Schiff Base Substituent-Triggered Efficient Deboration Reaction and Its Application in Highly Sensitive Hydrogen Peroxide Vapor Detection

Article abstract of DOI:10.1021/acs.analchem.6b01057

The organic thin-film fluorescence probe, with the advantages of not polluting the analyte and fast response, has attracted much attention in explosive detection. Different with nitro explosives, the peroxide-based explosives are hardly to be detected bec

Full text of DOI:10.1021/acs.analchem.6b01057

Subscriber access provided by Weizmann Institute of Science
Article
A Schiff Base Substituent Triggered Efficient Deboration Reaction and
Its Application in Highly Sensitive Hydrogen Peroxide Vapour Detection
Yanyan Fu, Jun Jun Yao, Wei Xu, Tianchi Fan, Zinuo Jiao,
Qingguo He, Defeng Zhu, Huimin Cao, and Jiangong Cheng
Anal. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.analchem.6b01057 • Publication Date (Web): 20 Apr 2016
Downloaded from http://pubs.acs.org on April 21, 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.
Analytical 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 8
Analytical Chemistry
1
2
3
4
5
6
7
8
9
A Schiff Base Substituent Triggered Efficient Deboration Re-
action and Its Application in Highly Sensitive Hydrogen Per-
oxide Vapour Detection
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
Yanyan Fu*a , Junjun Yaoa,b , Wei Xu a,b, Tianchi Fan a,b, Zinuo Jiaoa,b, Qingguo He*a, Defeng Zhu a,
Huimin Cao a, and Jiangong Cheng*a
aState Key Lab of Transducer Technology, Shanghai Institute of Microsystem andInformation Technology, Chinese
Academy of Sciences, Changning Road 865,Shanghai 200050, China. E-mail: hqg@mail.sim.ac.cn;
jgcheng@mail.sim.ac.cn; fuyy@mail.sim.ac.cn
bUniversity of the Chinese Academy of Sciences, Yuquan Road 19, Beijing,100039, China
ABSTRACT: Organic thin film fluorescence probe, with the advantages of no polluting the analyte and fast response, has
attracted many attention in explosive detection. Different with nitro explosive, the peroxide-based explosives is hardly to
be detected because of its poor ultraviolet absorption and lack of aromatic ring. As the signature compound of peroxide-
based explosives, H2O2 vapour detection became more and more important. Boron ester or acid is considered to be a suit-
able functional group for the detection of hydrogen peroxide due to its reliable reactive activity. Its only drawback lies on
its slow degradation velocity. In this work, we try to introduce some functional group to make the boron ester easily to be
oxidized by H2O2. Herein, OTB was synthesized and its imine derivatives OTBXA were easily obtained just by putting
OTB films in different primary amines vapours. OTBXA shows fast deboronation velocity in H2O2 vapour compared with
OTB. The complete reaction time of OTBPA was even shortened 40 times with a response time of second. The detection
limit for H2O2 vapour was as low as 4.1 ppt. Further study showed that it is a general approach to enhance the sensing
performance of borate to hydrogen peroxide (H2O2) vapour by introducing imine into aromatic borate molecule via a sol-
id/vapour reaction.
precursor chemicals still pose challenges considering
1. Introduction
During the latest decades, trace explosive detection
their sensitivity to mechanical stress, low stability as well
as lack of UV absorbance or fluorescence.7-11 Compared to
continue to receive particular attention due to the exigent
demand from public security.1 Among the explosives, de-
tection methods for nitro explosive such as TNT, DNT
received a wide attention.2-6 However, a reliable detection
method for peroxide-based explosives (such as triacetone
triperoxide (TATP), diacetone diperoxide (DADP), and
hexamethylene triperoxide diamine (HMTD)) and their
other mature detection method like electrochemical
method and mass spectrometry, fluorimetric sensing is a
promising approach to detect peroxide-based explosives
because of its high sensitivity, low cost and portable de-
tection devices.12
As the most important starting material and degrada-
tion product of peroxide explosive, H2O2 is considered as
ACS Paragon Plus Environment

Analytical Chemistry
Page 2 of 8
signature compound for peroxide-based explosives.13
2. Experimental Section
2.1 Materials and Measurements
1
2
3
4
5
6
7
8
There are many smart fluorescent receptors have been
reported by researchers14-16 capable for H2O2 detection.
