Enantioselective Recognition for Many Different Kinds of Chiral Guests by One Chiral Receptor Based on Tetraphenylethylene Cyclohexylbisurea

Article abstract of DOI:10.1021/acs.joc.6b00371

A neutral chiral receptor based on TPE cyclohexylbisurea was synthesized and could discriminate the enantiomers of many different kinds of chiral reagents, including chiral acidic compounds, basic compounds, amino acids, and even neutral alcohols. The ¹H NMR spectra disclosed that the ability of chiral recognition could be ascribed to the multiple hydrogen bonds and CH interactions between the TPE urea receptor and the enantiomer of the chiral guest, which led to the selective aggregation of the receptor with one of the two enantiomers. This result exhibited a great potential in enantiomer discernment and high-throughput analysis of enantiomer composition of these chiral analytes by one chiral AIE molecule.

Full text of DOI:10.1021/acs.joc.6b00371

Subscriber access provided by UNIV LAVAL
Article
Enantioselective Recognition for Many Different Kinds of Chiral Guests
by One Chiral Receptor Based on Tetraphenylethylene Cyclohexylbisurea
Jia-Bin Xiong, Wen-Zhao Xie, Jian-Ping Sun, Jin-Hua Wang, Zhi-
Hua Zhu, Hai-Tao Feng, Dong Guo, Hui Zhang, and Yan-Song Zheng
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.6b00371 • Publication Date (Web): 31 Mar 2016
Downloaded from http://pubs.acs.org on April 5, 2016
Just Accepted
“Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted
online prior to technical editing, formatting for publication and author proofing. The American Chemical
Society provides “Just Accepted” as a free service to the research community to expedite the
dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts
appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been
fully peer reviewed, but should not be considered the official version of record. They are accessible to all
readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered
to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published
in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just
Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor
changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers
and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors
or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
The Journal of Organic Chemistry is published by the American Chemical Society.
1155 Sixteenth Street N.W., Washington, DC 20036
Published by American Chemical Society. Copyright © American Chemical Society.
However, no copyright claim is made to original U.S. Government works, or works
produced by employees of any Commonwealth realm Crown government in the course
of their duties.

Page 1 of 20
The Journal of Organic Chemistry
1
2
3
4
5
6
7
8
9
Enantioselective Recognition for Many Different Kinds of Chiral Guests by One Chiral
Receptor Based on Tetraphenylethylene Cyclohexylbisurea
a
a
a
a
a
a
JiaꢀBin Xiong, WenꢀZhao Xie, JianꢀPing Sun, JinꢀHua Wang, ZhiꢀHua Zhu, HaiꢀTao Feng,
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
b
b
a
Dong Guo, Hui Zhang, and YanꢀSong Zheng *
a
Key Laboratory for Chemistry of Energy Conversion and Storage Materials, Ministry of
Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and
b
Technology, Wuhan, China. College of Chemistry and Chemical Engineering, Xiamen University,
Xiamen 361005, China.
Eꢀmail: zyansong@hotmail.com
TABLE OF CONTENTS
ABSTRACT: A neutral chiral receptor based on TPE cyclohexylbisurea was synthesized and
could discriminate the enantiomers of many different kinds of chiral reagents including chiral
1
acidic compounds, basic ones, amino acids and even neutral alcohols. The H NMR spectra
disclosed that the supra ability of chiral recognition should be ascribed to the multiple hydrogen
bonds and CHꢀpi interactions between the TPE urea receptor and the enantiomer of the chiral
guest, which led to the selective aggregation of the receptor with one of the two enantimers. This
result exhibited a great potential in enantiomer discernment and high throughput analysis of
enantiomer composition of these chiral analytes by one chiral AIE molecule.
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 2 of 20
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
INTRODUCTION
Most of drug molecules are chiral and the enantiomers of them often show different physiological
activity. Therefore, single enantiomer must be obtained and the enantiomeric purity must be
known in research and development of chiral drugs. Although there already are many methods for
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
,2
measurement of enantiomeric purity, the fluorescent spectroscopic approach is the most
promising due to its costꢀeffectiveness, accuracy and sensitivity, which are very qualified for high
2
throughput screening of potential chiral drugs. In this context, fluorescent receptors for
discrimination and analysis of enantiomers are attracting more and more attentions. Up to now, a
large number of excellent fluorescent receptors for analyzing enantiomers of one class of chiral
compounds, but to discriminate enantiomers of different kinds of chiral molecules with one
3
fluorescent receptor is rare although other methods such as NMR and circular dichroism probes
4,5
often have the efficiency of one stone two birds.
Recently, a new class of organic compounds with amazing aggregationꢀinduced emission
(
AIE) effect, that is, having no fluorescence in solution but emitting strong light in aggregation
state, are rapidly making progress because they can overcome the disadvantages of
aggregationꢀcaused quenching (ACQ) of most of fluorophores in solid state and showed a
6
remarkable potential in optoelectronic materials. Meanwhile, the fluorescence change from AIE
effect also make the organic compounds of this class versatile and exceptional
6
,7
chemo/biosensors. By introducing optically pure groups into the AIE molecules, the prepared
chiral AIE molecules may become excellent chiral sensors for discrimination and analysis of
8
−12,15
enantiomers of chiral analytes.
