Phenazine-based colorimetric and fluorometric probes for rapid recognizing of Hg2+ with high sensitivity and selectivity

Article abstract of DOI:10.1016/j.tet.2016.03.036

Two colorimetric and fluorometric probes, namely 2a and 2b, based on N,N′-disubstituted-dihydrophenazine analogues for rapid detection of Hg²⁺ with high sensitivity and selectivity were designed and synthesized by Heck coupling reaction. The responsive optical properties of the two sensors were investigated by UV-vis absorption and fluorescence spectroscopy in THF solution and 2a-b were found to be exclusively responsive to Hg²⁺ rapidly. Remarkably, the detection limits of 2a-b for Hg²⁺ were determined to be 4.8 and 2.6 nM, respectively. Moreover, the AIE and pH sensing properties of 2a-b were investigated.

Full text of DOI:10.1016/j.tet.2016.03.036

Tetrahedron 72 (2016) 2300e2305
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Phenazine-based colorimetric and fluorometric probes for rapid
recognizing of Hg2 with high sensitivity and selectivity
þ
a
b
a
a
a
a
a,
*
Haitao Zhou , Lu Sun , Wei Chen , Guojian Tian , Yi Chen , Yiru Li , Jianhua Su
a
Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science & Technology, Shanghai 200237, PR China
Institute of Modern Optics, Nankai University, Tianjin 300071, PR China
b
a r t i c l e i n f o
a b s t r a c t
0
Article history:
Two colorimetric and fluorometric probes, namely 2a and 2b, based on N,N -disubstituted-dihy-
Received 11 January 2016
Received in revised form 7 March 2016
Accepted 11 March 2016
Available online 12 March 2016
2þ
drophenazine analogues for rapid detection of Hg with high sensitivityand selectivity were designed and
synthesized by Heck coupling reaction. The responsive optical properties of the two sensors were in-
vestigated by UVevis absorption and fluorescence spectroscopy in THF solution and 2aeb were found to be
exclusively responsive to Hg2 rapidly. Remarkably, the detection limits of 2aeb for Hg were determined
to be 4.8 and 2.6 nM, respectively. Moreover, the AIE and pH sensing properties of 2aeb were investigated.
Ó 2016 Elsevier Ltd. All rights reserved.
þ
2þ
Keywords:
Phenazine
Colorimetric
Fluorometric
Probe
2þ
Hg
1. Introduction
[a,c]phenazine (DPAC, see Scheme 1), possesses structure features
of both triphenylamine and carbazole, which are widely employed
9
Mercury, as one of the most toxic heavy and transition metals
HTM), can be accumulated over time through the food chain and
in building optoelectronic materials. However, there are few re-
ports on DPAC and its application as fluorescent probe for metal
ions has not been reported to date. Herein, we present two novel
1
(
cause serious damage to the brain, kidney, and nervous system of
2
both human and animals, and the US Environmental Protection
probes 2a and 2b (Scheme 1) based on DPAC and pyridine for de-
termining Hg in THF solution. Pyridine can constitute
gated D-A molecules when coupled with DPAC. The ethenyl was
designed as linkage to modulate the communication between the
2
þ
2þ
Agency (EPA) has set the maximum permissible level of Hg in
p
-conju-
3
drinking water at 2 ppb (10 nM). Thus exploring methods for
detecting Hg2 with high selectivity and sensitivity are of great
þ
importance. Compared with conventional techniques such as
4
atomic absorption spectroscopy, coupled plasma mass spectros-
5
copy, etc., which generally requiring expensive equipments and
6
complicated operations, optochemical technology based on ab-
sorption or fluorescent detection takes advantages of simple de-
tection procedures, high sensitivity, and with no requirement of
7
expensive equipments. Therefore, tremendous efforts have been
directed towards the design and synthesis of fluorescent probes for
2
þ
selective and sensitive detection of Hg
.
Recently, pyridine-appended -conjugated analogues with D-A
p
structure involving the lone-pair electrons on the pyridine nitrogen
atom have been widely used as HTM sensors, in which the pyridyl
8
group(s) acts as the monodentate ligand(s) for metal ions. The
phenazine-based derivative, 9,14-diphenyl-9,14-dihydrodibenzo
Scheme 1. Synthesis route of 2aeb. Reagents and conditions: i) TiCl
4
, toluene; ii) Li,
*
Corresponding author. Tel./fax: þ86 21 6425 2288; e-mail address: bbsjh@
MeOH; iii) Cu (CF
reflux.