Among them, one of the most commonly used functional
group is an aromatic boron ester or acid 17 for its excellent
photostability, reliable reactivity as well as its easy syn-
thesis. The only drawback is that the deboronation reac-
tion rate is usually slow (costing many minutes or even
several hours) making the sensing process time-
consuming.18 To accelerate the deboronation reaction in
H2O2, our group once proposed using ordered assembly
arrays of ZnO nanorods as catalyzing substrate and the
deboronation reaction was 42 times faster compared with
that on quartz substrate.19, 20 Nevertheless, the prepara-
tion of such nanorodes still needs additional effort. Zang
et al reported that H2O2-mediated oxidation of aryl
boronates can be speeded by addition of some organic
base, such as trtrabutylammonium hydroxide (TBAH).21, 22
However, our group discovered that these stronger amine
like TBAH and secondary amine could accelerate the pho-
to-oxidation of special arylboronate offering correspond-
ing phenols without H2O2.23, 24 In this contribution, we
search for a versatile and easy way to realize the efficient
detection of H2O2. Considering the phase separation of
the additive or special nano substrate, a direct molecular
modification of aromatic borate will be a more efficient
way to get an excellent H2O2 probe.
All solvents and reagents were obtained from commer-
cial sources and used as received. UV-vis absorption and
fluorescence analysis were conducted on a Jasco V-670
spectrophotometer and a Jasco FP 6500 spectrometer,
respectively. The NMR spectra were obtained on a Bruck-
er DRX500 instrument, and tetramethylsilane (TMS) was
used as an internal standard. Mass spectra were recorded
on BIFLEX III MALDI-TOF (Brucker Daltonics Inc.) and
GCT-MS Micromass UK mass spectrometers. Unless oth-
erwise noted, all the films were prepared from their THF
solutions with concentrations as 5mg/mL on (10×20 mm)
quartz plates by spin-coating method at 2200 rpm. The
films were all placed in vacuum for 1 hour before use. The
fluorescence responses of films to various analytes were
progressed by inserting the films into sealed vials (3.8 mL)
containing cotton and analytes at room temperature,
which prevents direct film analyte contact and helps to
maintain a constant vapour pressure. The fluorescence
time-course responses were recorded immediately after
exposing the films to analytes at an angle of 60° to the
incident light. All the theoretical calculations were per-
formed by DMol3 program in the Materials Studio 8.0,
which is one of the quantum mechanical code using den-
sity functional theory. BLYP function of generalized gra-
dient approximation (GGA) level was used to calculate
the optical absorption spectra and the energy level of the
molecular orbital. The detail methodology and parame-
ters are listed in Table S1 in the supporting information.
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
Based on this cognition, we propose that introducing a
specific organic amine in molecule with moderate alka-
line may accelerate the oxidation conversion rate of boron
ester by H2O2 and also keep its stability in O2. Consider-
ing that, firstly, the alkalescence of imine is weaker than
that of secondary amine. Secondly, the imine is easily
formed via a simple Schiff-base reaction, and thirdly,
imine is easily decomposed during a column chromatog-
raphy separation. Thus we designed a precursor molecule
OTB, followed by a solid/vapour Schiff base reaction be-
tween OTB film and primary amine vapour to afford the
probe (OTBXA).
2.2 Synthesis
Synthesis of 4-(phenyl(4-(4,4,5,5-tetramethyl-1,3,2-
dioxaborolan-2-yl)phenyl)amino)benzaldehyde
(OTB): To a solution of 742 mg N, N-diphenyl-4-(4,4,5,5-
tetramethyl-1,3,2-dioxaborolan-2-yl) aniline in 4 mL DMF,
1.5 mL POCl3 were added. The mixture was stirring at
90°C for 1 hour. After the reaction solution was cooled to
room temperature, it was poured into the ice-water mix-
ture and stirred for another hour. Then the solution was
extracted with dichloromethane. And the extract was
dried over anhydrous MgSO4. After filtration, the solvent
was removed through rotary evapouration and the resi-
due was purified by silica gel chromatography eluted with
petroleum ether and dichloromethane to light yellow sol-
id (410 mg, 51%).1H NMR (500 MHz, CDCl3, ppm) δ 9.81
(s, 1H), 7.77-7.75 (d, 2H, J = 8.5 Hz), 7.69-7.67 (d, 2H, J =
8.5 Hz), 7.34-7.31 (m, 2H), 7.18-7.12 (m, 5H), 7.07-7.05 (d,
2H, J = 8.5 Hz), 1.34 (s, 12H) 13C NMR (125MHz, CDCl3) δ
190.36, 152.97, 148.92, 146.01, 136.19, 131.20，129.73, 129.69,
126.46, 125.26, 124.47, 120.44, 83.78, 29.65, 24.84 HRMS:
Scheme 1 Deboronation of OTB and OTBXA.
