-1693/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.ica.2013.11.038

6
8
S. Lohar et al. / Inorganica Chimica Acta 412 (2014) 67–72
group may reduce its Al3+ binding ability whereas at alkaline pH,
precipitation of Al(OH) occurs. This is reflected in our experiments
3
where we have observed the maximum emission intensity at pH
ranging 7.0–8.5. Therefore, entire studies have been carried out
in HEPES buffer solution at pH 7.4. Figs. S4–S6 (ESI) give the
absorption, excitation and emission spectra of APSAL, AQSAL and
HNAP. All three probes can selectively discriminate Al3 from other
+
2
+
2+
common and biologically relevant metal ions such as Mg , Zn
,
2
+
2+
3+
2+
2+
2+
3+
2+
2+
2+
Cd , Fe , Cr , Hg , Mn , Cu , Fe , Co , Pb and Ni . The
emission spectrum of APSAL (kex = 350 nm, kem = 505 nm) under-
3+
goes 34 nm blue shift to 471 nm in presence of Al and increases
gradually with increasing Al3 concentration (quantum yield
changes from 0.016 ± 0.001 to 0.061 ± 0.002) (Fig. S7, ESI). For
other cations, this phenomenon is not observed (Fig. S8, ESI). Job’s
plot (Fig. S9, ESI) shows the probe to Al(III) stoichiometry as 2:1 for
+
3
+
the [APSAL-Al ] complex, also corroborated from its ESI-TOF
MS(+) mass spectrum (Fig. S10).
The emission spectrum of AQSAL (kex = 330 nm, kem = 450 nm)
shows a shoulder at 380 nm, in addition to the principal emission
peak, both of which increases upon gradual addition of Al3+ (quan-
tum yield changes from 0.010 ± 0.001 to 0.057 ± 0.001) (Fig. S11).
Other common cations (Fig. S12) failed to do so. The composition
Fig. 2. Changes of absorbance of HNAP (10
0, 15, 20, 30, 40, 50, 60, 80, 100, 150, 200
(methanol/water = 3/7, v/v, pH 7.4).
l
M) upon gradual addition of Al3+ (1, 5,
lM) in HEPES buffered (0.1 M) solution
1
3
+
3+
of the [AQSAL-Al ] complex is 2:1 (AQSAL: Al , Fig. S13). ESI-
TOF MS (+) data of the adduct (Fig. S14) supports the composition.
3
+
In presence of Al , the emission peak of HNAP (kex = 380 nm,
k
em = 510 nm) undergoes 49 nm blue shift, the intensity of which
restricting the rotation around the C@N bond, and is responsible
for fluorescence enhancement [26].
3+
gradually increases with increasing Al concentration (quantum
yield changes from 0.013 to 0.09) (Fig. 1). This blue shift of the
emission band is not observed with other cations (Fig. S15, ESI).
Job’s plot (Fig. S16, ESI) and ESI-TOF MS (+) data (Fig. S17, ESI) indi-
cate 2:1stoichiometry of the [HNAP-Al3 ] complex.
UV–Vis spectra have been recorded in HEPES buffered (0.1 M)
solution (methanol/water = 3/7, v/v, pH 7.4). APSAL shows a peak
at 346 nm along with two shoulders at 316 and 300 nm (Fig. S21,
+
3+
ESI). Upon addition of Al , the absorbance at 346 nm decreases
The detection limits are estimated from the fluorescence titra-
tion data based on a reported and broadly used method [24,25].
The fluorescence titration experiment for APSAL (at 471 nm), AQ-
SAL (450 nm) and HNAP (at 461 nm) have been normalized be-
sharply while that of 316 nm increases to some extent. The inten-
sity of a new peak that appears at 390 nm, gradually increases with
3
+
increasing Al concentration. For AQSAL, 335 nm peak decreases
sharply with appearance of two new peaks at 271 and 413 nm
(Fig. S22, ESI). HNAP shows peaks at 381, 334 and 321 nm
3+
tween the minimum (0.0 equivalent Al ) and the maximum
intensities. A linear regression curve is then fitted to the normal-
ized fluorescence intensity data, and the point at which the line
crosses the ordinate axis corresponds to its detection limit.
