10.1002/chem.201604474
Chemistry - A European Journal
FULL PAPER
(bovine; [M+1]avg = 5734.59 Da) and was mixed with 10 µL of the CHCA
solution. Each mixture (sample and calibrant) was spotted (1.0 µL) on a
100 well MALDI plate in separate wells and the solvent was allowed to
evaporate under ambient conditions. MS data was collected in reflector
mode for high resolution.
(a)
(b)
1800000
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1200000
900000
600000
300000
0
1 min
2 min
4 min
30
25
20
15
10
5
Y = -1.17044 + 33.86261X
R-square = 0.987
10 min
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30 min
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80 min
110 min
150 min
190 min
Synthetic Procedure
Synthesis of compound 1: p-Difluoromethylbenzoic acid (144 mg, 0.84
mmol) was added into non-aqueous dichloromethane (8 mL) and the
suspension was cooled to 0 οC. Oxalyl chloride (77.5 µL, 0.90 mmol) was
added dropwise to the ice-cold suspension, followed by several drops of
N, N-dimethylformamide. The solution was kept under 0 οC for 10 min and
then was heated under 70 οC for 1 h. The solution was cooled to room
temperature and concentrated under reduced pressure. The resulting
residue was re-dissolved in acetone (3 mL) and cooled to 0 οC. A solution
of sodium azide (163 mg, 2.51 mmol; dissolved in 3 mL water) was added
dropwise, and the reaction solution was stirred at 0 οC for 1 h. The solution
was diluted with ethyl acetate (20 mL) and the layers were separated. The
organic layer was dried over magnesium sulphate, the solids were filtered
0
450 500 550 600 650 700
0.0
0.2
0.4
0.6
0.8
Wavelength (nm)
Volume (%)
Figure 7. (a) Kinetic fluorescence spectra from sensing system 2 (4 µM) to test
the fluoride (0.05% volume from 1st vial) amplified by the autoinductive system
1 (1 mM), in acetonitrile; (b) Fluorescence quantification curve from system 2
(10 µM) in the presence of fluoride after amplification, various volumes of
solution referring to the first vial (0.02, 0.04, 0.08, 0.12, 0.16, 0.24, 0.4, 0.8
vol.%). Ex = 405 nm, Ex Slit/Em Slit: 5 nm/5 nm.
through
a fritted Büchner funnel, and the remaining liquid was
concentrated under reduced pressure. The residue was dissolved in
toluene (5 mL), and this solution was heated to 100 οC for 1 h. The reaction
mixture was allowed to cool to room temperature, and compound (2-((tert-
butyldimethylsilyl)oxy)benzene-1,3,5-triyl)trimethanol (50.0 mg, 0.17
mmol) was added in one portion. The reaction mixture was heated to 100
οC, and was stirred at this temperature for 16 h. The solution was cooled
to room temperature and concentrated, and the resulting residue was
purified via column chromatography (elution with 20% EtOAc–hexanes) to
afford compound 1 as a yellow solid (50.1 mg). Yield: 37 %. 1H NMR (400
MHz, CDCl3); δ 7.49 (d, J = 8.6 Hz, 4H), 7.46–7.38 (m, 8H), 7.35 (s, 2H),
7.11 (s, 2H), 6.98 (s, 1H), 6.74 (dd, J = 6.6, 1.8 Hz, 1H), 6.59 (dd, J = 6.6,
1.9 Hz, 1H), 6.45 (dd, J = 6.6, 1.7 Hz, 1H), 5.19 (s, 4H), 5.07 (s, 2H), 1.02
(s, 9H), 0.21 (s, 6H). 13C NMR (101 MHz, CDCl3) δ 153.43, 153.33, 151.43,
140.12, 140.10, 130.31, 129.63, 129.58, 129.54, 127.71, 126.86, 126.85,
126.80, 126.79, 126.74, 126.73, 120.61, 118.53, 117.07, 117.03, 114.71,
114.66, 112.34, 77.52, 77.20, 76.88, 66.72, 62.52, 25.92, 18.83, -3.32.
HRMS m/z calc. for C39H41F6N3O7Si: 805.2618; found: 828.2514 [M + Na]+.