ACS Paragon Plus Environment

Page 3 of 8
Analytical Chemistry
calcd M+ for 400.2083 C25H27BNO3; found 400.2083.
1
2
3
4
5
6
7
8
Synthesis of 4-(phenyl(4-(6-(4,4,5,5-tetramethyl-1,3,2-
dioxaborolan-2-yl)pyren-1-
yl)phenyl)amino)benzaldehyde (OTPB): To a mixture
of 454mg 1,6-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-
Synthesis of (E)-N-phenyl-4-((propylimino)methyl)-
N-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-
yl)phenyl) aniline (OTBPA): The drop-casted film of 4-
(phenyl (4-(4, 4, 5, 5-tetramethyl-1, 3, 2-dioxaborolan-2-yl)
phenyl) amino) benzaldehyde (OTB) was put aside in an
atmosphere of n-propylamine vapour. After 5 minutes,
the exposed film was taken out and dried in vacuum oven
to remove the volatile remainder. Then the species on the
9
yl)pyrene,
351mg
4-((4-
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
bromophenyl)(phenyl)amino)benzaldehyde in THF solu-
tion, tetra (triphenylphosphine)-palladium [Pd(PPh3)4]
(1.0 Mol %) in degassed THF and a drop of 2 M potassium
carbonate aqueous solution were added. The mixture was
stirred at 70 °C for 72 h under the protection of argon.
Then the solvent was evapourated and the residue was
purified by column chromatography on silica gel using
hexane and dichloromethane as eluent to afford pale yel-
low product OTPB (yield 32%). 1H-NMR(500MHz, CDCl3,
25 °C, TMS): δ=9.85 (s, 1H), 9.10-9.07(m, 1H), 8.56-8.54 (d,
1H, J= 7.5Hz), 8.33-8.21 (m, 2H), 8.17-7.99 (m, 4H), 7.76-
7.74 (m, 2H), 7.61-7.59 (m, 2H), 7.43-7.40 (m, 2H), 7.24-
7.22 (m, 4H)，7.18-7.16 (m, 2H), 1.47(s, 12H) 13C NMR
(125MHz, CDCl3) δ153.37, 146.24, 145.36, 137.83, 137.25,
137.06, 136.04, 136.25, 134.11, 133.83, 133.26, 132.98, 131.98,
131.94, 131.41, 130.68, 130.32, 129.91, 129.45, 139.41, 128.56,
128.46, 128.26, 128.16, 127.80, 127.69, 127.64, 127.47, 127.36,
126.64, 126.61, 126.24, 125.82, 124.97, 124.70, 124.97,124.70,
124.36, 124.02, 119.85, 119.78, 83.97,83.93, 39.01, 38.71, 34.16,
29.52, 25.11, 22.99, 22.68, 20.19, 19.20, 14.43, 11.42 HRMS:
calcd M+ for C41H34BO3N 598.2663; found 598.2673.
1
film were dissolved in CDCl3 and the H-NMR spectrum
was recorded. The high resolution mass spectrum (HR-
1
MS), H-NMR and 13C NMR spectroscopies exhibit that
the structure of the final product was consistent with the
expected
Schiff’s
base
structure
OTBPA. 1H-
NMR(500MHz, CDCl3, 25 °C, TMS): δ=8.18 (s, 1H)，7.70-
7.68 (d, 2H, J=10 Hz), 7.59-7.57 ((d, 2H, J=10 Hz), 7.12-
7.05(m, 9H), 3.56-3.53 (m, 2H), 1.73-1.69 (m, 2H),1.37 (s,
12H), 0.96-0.93 (m, 3H). 13C NMR (125MHz, CDCl3)
δ160.31, 149.97，149.54, 146.91，138.68，135.96，130.52,
129.46, 129.10, 128.39, 125.63, 124.16,124.09, 123.19, 122.99,
122.91, 120.26,116.67, 83.67, 63.45, 43.72, 29.69, 26.23, 24.86,
24.60, 24.13, 24.08, 23.65, 11.83, 11.78, 11.25 HRMS: calcd M+
for C28H34BN2O2 441.2709; found 441.2713.