For example, AIE compounds bearing chiral carboxylic group
can enantioselectively form a suspension with one enantiomer but a clear solution with the other
ACS Paragon Plus Environment

Page 3 of 20
The Journal of Organic Chemistry
1
2
3
4
5
6
7
8
9
enantiomer of chiral amines, in which the suspension emitted strong fluorescence but the solution
8
had nonꢀemission. In similar way, the chiral AIE amine can discriminate the two enantiomers of
9
chiral acidic compounds by enantioselective aggregation. Pu and Hou et al also reported that one
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
1
,1’ꢀbiꢀ2ꢀnaphtholamine receptor could enantioselectively induce precipitation and solidꢀstate
1
0
fluorescence enhancement with one enantiomer of αꢀhydroxycarboxylic acids. In 2014, Tang and
Wong found that a AIE silole bearing two optically pure thiourea groups could form helical
aggregates with the enantiomers of chiral carboxylic acids and emit complexationꢀinduced
11
circularly polarized luminescence (CPL) in the solid thin film state. Very recently, our group
reported that AIE macrocycles bearing optical pure diphenyldiaminoethylene group displayed
enantiomer discrimination not only for chiral acidic compounds but also for unprotected αꢀamino
12
acids. Here a chiral AIE receptor based on tetraphenylethylene (TPE) cyclohexylbisurea was
synthesized and could discriminate enantiomers of both acidic compounds, basic ones, amino
acids and even neutral alcohols.
RESULTS AND DISCUSSION
The chiral TPE receptor was synthesized in light of the reaction route shown in Scheme 1. TPE 1
could be selectively nitrated to give mononitroTPE 2 in excellent yield (90%) with nitric acid in a
mixed solvent of acetic acid and dichloromethane as long as the temperature and the amount of the
nitrating agent was controlled right. Then the mononitroTPE 2 was reduced to TPE monoamine 3
in 91% yield by hydrazine hydrate in the presence of Pd/C, which was further transferred to
isocyanate 4. Without being purified, the isocyanate 4 underwent a condensation reaction with
optically pure (1R,2R)ꢀ or (1S,2S)ꢀ1,2ꢀcyclohexanediamine to offer the target product chiral TPE
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 4 of 20
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
cyclohexylbisurea 5 in 42% or 45% yield.
Scheme 1. The synthesis of the chiral TPE cyclohexylbisurea 5.
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
NO
NH2
2
HNO
3
(65%)
2 4 2
N H H O
10% Pd/C
HAc/DCM
9
0%
EtOH
9
1%
1
2
3
NH
NH
2
2
H
NCO
O
O
N
NH
NH
Triphosgene
(
R,R)- or (S,S)-
3
Et N/DCM
DCM
2-45%
N
4
H
4
(
R,R)-5 or (S,S)-5
The chiral TPE cyclohexylbisurea 5 was soluble in convenient organic solvent such as
chloroform, 1,2ꢀdichloroethane and THF, but insoluble in hexane and water. After it was dissolved
ꢀ
4
in 1,2ꢀdichloroethane, the resultant solution (1.0 × 10 M) did not emit fluorescent light. When 80%
fraction of hexane was added into the solution and turbid appeared, the solution started to give
fluorescent emission. As the hexane fraction was continued to increase and the solution become
more turbid, the fluorescent intensity increased rapidly. At the 95% fraction of hexane, the
intensity was increased by 203 fold compared with the solution without added hexane (Fig. 1).
Therefore, the chiral TPE cyclohexylbisurea 5 is a AIE compound.
4
00
400
300
300
200
100
0
0
20 40 60 80 100
Hexane %
2
1
00
00
0
4
00
500
Wavelength (nm)
600
ꢀ4
Fig. 1. Change in the fluorescent spectra of (S,S)ꢀ5 (1.0 × 10 M) in 1,2ꢀdichloroethane with the
ACS Paragon Plus Environment

Page 5 of 20
The Journal of Organic Chemistry
1
2
3
4
5
6
7
8
9
added hexane. λex = 366 nm, ex/em slits = 3/3 nm. Inset: curve of fluorescent intensity vs hexane
percentage in 1,2ꢀdichloroethane measured at 468 nm.
Interestingly, when the concentration of R,Rꢀ or S,Sꢀ5 in 1,2ꢀdichloroethane was increased to
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
ꢀ2
ꢀ4
1
.0 × 10 M from 1.0 × 10 M, the solution became transparent gel after it was standing at room
temperature for several minutes. Upon heating, the gel come back to the solution but it became the
gel again after the heated solution was cooled to room temperature (Fig. 2A). This process could
be reversible for many times. Meanwhile, while the solution did not display emission, the gel
showed strong fluorescence under a portable 365 nm UV lamp. This result indicated that the chiral
TPE cyclohexylbisurea 5 tended to aggregate at high concentration probably due to the two urea
groups which easily formed multiple hydrogen bonds between molecules. This is in accordance
with the literature's reports in which one urea group that is conjugated to long aliphatic chains can
13
easily form stable gel because of hydrogen bonding interactions between urea groups. However,
TEM images disclosed that the gel was composed of nanospheres with diameter of 50 nm − 500
nm, and SEM images also confirmed the formation of nanospheres with the similar diameter range
from 50 nm to 500 nm (Fig. 2B−2C). In general, organic gel is often formed by nanofibers which
could interdigitate to produce many micro 3D spaces and immobile the solvent. The gel formed by
14
nanospheres is very rare.
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 6 of 20
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Fig. 2. (A) Photos of gel formed by 10 mg of (R,R)ꢀ5 in 1.0 mL of 1,2ꢀdichloroethane under a
portable 365 nm UV lamp (left) and interꢀconversion of the gel and solution by cooling and
heating (right). (B) TEM image and (C) FEꢀSEM image of the gel.
Although the morphology of the aggregates of 5 in 1,2ꢀdichloroethane was nanospheres, the
circular dichroism (CD) spectra of the solution of 5 at different concentrations was measured (Fig.
