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The fluorescence quenching efficiency (h) for each analyte was cal-
culated by the following equation:
Experimental Section
Caution
PA, 2,4-DNP, and NP used in the present study are highly explosive
and should be handled only in small quantities.
h ¼ ðI
0
ÀIÞ=I Â 100 %
0
in which I and I were the fluorescence intensities in the absence
0
and presence of analyte, respectively.
Materials and methods
All solvents and reagents were purchased from commercial sources
and purified by using standard methods. The solvents for spectro-
scopic studies were of spectroscopic grade and used as received.
Synthesis and characterization
1
2,6-Dibromo-9,10-anthraquinone (1): 2,6-Diaminoanthraquinone
H NMR spectra were recorded on a 300/400/500 MHz Bruker spec-
(
5
4.8 g, 20 mmol), tert-butyl nitrite (5.2 g, 50 mmol), CuBr2 (11.1 g,
0 mmol), and CH CN (85 mL) were added to a one-neck flask, and
trometer and all the spectra were calibrated against tetramethylsi-
lane (TMS). The UV/Vis spectra of all samples were studied with
a Hewlett–Packard UV/Vis spectrophotometer (model: 8453). Fluo-
rescence studies for all samples, prepared in a sealed cuvette, were
carried out with Horiba Jobin Yvon Fluoromax 3 instrument. HRMS
were taken using a Quadruple-TOF (Q-TOF) micro MS system using
an electrospray ionization (Supporting Information) technique.
MALDI-TOF mass spectrometry was carried out with Bruker Dalton-
ics FLEX-PC. Fluorescence lifetimes were measured by using
a time-correlated single-photon counting fluorometer (Fluorecule,
Horiba Jobin Yvon). The system was excited with a 375 nm
NanoLED from Horiba Jobin Yvon, which has a lmax at 375 nm with
a pulse duration of <200 ps. Theoretical calculations of 3a–c have
been carried out using the Gaussian 09 suite of quantum chemistry
3
the mixture was heated at 658C for 2 h. The reaction was
quenched by adding 20% HCl (aq.) solution to the mixture. The re-
sulting precipitate was filtered, washed with CH CN, and chromato-
graphed on a silica gel column eluting with hexane/dichlorome-
3
thane (1:1, v/v) to afford a pale-yellow solid. Yield: 6.2 g (86%);
1
H NMR (500 MHz, CDCl ): d=8.44 (d, J=3.0 Hz, 2H), 8.18 (d, J=
3
9
.0 Hz, 2H), 7.95 ppm (dd, J=9.0, 3.0 Hz, 2H).
General procedure for the synthesis of the 2,6-dibromo-9,10-
akyloxyanthracenes (2a–c): To a two-neck flask, 2,6-dibromo-9,10-
anthraquinone (1 mmol), tetrabutylammonium bromide (0.9 equiv),
Na
S O
2 2 4
(6 equiv), and water were added under argon. The mixture
Cl was added. When the solution
was stirred for 10 min and CH
2
2
[30]
program. DFT calculations and Geometry optimization was per-
turned to a green color, 20% NaOH (aq.) was added and the solu-
tion became red and was stirred for 2 h. To this solution, n-alkyl
bromide (10 equiv) was added dropwise and stirred for 24 h. The
organic part was extracted with DCM and removed and MeOH was
immediately added. After an hour, the yellow precipitate appeared
and it was filtered and dried. Finally, the product was purified on
a silica column using hexane as the eluent.
[31,32]
formed at the B3LYP/6-31 G(d) level
All optimized geometries
were considered for single-point time-dependent DFT (TD-DFT) cal-
[33]
culations at the B3LYP/TZVP level.
X-ray crystallography
Suitable crystals of 3c and 3c-PA were mounted on glass fibers
coated with perfluoropolyether oil before mounting. Intensity data
for the aligned crystals were measured employing a Bruker SMART
APEX II CCD diffractometer equipped with a monochromatized
MoKa radiation (l=0.71073 ) source at 150 K for 3c. No crystal
decay was observed during the data collections. In all cases, ab-
sorption corrections based on multiscans using the SADABS soft-
2
,6-Dibromo-9,10-bis(butoloxy)anthracene (2a): 1-Bromobutane was
1
used to yield 58%. H NMR (400 MHz, CDCl ): d=1.08 (6H, t), 1.65–
1
3
.72 (4H, m), 1.97–2.03 (4H, m), 4.09 (4H, t), 7.52 (2H, dd), 8.11
13
(
2H, d), 8.39 ppm (2H, d); C NMR (400 MHz, CDCl ): d=14.2, 19.5,
3
32.8, 120.4, 124.3, 124.8, 125.0, 126.3, 129.4, 147.2 ppm.