Synthesis of (E)-4-(phenyl (4-((propylimino) methyl)
phenyl) amino) phenol: The drop-casted film of (E)-N-
phenyl-4-((propylimino) methyl)-N-(4-(4, 4, 5, 5-
tetramethyl-1, 3, 2-dioxaborolan-2-yl) phenyl) aniline
(OTBPA, R= propyl) was put aside in an atmosphere of
H2O2 vapour. After 5 minutes, the exposed film was taken
out and dried in vacuum oven to remove the volatile re-
mainder. Then the species on the film were dissolved in
Synthesis of 4-((4-(9,9-dioctyl-7-(4,4,5,5-tetramethyl-
1,3,2-dioxaborolan-2-yl)-9H-fluoren-2-
yl)phenyl)(phenyl)amino)benzaldehyde(OTFB) : To a
1:1.5 mixture of 9, 9-dioctylfluorene-2, 7-bis (4, 4, 5, 5-
tetramethyl-1,
bromophenyl)(phenyl)amino)benzaldehyde,
3,
2-dioxaborolane)
and
4-((4-
tetra
1
CDCl3 and the H-NMR spectrum was recorded. The high
resolution mass spectrum (HR-MS) and the 1H-NMR
spectroscopies exhibit that the structure of the final
(triphenylphosphine)-palladium [Pd(PPh3)4] (1.0 Mol %)
in degassed THF and a drop of 2 M potassium carbonate
aqueous solution were added. The mixture was stirred at
70 °C for 72 h under the protection of argon. Then the
solvent was evapourated and the residue was purified by
column chromatography on silica gel using hexane and
dichloromethane as eluent to afford pale yellow product
OTFB (yield 56%). 1H-NMR(500MHz, CDCl3, 25 °C, TMS):
δ=9.82 (s, 1H), 7.83-7.75 (m, 1H), 7.71-7.62 (m, 5H), 7.57-
7.55 (m, 2H), 7.38-7.31 (m, 3 H), 7.24-7.20 (m, 6H), 7.18-
7.17(d, 1H, J= 7.5 Hz), 7.15-7.14(d, 1H, J= 7.5 Hz), 2.05-1.99
(m, 4H), 1.39 (s, 12H), 1.20-1.17 (m, 4H), 1.15-1.03 (m, 16H),
0.87-0.77 (t, 6H), 0.64(m, 4H) 13C NMR (125MHz, CDCl3) δ
153.37, 153.23, 150.12, 146.12, 146.11, 145.28, 143.67, 140.33,
139.46, 138.19, 133.83, 131.33, 131.29, 129.80, 129.72, 129.32,
129.14,128.86, 128.32, 126.40, 126.31, 126.26, 125.67, 125.24,
1
product was. H-NMR(500MHz, CDCl3, 25 °C, TMS):
δ=8.14(s, 1H)，7.52-7.50 (d, 2H, J=8.5 Hz), 7.24-7.23 (d,
2H, J=8 Hz), 7.11-7.10 (d, 2H, J= 8 Hz), 7.02-7.01(m, 3H),
6.92-6.90 (d, 2H, J=8.5 Hz), 6.79-6.78 (d, 2H, J=8 Hz),
3.82(s, 1H), 3.56-3.53 (m, 2H), 1.76-1.73 (m, 2H), 0.95-0.88
13
(m, 3H). C NMR (125MHz, CDCl3) δ161.69, 154.70, 151.02,
147.08, 138.52, 135.98, 131.43, 129.60, 129.49, 129.23, 128.70,
128.58, 127.26, 125.83, 125.68, 124.80, 124.25, 123.16, 123.07,
117.90, 116.84, 116.72, 83.70, 82.95, 63.03, 24.84, 24.56,
23.96, 11.73 HRMS: calcd M+ for C22H23N2O 331.1805; found
331.1806.