ꢀ4
S9). When the concentration of (S,S)ꢀ5 was 1.0 × 10 M or less, no CD signal was observed,
demonstrating that (S,S)ꢀ5 was completely dispersed into 1,2ꢀdichloroethane, which was in
ꢀ4
accordance with the fluorescence test. After the concentration was increased to 5.0 × 10 M, a
broad CD band with negative Cotton effect between 365 nm to 260 nm appeared, and it become
ꢀ3
ꢀ3
stronger at 1.0 × 10 M (Fig. S9 and Fig. 3). When the concentration reached to 5.0 × 10 M at
which gelatinous solid started to appear in the solution, the CD signal was not only very strong but
also displayed many fine peaks. Because only did the aggregation lead to CD signals, the
aggregates should posses helical chirality which could result from the helical stacking of (S,S)ꢀ5 in
ꢀ3
one direction. At 1.0 × 10 M, the solution of (R,R)ꢀ5 instead of (S,S)ꢀ5 in 1,2ꢀdichloroethane
showed a broad CD band with positive Cotton effect between 365 nm to 260 nm, which was the
mirror image of that of (S,S)ꢀ5 ( Fig. 3). Therefore, the configuration of 5 determined the handed
direction of the helical chirality and the CD sign of the aggregates. Due to easily formed
aggregation, the chiral 5 could display CD signals in solution while other all chiral AIE
compounds that have been reported up to now often only exhibited CD signals in solid or in
ACS Paragon Plus Environment

Page 7 of 20
The Journal of Organic Chemistry
1
2
3
4
5
6
7
8
9
11,15
polymer film.
.
3
1
0
5
0
(
S,S
)
)
-5
-5
(R,R
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
-
15
30
-
3
00
350
400
450
Wavelength (nm)
ꢀ3
Fig. 3. CD spectra of (R,R)ꢀ5 and (S,S)ꢀ5 in 1,2ꢀdichloroethane, respectively, at 1.0 × 10 M.
To measure the ability of the chiral recognition of the chiral TPE 5, the effect of enantiomers
of a wide variety of chiral analytes on the aggregation of 5 in solution was tested. It was
surprisingly found that the enantiomers of , not only chiral acidic compounds, but also chiral basic
amines, zwitterionic amino acids, and even completely neutral chiral alcohols could selectively
affect the aggregation of 5. When the nonꢀsolvent hexane was added into the solution of the
enantiomers of 2ꢀchloromandelic acid 6 and (R,R)ꢀ5 in 1,2ꢀdichloroethane, it was found that the
mixture of Sꢀ6 and (R,R)ꢀ5 led to aggregation and resulted in suspension, but the mixture of Rꢀ6
and (R,R)ꢀ5 was still solution. The suspension emitted strong fluorescence while the solution
showed very weak emission (Fig. 4), and the fluorescence intensity ratio or enantioselectivity
(ISꢀ6/IRꢀ6) of the suspension to the solution was up to 8.8 (Table 1). Similarly, among the two
enantiomers of mandelic acid 7, Sꢀ7 led to aggregation of (R,R)ꢀ5 but (R)ꢀ7 did not, which gave
rise to enantioselectivity (ISꢀ7/IRꢀ7) of 5.9. For other chiral carboxylic acids, such as
1
,2,3,4ꢀtetrahedroꢀnaphthoic acid 8, 2,3ꢀdibenzoyltartaric acid 9 and 2,3ꢀdiꢀpꢀtoluoyltartaric acid
1
0, (R,R)ꢀ5 also exhibited an ability to discriminate the two enantiomers of them. Noticeably, for
camphor sulfonic acid 11 with strong acidity, (R,R)-5 displayed very high enantioselectivity
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 8 of 20
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
(
ILꢀ11/IDꢀ11) of 63 (Fig. S10 and Table 1).
150
B
A
R-2-chloromandelic acid 6
S-2-chloromandelic acid 6
R-mandelic acid 7
S-mandelic acid 7
2
00
1
00
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
100
0
50
0
4
00
500
Wavelength (nm)
600
400
500
Wavelength (nm)
600
Fig. 4. The fluorescence spectra of a mixture of enantiomer of chiral analyte and (R,R)ꢀ5 in
ꢀ5
ꢀ4
organic solvent(s). A) 7.8×10 M in hexane/1,2ꢀdichloroethane 3.5:1. B) 1.0×10 M in
hexane/1,2ꢀdichloroethane 2.7:1. [(R,R)ꢀ5] = [analyte].
For chiral amines, their enantiomers could be also discriminated by (R,R)-5 (Fig. S10 and
Table 1). When the nonꢀsolvent hexane was added into the solution of the enantiomers of
phenylglycinol 12 and (R,R)ꢀ5 in 1,2ꢀdichloroethane, the mixture of Sꢀ12 and (R,R)ꢀ5 gave rise to
suspension, but the mixture of Rꢀ12 and (R,R)ꢀ5 remained solution, which resulted in a
fluorescence intensity ratio (ISꢀ12/IRꢀ12) of 9.2 for the Sꢀ and Rꢀenantiomers. In similar way,
(S,S)ꢀisomer of 1,2ꢀdiphenylꢀethanediamine 13 and 1,2ꢀcyclohexanediamine 14 induced the
aggregation of(R,R)ꢀ5, but their (R,R)ꢀisomer did not make the aggregation of (R,R)ꢀ5, which gave
enantioselectivity of 2.4 and 33 for 13 and 14, respectively.