SO
3 3
)
, K
2 2
CO
3
, trichlorobenzene, reflux; iv) Pd(OAc)
2
, K CO , DMF, N ,
2
3
2
ecust.edu.cn (J. Su).
http://dx.doi.org/10.1016/j.tet.2016.03.036
0
040-4020/Ó 2016 Elsevier Ltd. All rights reserved.

H. Zhou et al. / Tetrahedron 72 (2016) 2300e2305
2301
pyridyl group and the DPAC core.10 Interestingly, remarkable
To investigate the relationship between the compounds’ optical
and charge transfer properties, three-dimensional geometries of
2aeb were optimized using density functional theory (DFT) at the
B3LYP/6-31G level of theory. Once the energies reached conver-
gence, single point energies and molecular orbitals were sub-
sequently computed with long-range corrected functionals cam-
B3LYP and the diffused and polarized triple-zeta basis set 6-
changes were observed both in absorption and fluorescence spectra
2
þ
of 2aeb when complexing with Hg
.
13
2
2
. Results and discussion
.1. Synthesis
1
4
3
11þG*. Seen from Table S2, the HOMOs receive contribution
The detailed synthetic route of 2aeb was described in Scheme 1.
from the styrylpyridine and piperazine moiety, while the LUMOs
are mostly localized on the styrylpyridine and phenanthrene moi-
ety. Upon photoexcitation, intramolecular charge transfer (ICT) is
expected to occur in these two compounds. ICT effect could be fa-
cilitated in polar solvent and that’s why the emission peaks of 2aeb
red shifted as the polarity of the solvent increased.
The key intermediates,1 and DPACeBr, was synthesized according to
previous literature.11 Compounds 2aeb were synthesized via Heck
1
coupling reaction between DPACeBr and 1aeb, and confirmed by H
NMR, 13C NMR and High-resolution mass spectroscopy (HRMS).
2
.2. Solvatochromic effect
2.3. Aggregation induced enhanced emission properties
The solvatochromic effect is usually observed in compounds
containing D-A pairs. Due to the presence of DPAC and pyridine, 2a
and 2b possess typical D- -A structure. To investigate the effect of
The optical properties of 2a and 2b were investigated in THF/
p
water (from 10:0 to 1:9) mixtures and the results are shown in
Fig. 2. It could be seen that both 2a and 2b showed very weak
fluorescence in pure THF. The photoluminescence (PL) intensity of
2a was slightly quenched when the water content was 10% and
stayed almost constant when water ratio below 80%. Noticeably,
when the water content increased from 80% to 90%, the PL intensity
boosted to the maximum with a 22-fold increase. In addition, the
emission maxima of 2a had a red shift of about 20 nm when the
water fraction increased from 0% to 90%, which could be ascribed to
the increasing accumulation of the molecules by aggregation.
Similar phenomenon was observed for 2b. It kept emitting weakly
when the water fraction increased from 0% to 80% and the PL in-
tensity reached maximum when water was added up to 90%, which
is nearly 20 times stronger than that in pure THF solution. There-
solvent polarity on the optical properties of the probes, the emis-
sion spectra of 2aeb in different solvents were recorded by in-
creasing the polarity from dioxane to acetonitrile and the results
are summarized in Fig. 1 and Fig. S1. As shown in Fig. S1, both the
absorption spectra of 2a and 2b exhibited minor changes in various
solvents. Meanwhile, as the polarity of the solvents increased, the
emission peaks of 2aeb gradually red shifted (2a: 428 nme479 nm;
2
b: 425 nme469 nm, from dioxane to acetonitrile) and accompa-
nied by a broadening of the emission bands in polar solvents, in-
dicating an intramolecular charge transfer (ICT) character in the
excited state. To evaluate the solvatochromism of the two probes,
the relationship between the solvent orientation polarizability (
Df)
and the Stokes shift ( v) was studied using the LipperteMataga
D
12
15
equation (see Table S1). The slopes of the fitting lines for 2aeb
fore, both 2a and 2b are AIEE active. What’s more, the absorption
were determined to be 7190 and 7390, respectively, according to
spectra of 2aeb in THF solution and in THF/water mixture were
observed (Fig. S3). It can be seen that the latter were slightly red-
shifted, which was caused by nano-aggregation.
the
D
vꢀ
Df plots (Fig. S2).