ACS Paragon Plus Environment

Analytical Chemistry
Page 4 of 8
tionship between the sensing behaviour of OTBPA films and
125.11, 121.14, 120.44, 119.64, 119.64, 119.36, 119.04, 83.72,
55.23, 40.25, 31.75, 29.95, 29.16, 24.94, 23.70, 22.57, 14.04
HRMS: calcd M+ for C54H66BNO3 787.5136; found 787.5145.
1
2
3
4
5
6
7
8
the concentration of film fabrication is inverstigated. Fig. S12
indicates that the photo bleaching of OTBPA films made
from different OTB concentration of 1 mg/mL, 5 mg/mL,
10mg/mL and 15mg/mL, respectively, are about 17%, 1%, 0.5%
and 0.4% upon continuous excitation within 300 s. It means
that the film made of concentrated solution has better opti-
cal stability. Contrary to the photo stability, upon exposure
to H2O2 vapour, corresponding fluorescence quenching of
OTBPA films are 92%, 89%, 51% and 21%, respectively. This
means thinner film is more favorable for vapour sensing. To
balance the photo stability and sensitivity, appropriate con-
centration should be chosen. Herein, 5 mg/mL is selected as
an optimized concentration for preparing OTBPA films.
3. Results and Discussion
3.1 Optical properties and structure characteriza-
tion
1.0
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
OTB
OTBPA
0.5
0.0
300
400
500
600
Wavelength(nm)
Figure 1. Normalized absorption and fluorescence spectra
of OTB and OTBPA in solid state.
As shown in Fig.1, the maximum absorption and emission
peak of OTB solid films were located at 366 and 466 nm,
respectively. Compared with OTB, the UV-vis spectra of
OTBPA kept almost unchanged with the max absorption
peak at 365 nm. Nevertheless, the fluorescent spectra shifted
from 466 to 445 nm. Such fluorescence changes were along
with the obvious fluorescence color from light blue to blue
violet.
3.2 Sensory properties
To study the efficiency of deboronation reaction between
OTB/OTBPA and H2O2 vapour, the sensory response of OTB
film on quartz plate to H2O2 was firstly investigated. Accord-
ing to our previous study, the sensing behaviour of fluores-
cent film is partly determined by the thickness of the film.
The thickness could be well controlled by the concentration
of the probe solution. Typically, a too low concentration re-
sults in a very thin film, nice sensing efficiency but large pho-
to bleaching effect. While a too high concentration leads to a
thick film, poor sensing performance but less photo bleach-
ing25. Unless other pointed, the probe concentration here
used for film fabrication is 5 mg/mL which is an optimized
concentration. As shown in Fig 2a, the OTB film showed
good photo stability upon consequent exposure to air. While
in H2O2 vapour, its fluorescence was quenched slowly with a
fluorescence quenching ration of 36% within 300 s. Such
fluorescence quenching could not easily be distinguished by
naked eye. Further study indicates it takes more than 100
min for OTB to completely quench its fluorescence in H2O2
vapour (Fig. S11). As for OTBPA, it also exhibited quite well
photo stability in air (Fig 2b). Upon exposure to H2O2 va-
pour, 89% fluorescence was quenched within 150 s exposure,
after that no any emission change could be detected exhibit-
ing a complete reaction time at about 150 s. The huge fluo-
rescence intensity change could be readily distinguished by
naked eyes fluorescence colour as shown in Fig 2b. The result
suggests that the reaction time was shortened at least 40
times when OTB was replaced by OTBPA. The detailed rela-
Figure 2. (a) Fluorescence stability of OTB film (black) in
air and its sensitivity to hydrogen peroxide vapour (blue) at
room temperature after 300 s exposure to H2O2 (ex 366nm,
em 466nm). The inset picture was its fluorescence responses
before and after exposure in H2O2 for 300 s. b) Fluorescence
stability of OTBPA (black) and its sensitivity to hydrogen
peroxide vapour (blue) at room temperature after 300s expo-
sure to H2O2 (ex 365nm, em 445nm). The inset picture was
their fluorescence responses before and after exposure for
300 s.