Due to larger polarity of amino acid, the mixed solvent THF and water instead of
1
,2ꢀdichloroethane and hexane was used for testing the enantioslective aggregation. After D or
Lꢀleucine 15 was added to (R,R)-5 in a mixed solvent of THF and water, only the mixture of
(
(
R,R)-5 and Lꢀ15 turned to be suspension and emitted strong fluorescence but the interaction of
R,R)-5 with Dꢀ15 gave solution which almost emitted no fluorescence (Fig. S10). The
enantiosectivity (ILꢀ15/IDꢀ15) was up to 156. For other αꢀamino acids, including phenylalanine 16,
ACS Paragon Plus Environment

Page 9 of 20
The Journal of Organic Chemistry
1
2
3
4
5
6
7
8
9
tryptophan 17, proline 18, threonine 19, arginine 20, and histidine 21, their enantiomers could be
discriminated by the chiral TPE bisurea (R,R)-5 with good enantioselectivity (Fig. S10 and Table
1).
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Very outstandingly, for neutral chiral alcohols, (R,R)-5 could also display a obvious chiral
recognition between their enantiomers (Fig. S10 and Table 1). When nonꢀsolvent was added to the
mixture of (R,R)-5 and the enantiomers of menthol 22 in THF, the mixture of (R,R)-5 and Lꢀ22
gave rise to suspension but that of (R,R)-5 and Lꢀ22 led to solution, which offered
enantioselectivity (ILꢀ22/IDꢀ22) of 2.5. In the same mixed solvent, the enantioselectivity was 2.0
(IRꢀ23/ISꢀ23) for binol 23. For methylmandelate 24 and diethyltartarate 25, (R,R)-5 showed high
enantioselectivity of 55 (ISꢀ24/IRꢀ24) and 3.3 (ILꢀ25/IDꢀ25), respectively, in a mixed solvent of hexane
and 1,2ꢀdichloroethane.
Table 1 The Fluorescent Intensity Ratio and State of the Mixture of Enantiomer of Analyte with
(
R,R)ꢀ5 in Solvent(s).
a
b
Entry
Analytes
I
1
/I
2
State
Solvent
Cl
OH
ꢀ5
1
8.8 (S/R)
5.9 (S/R)
3.6 (R/S)
3.8 (D/L)
9.2 (D/L)
Sus/Sol
Sus/Sol
Pre/Sol
Pre/Sol
Sus/Sol
7.8×10 M in
OH
O
6
hexane/DCE
3
.5:1
OH
ꢀ4
2
3
4
5
1.0×10 M in
OH
O
7
hexane/DCE
2
.7:1
O
OH
ꢀ
5
8.9×10 M in
hexane/DCE
4.0:1
8
ꢀ
5
HO
O
8.0×10 M in
O
O
O
hexane/ DCE
O
9
OH
O
5
.5:1
ꢀ5
HO
8.0×10 M in
hexane/DCE
4.0:1
O
O
O
O
O
OH
O
1
0
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 10 of 20
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
ꢀ
5
6
7
8
9
63 (L/D)
9.3 (S/R)
pre/sol
Sus/sol
Sus/Sol
Sus/Sol
8.5×10 M in
HO
3
S
O
11
hexane/DCE
5
.9:1
NH
2
ꢀ5
7.6×10 M in
HO
1
2
hexane/DCE
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
4
.0:1
ꢀ
5
NH
2
2.4 (SS/RR)
33 (SS/RR)
7.4×10 M in
hexane/DCE
3.9:1
13
NH
2
ꢀ
5
NH2
NH2 14
5.4×10 M in
hexane/DCE
6
.0:1
ꢀ4
10
NH
2
156 (L/D)
9.1 (L/D)
6.2 (L/D)
2.6 (D/L)
3.6 (D/L)
15.8 (L/D)
49 (L/D)
2.5 (L/D)
Sus/Sol
Sus/Sol
Sus/Sol
Sus/Sol
Sus/Sol
Sus/Sol
Sus/Sol
Sus/Sol
1.0×10 M in
COOH 15
H O/THF 4.0:1
2
ꢀ
4
1
1
2
3
4
NH
2
1.0×10 M in
O/THF 1.6:1
COOH
1
6
H
2
ꢀ
5
1
1
1
4.5×10 M in
NH
2
HN
COOH
1
7
H O/THF 1.9:1
2
ꢀ
4
COOH
1.0×10 M in
NH 18
H
2
O/THF 1.4:1
OH
ꢀ4
1.0×10 M in
NH
2
COOH 19
H O/THF 1.7:1
2
NH
ꢀ4
15
1.2×10 M in
NH
2
HN
N
H
COOH 20
H O/THF 1.6:1
2
ꢀ
4
1
6
7
NH2
1.0×10 M in
N
NH COOH 21
H O/THF 1.5:1
2
ꢀ4
1
1.3×10 M in
2
H O/THF 1.7:1
OH
2
2
ꢀ
4
18
OH OH
2.0 (R/S)
55 (S/R)
3.3 (L/D)
Sus/Sol
Sus/Sol
Sus/Sol
1.2×10 M in
H
2
O/THF 1.9:1
23
OH
O
ꢀ5
19
5.8×10 M in
O
24
hexane/DCE
3
.6:1
O
OH
ꢀ5
20
8.1×10 M in
O
O
OH
O
25
hexane/DCE
ACS Paragon Plus Environment

Page 11 of 20
The Journal of Organic Chemistry
1
2
3
4
5
6
7
8
9
4.0:1
a
b
Enantiomer 1/enantiomer 2, Pre = Precipitates; Sus = Suspension; Sol = Solution
Volume ratio of solvents; DCE = 1,2ꢀdichloroethane; [(R,R)ꢀ5] = [analyte].
