A novel pyridyl triphenylamine–BODIPY aldoxime: Naked-eye visible and fluorometric chemodosimeter for hypochlorite

Article abstract of DOI:10.1016/j.saa.2017.04.043

An aldoxime containing fluorescent probe based on vinylpydine-appended triphenylamine–BODIPY has been designed and used for hypochlorite detection. OX-PPA-BODIPY was developed by introducing an aldoxime group into the 2-position of BODIPY, which can be used for the detection of hypochlorite with a sharp color change from pink to green. The attachment of 4-vinylpyridine moiety to triphenylamine–BODIPY constructs a fluorogen with desirable conjugated system. The probe, which displays extremely weak fluorescence owing to the C[dbnd]N isomerization mechanism at 2-position of BODIPY, responds to HClO/ClO^? through a dramatic enhancement of its fluorescence intensity. This new probe, a naked-eye visible and fluorometric chemodosimeter, exhibits high selectivity and sensitivity toward hypochlorite over other reactive oxygen species (ROS) and anions. The detection is accompanied by a 20-fold increase in fluorescent intensity (Φ_F from 0.02 to 0.43). The detection limit of the probe for hypochlorite is 7.37?×?10^??7?M. Moreover, OX-PPA-BODIPY can be used to detect hypochlorite in real water samples.

Full text of DOI:10.1016/j.saa.2017.04.043

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 183 (2017) 356–361
Contents lists available at ScienceDirect
Spectrochimica Acta Part A: Molecular and Biomolecular
Spectroscopy
journal homepage: www.elsevier.com/locate/saa
A novel pyridyl triphenylamine–BODIPY aldoxime: Naked-eye visible
and fluorometric chemodosimeter for hypochlorite
⁎
Xiu-xiu Xu, Ying Qian
School of Chemistry and Chemical Engineering, Southeast University, Nanjing, China
a r t i c l e i n f o
a b s t r a c t
Article history:
An aldoxime containing fluorescent probe based on vinylpydine-appended triphenylamine–BODIPY has been
designed and used for hypochlorite detection. OX-PPA-BODIPY was developed by introducing an aldoxime
group into the 2-position of BODIPY, which can be used for the detection of hypochlorite with a sharp color
change from pink to green. The attachment of 4-vinylpyridine moiety to triphenylamine–BODIPY constructs a
fluorogen with desirable conjugated system. The probe, which displays extremely weak fluorescence owing to
the C_N isomerization mechanism at 2-position of BODIPY, responds to HClO/ClO− through a dramatic en-
hancement of its fluorescence intensity. This new probe, a naked-eye visible and fluorometric chemodosimeter,
exhibits high selectivity and sensitivity toward hypochlorite over other reactive oxygen species (ROS) and an-
ions. The detection is accompanied by a 20-fold increase in fluorescent intensity (ΦF from 0.02 to 0.43). The de-
tection limit of the probe for hypochlorite is 7.37 × 10−7 M. Moreover, OX-PPA-BODIPY can be used to detect
hypochlorite in real water samples.
Received 19 December 2016
Received in revised form 18 March 2017
Accepted 18 April 2017
Available online 20 April 2017
Keywords:
Aldoxime
Triphenylamine–BODIPY
Hypochlorite detection
C_N isomerization
Naked-eye visible
© 2017 Elsevier B.V. All rights reserved.
1. Introduction
[26] and his coworkers have demonstrated a highly sensitive and selec-
tive hypochlorite fluorescent probe based on oxidation of hydrazine via
Hypochlorous acid (HClO)/hypochlorite (ClO−) is known to be a
kind of biologically important reactive oxygen species (ROS) [1]. In liv-
ing organisms, hypochlorous acid is produced predominantly from hy-
drogen peroxide and chloride ions in a chemical reaction catalyzed by
the heme enzyme myeloperoxidase (MPO), which plays a pivotal role
in the immune defense against microorganisms and in inflammation
[2–5]. However, excessive amounts of hypochlorous acid/hypochlorite
in the physiological and pathological processes can lead to various dis-
eases, such as atherosclerosis, osteoarthritis, rheumatoid arthritis and
even cancers [6–10]. Thus, monitoring HClO/ClO− in living organisms
is highly demanded for the research in biology and medicine.