To further investigate the effect of different kind of imine
on the velocity of deboronation reaction, the OTB films were
put into several typical primary amines including n-
propylamine, n-hexylamine, n-octylamine and benzylamine
to prepare films containing different imines. The newly
formed films were named as OTBPA, OTBHA, OTBOA and
OTBA, respectively. Compared with OTB, the fluorescence
spectra of these newly formed films all showed blue shift
ACS Paragon Plus Environment

Page 5 of 8
Analytical Chemistry
with Δλmax of -21 nm, -23 nm, -23nm and -40 nm for OTBPA,
anol, toluene, ethyl acetate and water were selected as
1
2
3
4
5
6
7
8
OTBHA, OTBOA and OTBBA, respectively (Fig S13). Table 1
also summarized the complete degradation time (CDT) of
these new formed films upon exposure to H2O2 vapour. All of
the probe films with imine structure showed faster de-
boronation velocity compared with OTB. The CDT in satu-
rated H2O2 vapour are 100, 2.5, 11, 20 and 35 min for OTB,
OTBPA, OTBHA, OTBOA and OTBBA, respectively (Fig S11,
Fig S14-Fig S16). It seems that the longer alkyl chain (such as
hexyl and octyl) and the bigger steric hindrance (such as
benzyl) in imine are both adverse for the quick sensing.
OTBPA has the simplest structure but showed the best sens-
ing performance compared with other three probes.
interference reagents and the interaction of the probe
with these solvents were investigated. No obvious fluores-
cence intensity change (less than 2 %) of the films was
observed upon exposure to these vapours indicating the
sensing film possessed excellent selectivity towards H2O2
vapour.
3.3 Sensing mechanism and the expansion of
sensing method
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
To deeply investigate why imine can accelerate the de-
boronation reaction, we calculated the orbitals of OTB
and OTBPA using DMol3 of Materials Studio software.
Figure 4 presented the optimized molecular structures
and charge distribution of the HOMO and LUMO of OTB
and OTBPA. As shown in Fig 4, the HOMO and LUMO
level of OTB were -4.80 eV and -2.38 eV, respectively. As
for OTBPA, the HOMO level and LUMO level was elevat-
ed to -4.47 eV and -2.01 eV relative to OTB. It indicates
that the introduction of the imine can enhance the
HOMO level and reduce the energy gap of material. In
other words, the OTBPA is easier to be oxidized com-
pared with OTB.
OTB
OTBPA
OTBHA
OTBOA
OTBBA
PL,λmax (nm)
CDT (min)
466
445
443
443
426
100 ±5%
2.5±5%
11±5%
20±5%
35±5%
Table 1. The photoluminence emission maximum (PL λ
max) of OTB, OTBPA, OTBHA, OTBOA and OTBBA and
the complete deboronation time (CDT) of OTB, OTBPA,
OTBHA, OTBOA and OTBBA in saturated H2O2 vapour.
To estimate the detection limit, the changes in fluores-
cence intensity of OTBPA films exposed to H2O2 vapours
at eight different concentrations were measured. And the
intensity quenching data (1- I/I0) are well-fitted to the
Langmuir equation with an assumption that the quench-
ing efficiency or increasing efficiency is proportional to
the surface adsorption of amine vapour. The detection
limits could be obtained as low as ~4.1 ppt according to its
fitted plot.
1
0.1
0.01
4.1ppt
10-7 10-5 10-3 10-1 101
Concentration(ppm)
Figure 3 Fluorescence quenching efficiency (1-I/I0) as a
function of the vapour pressure of H2O2 at 445 nm: data (er-
ror ± 5%) fitted with the Langmuir equation.
Except for sensitivity and stability, selectivity, also
called anti-interference capability, is another important
factor of a probe. Several common organic solvents in-
cluding dichloromethane, tetrahydrofuran, acetone, eth-
ACS Paragon Plus Environment

Analytical Chemistry
Page 6 of 8
Figure 4. Optimized molecular structures and molecular
1
orbitals of OTB (top) and OTBPA (down).
2
3
1.0x10-4
4
5
6
7
8.0x10-5
6.0x10-5
4.0x10-5
OTB
Scheme 2 Structures of OTPB and OTFB.