2
,6-Dibromo-9,10-bis(octoloxy)anthracene (2b): 1-Bromoctane was
1
used to yield 70%. H NMR (400 MHz, CDCl ): d=0.91 (6H, m)
1
t), 7.52 (2H, dd), 8.11 (2H, d), 8.39 ppm (2H, d); C NMR (400 MHz,
CDCl ): d=14.2, 22.8, 26.3, 29.4, 29.5, 29.6, 30.7, 32.0,120.3, 124.3,
[34]
3
ware were applied. The structures were solved by direct meth-
.32–1.47 (16H, m), 1.55–1.67 (4H, m), 2.0–2.04 (4H, m), 4.11 (4H,
[
35]
2
ods and refined on F by a full-matrix least-squares procedure
13
1
2
2 2
2 2 =
2
based on all data minimizing: wR=[S[w(F ÀF ) ]/S(F ) ] , R=
0
c
0
1
2
2 2
=
2
3
Sj jF jÀjF j j/SjF j, and S=[S[w(F ÀF ) ]/(nÀp)] . SHELXL-2013
0
c
0
0
c
1
24.8, 125.0, 126.3,129.4, 147.2 ppm.
[36]
was used for both structure solutions and refinements. A sum-
mary of the relevant crystallographic data and the final refinement
details have been presented in Table S1, Supporting Information.
All non-hydrogen atoms were refined anisotropically. The hydrogen
atoms were calculated and isotropically fixed in the final refine-
ment (d(CÀH)=0.95 , with the isotropic thermal parameter of
2
,6-Dibromo-9,10-bis(dodecyloxy)anthracene (2c): 1-Bromododecane
1
was used to yield 70%. H NMR (400 MHz, CDCl ): d=0.91 (6H, m)
1
t), 7.52 (2H, dd), 8.11 (2H, d), 8.39 ppm (2H, d); C NMR (400 MHz,
CDCl ): d=147.2, 129.4, 126.3, 125.0, 124.8, 124.31, 120.3, 32.1,
30.7, 29.8, 29.8, 29.7, 29.5, 26.3, 22.8, 14.2 ppm; MALDI-TOF: m/z:
calcd for C H Br O : 704.66 [M+H] ; found: 704.49.
3
.32–1.47 (32H, m), 1.55–1.67 (4H, m), 2.0–2.04 (4H, m), 4.11 (4H,
13
3
[37]
U (H)=1.2U (C)). The SMART and SAINT software packages
iso
iso
+
38
56
2
2
were used for data collection and reduction, respectively. Crystallo-
graphic diagrams were drawn using the DIAMOND software pack-
2
,6-(Dipyridin-4-vinyl)-9,10-bis(dodecyloxy)anthracene (3c): A re-
action mixture of 4-vinyl pyridine (1 mL, 10 mmol), 2c (373 mg,
.53 mmol), triethylamine (5 mL), Pd(OAc)2 (026 mg, 0.17 mmol),
[
38]
age.
0
and tri-o-tolylphosphine (39 mg, 0.85 mmol) in dry DMF (15 mL)
were placed in a predried round-bottomed flask (100 mL). The re-
action mixture was then degassed by freeze-pump-thaw 3 times
before heating at 110 8C for 24 h. After cooling to room tempera-
ture, the reaction mixture was poured into water and extracted by
DCM. The organic solvent was removed and then MeOH was im-
mediately added. This mixture was kept in a deep fridge for 2–3 h
and a yellow precipitate appeared. The crude products were then
purified by flash column chromatography (v/v hexane/ethyl ace-
Fluorescence quenching titration in THF media
Fluorescence-quenching titrations were carried out by placing
À6
À1
2
mL of 110 molL solution of 3c in a quartz cuvette of 1 cm
width. Then, a THF solution of analytes (e.g., PA) was added in an
incremental fashion. For each addition, at least three fluorescence
spectra were recorded repeatedly at 298 K to obtain a concordant
value. For all measurements, 3c was excited at its l =360 nm
while keeping a 2 nm slit width for both source and detector.
ex
Chem. Eur. J. 2016, 22, 2012 – 2019
2018
ꢀ 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim