Chromogenic and Fluorescent Probes for Anion Detection
The structures were solved by direct methods23 and refined by a
Compound 1. A mixture of 4 (1.0 g, 2.87 mmol) and 2-hydroxy-
1-naphthaldehyde (0.98 g, 5.74 mmol) was placed in a reaction
flask containing 100 mL of methanol. The solution was then
refluxed for 48 h. The resulting orange precipitate was collected
by filtration and washed with methanol and recrystallized from
2
full-matrix least-squares technique based on F using the SHELXL97
program.2 The non-hydrogen atoms were refined anisotropically.
Hydrogen atoms were included in idealized positions but not
refined. All calculations were performed using the Bruker SHELX-
3b
24
1
TL crystallographic software package.
DMF/ether to give orange powder of 1 (1.7 g, 90%): H NMR
(
9
400 MHz, DMSO-d
.57 (2 H, s), 8.34 (2 H, d, J ) 8.6 Hz), 7.93 (4 H, m), 7.69 (2 H,
t, J ) 7.4 Hz), 7.43 (6 H, m), 7.29 (4 H, m), 7.13 (2 H, t, J ) 7.3
Hz); 13C NMR (100 MHz, DMSO-d
) δ 157.5, 144.5, 144.1, 137.2,
32.8, 132.0, 131.4, 129.2, 128.9, 127.7, 127.6, 125.7, 125.1, 123.4,
22.3, 120.5, 118.9, 114.1, 108.8; HRFABMS m/z 657.2477 (calcd
6
) δ 13.1 (2 H, s) 11.3 (2 H, s), 11.0 (2 H, s),
Absorption and fluorescence anion titrations were performed
using a 2.5 mL chemosensor solution in DMSO titrated with a
sample of the anions prepared with the same chemosensor solution.
Absorption and emission spectra were recorded following each
addition of anion. The apparent association constants, K, and Hill
coefficients, n, were determined by Hill eq 1:
6
1
1
+
m/z 657.2475 for M + H ). Anal. Calcd for C38
7.24; H, 5.05; N, 20.64. Found: C, 67.03; H, 4.67; N, 20.40.
Compound 2. A mixture of 4 (1.0 g, 2.87 mmol) and 1-naph-
28 2
H N10‚3H O: C,
6
log(y/(1 - y)) ) nlog[anion] + log K
(1)
thaldehyde (0.90 g, 5.74 mmol) was placed in a reaction flask
containing 100 mL of methanol. The solution was then refluxed
for 48 h. Subsequently, the red precipitate was collected by filtration
and washed with methanol and recrystallized from DMF/ether to
where y ) A/(Amax - A
0
), A is the absorbance at 560 nm at any
is the absorbance at 560 nm in the
given fluoride concentration, A
0
absence of fluoride, and Amax is the maxima absorbance at 560 nm
1
give a red powder of 2 (1.7 g, 95%): H NMR (400 MHz, DMSO-
in the presence of fluoride in solution.3
m,13
d
6
) δ 11.2 (2 H, s), 11.1, (2 H, s), 9.42 (2 H, s), 8.92 (2 H, d, J )
The association constants, K, listed in Table 3 were determined
from a 1:2 stoichiometry (probe to anion) by fitting the whole series
of spectra at 1 nm intervals using the software SPECFIT 3.0 from
Spectrum Software Associates, which employs a global system with
expanded factor analysis and Marquardt least-squares minimization
to obtain globally optimized parameters.
experiments were carried out in DMSO-d
concentration of the probe molecules.
1H NMR diffusion experiments were performed by using a
Bruker DRX 500 MHz spectrometer equipped with a gradient
system capable of producing magnetic-field pulse gradients in the
z-direction of about 52 Gcm . Diffusion measurements were
performed by using a stimulated echo sequence (STE). All H FIDs
8
.5 Hz), 8.12 (2 H, d, J ) 6.1 Hz), 8.04 (4 H, d, J ) 8.1 Hz), 7.75
(
(
7
1
1
2 H, t, J ) 7.5 Hz), 7.66 (4 H, m), 7.50 (2 H, d, J ) 7.8 Hz), 7.45
2 H, d, J ) 7.8 Hz), 7.24 (2 H, t, J ) 7.3 Hz), 7.12 (2 H, t, J )
13
.5 Hz); C NMR (100 MHz, DMSO-d
6
) δ 145.05, 145.02, 137.3,
33.5, 133.0, 130.2, 130.0, 129.9, 129.1, 128.7, 127.1, 126.5, 126.1,
1
1 1
H NMR titration
solution at 1-5 mM
25.7, 125.6, 124.9, 124.0, 122.1, 114.0; HRFABMS m/z 625.2585
6
+
(
2
calcd m/z 625.2577 for M + H ). Anal. Calcd for C38
H
28
N
10
‚
2
.5H O: C, 68.15; H, 4.97; N, 20.91. Found: C, 68.08; H, 4.69;
N, 20.95.
Compound 3. A mixture of 5 (1.0 g, 6.24 mmol) and 1-naph-
thaldehyde (1.1 g, 6.39 mmol) was placed in a reaction flask
containing 100 mL of methanol. The solution was then refluxed
for 48 h. Subsequently, the red precipitate was collected by filtration
and washed with methanol and recrystallized from DMF/ether to
-
1
1
were acquired at 298 K. Experiments were carried out with a
relaxation delay of 2 s, a diffusion delay (∆) of 50 ms, and a
gradient pulse duration (δ) of 7 ms. Gradient amplitudes were varied
1
give a yellow powder of 3 (1.7 g, 88%): H NMR (400 MHz,
DMSO-d ) δ 11.9 (2 H, br s), 9.17, (1 H, s), 8.76 (1 H, s), 8.49 (1
H, d, J ) 6.8 Hz), 7.89-7.86 (3 H, m), 7.70-7.67 (2 H, m), 7.61
1 H, t, J ) 6.3 Hz), 7.48 (1 H, br s), 7.39 (1 H, t, J ) 6.1 Hz),
6
-
1
from 0.66 to 32.4 Gcm . Individual FIDs were processed using
Bruker TOPSPIN 2.0 software.