Fig. 1. Normalized fluorescence spectra of 2a (a) and 2b (b) in various solvents at
concentration of 10 M.
Fig. 2. Photoluminescence spectra of 2a (a) and 2b (b), respectively, in THF/water
mixtures.
m

2302
H. Zhou et al. / Tetrahedron 72 (2016) 2300e2305
The AIE nature of 2aeb could be further clarified by the opti-
430 nm accompanied by the color of the solution turning from
colorless to yellow, which could be observed by the naked eye
(Fig. S4). Meanwhile, no significant changes were observed in the
parallel experiments with other metal ions. Fig. 4b showed the
absorbance ratios of the peak at 425 nm and 360 nm (A425/A360) in
the presence of various metal ions. It is clear that for 2a solution
mized geometries. It can be seen from Table S2 that both 2aeb
present highly twisted saddle-shaped configurations with two ro-
tatable phenyls, which are favorable for nonradiative decay in so-
lution. When aggregated, not only the intramolecular rotations are
hindered, but also the formation of
making the aggregates emit intensely.
pep stacking is prevented,
A
425/A360 showed little increase upon addition of various metal ions
2
þ
except for Hg . Similar properties were observed in 2b solution
2
.4. pH sensing
Due to the presence of pyridyl group, 2a and 2b possess pro-
(Fig. S5).
tonation and deprotonation process. Thus, the spectroscopic
properties of the two probes were studied in phosphate buffer
solutions (PBS) in a pH range from 2.20 to 10.04, and the results are
illustrated in Fig. 3. Below pH 3.08, 2a showed very weak fluores-
cence, which could be ascribed to the protonated 2a. Increasing the
pH value gives rise to higher fluorescence intensity at 467 nm,
which could be caused by aggregation of deprotonated 2a in water.
The situation was similar for 2b. It emitted weakly and remained
almost constant when pH below 4.04, and its PL intensity was
gradually enhanced alone with the further increase of pH value.
Therefore, both 2aeb could act as pH probes.
Fig. 4. (a) Absorption spectra of 2a in THF solution containing different metal ions
(1.0 equiv) at same concentration (10
mM); (b) Absorption intensity ratio (A425/A360) of
2
a (10 M) versus different metal ions.
m
Subsequently, fluorescence responses of 2a and 2b over various
metal ions have been tested, and the results are illustrated in Fig. 5.
In the absence of any ions, both 2a and 2b showed an emission in
2
þ
THF. The addition of Hg (1.0 equiv) caused the quenching of the
fluorescence of 2aeb. In contrast, there was no significant fluo-
rescence change observed in 2aeb solutions in the presence of
Fig. 3. Fluorescence spectra of 2a (a) and 2b (b) in aqueous solution as a function of
pH. Concentration: 10 mM. Excitation wavelength is 380 nm for 2a and 385 nm for 2b.
1
0.0 equiv other metal ions. Significantly, both 2a and 2b could bind
2
þ
to Hg within several seconds and the complexes could remain
2
.5. Optical response to various metal ions
The sensing behaviors of 2aeb were first studied by UVeVisible
stable for several days. These evidence suggest 2aeb possess good
2
þ
selectivity towards Hg and could be applied in rapid detection of
2þ
2þ
Hg . Thus Hg titration of 2aeb by absorption and fluorescence
spectroscopy methods were carried out.
absorption measurements in THF/water mixtures. However, 2aeb
couldn’t respond to any metal ion in various THF/water mixtures
but could selectively respond to Hg in pure THF. It was found that
both free 2aeb in THF were achromatous and showed absorption
maximum at around 360 nm. Absorption responses of 2aeb were
carried out upon addition of 1.0 equiv of various metal ions (Ag ,
Ca , Co , Cr , Cu , Fe , Fe , Hg , Mg , Mn , Ni , Pb and
Zn ) in aqueous solution. It could be seen from Fig. 4 and Fig. S5
We then explored the optical response of 2a by monitoring the
changes in the absorption and fluorescence spectra in THF with
2
þ
2
þ
continuous addition of aqueous Hg . Upon addition of 0e1.5 equiv
2
þ
of Hg , the absorbance at 360 nm decreased gradually, accompa-
nied by the enhancement of a new absorption band at 425 nm, and
with an isosbestic point at 388 nm (Fig. 6a), suggesting the for-
þ
2
þ
2þ
3þ
2þ
2þ
3þ
2þ
2þ
2þ
2þ
2þ
2
þ
2þ
mation of a complex between the probe and Hg . It happened that
that both 2a and 2b exhibit a remarkably distinctive spectro-
scopic response toward addition of Hg , resulting in the decrease
of absorbance at ca. 360 nm and a new absorption peak at ca.