Fluorescent probes have been evaluated as powerful tools to detect
biological agents in recent years, due to their high sensitivity and selectiv-
ity, real-time detection and easiness of manipulating [11–13]. In recent
years, a number of fluorescent probes for HClO/ClO− based on unique re-
action mechanisms have been developed, including oxidation of p-
methoxyphenol to benzoquinone [14], selenide to selenoxide [15–17],
oxime to aldehyde [18], and others [19]. Most of them are based on differ-
ent fluorophores that included rhodamine [20], boradiazaindacene
(BODIPY) [21], fluorescein [22], naphthalimide [23] and so on [24].
Chen et al. [25] developed a highly selective turn-on fluorescent probe
for hypochlorous acid based on hypochlorous acid-induced oxidative in-
tramolecular cyclization of boron dipyrromethene-hydrazone. Cheng
free radical mechanism. Mulay's group [27] constructed two closely relat-
ed phenyl selenyl based boron-dipyrromethene turn-on fluorescent
probes for the detection of hypochlorous acid (HClO). Sun [28] and his
group developed a probe for hypochlorous acid based on the cleavage
of carbon-carbon double bonds. Liu [29] synthesized a highly sensitive
and selective hypochlorite fluorescent probe based on oxidation of hy-
drazine via free radical mechanism. Recently, BODIPY dyes has attracted
more and more attention because of its exceptional photophysical
properties such as long emission wavelengths, high molar absorption
coefficients and fluorescence quantum yield [30–33]. In addition,
BODIPY, a group of luminogenic molecules, is easy to modify to obtain
desirable performance. According to the previous work, the reports on
the probe for HClO/ClO− based on BODIPY are still limited. A number
of BODIPY-based HClO/ClO− probes have been reported, however,
emission band of these probes majorly falled into the region of 500–
520 nm. Therefore, the development of fluorescent probes for HClO/
ClO− based on BODIPY is in urgent demand.
In our work, a naked-eye visible and fluorometric chemodosimeter
based on the HClO/ClO−-promoted oxidation of aldoxime for hypochlo-
rite was designed by combining pyridyl triphenylamine and BODIPY.
Based on the deoximation reaction some fluorescent probes were de-
signed. Compared with the previous reported sensors [34–36], the
structure of dye moiety is novel and used for the first time to sense hy-
pochlorite. As we know, triphenylamine-BODIPY derivatives with their
emissions are tunable from green to red exhibit highly efficient and sta-
ble photophysical properties [37]. Therefore, triphenylamine–BODIPY
⁎
Corresponding author.
E-mail address: yingqian@seu.edu.cn (Y. Qian).
http://dx.doi.org/10.1016/j.saa.2017.04.043
1386-1425/© 2017 Elsevier B.V. All rights reserved.

X. Xu, Y. Qian / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 183 (2017) 356–361
357
with tetramethylsilane (TMS) as internal standard. Chemical shifts are
given in parts per million (ppm). Mass spectra were recorded on Agilent
Technologies 6530 Accurate-Mass Q-TOF LC/MS. UV–visible absorption
spectra were determined on a Shimadzu UV-3600 spectrophotometer.
Fluorescence spectra were measured on a HORIBA FL-4 Max spectrom-
eter. 1 × 1 × 3 cm quartz cuvettes were used for absorption and emis-
sion spectral titration.
All reagents used were purchased and used without further purifica-
tion. All solvents used in spectroscopic measurements were of analytical
grade. Reactions were monitored by thin layer chromatography using
Merck TLC Silica gel 60 F254. Silica gel column chromatography was
performed over Merck Silica gel 60.
2.2. Synthesis
Scheme 1. Chemical structures of pyridyl triphenylamine–BODIPY aldoxime.
The synthetic routes are presented in Scheme 2. 2,4-dimethyl-pyr-
role, N,N-di (4-iodophenyl) aminobenzaldehyde, and other important
intermediates were synthesized according to literature procedures
[38–39]. All chemical structures were confirmed by 1H NMR, 13C NMR
and mass spectrometry.
was adopted as fluorogenic moiety. The attachment of 4-vinylpyridine
moiety to triphenylamine–BODIPY can successfully build a new
fluorogen and extend the conjugation system. In this probe, an
aldoxime group was employed as hypochlorite-responsive moiety. As
shown in Scheme 1, due to C_N isomerization, the probe is weak fluo-
rescent. OX-PPA-BODIPY could react rapidly with HClO/ClO−, while
HClO/ClO− mediated removal of the aldoxime group restores the fluo-
rescence of the BODIPY fluorogenic moiety.