8
9
2.0x10-5
0.0
4. Conclusion
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
In this work, an efficient method to enhance deborona-
tion efficiency of borate for hydrogen peroxide vapour
sensing has been developed. By exposure to primary
amine, the molecule which contains both arylboronate
group and aldehyde group such as OTB, OTPB, and
OTFB can all form new films with imine structures. These
new films sensing property to H2O2 are tremendously
improved, suggesting the introducing a moderate alkaline
in arylboronate molecule could accelerate the oxidation
conversion rate of boron ester. The response time is sev-
eral seconds and the detection limit can be as low as ∼4.1
ppt. Such work provides a smart strategy for the design of
highly efficient fluorescent probe for peroxide explosives
vapours. This Schiff base substitute aromatic boronate
molecules are an ideal candidate for chemical detection
and analysis of H2O2 vapour in environmental monitoring
and public safety.
-2.0x10-5
-4.0x10-5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
Potencial (V vs SCE)
1.0x10-4
8.0x10-5
6.0x10-5
4.0x10-5
OTB
2.0x10-5
0.0
-2.0x10-5
-4.0x10-5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
Potencial (V vs SCE)
ASSOCIATED CONTENT
Figure 5. Cyclic voltammetric curves of OTB and OTBPA.
SUPPORTING INFORMATION
To verify the calculation result, we also tested the cy-
clic voltammetry property of OTB and OTBPA (Fig 5).
The oxidation potential of OTB and OTBPA are 0.86 V
and 0.29 V, respectively. Obviously, the imine unit can
significantly improve the reductive ability of borate com-
pound. Therefore the rate of deboronation reaction will
be significantly improved. Both electrochemical data and
calculation result support that the introduction of a group
with moderately alkaline in borate molecule is beneficial
to accelerate the oxidation of the borate.
Additional figures as noted in text. The Supporting Infor-
mation is available free of charge on the ACS Publications
website.
AUTHOR INFORMATION
Corresponding Author
Qingguo He* E-mail: hqg@mail.sim.ac.cn;
Jiangong Cheng*Email: jgcheng@mail.sim.ac.cn.
Yanyan Fu*Email: fuyy@mail.sim.ac.cn.
As discussed above, after the aldehyde group was re-
placed by imine structure, a quick and efficient debora-
tion reaction appeared. To deeply explore the effectivity
of this method, we also synthesized another two precur-
sor probes named OTPB and OTFB which have an ex-
panded conjugation length by the introduction of pyrenyl
or fluorenyl units. When OTPB and OTFB films were put
into n-propylamine vapour for 5 min, respectively, the
probe films with imine unit were formed. Both probe
films demonstrated better reaction activities to H2O2 than
that of the precursor probe. The CDTs were also short-
ened 17 times and 20 times accordingly. And as expected,
both the orbital calculation and the cyclic voltammetry
revealed that the introduction of the imine will decrease
the oxidation potential and elevated HOMO level of
OTPB and OTFB making the sensing efficiency greatly
enhanced (Fig S17-Fig S24).
Notes
The authors declare no competing financial interest
ACKNOWLEDGMENT
This work is supported by National Nature Sciences Foun-
dation of China (No. 61325001, 21273267, 61321492, 51473182),
grant from Youth Innovation Promotion Association CAS
(2015190).
REFERENCES
ACS Paragon Plus Environment

Page 7 of 8
Analytical Chemistry
(1) Thomas, S. W. ; Joly G. D.; Swager, T. M. Chem. Rev., 2007,
1
2
3
4
5
6
7
8
107, 1339-1386.
(2) Feng, J. C.; Li, Y. ; Yang, M. J. Sens. Actuators, B 2010, 145,
438-443.
(3) Liu, T. H. ; Ding, L. P.; Zhao, K.; Wang, W. L. ; Fang, Y. J.
Mater. Chem. 2012, 22, 1069-1077.
(4) Novotney, J. L. ; Dichtel, W. R. ACS Macro Lett. 2013, 2,
423-426
(5) Andrew, T. L.; Swager, T. M. J. Org. Chem. 2011, 76, 2976-
2993
9
(6) Deng, C. M. ; Gong, P. ; He, Q. G.; Cheng, J. G.; He, C. ; Shi,
L. Q.; Zhu, D. F.; Lin, T. Chem. Phys. Lett. 2009, 483, 219-223.
(7) Laine, D. F.; Roske, C. W. ; Cheng, I. F. Anal. Chim. Acta,
2008, 608, 56-60.