3
+
(Fig. 2). In presence of Al , the absorbance at 381 nm decreases
sharply along with disappearance of two other peaks, viz. 334
and 321 nm. On the other hand, several new peaks viz. 343 and
417 nm along with two shoulders at 396 and 440 nm have ap-
ꢁ7
APSAL, AQSAL and HNAP can detect as low as 5 ꢀ 10 M,
ꢁ
7
ꢁ8
3+
3+
5
.8 ꢀ 10 M and 1.8 ꢀ 10 M Al (Figs. S18–S20, ESI). Chelation
peared. All the three probes allow to detect Al by naked eye, how-
3
+
3+
of the probes with Al inhibits the cis–trans inter-conversion by
ever, [HNAP-Al ] complex shows luminescence (Fig. 3).
3
+
The binding constants of different probes for Al are deter-
mined using the following Benesi–Hildebrand equation [27]
(Figs. S23–S25, ESI).
n
F
lim ꢁ F
0
=F
X
ꢁ F
0
¼ 1 þ ð1=K½Cꢂ Þ
ð1Þ
where F
absence of Al , at an intermediate Al concentration, and at a con-
0
, F
x
, and Flim are the emission intensities of the probes in
3
+
3+
3
+
centration of complete interaction with Al respectively. K is the
3
+
binding constant, C is the concentration of Al and n is the number
3
+
of Al ion bound per probe molecule (here, n = 1/2). The value of K,
3
2
obtained from the slope are 1.06 ꢀ 10 , 8.3 ꢀ 10
and
4
ꢁ1/2
6
.4 ꢀ 10 M
for APSAL, AQSAL and HNAP respectively.
Table 1 shows different photo-physical properties of the probes
that allow a quick comparison.
The selectivity of different probes (APSAL, AQSAL and HNAP)
3
+
for Al over other common cations is examined (Figs. S26, S27,
ESI and Fig. 4). No significant interference is observed. Slight inter-
2
+
ꢁ
ference from Cu has been eliminated using SCN as masking
3
+
agent. The excitation spectrum of HNAP-Al complex lies mostly
in the visible region, which might be responsible for green lumi-
nescence (Fig. S27, ESI). Fig. 5 clearly shows that the probes are
easily permeable to all types of tested living cells and apparently
harmless (as the cells remain alive even after a considerable time
Fig. 1. Fluorescence spectral changes of HNAP (10
lM) in HEPES buffered (0.1 M)
solution (methanol/water = 3:7, v/v, pH 7.4). Upon addition of different concentra-
tion of Al3 (bottom: [Al ] = 0, top: [Al ] = 200
lM), kex = 380 nm, kem = 461 nm.
+
3+
3+

S. Lohar et al. / Inorganica Chimica Acta 412 (2014) 67–72
69
Fig. 4. Relative emission intensities of [HNAP-Al3+] system in the presence of
various anions in HEPES buffered (0.1 M) solution (methanol/water = 3/7, v/v, pH
7
.4). Black bar: HNAP (10.0
l
M). Red bar: HNAP (10.0
l
M) with 30 equivalent of
3+
3+
2+
Al . Blue bar: 10.0
l
M of HNAP and 30 equivalent of Al with 100 equivalent of
cations as stated, Mn (2), Co (3), Ni (4), Cd (5), Hg (6), Zn (7), Fe (8), Ag+
2
+
2+
2+
2+
2+
3+
9), Cu2 (10), Na (11), K (12), Ca (13), Mg (14), Fe3+ (15) (kex = 380 nm,
+
+
+
2+
2+
(
kem = 461 nm). (For interpretation of the references to colour in this figure legend,
the reader is referred to the web version of this article.)
experimentally observed peaks as reported supra. The higher Al3+
sensing efficiency of HNAP relative to other two (APSAL and AQ-
SAL) is due to the extended conjugation involving the naphthalene
moiety.
3
. Experimental
3.1. Materials and methods
Fig. 3. Naked eye view of three probes (10
300 M).
lM) in presence of different metal ions
(
l
Salicylaldehyde, 2-hydroxy-1-naphthaldehyde, 4-aminoantipy-
rine and 8-aminoquinoline have been used as received from Sigma
Aldrich. All other chemicals and solvents are of analytical grade
and used without further purification. Al(III) stock solution have
of exposure to the probes). Thus, the probes are suitable to detect
Al ion in living cells.