the absorption spectrum of 2a became constant after adding
1.5 equiv of Hg . As for the fluorescence spectrum of 2a, it
exhibited noticeable fluorescence quenching caused by spin-orbit
2
þ
2þ

H. Zhou et al. / Tetrahedron 72 (2016) 2300e2305
2303
Similarly, probe 2b showed main absorption band centering at
2þ
3
66 nm, and it also decreased gradually as Hg was added, ac-
companied by a new rise at 432 nm (Fig. 7a). The absorption
spectrum of 2b remained unchanged after adding more than
2
þ
1
.5 equiv of Hg . Interestingly, 2b exhibited weakened emission
2
þ
spectra and red shifted from 450 to 520 nm when Hg was added
Fig. 7b). Notably, the detection limits of 2aeb for Hg were de-
2
þ
(
termined by the absorption spectroscopy measurements (see
Fig. S6) to be 4.8 and 2.6 nM, respectively, which is much lower
than 10 nM, the maximum contaminant limit defined by the US EPA
for drinking water. Additionally, the detection limits of 2aeb were
also calculated by the fluorescence spectroscopy measurements
(see Fig. S7).
Fig. 5. (a) Fluorescence intensities at 450 nm of 2a (10
m
M) in THF in the presence of
ex¼360 nm); (b)
M) in THF in the presence of various ions
1.0 equiv for Hg and 10.0 equiv for other ions,
ex¼366 nm).
various ions (1.0 equiv for Hg2 and 10.0 equiv for other ions,
þ
l
Maximum fluorescence intensities of 2b (10
(
m
2þ
l
coupling or electron transfer16 upon progressively addition of Hg
and reached saturation point when Hg
2þ
2þ
concentration was
1.5 equiv, which is in line with the tendency observed in absorption
studies (Fig. 6b).
Fig. 7. Absorption (a) and fluorescence (b) spectra of 2b in THF (10 mM) upon addition
2þ
of 0e1.5 equiv of aqueous Hg
; lex¼390 nm.
2.6. Mechanism studies
1
H NMR titration spectra were studied to make certain of the
2
þ
1
coordination mechanism of 2ae2b with Hg . Fig. 8 presents the H
NMR spectra of 2a in DMSO-d in the presence of different equiv-
alent of Hg . After carefully comparing the H NMR titration
6
2
þ
1
2þ
spectra of 2a in the presence and absence of Hg , we found that
the chemical shifts of the resonances associated with the pyridyl
protons (H
1
, H
2
, H
3
and H
4
) and the ethenyl protons (H
5
and H
6
)
2
þ
showed significant changes upon complexation with Hg , while
the chemical shifts of the protons in DPAC moiety just displayed
2
þ
negligible changes. These observations revealed that Hg has co-
ordinated with pyridine moiety. What’s more, the spectrum
2
þ
remained unchanged after adding 0.5 equiv of Hg , suggesting the
2
þ
2
:1 stoichiometry of the complexes between 2a and Hg . The 2:1
2
þ
stoichiometry between 2a and Hg was then supported by the
MALDI-TOF MS spectrum (Fig. S9a) in which the labeled signal at m/
z
638.18 (calcd for
C
78
H
54HgN
6
, 638.21) was assigned to
2þ
2þ
[2a$Hg $2a] ion. Moreover, the result of Job’s plot analysis fur-
ther confirmed the 2:1 stoichiometry (Fig. S10a). Similar changes
1
were observed in the H NMR titration spectra of 2b (Fig. S8) and
2
þ
the 2:1 stoichiometry between 2b and Hg was also fully validated
by the MALDI-TOF MS (Fig. S9b) and the Job’s plot analysis
(Fig. S10b).