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Because of inherent chiral recognition, when (S,S)ꢀ5 was used as receptor, the interaction of
chiral analytes with (S,S)ꢀ5 would result in contrary enantioselective aggregation compared with
R,R)ꢀ5. Therefore, by using (R,R)ꢀ5 and (S,S)ꢀ5, the enantiomeric purity of the chiral analyte
(
could be quantitatively measured, which was demonstrated by the example shown in Fig. 5.
Making the concentration of the chiral receptor 5 and the total concentration of the two
ꢀ5
enantiomers of 2ꢀchloromandelic acid 6 invariant (7.8 × 10 M), with (S,S)ꢀ5 as receptor, the
fluorescence intensity increased with increasing the molar percent of Rꢀ6 in enantiomer
composition. In contrary, with (R,R)ꢀ5 as receptor, the fluorescence intensity decreased with
increasing the molar percent of Rꢀ6. The resultant two standard curves would be used to determine
the enantiomeric purity of chiral carboxylic acid 6. This has a great potential for high throughput
analysis of enantiomer purity of chiral drugs and reagents.
3
00
300
200
100
0
200
S,S-5
R,R-5
100
0
0
20
40
60
R-6%
80
100
Fig. 5. Change of fluorescence intensity of the mixture of (R,R)ꢀ5 or (S,S)ꢀ5 and 2ꢀchloromandelic
acid 6 with enantiomer content in hexane/1,2ꢀdichlororethane 3.5:1. [R,Rꢀ5] = [S,Sꢀ5] = [Rꢀ6] +
ꢀ5
[
Sꢀ6] = 7.8 × 10 M.
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 12 of 20
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
1
To have insight into the interaction mechanism of (R,R)ꢀ5 with the chiral acid 6, the H NMR
spectra of the mixture of (R,R)ꢀ5 and R/Sꢀ6 and the NMR titration of (R,R)ꢀ5 with Rꢀ6 or Sꢀ6 in
3
CDCl were recorded. When (R,R)ꢀ5 was mixed with the 0.5 equivalent of Rꢀ6 and 1 equivalent
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
of Sꢀ6, the proton signals of both the urea 5 and the chiral acid 6 showed obvious change (Fig. 6).
On the respect of the chiral acid 6, the signals of aromatic protons had upfield shift of about 0.05
ppm to 0.06 ppm from 7.31 ppm to 7.25 ppm and 7.42 ppm to 7.37 ppm. The methine proton also
displayed upfield shift from 5.66 ppm to 5.61 ppm for Rꢀ6 and upfield one from 5.66 ppm to 5.59
ppm for Sꢀ6, indicating that Sꢀ6 had 0.02 ppm bigger upfield shift than Rꢀ6 and these two
enantiomers could be discriminated in NMR spectrum. On the respect of the receptor (R,R)ꢀ5, the
proton signals of the urea groups were not easily observed because of the fast exchange with
carboxylic proton or protons of water that was not completely removed from the solvent. However,
the proton signals of the aniline rings of the TPE unit appeared to have the largest upfield shift of
0.08 ppm while the protons of other phenyl rings showed almost no signal change. In addition, it
was the βꢀmethylene protons rather than the αꢀmethine proton connected to the amino group in
cyclohexyl unit that displayed significant upfield shift of 0.06 ppm becauseonly 0.003 ppm upfield
shift came from the αꢀmethine proton. The distinct upfield shift of both the aniline protons and the
βꢀmethlene protons of (R,R)ꢀ5 implied that they were placed among the shield area of the phenyl
ring of the guest acid and showed obvious CHꢀπ interactions due to attractions of the hydrogen
bonds of the carboxylic group and the urea ones (Fig. 7).
ACS Paragon Plus Environment

Page 13 of 20
The Journal of Organic Chemistry
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
1
Fig. 6. The H NMR spectra of (R,R)ꢀ5, the mixture of (R,R)ꢀ5, Rꢀ6, and Sꢀ6 (molar ratio, 1:0.5:1),
ꢀ3
and the mixture of Rꢀ6 and Sꢀ6 (molar ratio, 0.5:1) in CDCl . [(R,R)ꢀ5] = 3.0 × 10 M.
3
Fig. 7. Diagram of both the aniline protons and the βꢀmethlene protons of (R,R)ꢀ5 that were placed
among the shield area of the phenyl ring of the guest acid Sꢀ6. Sꢀ6 was drawn in ball and stick;
(
R,R)ꢀ5 was drawn in stick with omission of one TPE unit for clarity.
The NMR titration of (R,R)ꢀ5 with Rꢀ6 or Sꢀ6 further demonstrated that the obvious proton
signal change was upfield shift with the addition of the guest acid (Fig. 8). From the Job plots of
1
the H NMR titration, it was found that both Rꢀ6 and Sꢀ6 formed a 1:1 complex with (R,R)-5 (Fig.
S12 and Fig. S12). By nonlinear fitting analysis, the association constants of (R,R)-5-Rꢀ6 and
ꢀ1
ꢀ1
(R,R)-5-Sꢀ6 complexes were 67 ± 16 M and 83 ± 8.0 M , respectively (Fig. S13 and Fig. S14).