8-{4-{N,N-bis{4-[2-(4-pyridyl)ethenyl]phenyl}amino}phenyl}-
1,3,5,7-tetramethyl-4,4′-difluoro-4-bora-3a,4a-diaza-s-indacene(PPA-
BODIPY). A mixture of IPA-BODIPY (0.50 g, 0.67 mmol), 4-vinylpyridine
(0.17 g, 1.62 mmol), Pd(OAc)2 (4.53 mg, 0.02 mmol), K3PO4 (0.21 g,
1.01 mmol) and Tri(o-tolyl)phosphine (0.02 g, 0.07 mmol) in DMF
(6 mL)was stirred for 24 h at the temperature of 130 °C in nitrogen at-
mosphere. Then, the reaction mixture was brought to room tempera-
ture, washed with water and extracted by filtration method. The
residue was purified by column chromatography on silica gel to obtain
the pure product PPA-BODIPY as an orange powder in 75.8% yield. 1H
NMR (300 MHz, CDCl3) δ: 8.57 (d, J = 3.00 Hz, 4H), 7.48 (d, J =
9.00 Hz, 4H), 7.35 (d, J = 6.00 Hz, 4H), 7.27 (m, 4H),7.19 (d, J =
9.00 Hz, 2H), 7.13 (d, J = 9.00 Hz, 4H), 6.94 (d, J = 15.00 Hz, 2H),
2. Experiment
2.1. Chemicals and Instruments
Chemical structures were confirmed by NMR analysis and mass
spectrometry. 1H NMR and 13C NMR spectra were recorded on a Bruker
300 MHz spectrometer and a Bruker 300 MHz spectrometer in CDCl3
Scheme 2. Synthesis of pyridyl triphenylamine-BODIPY derivative.

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X. Xu, Y. Qian / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 183 (2017) 356–361
Fig. 1. Absorption spectra of OX-PPA-BODIPY (10−5 M) and OX-PPA-BODIPY + HOCl (5
× 10−4 M, 50 equiv.) in PBS buffer (pH = 7.4) and THF mixed solvent systems (1/1, v/
v). Inset: the colorimetric detection of HOCl.
Fig. 3. Fluorescence spectra of probe OX-PPA-BODIPY (10 μM) with increasing amount of
NaOCl in PBS buffer (pH = 7.4) and THF (1/1, v/v) solution. The excitation wavelength was
450 nm.
6.02 (s, 2H), 2.56 (s, 6H), 1.60 (s, 6H). 13C NMR (300 MHz, CDCl3) δ:
155.52, 149.96, 147.59, 147.33, 144.89, 142.75, 141.35, 132.42, 131.40,
129.88, 129.33, 128.28, 124.91, 124.81, 124.24, 121.30, 120.73, 14.55.
HRMS-MALDI-TOF calcd for C45H38BF2N5 [M + H]+ = 698.3261
found: 698.3228.
δ: 185.85, 150.02, 147.14, 144.80, 132.31, 131.73, 129.11, 128.34,
125.15, 124.84, 124.48, 120.73, 53.38, 29.66, 15.10, 12.84, 11.91.
HRMS-MALDI-TOF calcd for C46H38BF2N5O [M + H]+ = 726.3215
found: 726.3267.