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
(8) Dubnikova, F.; Kosloff, R. ; Zeiri, Y. ; Karpas, Z. J. Phys.
Chem. A, 2002, 106, 4951-4956.
(9) Schulte-Ladbeck, R. ; Kolla, P.; Karst, U. Anal. Chem.,
2003, 75, 731-735.
(10) Eren, S.; Uzer, A.; Can, Z.; Kapudan, T. ; Ercag, E.; Apak,
R. Analyst, 2010, 135, 2085-2091.
(11) Schulte-Ladbeck, R.; Edelmann, A.; Quintas, G.; Lendl, B.;
Karst, U. Anal. Chem., 2006, 78, 8150-8155.
(12) Zyryanov, G. V.; Palacios, M. A.; Anzenbacher, P. Org.
Lett., 2008, 10, 3681-3684.
(13) Lee, S.; Oh, J.; Ruoff, R. S.; Park, S. Carbon, 2012, 50, 1442-
1444.
(14) Laine, D. F.; Roske, C. W.; Cheng, I. F. Anal. Chim. Acta,
2008, 608, 56-60..
(15) Dubnikova, F.; Kosloff, R. ; Almog, J. ; Zeiri, Y. ; Boese, R.;
Itzhaky, H.; Alt, A.; Keinan, E. J. Am. Chem. Soc., 2005, 127, 1146-
1159..
(16) Burks, R. M. ; Hage, D. S. Anal. Bioanal. Chem., 2009, 395,
301-313.
(17) Sanchez, J. C.; Trogler, W. C. J Mater Chem, 2008, 18, 5134-
5141.
(18) Chen, L. ; Gao, Y. X.; Fu, Y. Y.; Zhu, D. F.; He, Q. G.; Cao,
H. M.; Cheng, J. G. RSC Adv., 2015, 5, 29624-29630.
(19) Zhu, D. F.; Chen, Q.; Fu, Y. Y. ; He, C.; Shi, L. Q. ; Meng,
X.; Deng, C. M.; Cao H. M.; Cheng, J. G. ACS Nano, 2011, 5, 4293-
4299.
(20) He, C.; Zhu, D. F.; He, Q. G.; Shi, L. Q.; Fu, Y. Y.; Wen,
D.; Cao H. M.; Cheng, J. G. Chem. Commun., 2012, 48, 5739-5741..
(21) Xu, M.; Han, J.; Wang, C. ; Yang, X.; Pei, J.; Zang, L. ACS
Appl. Mater. Interfaces 2014, 6, 8708-8714.
(22) Xu, M.; Han, J.; Zhang, Y.; Yang, X.; Zang, L. Chem.
Commun. 2013, 49, 11779-11781.
(23) Fu, Y. Y.; He, Q. G.; Zhu, D. F.; Wang, Y. R.; Gao, Y. X.;
Cao, H. M.; Cheng, J. G. Chem. Commun. 2013, 49, 11266-11268.
(24) Fu, Y. Y.; Gao, Y. X.; Chen, L.; He, Q. G. ; Zhu, D. F.; Cao,
H. M.; Cheng, J. G RSC Adv., 2014, 4, 46631-46634.
(25) Fu, Y. Y.; Yao, Y. Y.; Xu, W. ; Fan, T. C.; He, Q. G.; Zhu,
D. F.; Cao, H. M. ; Cheng, J. G. Reversible and “Fingerprint”
Fluorescence Differentiation of Organic Amine Vapours Using a
Single Conjugated Polymer Probe Polym. Chem., 2015, 6, 2179-
2182.
ACS Paragon Plus Environment

Analytical Chemistry
Page 8 of 8
Table of Contents/Abstract Graphics
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
A general approach to enhance the sensing performance of borate to hydrogen peroxide
(H2O2) vapour is presented. By introducing imine into aromatic borate molecule via a
solid/vapour reaction, the velocity of deboronation reaction in H2O2 vapour was inꢀ
creased significantly, which resulted in a response of seconds and a sensitivity of ppt levꢀ
el.
8
ACS Paragon Plus Environment