Fig. 6. Absorption (a) and fluorescence (b) spectra of 2a in THF (10
mM) upon addition
of 0e1.5 equiv of aqueous Hg2
þ
;
l
ex¼388 nm.

2304
H. Zhou et al. / Tetrahedron 72 (2016) 2300e2305
their band gaps and HOMO levels to be ꢀ2.55 and ꢀ2.59 eV,
respectively.
3. Conclusion
In summary, we’ve presented the synthesis and properties of
2þ
two phenazine-based probes, 2aeb, for rapid recognizing of Hg
with high selectivity and sensitivity in THF. Both the sensors
exhibited a gradual diminution at their original maximum wave-
length accompanied by an enhancement at a longer wavelength,
and the color changes from achromatous to yellow upon addition of
2þ
Hg , thus could serve as naked eye probes. Meanwhile, 2a and 2b
displayed a progressively decrease in fluorescence intensity upon
2
þ
2þ
addition of Hg , therefore 2aeb could detect quantitative Hg by
both absorption and fluorescence spectroscopy methods. Notably,
the detection limit of 2aeb was determined to be 4.8 and 2.6 nM,
respectively, by the absorption spectroscopy method. It’s men-
2
þ
tionable that both 2a and 2b could rapidly response to Hg in
several seconds. In addition, 2aeb showed AIE effect in THF/water
mixtures and could act as pH probes. These properties can promote
DPAC as promising building block for constructing Hg probes
with high performance.
2þ
Fig. 8. Partial 1H NMR spectra of 2a in DMSO-d
2þ
.
6
with increasing concentration of Hg
4
4
. Experimental section
.1. Materials
2
.7. Electrochemical properties
The electrochemical properties of 2ae2b were investigated by
cyclic voltammetry (CV). Pertinent data are listed in Table 1. The CV
of 2ae2b was measured in THF solution with 0.1 M n-Bu NPF as
supporting electrolyte, with an SCE reference electrode, platinum-
button working electrodes, and a platinum-wire counter electrode,
as shown in Fig. 9. Both the onset oxidation potentials of 2ae2b are
1
a and 1bwere purchased from Energy Chemical Reagent Co., Ltd.
The salts used in stock solutions of metal ions were AgNO , CaCl
CoCl $6H O, CrCl $6H O, CuCl $2H O, FeSO $7H O, FeCl $6H O,
Hg(ClO $3H O, MgCl $6H O, MnCl $4H O, NiSO $6H O, PbCl
ZnCl . All of them were of analytical reagent grade and used without
3
2
,
4
6
2
2
3
2
2
2
4
2
3
2
4
)
2
2
2
2
2
2
4
2
2
,
2
purification. Water used in experiment was double distilled water.
THF was pre-dried over sodium for 24 h and then redistilled under
argon atmosphere with sodium prior to use.
0
.74 V according to the CV curve. Thus, the HOMO values for 2ae2b
are both ꢀ5.54 eV, derived from the onset oxidation potentials
given above. The LUMO values of 2ae2b can be determined from
4.2. Instruments
Table 1
1H and 13C NMR spectra were measured on Bruker AM-400
a
Electrochemical and optical properties of 2ae2b
spectrometer using DMSO-d
(TMS,
¼0 ppm) as internal standard. Mass spectra were recorded
on Waters LCT Premier XE spectrometer. MS of complexes formed
6
as solvent and tetramethylsilane
E
onset-ox (V)
HOMO (eV)
l
onset (nm)
E
g
(eV)
LUMO (eV)
d
2
2
a
b
0.74
0.74
ꢀ5.54
ꢀ5.54
415
420
2.99
2.95
ꢀ2.55
ꢀ2.59
2þ
by 2a/2b with Hg were measured on an AB Sciex 4800 plus
Matrix-Assisted Laser Desorption Ionization Time of Flight (MALDI-
TOF) mass spectrometer. The UV/Vis spectra were recorded on
Nicolet CARY 100 spectrophotometer. The PL spectra were taken on
Varian-Cary fluorescence spectrophotometer or Horiba Fluoromax
a
Abbreviation: Eonset-ox (onset oxidation potential) was measured versus ferro-
onset¼onset absorption wave-
onset, LUMO¼E þHOMO.
cene, HOMO¼ꢀ(Eonset-oxꢀE1/2(ferrocene)þ4.8) eV,
length, E
¼energy band gap determined form
l
g
l
g
4
4
. The pH values between 2.20 and 10.04 were measured by PHSJ-
A pH meter. The quantum yield for solid powders was measured
by Quanta-w F-3029 Integrating Sphere.