8-{4-{N,N-bis{4-[2-(4-pyridyl)ethenyl]phenyl}amino}phenyl}-
2-(hydroxyimino)methyl-1,3,5,7-tetramethyl-4,4′-difluoro-4-bora-
3a,4a-diaza-s-indacene(OX-PPA-BODIPY). PPA-BODIPY-CHO(0.15 g,
0.210 mmol)was dissolved in methylene chloride and ethanol mixed
solvent(30 mL),and excess hydroxylammonium chloride(0.04 g,
0.630 mmol) was added, then sodium acetate(0.08 g, 0.944 mmol)was
added as catalyst. The mixture was stirred for 5 h at 85 °C. After the evap-
oration of CH2Cl2 and C2H5OH, the residue was purified by silica gel col-
umn chromatography to afford the final product OX-PPA-BODIPY as an
orange red powder in 95% yield. 1H NMR (300 MHz, CDCl3) δ: 8.57
(d,6.00 Hz,4H), 8.15 (s,1H), 7.49 (d,9.00 Hz,4H), 7.36 (d,6.00 Hz,4H),
7.30–7.26 (m,5H), 7.19 (d,9.00 Hz,2H), 7.13 (d,6.00 Hz,4H), 6.95
(d,15.00 Hz, 2H), 6.08 (s,1H), 2.65 (d,12.00 Hz, 6H), 1.66
(d,27.00 Hz,6H). 13C NMR (300 MHz, CDCl3) δ: 160.69,157.44,
8-{4-{N,N-bis{4-[2-(4-pyridyl)ethenyl]phenyl}amino}phenyl}-
2-formyl-1,3,5,7-tetramethyl-4,4′-difluoro-4-bora-3a,4a-diaza-s-
indacene(PPA-BODIPY-CHO). DMF (6 mL) was stirred in ice bath and
POCl3 (6 mL) was added dropwise. After the solution was warmed to
room temperature, it was stirred for additional 30 min. PPA-BODIPY
(0.50 g, 0.60 mmol) in dichloroethane (30 mL) was added to this re-
action mixture. The temperature was raised to 60 °C, and the mixture
was stirred for an additional 3 h. The reaction mixture was cooled to
room temperature and slowly poured in saturated aqueous NaHCO3
(150 mL) under ice-cold condition, which was extracted CH2Cl2.
After the evaporation of CH2Cl2, the residue was purified by silica
gel column chromatography to get the pure product PPA-BODIPY-
CHO as a deep red powder in 89.6% yield. 1H NMR (300 MHz,
CDCl3) δ: 10.07 (s, 1H), 8.59 (d, J = 6.00 Hz, 4H), 7.52 (d, J =
6.00 Hz, 4H), 7.37 (d, J = 6.00 Hz, 4H), 7.33–7.27 (m, 4H), 7.22–
7.14 (m, 4H), 6.98 (d, J = 15.00 Hz, 2H), 6.22 (s, 1H), 2.84 (s, 3H),
2.65 (s, 3H), 1.81 (s, 3H), 1.69 (s, 3H). 13C NMR (300 MHz, CDCl3)
152.72,150.80,150.25,147.75,
147.69,147.25,144.97,142.53,136.23,
135.40,134.51,133.82,132.48,132.33,131.30,128.03,127.73,127.33,125.3-
7,125.09,80.43,80.00,79.58,32.66,17.80,16.91,15.64. HRMS-MALDI-TOF
calcd for C46H39BF2N6O [M + H]+ = 741.3324 found: 741.3341.
Fig. 2. Absorption spectra of probe OX-PPA-BODIPY (10 μM) with increasing amount of
NaOCl in PBS buffer (pH = 7.4) and THF (1/1, v/v) solution.
Fig. 4. Fluorescence intensity of OX-PPA-BODIPY (10−5 M) in the absence (■) or presence
(
) of OCl− (10 × 10−5 M) as a function of pH. Excitation wavelength was 450 nm.

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359
catalyzed Heck reaction of TPA-BODIPY with 4-vinylpyridine with
good yield (75.8%). Through such synthetic routes, 4-vinylpyridine
substituents are linked to BODIPY core on 8-position through a
vinyl bridge. PPA-BODIPY-CHO was obtained by formylation reaction
of PPA-BODIPY. Afterwards PPA-BODIPY-CHO was allowed to react
with HONH2·HCl to produce the final product OX-PPA-BODIPY. The
compounds were confirmed by magnetic resonance (1H NMR and
13C NMR) and high resolution mass spectrometry (HRMS-MALDI-
TOF). The structural characterization data of the product by spectro-
scopic methods are given in the Experimental Section. The purity of
the resultant products and intermediates has been confirmed by 1H
NMR, 13C NMR, and high-resolution mass (MALDI-TOF) spectroscop-
ic techniques (see Figs. S1–S5, Supporting information).