3
+
2+
2+
3 3 2
been prepared from Al(NO ) .9H O. The sources of Mg , Zn ,
2
+
2+
3+
2+
2+
2+
3+
2+
2+
2+
Cd , Fe , Cr , Hg , Mn , Cu , Fe , Co , Pb and Ni ions
are either their chloride or nitrate salts. Absorption and emission
spectra have been recorded on Shimadzu Multi Spec 1501 absorp-
tion spectrophotometer and Hitachi 4500 fluorescence spectrome-
ter respectively. Mass spectra have been recorded in QTOF Micro
YA 263 mass spectrometer in ESI positive mode. IR spectra are re-
corded on a Perkin Elmer FTIR spectrophotometer (model: RX-1).
2.1. DFT studies
Molecular level interactions between different probes with Al3+
have been examined using DFT method with B3LYP/ 6-31G and
Lanl2dZ basis set [28]. The HOMO–LUMO energy gaps in free AP-
3
+
SAL and [APSAL-Al ] complex are 3.3763 and 3.3001 eV respec-
tively (Fig. S28, ESI). In case of AQSAL, HOMO–LUMO energy gap
is 3.6234 eV whereas the value for its Al3 complex is 2.9475 eV
+
3.2. Calculation of quantum yield
(Fig. S29, ESI). On the other hand, in HNAP the energy gap between
HOMO and LUMO is 3.5788 eV and the value reduces to 2.0057 eV
3
+
Fluorescence quantum yields (U) are estimated by integrating
the area under the fluorescence curves using the equation,
for its Al complex (Fig. 6). Thus, HOMO–LUMO energy gap is min-
3
+
imum in [HNAP-Al ] complex. With the optimized structures of
the complexes, electronic transition energies are calculated by
TD-DFT method.To account the effect of solvent (methanol), the
conductor like polarisable continuu model (CPCM) is used. The cal-
culated transition energies of the prominent absorption bands are
shown in Tables S1–S3 (ESI) which are in close agreement with the
ODstandard ꢀ Asample
/
¼
ꢀ /standard
sample
ODsample ꢀ Astandard
where, A is the area under the fluorescence spectral curve and OD is
optical density of the compound at the excitation wavelength [29].
Table 1
Comparison of photo-physical properties of the three probes.
Probe name
Binding constant for Al3+
Lowest detection limit
Detection
Stabilization energy after complexation with Al3+
kEx and kEm
3
ꢁ1/2
ꢁ7
APSAL
AQSAL
HNAP
1.06 ꢀ 10
M
5 ꢀ 10
M
M
M
Yellow color generation
Yellow color generation
Green luminescence
(3.3763–3.3001 eV) = 0.0762 eV
(3.6234–2.9475 eV) = 0.6759 eV
(3.5788–2.0057 eV) = 1.5731 eV
350 and 505 nm
330 and 450 nm
380 and 510 nm
2
ꢁ1/2
ꢁ7
8.3 ꢀ 10
M
M
5.8 ꢀ 10
1.8 ꢀ 10
4
ꢁ1/2
ꢁ8
6.4 ꢀ 10

7
0
S. Lohar et al. / Inorganica Chimica Acta 412 (2014) 67–72
3
+
Fig. 5. Fluorescence images: (a), (b) and (c) are for controls, i.e. cells treated with free APSAL, AQSAL and HNAP respectively. Whereas images, (d), (g) and (j) are Al
3+
incubated Bacillus sp. cells after adding APSAL, AQSAL and HNAP respectively; Similarly, (e), (h) and (k) are the images for Al incubated Candida albicans cells after adding
APSAL, AQSAL and HNAP respectively; (f), (i) and (l) are Al incubated pollen grains of Allamandapuberula (Aapocynaceae) after adding APSAL, AQSAL and HNAP respectively.
3
+
Anthracene is used as quantum yield standard (quantum yield is
0
.27 in ethanol) [30] for measuring the quantum yields of APSAL,
3
+
AQSAL, HNAP and their Al complexes.