4.3. Synthesis
4
.3.1. N
9
,N10-Diphenylphenanthrene-9,10-diamine (1). 1 mL TiCl
4
ꢁ
was dropwise added through an injector to a cooled solution (0 C) of
benzil (5.0 g, 23.8 mmol) and aniline (5.4 mL, 59.5 mmol) in toluene
(
70 mL). The solution was stirred at rt for 12 h. The reactant was
isolated with solvent under reduced pressure and dissolved in
00 mL THF. Lithium silk (0.41 g, 59.5 mmol) was added in portion at
1
rt and refluxed for 8 h. Methanol was added dropwise to the filtrate
with continued stirring until the evolution of hydrogen ceased. Then
water was added, and the product was extracted with DCM. After
4
drying with MgSO and removal of DCM, the resulting precipitate
was refluxed in ethanol, filtrated, washed with ethanol and dried
1
under vacuum to give a pale yellow solid (6.1 g). Yield: 71.2%. H NMR
Fig. 9. Cyclic voltammograms of 2ae2b in THF solution with 0.1 M of tetrabut-
ylmmonium hexafluorophosphate (n-Bu NPF ).
4
6
6
(DMSO-d , 400 MHz, TMS),
d
: 8.88 (d, J¼8.0 Hz, 2H), 7.93 (d, J¼8.0 Hz,

H. Zhou et al. / Tetrahedron 72 (2016) 2300e2305
2305
2
H), 7.68 (s, 2H), 7.65 (t, J¼8.0 Hz, 2H), 7.55 (7, J¼7.6 Hz, 2H), 7.00 (t,
128.13, 127.93, 127.39, 137.32, 132.23, 127.06, 127.05, 127.00, 126.01,
J¼8.0 Hz, 4H), 6.60 (t, J¼7.2 Hz, 2H), 6.52 (d, J¼7.6 Hz, 4H).
125.72, 123.83, 123.74, 123.70, 123.68, 123.47, 121.57, 120.48, 117.10,
þ
1
16.23. HRMS (m/z): [MþH] calcd for: C39
28 3
H N , 538.2283,
4
.3.2. 9-(4-Methoxyphenyl)-14-phenyl-9,14-dihydrodibenzo[a,c]ph-
enazine (DPACeBr). In 100 mL three-neck flask, 5.0
,N10-diphenylphenanthrene-9,10-diamine, 3.9 g
13.87 mmol) bromo-4-iodobenzene, 2.5 g (18.09 mmol) K CO
.25 g (3.45 mmol) Cu(CF SO ,10.0 g trichlorobenzene was added.
found: 538.2288.
a
g
(
(
13.87 mmol) N
9
Acknowledgements
2
3
,
1
3
3
)
2
This work was supported by National Natural Science Founda-
tion of China (20772031), the National Basic Research 973 Program
(2006CB806200), the Fundamental Research Funds for the Central
Universities (WJ0913001), and the Scientific Committee of Shang-
hai (10520709700).
The mixture stirred for 8 h under refluxed. The trichlorobenzene
was taken out by vacuum distillation. After cooling, added 50 mL
DCM and stirred for 20 min, filtered the mixture. The combined
organic layer was purified by column chromatography on silica
(
PE:DCM¼10:1 v/v) to give a light yellow solid (2.5 g). Yield: 35.1%.
1
H NMR (DMSO-d
.93e7.98 (m, 3H), 7.88e7.91 (m, 1H), 7.59e7.76 (m, 4H), 7.43e7.46
m, 2H), 7.22 (d, J¼9.2 Hz, 2H), 7.07e7.12 (m, 2H), 7.01 (d, J¼7.6 Hz,
H), 6.82e6.91 (m, 3H). HRMS (m/z): M calcd for: C32 21BrN
6
, 400 MHz, TMS),
d
: 8.95 (d, J¼8.4 Hz, 2H),
Supplementary data
7
(
2
Supplementary data (The characterization (NMR and HRMS)
and computational analysis data of 2aeb are available) associated
with this article can be found in the online version, at http://
dx.doi.org/10.1016/j.tet.2016.03.036.