3.2. Naked-eye Visible and Fluorometric Chemodosimeter for Hypochlorous
Acid
The spectral properties of the probe toward the addition of ClO−
were examined in PBS buffer (pH = 7.4) and THF mixed solvent sys-
tems (1/1, v/v) was shown in Fig. 1. According to Fig.1, two major ab-
sorption bands of OX-PPA-BODIPY located at 393 nm and 520 nm are
observed. The former is ascribed to the localized π-π* transition of aro-
matic moieties in the molecular level, while the latter attributed to the
BODIPY core with attachment of aldoxime. Meanwhile, upon addition
of ClO− to the solution of OX-PPA-BODIPY, the absorption peak located
at 520 nm decreased dramatically (Fig. 2). Accordingly, the addition of
ClO− to the probe produces a colorimetric change from pink to green,
which can be detected by the naked eye (Fig. 1).
The plot of the fluorescence intensity of OX-PPA-BODIPY against the
increase in ClO− concentration is displayed in Fig. 3. As shown, OX-
PPA-BODIPY in solution is weak emissive (ΦF = 0.02) possibly due to a
non-radiative deactivation through rapid isomerization of the C_N\\OH
group. The emission spectra of PPA-BODIPY displays two emission peaks
located at 508 nm and 555 nm. The detection of OX-PPA-BODIPY toward
ClO− were studied by addition of different equivalent of ClO− solution
(0–50 equivalent) to a solution of OX-PPA-BODIPY in PBS buffer (pH
= 7.4) with 50% water (Fig. 1). From Fig. 3, the intensity of the emission
Fig. 5. Time dependent fluorescence intensity changes of probe OX-PPA-BODIPY (10−5 M)
with 10 equiv. NaClO in a mixture of PBS buffer (pH = 7.4) and THF (1/1, v/v, λex
=
450 nm).
3. Results and Discussion
3.1. Design and Synthesis of Pyridyl Triphenylamine-BODIPY Aldoxime
The synthetic routes of the probe OX-PPA-BODIPY are shown in
Scheme 2. The detailed synthetic procedures and data of the struc-
ture characterization are described in the Experimental section and
Supporting information. Our strategy is based on the following de-
sign principles: Firstly, triphenylamine–BODIPY was adopted as
fluorogenic moiety. Secondly, the modifier of pyridine linked to the
triphenylamine–BODIPY core with C_C double bond will extend
the conjugation and lead to a redshifted emission. Finally, the intro-
duction of an aldoxime unit at the 2-position of BODIPY was used as
“off - on” reactor. PPA-BODIPY was synthesized through Palladium-
Scheme 3. OCl− promoted oxidative deoximation reaction of OX-PPA-BODIPY.

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X. Xu, Y. Qian / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 183 (2017) 356–361
The reaction mechanism of the present system was investigated.
It is assumed that the color change and fluorescence increasing could
be attributed to aldoxime oxidation to aldehydes in the presence of
ClO− (Scheme 3). As we all known, the removal of a C_N bond in a
fluorogenic molecule via the reaction of an oxime and ClO− restores
the strong fluorescence. It is speculated that the mechanism is based
on a specific reaction promoted by hypochlorite. The HRMS spectra
of the reaction mixture of OX-PPA-BODIPY with OCl− (Fig. S6) veri-
fied the aldoxime oxidation to aldehyde, which showed peaks at
748.5490/764.5820 (for [PPA-BODIPY-CHO + Na]+ / [PPA-BODIPY-
CHO + K]+).
3.3. Response of OX-PPA-BODIPY to Different Anions and ROS
Selectivity is the most important requirement for all kinds of detection
methods. The turn-on response of OX-PPA-BODIPY to other reactive oxy-
gen species (ROS) such as TBHP, H2O2, O2,·OH, TBO· and anions including
NO2−, PO34−, S2−, SCN−, SO32−, SO24−, HCO−3 , HSO−3 , I−, Br− was also tested.
In the test system, 10 equiv. ClO− as well as other ROS and different an-
ions were added respectively to a 10−5 M solution of OX-PPA-BODIPY.
Only ClO− induced robust fluorescence intensity enhancement, other
analytes show negligible changes in absorbance spectra under the same
conditions. As shown in Fig. 6, only ClO− caused a robust fluorescence in-
tensity enhancement while the others exhibited almost no change in fluo-
rescence behaviour. A significant feature of the probe was its high
selectivity toward ClO− over other competitive ROS and different anions
(Fig. 7). The result indicated that OX-PPA-BODIPY showed high sensitivity
toward hypochlorite with low interference. The detailed photophysical
properties of OX-PPA-BODIPY and OX-PPA-BODIPY + ClO− in a
mixture of PBS buffer (pH = 7.4) and THF (1/1, v/v) were summarized
in Table 1.