3.3. General method of synthesis of AQSAL
Syntheses of APSAL and HNAP have been made as reported ear-
lier.2
0,21
Scheme 1 shows the synthesis of 2-((Z)-(quinolin-8-ylimi-
no)methyl) phenol (AQSAL). 8-Aminoquinoline (200 mg,
.39 mmol) is dissolved in 20 mL dry methanol. 15 mL solution
1
of salicylaldehyde (170 mg, 1.39 mmol) in methanol is added drop
wise under stirring condition followed by refluxing for 6 h. Slow
evaporation of the solvent has yielded colorless crystals of AQSAL.
Single crystal X-ray structure of AQSAL is presented in Fig. 1. Yield,
+
0
2
.31 g (90%). ESI-TOF MS (+) (Fig. S30, ESI): 249.08 for [L+H] and
+
1
3
71.08 for [L+Na] . H NMR spectrum (400 MHz, CDCl , Fig. S31,
ESI), d, ppm: 14 (1H, S), 8.943 (1H,S), 8.785 (1H, d, J = 2.4), 8.209
1H, d, J = 6.4), 7.735 (1H, d, J = 1.2), 7.490 (2H, m, J = 4.4), 7.441
(1H, m, J = 1.6), 7.355 (1H, S), 7.184 (1H, d, J = 0.8), 7.115 (1H, d,
(
Fig. 6. Energy optimized structure and HOMO–LUMO energy gap of HNAP and its
Al complex.
3+

S. Lohar et al. / Inorganica Chimica Acta 412 (2014) 67–72
71
Fig. 7. Single crystal X-ray structure of AQSAL.
Scheme 1. Synthesis of the probes APSAL, AQSAL and HNAP.
J = 8.4), 6.980 (1H, m, J = 6). FTIR (Fig. S32, ESI): 3452 (O–H); 1618
C@N).
(
3+
3
.4. Synthesis of Al -probe complexes
Al(NO
added to a magnetically stirred solution of APSAL (0.050 g,
.162 mmol) in the same solvent (10 mL). The mixture is stirred
3 2
)3ꢃ9H O (0.031 g, 0.082 mmol) in MeOH (10 mL) is slowly
0
for 0.5 h. ESI-TOF (+) mass (Fig. S10, ESI) spectrum for the complex
shows a peak at 639.10, attributed to [2APSAL–2H + Al3 . Simi-
+]+
larly, Al(NO
.2 mmol) and Al(NO
0.050 g, 0.14 mmol) are mixed to obtain respective complexes.
ESI-TOF (+) mass spectra (Fig. S14 and S17, ESI) show peaka at
3
)
3
ꢃ9H
2
O (0.038 g, 0.1 mmol) with AQSAL (0.050 g,
Fig. 8. Crystal packing of AQSAL.
0
(
3
)
3
ꢃ9H O (0.027 g, 0.07 mmol) with HNAP
2
20.93 for [2AQSAL–2H + Al3
+ +
]
and 738.96 for [2HNAP–
5
2
extended conjugation and an intra-molecular H bond between
O–H and N center of imine bond (Fig. 7). Moreover, molecules of
AQSAL are perfectly stacked as evident from its crystal packing
3
+ +
H + Al ] respectively.
Normalized excitation spectra of three complexes are presented
in Fig. S33.
(Fig. 8).
3.5. Preparation of cells
4
. Conclusion
Candida albicans cells (IMTECH No. 3018) are grown in yeast
extract glucose broth medium (incubation temperature, 37 °C)
for 24 h. It is centrifuged at 6000 rpm for 3 min and washed with
normal saline. The cells are then treated with aqueous aluminum
In summary, APSAL, AQSAL and HNAP can selectively recognize
Al3+ through CHEF mechanism. Moreover, HNAP shows intense
3+
green luminescence in presence of Al , enabling its naked eye
ꢁ
1
nitrate (1 mg mL ) solution. After incubation, cells are washed
again with normal saline and observed under a fluorescence micro-
scope equipped with UV filter after adding different probes (AP-
SAL, AQSAL and HNAP). Cells incubated with different probes in
detection while the other probes generate yellow color. The excita-
3+
tion spectrum of HNAP-Al complex lies mostly in the visible re-
gion, which might be responsible for green luminescence.
3+
Binding constant of HNAP for Al is nearly 10 times higher than
3
+
absence of Al are used as control. Similar studies with other cells
viz. Bacillus sp. and Allamandapuberula (Aapocynaceae, collected
from fresh pollen grains) have also been performed.
that of two other probes. In fact, there is immense scope for the
development of low cost Al(III) sensitive luminescent probes with
much lower detection limit, that will function in greener solvents.
