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TRANSCRIPT
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S1
Electronic Supporting Information
A Fluorescence ‘turn-on’ chemodosimeter for selective detection of
Nb5+
ions in mixed aqueous media
Abhishek Kumar Gupta, Abhimanew Dhir, Chullikkattil P. Pradeep*
School of Basic Sciences, Indian Institute of Technology Mandi, Himachal Pradesh 175001, India
Email Address: [email protected]
S2 Instruments and experimental procedures
S3 Synthetic details of 3
S4 1H NMR spectrum of 3
S5 13
C NMR spectrum of 3
S6 Mass spectrum of 3
S7 Fluorescence spectra response of 3 (1 μM) upon addition of various metal ions (1 -
320 μM) in THF/H2O (95:5, v/v) solutions
S8 1H NMR spectra of 3 + Nb
5+ and 3 in DMSO-d6
S9 1H NMR spectrum of 1 in DMSO-d6
S10 Fluorescence emission spectrum of 1-aminopyrene 2(1 μM) in THF/H2O (95:5, v/v)
S11 – S12 Mechanism of acid catalyzed hydrolysis of 3
S13 – S14 Mechanism of metal catalyzed hydrolysis of imines
S15 – S16 Spectrofluorometric titration of 3 (1 μM) with addition of Nb5+
(1.0 - 320.0 equiv.) in
THF/H2O (90:10, v/v) & (80:20, v/v) solutions.
Electronic Supplementary Material (ESI) for Dalton TransactionsThis journal is © The Royal Society of Chemistry 2013
mailto:[email protected]
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S2
Instruments and experimental procedures
All reagents were purchased from Sigma Aldrich and were used without further purification.
HPLC grade THF was used to perform analytical studies. All the fluorescence spectra were
recorded on Agilent Technologies Cary Eclipse fluorescence spectrometer. UV-Vis spectra were
recorded on Shimadzu UV-2450 spectrophotometer and FT-IR spectra were recorded on
PerkinElmer FT-IR spectrometer (Spectrum Two, Serial No:88689). ESI-MS spectra were
recorded by using Waters-Q-Tof Premier-HAB213 instrument. 1H and
13C NMR spectra were
recorded on Bruker Avance II 400 NMR spectrometer using CDCl3 or DMSO-d6 as solvents and
TMS as internal standard. Data are reported as follows: chemical shift in ppm (), multiplicity (s
= singlet, d = doublet, br = broad singlet, m = multiplet), coupling constant J (Hz), integration,
and interpretation. Solution of compound 3 and metal chlorides were prepared in THF/H2O
(95:5, v/v). The H2O used for making THF/H2O mixtures was buffered with HEPES, pH = 7.0.1
1. D. D. Perrin, B. Dempsey, Buffers for pH and Metal Ion Control; John Wiley & Sons:
New York, 1974.
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S3
Synthesis of 3 (C26H19NO3)
First we dissolved ethyl-3-formyl-4-hydroxybenzoate (1) (1mmol, 0.19 g) in 10 mL of MeOH.
To this solution, 1-aminopyrene (2) (1mmol, 0.22 g) in 10 mL MeOH was added drop wise. The
resulting solution turned from dark green to orange in color within 10 min. After 6 h, orange
colored precipitates were formed which were filtered, washed with cold ethanol and dried under
vacuum to get 3 in 85% yield;m.p 170C. IR(KBr, cm
-1)max = 1711 (C=O, ester), 1610 (C=N);
1H NMR (CDCl3, 400 MHz): m, H, CH3], 4.40 [m, 2H, CH2], 7.15 [d, J = 8.0Hz, 1H,
Ar-H] , 7.82 [d, J = 8.0 Hz, 1H, Ar-H], 8.01 - 8.27 [m, 9H, pyrene], 8.48 [d, J = 12.0 Hz, 1H,
Ar-H], 8.92 [s, 1H, HC=N], 14.26 [s, 1H, OH]. 13
C NMR (CDCl3, 100MHz): 14.4[CH3],
60.9[OCH2], 115.6 [Ar-C], 117.5[Ar-C], 119.1 [Ar-C], 121.8 [Ar-C], 122.1 [Ar-C], 124.6 [Ar-
C], 125.1 [Ar-C], 125.3 [Ar-C], 125.5 [Ar-C], 125.6 [Ar-C], 125.6 [Ar-C], 126.4 [Ar-C], 127.1
[Ar-C], 127.6 [Ar-C], 128.3 [Ar-C], 130.6 [Ar-C], 131.2 [Ar-C], 131.4 [Ar-C], 134.5 [Ar-
C],134.6 [Ar-C], 141.5 [Ar-C], 162.8 [Ar-C], 165.1 [Ar-C], 165.9 [Ar-C=N] ppm. ESI-MS: m/z
= 394.14 [M + H]+.