Fig. 6. Fluorescence responses of OX-PPA-BODIPY (10−5 M) to NaClO (10 equiv.) and
other ROS and different anions at 520 nm. Conditions: PBS buffer (pH = 7.4) and THF
(1/1, v/v). λem = 450 nm.
peaks at 508 nm and 550 nm both increased, gradually merging into a
peak at 520 nm, which also resulted in a visual fluorescence change
(from pink to green) under illumination with a 365 nm UV lamp.
When the amount of ClO− added reached 50 equivalents with respect
to the probe, these changes were found to reach a plateau, with a 20-
fold fluorescence enhancement accompanied. Fluorescence titration
was carried out in PBS-buffered solution (pH = 7.4) to determine the de-
tection limit, which was then calculated with the equation: detection
limit = 3σ/k [40], where σ is the standard deviation of blank measure-
ments, and k is the slope between intensity and sample concentration.
Thus, the detection limit was determined to be 7.37 × 10−7 M.
In addition, a pH-dependence experiment of OX-PPA-BODIPY was
conducted to investigate a suitable pH range for ClO− sensing. The pH
titration curve (Fig. 4) also reveals that the fluorescence intensity of
OX-PPA-BODIPY and the corresponding product toward ClO− maintain
almost constant values at pH 1–13, demonstrating that OX-PPA-BODIPY
can work in the biological pH range without influence.
More, Time-dependent modulations in the fluorescence spectra of
the probe were monitored in the presence of 10 equiv. of ClO− (Fig. 5).
The kinetic study showed that the reaction was completed within
5 min for ClO−, indicating that the probe reacts rapidly with ClO−
under the experimental conditions. The addition of ClO− (aq.) to a solu-
tion containing OX-PPA-BODIPY results in an immediate, strong increase
in the fluorescence intensity (Fig. 3). During the titration of ClO− with
OX-PPA-BODIPY, a new emission band appeared at 520 nm. The emis-
sion intensity reached its maximum after the addition of one equivalent
of ClO−. The quantum yield of the oxidized form was 0.43, which is 21-
fold greater than that of OX-PPA-BODIPY (0.02).
4. Conclusions
In summary, a fluorescence probe OX-PPA-BODIPY based on
triphenylamine-BODIPY platform that can selectively detect HClO/
ClO− over other ROS species and anions in aqueous media. The probe
exhibited an obvious HClO/ClO− induced a large fluorescence enhance-
ment in the emission spectra resulting in a change of solution color from
pink to green with fast response and selectivity. Furthermore, OX-PPA-
BODIPY was almost nonfluorescent (turn-off) and the fluorescence
emission of the probe can be turned on upon addition of HClO/ClO−
,
which resulted in an increase of the emission intensity up to 20-fold
with fluorescence quantum yield of 0.43. The addition of HClO/ClO−
to the probe solution developed an instantaneous color and fluores-
cence change. Which was easily detectable by the naked eyes under
light and UV irradiation. The detection limit of OX-PPA-BODIPY was
measured to be 7.37 × 10−7 M. This probe is expected to be a useful
tool in various biological and pathological processes.
Fig. 7. The corresponding photographs of dosimeter OX-PPA-BODIPY after the addition NaClO (10 equiv.) and other ROS and different anions in aqueous media. Conditions: PBS buffer (pH
= 7.4) and THF (1/1, v/v).

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Table 1
Photophysical properties of OX-PPA-BODIPY and OX-PPA-BODIPY + NaOCl in a mixture of
PBS buffer (pH = 7.4) and THF (1/1, v/v).
Compounds
λ
ab (nm)
ε
max (104 cm−1 ∗ M−1
)
λem (nm) ΦF
OX-PPA-BODIPY
393
520
4.94
4.22
5.09
0.37
550
520
0.02
0.43
OX-PPA-BODIPY+ ClO− 399
510
λ
ab UV absorption; λem fluorescence emission maximum; Ɛmax maximum molar extinc-
tion coefficient; ΦF fluorescence quantum yield.
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Appendix A. Supplementary Data
Supplementary data to this article can be found online at http://dx.
doi.org/10.1016/j.saa.2017.04.043.
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a
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