Conclusions
We introduced a new strategy for the chemosensing of G-series
nerve agents through tracking the side-product fluoride. An
autoinductive cascade was utilized for the amplification of fluoride,
coming originally from the reaction between nerve agent
surrogate DFP and benzaldoxime. Both colorimetric detection,
along with a fluorescent approach, was used for the tracking of
fluoride after amplification. Importantly, both colorimetric and
fluorometric linear curves were obtained for different aliquots of
the original test solutions, thereby providing a reproducible
platform for testing the presence of fluoride after a potential G-
nerve agent attack. Currently, we are generating thiol self-
immolative systems, as a means of distinguishing sulfur-
containing V-series nerve agent from G-agents.
Synthesis of compound 2: To a mixture of 4-amino-9-(n-butyl)-1,8-
naphthalimide (100 mg, 0.37 mmol) and DMAP (136 mg, 1.12 mmol) in
toluene (5 mL) was added a solution of triphosgene (110 mg, 0.37 mmol)
in toluene (3 mL) dropwise at 0 οC. After stirring at 0 οC for another 30 mins,
the solution was heated to reflux for 4 h. Then cooling to room temperature,
the reaction mixture was diluted with CH2Cl2 (10 mL) and filtered. To the
clear filtrate solution was added (2-((tert-butyldimethylsilyl)oxy)benzene-
1,3,5-triyl)trimethanol (40 mg, 0.13) and the suspension was heated to
reflux for 20 h. After cooling to room temperature, the solvent was removed
under vacuum. The resulting yellow solid was purified by column
chromatography (CH2Cl2:MeOH = 20:1) to give yellow solid (87 mg). Yield:
19 %. 1H NMR (400 MHz, DMSO-d6) δ 10.41 (s, 2H), 10.25 (s, 1H), 8.58
(d, J = 8.7 Hz, 2H), 8.47 – 8.40 (m, 1H), 8.37 (dd, J = 7.3, 1.1 Hz, 2H),
8.32–8.22 (m, 3H), 8.12–7.97 (m, 3H), 7.71 (dd, J = 8.6, 7.3 Hz, 2H), 7.67–
7.53 (m, 3H), 7.44 (s, 1H), 5.33 (d, J = 2.7 Hz, 5H), 3.97 (ddd, J = 14.8,
8.6, 6.5 Hz, 6H), 1.58 (q, J = 7.9 Hz, 6H), 1.34 (q, J = 7.4 Hz, 6H), 1.04 (s,
Experimental Section
General procedure
All materials were purchased from Sigma-Aldrich Chemical Co., Acros
Organics, Tokyo Chemical Industry, etc. and used without further
purification. The UV-Vis absorbance spectra and kinetics were obtained in
Cary 100 UV-Vis spectrophotometer from Agilent Technology.
Fluorescence emission spectra and kinetics were obtained from Photon
Technology International. All cuvettes made by fused quartz were
purchased from Starna Cells with standard screw and septum top.
7H), 0.92 (t, J = 7.3 Hz, 9H), 0.84 (s, 2H), 0.29 (s, 5H), -0.05 (s, 1H); 13
C
NMR (101 MHz, DMSO-d6) δ 170.74, 164.14, 163.65, 163.28, 163.08,
154.26, 153.07, 140.77, 131.35, 129.65, 128.11, 126.57, 124.34, 122.18,
119.75, 117.31, 108.54, 107.96, 62.45, 62.44, 60.17, 58.59, 40.56, 40.35,
40.19, 40.14, 39.93, 39.72, 39.51, 39.30, 36.63, 30.04, 26.27, 26.22, 26.16,
25.86, 21.18, 20.27, 20.25, 18.83, 14.51, 14.18, 14.14, -2.78, -3.30. HRMS
m/z calc. for C66H68N6O13Si: 1180.4614; found: 1203.4499 [M + Na]+.
MALDI Procedure
The α-cyano-4-hydroxycinnamic acid (CHCA) matrix was dissolved in
60:40 MeCN:H2O with 0.1% formic acid (c = 5.0 mg/mL) and 10 µL was
mixed with 10 µL of the reaction solution in an Eppendorf tube. The protein
mixture used for mass calibration included angiotensin I ([M+1]avg =
1297.51 Da), ACTH fragments (clip 1-17, [M+1]avg = 2094.46 Da; clip 18-
39, [M+1]avg = 2466.72 Da; clip 7-38, [M+1]avg = 3660.19 Da), and insulin
Acknowledgements
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