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 14 of 20
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
From Fig. 7, the interaction difference of Rꢀ6 and Sꢀ6 with (R,R)-5 should come from the different
binding position if Sꢀ6 was replaced with Rꢀ6 or position of any two substituents at the chiral
carbon of 6 was exchanged. Although the binding force from hydrogen bonds and CHꢀπ
interactions is much less than the Coulomb attraction of basic receptor with acidic guest, which
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
9
usually led to association constant at several ten thousands level, the interaction difference of Rꢀ6
and Sꢀ6 with (R,R)-5, respectively, was enough to result in different polarity and solubility of the
diastereomers (R,R)-5-Sꢀ6 and (R,R)-5-Rꢀ6 complex in the mixed solvent due to different
interaction force of (R,R)-5 with Sꢀ6 and Rꢀ6. The diastereomer (R,R)-5-Sꢀ6 complex had less
solubility and more easily aggregated than the diastereomer (R,R)-5-Rꢀ6 one, therefore,
(
R,R)-5-Sꢀ6 complex emitted stronger fluorescence, which led to enantioselectivity.
2
.1 eq
1
1
.9 eq
.4 eq
1.2 eq
1.1 eq
1.0 eq
0
.9 eq
0
0
0
.8 eq
.6 eq
.4 eq
0
.2 eq
.1 eq
0 eq
0
ppm
1
3
Fig. 8 Changes of H NMR spectra of (R,R)-5 with increasing Sꢀ6 in CDCl . [(R,R)-5] = 3.0 mM,
the number over the spectrum is the molar ratio of Sꢀ6 vs. (R,R)-5.
CONCLUSIONS
In conclusion, a neutral chiral receptor based on TPE cyclohexylbisurea was synthesized and
easily formed aggregates in 1,2ꢀdichloroethane, which resulted in both AIE effect and distinct CD
signals. The aggregation could be selectively triggered by only one enantiomer but could not by
ACS Paragon Plus Environment

Page 15 of 20
The Journal of Organic Chemistry
1
2
3
4
5
6
7
8
9
the other enantiomer of a wide variety of chiral reagents including chiral acidic compounds, basic
1
ones, amino acids and even neutral alcohols. H NMR spectra disclosed that the multiple hydrogen
bonds and CHꢀπ interactions between the TPE urea receptor and the enantiomer of the chiral guest
played key role on the selective aggregation. This result exhibited a great potential in enantiomer
discernment and high throughput analysis of enantiomer composition of many chiral analytes by
one chiral AIE compound.EXPERIMENTAL SECTION
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
1
H NMR titration was carried out by addition of concentrated solution of chiral acid 6
3
into the solution of receptor 5 in CDCl . To keep constant concentration of sensor 5 and
account for dilution effects during titration, the solution of 6 was prepared with the solution
of 5 at its initial concentration as a solvent. The association constants were calculated by
1
6
nonlinearly curve fitting in Origin 7.5 using following equation:
_
2
(
[H] + [G] + 1/Ka)
([H] + [G] + 1/K ) ꢀ 4[H][G]
a
_
δobs = δΗ
+
.
(δcom
δ )
H
2
[H]
δ
6
δ
obs: chemical shift of the βꢀmethylene protons in cyclohexyl unit of (R,R)ꢀ5 after enantiomer of
was gradually added;
H
: chemical shift of the βꢀmethylene protons in cyclohexyl unit of (R,R)ꢀ5 without 6;
δcom: chemical shift of the βꢀmethylene protons in cyclohexyl unit of (R,R)ꢀ5 in 5ꢀ6 complex;
[
[
H]: molar concentration of (R,R)ꢀ5;
G]: molar concentration of enantiomer of 6 added during titration.
1
7
Synthesis of compound 2. To a flask tetraphenylethylene 1 (2.64 g, 8 mmol), glacial acetic
acid (1.9 mL, 32 mmol) and dichloromethane (80 mL) were added. After the solution was cooled
o
to −15 C with iceꢀsalt bath, concentrated nitric acid (1.6 mL, 24 mmol) was added under rigorous
magnetic stirring. The reaction solution was continued to stir for about 15 min at the iced
temperature and then was quenched with cold water. The organic phase was immediately
2 4
separated and washed with water for three times (3 × 50 mL). Upon dried over anhydrous Na SO
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 16 of 20
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
and filtrated, the solution was evaporated to dryness under vacuum. The yellow residue was
recrystallized from MeOH to give 2 as a yellow powder (2.25 g, 90%)
.
1
8
Synthesis of compound 3. To a flask mononitroTPE 2 (1.2 g, 3.18 mmol), 10% Pd/C (100
mg), and EtOH (100 mL) were added and stirred for 15 min at room temperature. Then 85%
hydrazine hydrate (5.4 mL, 95.4 mmol) was added and refluxed for 4 h. Upon cooled to room
temperature, the reaction mixture was diluted with dichloromethane (30 mL) and filtrated through
a layer of Celite. After the solvent was removed under vacuum, the resultant white solid was
dissolved in dichloromethane (50 mL) and washed with water for three times (3 × 30 mL). The
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
2 4
organic phase was dried over anhydrous Na SO , filtrated, and evaporated under reduced pressure.
The residue was recrystallized with MeOH to give 3 as a white solid (1.02 g, 91%)
.