3.6. Single crystal X-ray structural characterization of AQSAL
Acknowledgements
Single crystal X-ray diffraction studies on a colorless ortho-
rhombic crystal obtained after slow evaporation of an ethanol solu-
tion of AQSAL consists of crystallographically independent
molecules that comprise one quinoline unit connected by a –
C@N– group to a o-hydroxy benzene unit. Table S4 (ESI) shows
the bond distances and angles for free AQSAL that fall within the
expected ranges. The planar conformation is stabilized through
S. Lohar and A. Sahana are grateful to CSIR, New Delhi for fel-
lowship. Financial assistance from UGC-DAE-CSR-Kolkata is grate-
fully acknowledged. Authors gratefully acknowledge Indian
Institute of Chemical Biology (IICB, Kolkata) for mass spectral facil-
ities. We sincerely thank University Science Instrumentation Cen-
ter (USIC), Burdwan University for fluorescence microscope facility.

7
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S. Lohar et al. / Inorganica Chimica Acta 412 (2014) 67–72
[
18] (a) Y. Zhao, Z. Lin, H. Liao, C. Duan, Q. Meng, Inorg. Chem. Commun. 9 (2006)
66;
b) X. Jiang, B. Wang, Z. Yang, Y. Liu, T. Li, Z. Liu, Inorg. Chem. Commun. 14
Appendix A. Supplementary material
9
(
CCDC 883038 contains the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via http://www.ccdc.cam.
ac.uk/data_request/cif. Supplementary data associated with this
article can be found, in the online version, at http://dx.doi.org/
(2011) 1224;
(c) D. Maity, T. Govindaraju, Chem. Commun. 48 (2012) 1039.
19] D. Karak, S. Lohar, A. Sahana, S. Guha, A. Banerjee, D. Das, Anal. Methods 4
[
[
(
2012) 1906.
20] (a) S. Das, D. Karak, S. Lohar, A. Banerjee, A. Sahana, D. Das, Anal. Methods 4
(2012) 3620;
(
b) D. Karak, S. Lohar, A. Banerjee, A. Sahana, I. Hauli, S.K. Mukhopadhyay, J.S.
Matalobos, D. Das, RSC Adv. 2 (2012) 12447;
c) A. Banerjee, A. Sahana, S. Das, S. Lohar, S. Guha, B. Sarkar, S.K.
Mukhopadhyay, A.K. Mukherjee, D. Das, Analyst 137 (2012) 2166;
d) S. Das, A. Sahana, A. Banerjee, S. Lohar, D.A. Safin, M.G. Babashkina, M.
Bolte, Y. Garcia, I. Hauli, S.K. Mukhopadhyay, D. Das, Dalton Trans. 42 (2013)
757;
e) A. Sahana, A. Banerjee, S. Lohar, B. Sarkar, S.K. Mukhopadhyay, D. Das, Inorg.
1
0.1016/j.ica.2013.11.038.
(
References
(
[
[
[
[
1] R.H. Newman, M.D. Fosbrink, J. Zhang, Chem. Rev. 111 (2011) 3614.
2] J.F. Zhang, Y. Zhou, J. Yoon, J.S. Kim, Chem. Soc. Rev. 40 (2011) 3416.
3] J. Wu, W. Liu, J. Ge, H. Zhang, P. Wang, Chem. Soc. Rev. 40 (2011) 3483.
4] (a) D. Maity, T. Govindaraju, Inorg. Chem. 49 (2010) 7229;
4
(
Chem. 52 (2013) 3627.
[
21] S. Lohar, A. Sahana, A. Banerjee, A. Banik, S.K. Mukhopadhyay, J.S. Matalobos, D.
Das, Anal. Chem. 85 (2013) 1778.
22] Z.L. You, J. Wanga, J.Y. Chi, Acta Crystallogr., Sect. E 62 (2006) 1652.
23] H.M. Park, B.N. Oh, J.H. Kim, W. Qiong, I.H. Hwang, Tetrahedron Lett. 52 (2011)
(
b) S.C. Warren-Smith, S. Heng, H. Ebendorff-Heidepriem, A.D. Abell, T.M.