H
2
,
5
12.0888, found: 512.0889.
4
.3.3. (E)-9-Phenyl-14-(4-(2-(pyridin-2-yl)vinyl)phenyl)-9,14-
round-bottom flask,
dihydrodibenzo[a,c]phenazine (2a). In
a
References and notes
DPACeBr (0.2 g, 0.39 mmol), 1a (82 mg, 0.78 mmol) and potassium
carbonate (65 mg, 0.47 mmol) were dissolved in 30 mL DMF, and
catalytic amount of palladium acetate was added, then the mixture
was refluxed under N
removed under reduced pressure, the residue was dissolved in
CH Cl , washed with water, dried over anhydrous MgSO and
concentrated using a rotary evaporator. The residue was purified by
column chromatography on silica (PE/CH Cl
¼1:3 v/v) to give
a pale yellow solid (0.1 g). Yield: 47.7%. Melting point: 256e258 C.
1. de Silva, A. P.; Fox, D. B.; Huxley, A. J. M.; Moody, T. S. Coord. Chem. Rev. 2000,
205, 41e57.
2
. (a) Boening, D. W. Chemosphere 2000, 40, 1335e1351; (b) Benoit, J. M.; Fitz-
gerald, W. F.; Damman, A. W. Environ. Res. 1998, 78, 118e133; (c) Gutknecht, J. J.
Membr. Biol. 1981, 61, 61e66.
2
atmosphere for 18 h. Upon cooling, DMF was
3. EPA Fact Sheet EPA-823-F-01e001Mercury Update: Impact on Fish Advisories;
Environmental Protection Agency, Office of Water: Washington, DC, 2001.
2
2
4
4. Zheng, C.; Li, Y.; He, Y.; Ma, Q.; Hou, X. J. Anal. At. Spectrom. 2005, 20, 746e750.
2
2
5. Beauchemin, D. Anal. Chem. 2008, 80, 4455e4486.
6. Quang, D. T.; Kim, J. S. Chem. Rev. 2010, 110, 6280e6301.
7. (a) Sarkar, M.; Banthia, S.; Samanta, A. Tetrahedron Lett. 2006, 47, 7575e7578;
ꢁ
ꢀ
1
FTIR (KBr, cm ): 3058.0 (v, ]CeH), 1589.1, 1496.5 (v, AreC]C),
(b) Cheung, S. M.; Chan, W. H. Tetrahedron 2006, 62, 8379e8383.
1
1
337.2 (AreCeN). H NMR (DMSO-d
J¼8.0 Hz, 2H), 8.50 (d, J¼4.0 Hz, 1H), 8.00e7.94 (m, 4H), 7.76e7.61
m, 5H), 7.51e7.37 (m, 6H), 7.20e7.16 (m, 1H), 7.12e6.98 (m, 7H),
.85e6.82 (m, 1H). 13C NMR (DMSO-d
, 100 MHz), : 155.25, 149.41,
49.32, 147.05, 147.03, 144.12, 143.43, 137.32, 136.68, 131.41, 129.59,
29.44, 129.31, 129.04, 128.27, 128.21, 127.92, 127.45, 127.36, 127.24,
27.08, 127.04, 126.00, 125.82, 125.74, 123.86, 123.83, 123.75, 121.89,
6
, 400 MHz, TMS), d: 8.97 (d,
8
. (a) Xue, H.; Tang, X. J.; Wu, L. Z.; Zhang, L. P.; Tung, C. H. J. Org. Chem. 2005, 70,
9727e9734; (b) Brombosz, S. M.; Zucchero, A. J.; Phillips, R. L.; Vazquez, D.;
Wilson, A.; Bunz, U. H. F. Org. Lett. 2007, 9, 4519e4522; (c) Feng, X. J.; Tian, P. Z.;
Xu, Z.; Chen, S. F.; Wong, M. S. J. Org. Chem. 2013, 78, 11318e11325.
(
6
1
1
6
d
9
. (a) Wang, B.; Wang, Y. C.; Hua, J. L.; Jiang, Y. H.; Huang, J. H.; Qian, S. X.; Tian, H.
Chem.dEur. J. 2011, 17, 2647e2655; (b) Jiang, Y. H.; Wang, Y. C.; Hua, J. L.; Tang,
J.; Li, B.; Qian, S. X.; Tian, H. Chem. Commun. 2010, 46, 4689e4691; (c) Huang,
W.; Tang, F. S.; Li, B.; Su, J. H.; Tian, H. J. Mater. Chem. C 2014, 2, 1141e1148.