Synthesis of compound (R,R)-5. TPE amine 3 (1.0 g, 2.88 mmol) and Et N (0.48 mL, 3.54
3
o
mmol) were dissolved in dichloromethane (50 mL) and the solution was cooled to 0 C with iced
bath under stirring. After a solution of triphosgene (342 mg, 1.15 mmol) in dichloromethane (10
mL) was dropwise added within 15 min, the reaction solution was stirred for 2 h until complete
disappearance of 3 and no further increase of 4. Then (1R,2R)ꢀcyclohexanediamine (164 mg, 1.44
mmol) was added and stirred over night at ambient temperature. The solution was washed with
2 4
water for three times and dried over anhydrous Na SO . Upon filtrated, the solvent was removed
under vacuum and the resident was purified by flash chromatography (silica gel; eluant,
2
0
dichloromethane/methanol 80:1) to give (R,R)ꢀ5 as a white solid (0.52 g, 42%). [α]
D
= +38.8 (10
o
1
mg/mL, CHCl
3
); Mp 251−252 C; H NMR (400 MHz, CDCl ) δ 7.20−6.90 (m, 30H), 6.87 (d, J =
3
8.4 Hz, 4H), 6.80 (d, J = 8.5 Hz, 4H), 5.80−5.50 (w, 2H), 3.60−3.35 (w, 2H), 2.20−1.85 (m, 4H),
13
1
.75−1.60 (m, 2H), 1.30−1.10 (m, 4H); C NMR (100 MHz, CDCl
3
) δ 156.5, 143.9, 143.7, 140.5,
ACS Paragon Plus Environment

Page 17 of 20
The Journal of Organic Chemistry
1
2
3
4
5
6
7
8
9
1
40.4, 138.5, 136.9, 132.1, 131.4, 131.3, 127.7, 127.6, 127.6, 126.4, 126.4, 126.3, 119.3, 54.5,
33.0, 24.9; IR (KBr) ν 3337, 3078, 3053, 2931, 2857, 1656, 1593, 1551, 1444, 1404, 1316, 1225,
ꢀ1
+
1182, 1154, 1117, 1074, 1029, 912, 847, 821, 757, 698, 626 cm ; ES HRMS m/z calcd for
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
C
60
H
53
N
4
O
2
861.4169 [M+H], found 861.4220 [M+H]
.
Synthesis of (S,S)-5. (S,S)ꢀ5 was synthesized in the same procedure of (R,R)ꢀ5. (S,S)ꢀ5 obtained as
20
D
o
1
a white solid (0.56 g, 45%). [α] = −43.6 (10 mg/mL, CHCl ); Mp 252−253 C; H NMR (400
3
MHz, CDCl
3
) δ 7.24−6.93 (m, 30H), 6.87 (d, J = 8.4 Hz, 4H), 6.79 (d, J = 8.5 Hz, 4H), 5.90−5.59
(
(
w, 2H), 3.55−3.35 (w, 2H), 2.36−2.06 (w, 2H), 2.06−1.90 (m, 2H), 1.78−1.59 (m, 2H), 1.33−1.08
13
m, 4H); C NMR (100 MHz, CDCl
3
) δ 156.5, 143.8, 143.7, 140.5, 140.3, 138.5, 136.8, 132.1,
1
3
31.4, 131.3, 127.7, 127.65, 127.61, 126.4, 126.38, 126.31, 119.3, 54.5, 32.9, 24.9; IR (KBr) ν
ꢀ1
329, 3078, 3052, 2934, 2857, 1655, 1594, 1561, 1404, 1316, 1250, 1226, 762, 689, 628 cm ;
+
ES HRMS m/z calcd for C60
H
53
N
4
O
2
861.4169 [M+H], found 861.4174 [M+H]
.
ACKNOWLEDGMENT
The authors thank National Natural Science Foundation of China (21072067) and HUST
Interdisciplinary Innovation Team (2015ZDTD055) for financial support, and thank the Analytical
and Testing Centre at Huazhong University of Science and Technology for measurement.
AUTHOR INFORMATION
Corresponding author
*Eꢀmail: zyansong@hotmail.com
Notes
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 18 of 20
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
The authors declare no competing financial interest.
SUPPORTING INFORMATION
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
13
H and C NMR, IR, HRMS spectra, and nonlinear fittings for the association constant. This
material is available free of charge via the Internet at http://pubs.acs.org.
REFERENCES
(
1) (a) Lesot, P.; Aroulanda, C.; Zimmermann, H.; Luz, Z. Chem. Soc. Rev. 2015, 44, 2330–2375.
b) Zhang, J.ꢀH.; Xie, S.ꢀM.; Chen, L.; Wang, B.ꢀJ.; He, P.ꢀG.; Yuan, L.ꢀM. Anal. Chem. 2015, 87,
(
7
817−7824. (c) Heo, J.; Mirkin, C. A. Angew. Chem. Int. Ed. 2006, 45, 941–944. (d) Mei, X. F.;
Wolf, C. J. Am. Chem. Soc. 2004, 126, 14736–14737. (e) Seifert, H. M.; Jiang, Y.ꢀB.; Anslyn, E. V.
Chem. Commun. 2014, 50, 15330−15332. (f) Jo, H. H.; Lin, C. Y.; Anslyn, E. V. Acc. Chem. Res.
2014, 47, 2212−2221.
(2) Reviews for chiral recognition in fluorescence: (a) Pu, L. Chem. Rev. 2004, 104, 1687–1716.
(b) You, L.; Zha, D.; Anslyn, E. V. Chem. Rev. 2015, 115, 7840−7892. (c) Zhang, X.; Yin, J.; Yoon,
J. Chem. Rev. 2014, 114, 4918–4959. (d) Pu, L. Acc. Chem. Res. 2012, 45, 150–163. (e) Leung, D.;
Kang, S. O.; Anslyn, E. V. Chem. Soc. Rev. 2012, 41, 448–479. (f) Carr, R.; Evans, N. H.; Parker,
D. Chem. Soc. Rev. 2012, 41, 7673–7686. (g) Accetta, A.; Corradini, R.; Marchelli, R. Top. Curr.
Chem. 2011, 300, 175–216.
(3) Zhu, L.; Zhong, Z.; Anslyn, E. V. J. Am. Chem. Soc. 2005, 127, 4260–4269.