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S4
1H NMR spectrum of 3
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S5
13C NMR spectrum of 3
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S6
Mass spectrum of 3
The peak at m/z 394.14 corresponds to [3+H]+
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S7
Figure S1. Fluorescence spectra of 3 (1M) upon addition of various metal ions (1320 M) in
THF/H2O (95:5, v/v) solutions, ex= 342 nm.
400 450 500 550 600
0
30
60
90
120
150
180
Ta5+
Nb5+
3
V3+
Cr2+
Mn2+
Fe2+
Co2+
Ni2+
Cu2+
Zn2+
Zr4+
Nb5+
Mo5+
Ru4+
Rh3+
Pd2+
Ag+
Cd2+
Ta5+
W6+
Au3+
Hg2+
Pb2+
em = 428 nm
W6+
Inte
nsity (
a.u
)
Wavelength (nm)
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S8
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S9
NMR of 1 in DMSO
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S10
Figure S2. Fluorescence emission spectrum of 1-aminopyrene 2 (1 µM) in THF/H2O (95:5,
v/v),ex= 342 nm.
350 400 450 500 550 600
0
50
100
150
200
250
Inte
nsity (
a.u
)
Wavelength (nm)
em= 428 nm
1-aminopyrene, 2
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S11
Mechanism of acid catalyzed hydrolysis of 3
The detailed steps involved in acid catalyzed hydrolysis of imines are known.2
Based on that, the
possible steps in the case of 3 are given below.
Scheme S1
COOEt
OH
N H+
COOEt
OH
N
H
+
(I) (II)
H H
COOEt
OH
N
H
+
(II)
COOEt
OH
N
H
+
(II b)
HH
H
OH
COOEt
OH
CN
HO
H +
COOEt
OH
N+
(II b)
H H
(III)
HH
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S12
OH
CN
HO
H
H
(III)
-H+
COOEt
OH
CN
O
H
H H
(IV)
H
COOEt
2. A. S. Kirdant, B. K. Magar and T. K. Chondhekar, J. Chem. Bio. Phy. Sci. Sec. A, 2011-2012,
2, 147 – 153.
COOEt
OH
H2N
O
+
COOEt
OH
N
OH
H
H+
(V)
-H+
Products
H
COOEt
OH
N
OH
H
H+
COOEt
OH
CN
O
H
H
(IV)
H
H+
(V)
H
Electronic Supplementary Material (ESI) for Dalton TransactionsThis journal is © The Royal Society of Chemistry 2013
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S13
Mechanismof metal catalyzed hydrolysis of imines
The following intermediates are proposed for metal assisted hydrolysis of imines, in which an
enhancement of the substrate reactivity after association with the metal ion is observed.3
Scheme S2
In an alternate arrangement, the role of the metal ion is to activate the attacking water molecule
by bringing it closer to the C=N bond as shown below.
Scheme S3
N
Ar
OH
H
Mz+
N
ArO
H
H
Mz+
(B)
NAr
Mz+
NAr
Mz+
OHHO
HH
(A)
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S14
For compound 3, the intermediates (A) and (B) can be written as follows, where there will be an
extra stabilization for the association of the metal ion with the substrate due to the involvement
of ortho phenolic O‒
group .
Scheme S4
3. V. G. Machado, M. G. Nascimento and M. C. Rezende, J. Braz. Chem. Soc., 1993, 4, 76 – 79.
O
N
Nb5+
O
HH
+
N
O
ONb5+
H
H
+
EtOOC
EtOOC
(A) (B)
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S15
Figure S3. Spectrofluorometric titration of 3 (1 μM) with addition of Nb5+
(1.0-320.0 equiv) in
THF/H2O (90:10, v/v); λex= 342 nm; buffered with HEPES.
Electronic Supplementary Material (ESI) for Dalton TransactionsThis journal is © The Royal Society of Chemistry 2013
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S16
Figure S4. Spectrofluorimetric titration of 3 (1 μM) with addition of Nb5+
(1.0-320.0 equiv) in
THF/H2O (80:20, v/v); λex= 342 nm; buffered with HEPES.
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Electronic Supplementary Material (ESI) for Dalton TransactionsThis journal is © The Royal Society of Chemistry 2013