(
13
Synthesis. Compound 4. A mixture of 2,3-dichloroquinoxaline
6
7.24 (1 H, d, J ) 7.0 Hz); C NMR (100 MHz, DMSO-d ) δ 156.9,
149.0, 142.1, 141.1, 137.8, 136.8, 131.8, 131.2, 130.4, 128.8, 128.7,
128.0, 127.6, 126.4, 125.2, 123.4, 124.8, 118.6, 109.8; HREIMS
(10 g, 0.05 mol) and hydrazine hydrate (50 mL) was placed in a
reaction flask. The solution was refluxed for 5 days. The yellow
precipitate was collected by filtration and washed with methanol
and recrystallized from DMF to give a yellow powder of 4 (7.8 g,
+
m/z 314.1161 (calcd m/z 314.1168 for M ). Anal. Calcd for
19 14 4
C H N O: C, 72.60; H, 4.49; N, 17.82. Found: C, 72.61; H, 4.40;
9
0%): 1H NMR (400 MHz, DMSO-d
6
) δ 10.8 (2 H, s), 8.92 (2 H,
N, 17.85.
s), 7.27 (2 H, d, J ) 7.6 Hz), 7.21 (2 H, d, J ) 7.7 Hz), 7.05 (2 H,
Compound 6. To 100 mL of methanol were added 1-naphthal-
dehyde (100 mg, 0.58 mmol) and hydrazine hydrate (0.2 mL), and
the mixture was refluxed under nitrogen for 6 h. The volatile was
removed under reduced pressure, and the residue was washed with
13
d, J ) 7.5 Hz), 6.97 (2 H, d, J ) 7.6 Hz), 4.54 (4 H, s); C NMR
100 MHz, DMSO-d
(
1
6
) δ 150.6, 137.9, 134.0, 129.3, 124.9, 123.7,
22.2, 114.2; HREIMS m/z 348.1566 (calcd m/z 348.1559 for M );
+
1
Anal. Calcd for C16
H
16
N
10: C, 55.16; H, 4.63; N, 40.21. Found:
hexane to afford a yellow powder of 6 (82 mg, 76%): H NMR
C, 54.93; H, 4.72; N, 40.36.
Compound 5 was prepared in a similar manner to compound 4
by refluxing 2-chloroquinoxaline in hydrazine hydrate for 5 days.
6
(400 MHz, DMSO-d ) δ 12.7 (1 H, br s), 8.86, (1 H, s), 8.08 (1 H,
d, J ) 6.8 Hz), 7.81 (1 H, d, J ) 6.3 Hz), 7.73 (1 H, d, J ) 7.1
Hz), 7.50 (1 H, t, J ) 6.2 Hz), 7.33 (1 H, t, J ) 6.1 Hz), 7.11 (1
H, d, J ) 7.1 Hz), 6.98 (2 H, s); 13C NMR (100 MHz, DMSO-d
)
Recrystallization from CH
8
3
OH afforded a yellow powder of 5 in
) δ 8.68 (1 H, s), 8.36
1 H, s), 7.77 (1 H, d, J ) 8.0 Hz), 7.76-7.54 (2 H, m), 7.35-
6
2% yield: 1H NMR (400 MHz, DMSO-d
δ 156.1, 139.8, 130.8, 129.7, 128.7, 127.7, 126.9, 123.0, 120.4,
18.6, 109.6; HREIMS m/z 187.0874 (calcd m/z 187.0871 for M
6
1
(
7
1
+
.30 (1 H, m), 4.44 (2 H, s); 1 C NMR (100 MHz, DMSO-d
3
+ H ). Anal. Calcd for C H N O: C, 70.95; H, 5.44; N, 15.04.
11 10
2
6
) δ
53.9, 141.5, 138.3, 136.6, 129.6, 128.4, 125.4, 123.4; HREIMS
Found: C, 70.58; H, 5.38; N, 15.09.
+
m/z 160.0749 (calcd m/z 160.0749 for M ). Anal. Calcd for
: C, 59.99; H, 5.03; N, 34.98. Found: C, 59.89; H, 5.21;
N, 35.15.
Acknowledgment. We thank the National Science Council
in Taiwan (Grants 94-2113-M-001-014 and 95-2113-M-001-
8 8 4
C H N
0
33-MY2) and Academia Sinica for support of this research.
Supporting Information Available: X-ray crystallographic
(
23) Sheldrick, G. M. SHELXS97, Program for Crystal Structure
1
13
details of 2 and 4 in cif format, H and C NMR spectra of all
new compounds, and additional anion titration spectra. This material
is available free of charge via the Internet at http://pubs.acs.org.
Solution; University of G o¨ ttingen: G o¨ ttingen, Germany, 1997. (b) Sheldrick,
G. M. SHELXL97, Program for Crystal Structure Solution; University of
G o¨ ttingen: G o¨ ttingen, Germany, 1997.
(24) Shelxtl for WindowsNT: Crystal Structure Analysis Package;
Bruker: Madison, WI, 1997.
JO7019916
J. Org. Chem, Vol. 73, No. 3, 2008 911