1
10. Xue, H.; Tang, X. J.; Wu, L. Z.; Tung, C. H. J. Org. Chem. 2005, 70, 9727e9734.
þ
1
5
21.61, 117.14, 116.36. HRMS (m/z): [MþH] calcd for: C39
H
28
N
3
,
11. (a) Su, J. H.; Shen, L. P.; Zhao, D. M.; Zhang, Z. Y.; Wang, T. H.; Han, J. L.; Tian, H.
Faming Zhuanli Shenqing 2012 CN 102491950 A 20120613; (b) Ullah, F.; Kind-
ermann, M. K.; Jones, P. G.; Heinicke, J. Organometallics 2009, 28, 2441e2449.
38.2283, found: 538.2279.
1
2. Mataga, N.; Kaifu, Y.; Koizumi, M. Bull. Chem. Soc. Jpn. 1956, 29, 465e470.
4
.3.4. (E)-9-Phenyl-14-(4-(2-(pyridin-4-yl)vinyl)phenyl)-9,14-
13. (a) Becke, A. D. J. Chem. Phys.1993, 98, 5648ꢀ5642; (b) Lee, C.; Yang, W. T.; Parr, R.
G. Phys. Rev. B 1988, 37, 785e789; (c) Petersson, G. A.; Bennett, A.; Tensfeldt, T. G.;
Al-Laham, M. A.; Shirley, W. A.; Mantzaris, J. J. Chem. Phys. 1988, 89, 2193e2218.
dihydrodibenzo[a,c]phenazine (2b). Probe 2b was synthesized by
the same procedure as described above for 2a using compound 1
and compound 1b. Yield: 55.2%. Melting point: 180e182 C. FTIR
14. (a) Yanai, T.; Tew, D. P.; Handy, N. C. Chem. Phys. Lett. 2004, 393, 51e57; (b)
ꢁ
McLean, A. D.; Chandler, G. S. J. Chem. Phys. 1980, 72, 5639e5648.
ꢀ
1
(
(
KBr, cm ): 3068.9 (v,¼CeH), 1594.9, 1496.5 (v, AreC]C), 1340.3
15. (a) Hong, Y. N.; Lam, J. W. Y.; Tang, B. Z. Chem. Commun. 2009, 4332e4353; (b)
Hong, Y. N.; Lam, J. W. Y.; Tang, B. Z. Chem. Soc. Rev. 2011, 40, 5361e5388; (c)
Mei, J.; Hong, Y. N.; Lam, J. W. Y.; Qin, A. J.; Tang, Y. H.; Tang, B. Z. Adv. Mater.
1
6
AreCeN). H NMR (DMSO-d , 400 MHz, TMS), d: 8.95 (d,
J¼12.0 Hz, 2H), 8.46 (d, J¼8.0 Hz, 2H), 7.99e7.92 (m, 4H),
2014, 26, 5429e5479; (d) Mei, J.; Leung, N. L. C.; Kwok, R. T. K.; Lam, J. W. Y.;
7
.75e7.70 (m, 2H), 7.63 (dd, J¼8.0, 12.0 Hz, 2H), 7.47e7.41 (m, 4H),
Tang, B. Z. Chem. Rev. 2015, 115, 11718e11940.
13
16. (a) McClure, D. S. J. Chem. Phys. 1952, 20, 682e686; (b) Yu, M. X.; Shi, M.; Chen,
Z. G.; Li, F. Y.; Li, X. X.; Gao, Y. H.; Xu, J.; Yang, H.; Zhou, Z. G.; Yi, T.; Huang, C.
Chem.dEur. J. 2008, 14, 6892e6900; (c) Li, G. K.; Xu, Z. X.; Chen, C. F.; Huang, Z.
T. Chem. Commun. 2008, 15, 1774e1776.
7
.37e7.32 (m, 3H), 7.10e6.92 (m, 7H), 6.82 (m, 1H). C NMR
DMSO-d , 100 MHz), : 149.86, 147.20, 147.00, 144.48, 144.14,
43.36, 137.37, 136.62, 132.35, 129.56, 129.40, 128.99, 128.23,
(
1
6
d