(4) (a) Ema, T.; Tanida, D.; Sakai, T. J. Am. Chem. Soc. 2007, 129, 10591–10596. (b) Seo, M.ꢀS.;
Kim, H. J. Am. Chem. Soc. 2015, 137, 14190−14195.
ACS Paragon Plus Environment

Page 19 of 20
The Journal of Organic Chemistry
1
2
3
4
5
6
7
8
9
(
5) Bentley, K. W.; Nam, Y. G.; Murphy, J. M.; Wolf, C. J. Am. Chem. Soc. 2013, 135,
1
8052−18055.
6) (a) Mei, J.; Leung, N. L. C.; Kwok, R. T. K.; Lam, J. W. Y.; Tang, B. Z. Chem. Rev. 2015, 115,
1718–11940. (b) Zhao, Z.; He, B.; Tang, B. Z. Chem. Sci. 2015, 6, 5347–5365. (c) Mei, J.; Hong,
(
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
1
Y.; Lam, J. W. Y.; Qin, A.; Tang, Y.; Tang, B. Z. Adv. Mater. 2014, 26, 5429–5479. (d) Hu, R.;
Leung, N. L. C.; Tang, B. Z. Chem. Soc. Rev., 2014, 43, 4494–7562.
(7) (a) Kwok, R. T. K.; C. Leung, W. T.; Lam, J. W. Y.; Tang, B. Z. Chem. Soc. Rev. 2015, 44,
4228−4238. (b) Ding, D.; Li, K.; Liu, B.; Tang, B. Z. Acc. Chem. Res. 2013, 46, 2441–2453. (c)
Zhang, G.; Hu, F.; Zhang, D. Langmuir 2015, 31, 4593−4604. (d) Wu, J.; Liu, W.; Ge, J.; Zhang,
H.; Wang, P. Chem. Soc. Rev. 2011, 40, 3483–3495.
(8) (a) Zheng, Y.ꢀS.; Hu, Y.ꢀJ. J. Org. Chem. 2009, 74, 5660–5663. (b) Li, D.ꢀM.; Zheng, Y.ꢀS. J.
Org. Chem. 2011, 76, 1100–1108.
(9) (a) Li, D.ꢀM.; Zheng, Y.ꢀS. Chem. Commun. 2011, 47, 10139–10141. (b) Liu, N.ꢀN.; Song, S.;
Li, D.ꢀM.; Zheng, Y.ꢀS. Chem. Commun. 2012, 48, 4908–4910. (c) Li, D.ꢀM.; Wang, H.; Zheng,
Y.ꢀS. Chem. Commun. 2012, 48, 3176–3178.
(10) Liu, H.ꢀL.; Hou, X.ꢀL.; Pu, L. Angew. Chem. Int. Ed. 2009, 48, 382–385.
(11) Ng, J. C. Y.; Liu, J.; Su, H.; Hong, Y.; Li, H.; Lam, J. W. Y.; Wong, K. S.; Tang, B. Z. J. Mater.
Chem. C 2014, 2, 78–83.
(12) Feng, H.ꢀT.; Zhang, X.; Zheng, Y.ꢀS. J. Org. Chem. 2015, 80, 8096−8101.
(13) Wang, C.; Zhang, D.; Zhu, D. J. Am. Chem. Soc. 2005, 127, 16372–16373.
(14) Zhou, J.ꢀL.; Chen, X.ꢀJ.; Zheng, Y.ꢀS. Chem. Commun. 2007, 5200–5202.
(15) (a) Ye, Q.; Zhu, D.; Zhang, H.; Lu, X.; Lu, Q. J. Mater. Chem. C 2015, 3, 6997−7003. (b) Li,
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 20 of 20
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
H.; Cheng, J.; Deng, H.; Zhao, E.; Shen, B.; Lam, J. W. Y.; Wong, K. S.; Wu, H.; Li, B. S.; Tang, B.
Z. J. Mater. Chem. C 2015, 3, 2399–2404. (c) Zhang, S.; Wang, Y.; Meng, F.; Dai, C.; Cheng, Y.;
Zhu, C. Chem. Commun. 2015, 51, 9014−9017. (d) Liu, X.; Jiao, J.; Jiang, X.; Li, J.; Cheng, Y.;
Zhu, C. J. Mater. Chem. C 2013, 1, 4713–4719. (e) Ng, J. C. Y.; Li, H.; Yuan, Q.; Liu, J.; Liu, C.;
Fan, X.; Li, B. S.; Tang, B. Z. J. Mater. Chem. C 2014, 2, 4615–4621. (f) Zhang, S.; Sheng, Y.;
Wei, G.; Quan, Y.; Cheng, Y.; Zhu, C. Polym. Chem. 2015, 6, 2416–2422. (g) Ye, Q.; Zhu, D.; Xu,
L.; Lu, X.; Lu, Q. J. Mater. Chem. C 2016, 4, 1497−1503.
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
(
16) Bisson, A. P.; Hunter, C. A.; Morales, J. C.; Young, K. Chem. Eur. J. 1998, 4, 845−851..
17) (a) Tsvelikhovsky, D.; Blum, J. Eur. J. Org. Chem. 2008, 14, 2417−2422. (b) Jiang, H.ꢀF.; Xu,
(
Q.ꢀX.; Wang, A.ꢀZ. J. Supercrit. Fluid. 2009, 49, 377−384.
18) Wang,Y. J.; Li, Z.; Tong, J.; Shen, X. Y.; Qin, A.; Sun, J. Z.; Tang, B. Z. J. Mater. Chem. C,
2015, 3, 3559−3568.
(
ACS Paragon Plus Environment