Monro, Langmuir 27 (2011) 5680.
[
[
[
5] Y. Liu, C. Deng, L. Tang, A. Qin, R. Hu, J.Z. Sun, B.Z. Tang, J. Am. Chem. Soc. 133
(
2011) 660.
5581.
[
[
6] Y. Kurishita, T. Kohira, A. Ojida, I. Hamachi, J. Am. Chem. Soc. 132 (2010) 13290.
7] Z. Xu, K.H. Baek, H.N. Kim, J. Cui, X. Qian, D.R. Spring, J.Y.I. Shin, J. Am. Chem.
Soc. 132 (2010) 601.
[
24] (a) L. Wang, W. Qin, X. Tang, W. Dou, W. Liu, Q. Teng, X. Yao, Org. Biomol.
Chem. 8 (2010) 3751;
(
(
b) D. Maity, T. Govindaraju, Chem. Commun. 46 (2010) 4499;
c) M. Arduini, F. Felluga, F. Mancin, P. Rossi, P. Tecilla, U. Tonellato, N.
[
[
8] G.H. Robinson, Chem. Eng. News 81 (2003) 54.
9] E.R. Scerri, The Periodic Table: Its Story and Its Significance, Oxford University
Press, 2007.
Valentinuzzi, Chem. Commun. (2003) 1606;
d) Y.W. Wang, M.X. Yu, Y.H. Yu, Z.P. Bai, Z. Shen, F.Y. Li, X.Z. You, Tetrahedron
(
[
[
[
10] C. Exley, J. Inorg. Biochem. 99 (2005) 1747.
11] D.P. Perl, A.R. Brody, Science 208 (1980) 297.
12] D.P. Perl, D.C. Gajdusek, R.M. Garruto, R.T. Yanagihara, C.J. Gibbs, Science 217
Lett. 50 (2009) 6169.
[
[
25] (a) M. Shortreed, R. Kopelman, M. Kuhn, B. Hoyland, Anal. Chem. 68 (1996)
1414;
(
1982) 1053.
(
b) A. Caballero, R. Martinez, V. Lloveras, I. Ratera, J. Vidal-Gancedo, K. Wurst,
[
[
13] A. Sahana, A. Banerjee, S. Das, S. Lohar, D. Karak, B. Sarkar, S.K. Mukhopadhyay,
A.K. Mukherjee, D. Das, Org. Biomol. Chem. 9 (2011) 5523.
14] A. Banerjee, A. Sahana, S. Das, S. Lohar, S. Guha, B. Sarkar, S.K. Mukhopadhyay,
A.K. Mukherjee, D. Das, Inorg. Chem. 51 (2012) 5699.
A. Tárraga, P. Molina, J. Veciana , J. Am. Chem. Soc. 127 (2005) 15666.
26] (a) K.K. Upadhyay, A. Kumar, Org. Biomol. Chem. 8 (2010) 4892;
(
b) J.-S. Wu, W.-M. Liu, X.-Q. Zhuang, F. Wang, P.-F. Wang, S.-L. Tao, X.-H.
Zhang, S.-K. Wu, S.-T. Lee, Org. Lett. 9 (2007) 33.
[
[
15] S. Samanta, B. Nath, J.B. Baruah, Inorg. Chem. Commun. 22 (2012) 98.
16] S. Kim, J.Y. Noh, K.Y. Kim, J.H. Kim, H.K. Kang, S.W. Nam, S.H. Kim, S. Park, C.
Kim, J. Kim, Inorg. Chem. 51 (2012) 3597.
[
[
[
[
27] H.A. Benesi, J.H. Hildebrand, J. Am. Chem. Soc. 71 (1949) 2703.
28] Gaussian Inc., Gaussian 03, Rev. C.02, Gaussian Inc., Wallingford, CT, 2004.
29] E. Austin, M. Gouterman, Bioinorg. Chem. 9 (1978) 281.
30] W.H. Melhuish, J. Phys. Chem. 65 (1961) 229.
[
17] Y.W. Wanga, M.X. Yu, Y.H. Yu, Z.P. Bai, Z. Shen, F.Y. Li, X.Z. You, Tetrahedron
Lett. 50 (2009) 6169.