Light-Activated Sensitive Probes for Amine Detection

Article abstract of DOI:10.1002/anie.201609989

Our new, simple, and accurate colorimetric method is based on diarylethenes (DAEs) for the rapid detection of a wide range of primary and secondary amines. The probes consist of aldehyde- or ketone-substituted diarylethenes, which undergo an amine-induced decoloration reaction, selectively to give the ring-closed isomer. Thus, these probes can be activated at the desired moment by light irradiation, with a sensitivity that allows the detection of amines at concentrations as low as 10^?6m in solution. In addition, the practical immobilization of DAEs on paper makes it possible to detect biogenic amines, such as cadaverine, in the gas phase above a threshold of 12 ppbv within 30 seconds.

Full text of DOI:10.1002/anie.201609989

Angewandte
Communications
Chemie
International Edition: DOI: 10.1002/anie.201609989
German Edition: DOI: 10.1002/ange.201609989
Colorimetric Detection of Amines
Light-Activated Sensitive Probes for Amine Detection
+
+
Virginia Valderrey , Aurelio Bonasera , Sebastian Fredrich, and Stefan Hecht*
[
7]
[8]
Abstract: Our new, simple, and accurate colorimetric method
is based on diarylethenes (DAEs) for the rapid detection of
a wide range of primary and secondary amines. The probes
consist of aldehyde- or ketone-substituted diarylethenes, which
undergo an amine-induced decoloration reaction, selectively to
give the ring-closed isomer. Thus, these probes can be activated
at the desired moment by light irradiation, with a sensitivity
boxylic acids, Anslynꢀs receptors, Severinꢀs coumarin
[9]
[10]
probe, Miljani c´ ꢀs cruciform, and Kanedaꢀs cyclodextrin
dye, have been developed. A colorimetric sensor for
amines that combines enzymes and chromophores has also
been described.
have been employed as sensing units for the detection of
different analytes, such as amino acids, cyanide anions, thiols,
and organophosphorus compounds. In these examples, the
reactivity of the chromophore can be triggered by means of
irradiation with UV or visible light. This approach is more
suitable for practical applications, since the sensor can be
stored in its dormant form until the activation of the molecule
shortly before the use. Moreover, the pre-exposure of the
inactive sensor to an amine-containing environment will not
affect the performance of the active form, thus preventing
overestimation of the analyte detection. Herein, we describe
a methodology for the efficient recognition and quantification
of amines by specific diarylethenes (DAEs), which can be
activated at the desired point in time and at defined areas of
a surface using light as a remote control, without influencing
the local concentration.
[
11]
[
12]
More recently, photochromic materials
[
13]
that allows the detection of amines at concentrations as low as
À6
1
0
m in solution. In addition, the practical immobilization of
DAEs on paper makes it possible to detect biogenic amines,
such as cadaverine, in the gas phase above a threshold of
1
2 ppbv within 30 seconds.
A
mines are ubiquitous natural constituents of all living
beings (i.e. amino acids, neurotransmitters, etc.) and beyond
certain concentrations some of them can be indicative of
[
1]
industrial effluvia or food spoilage. Various biogenic amines,
such as cadaverine, histamine, tyramine, putrescine, spermi-
dine, spermine, and ethanolamine are products of thermal or
enzymatic decarboxylation of amino acids by bacteria.
Consequently, the accumulation of these amines can serve
[
2]
[
3]
as an indicator of food quality or hygiene. The detection and
discrimination of compounds related to a given environ-
mental hazard continues to challenge the scientific commun-
ity and therefore, amine sensing has been widely investigated
with several detection protocols described in the literature. Of
these, chromatographic techniques coupled with mass spec-
trometry are preferentially employed, because they provide
DAEs typically undergo 6p-electrocyclization and cyclo-
reversion reactions upon irradiation with UVand visible light,
[
14]
respectively. This photochemical reaction is accompanied
by visible color changes: the open isomer, absorbing in the
near-UV region, is converted into the closed one, with distinct
red-shifted absorption, in a reversible manner. In addition,
the electronic changes originating from the photoisomeriza-
tion make it possible to control the reactivity of properly
substituted DAEs, for example aldehyde-substituted DAEs in
[
4]
good detection limits towards amines. However, these
methods are limited by extended analysis times as well as
expensive and large instrumentation. Antibodies and
enzymes have been employed and have also provided good
[
15]
condensation reactions with amines.
Inspired by these
examples, we envisaged that DAEs containing a carbonyl
group at the end of the hexatriene system should experience
an even more dramatic change in the reactivity towards
amines. We therefore synthesized a series of photoswitchable
DAEs, functionalized at the reactive position of one of the
two heteroaryl fragments with a formyl (1o–3o) or an acetyl
(4o) group (Scheme 1). Ring-closure of open DAEs (1o–4o)
with UV light converts the less reactive aromatic carbonyl
[
5]
sensitivities; nevertheless, the main drawback of these
approaches is the use of materials that are sensitive to
chemicals and temperature. In addition, antibodies have to be
raised, representing a limiting factor in the availability of the
active materials. Several colorimetric sensors based on simple
chromophores, which recognize amines by noncovalent
interactions, have been designed in order to overcome those
drawbacks. Different concepts for amine sensing, such as
[
16]
group into a more reactive aliphatic one.
UV/Vis absorption spectroscopy of a 4 ꢁ 10 m solution of
o in acetonitrile indicates that the open isomer 1o undergoes
[
6]
À5
Suslickꢀs colorimetric arrays, Lavigneꢀs polythiophene car-
1
an electrocyclization reaction upon irradiation with 365 nm
light (see Figure S10 in the Supporting Information). This is
evidenced by the formation of a band in the visible region
[
+]
[+]
[
*] Dr. V. Valderrey, Dr. A. Bonasera, S. Fredrich, Prof. S. Hecht
Institut fꢀr Chemie & IRIS Adlershof
Humboldt-Universitꢁt zu Berlin
Brook-Taylor-Strasse 2, 12489 Berlin (Germany)
E-mail: sh@chemie.hu-berlin.de
(lmax = 564 nm), which implies a change in the color of the
solution from colorless to violet. Ultraperformance liquid
chromatography (UPLC) analysis of the irradiated solution
shows that in the photostationary state (PSS) approximately
+
[
] These authors contributed equally to this work.
Supporting information (details on the synthesis and character-
ization data) and the ORCID identification numbers for the authors
of this article can be found under http://dx.doi.org/10.1002/anie.
8
0% of 1o has been converted to the closed isomer 1c.
Irradiation of the solution of 1 in the PSS with 500 nm light
recovers the pure open isomer 1o. This process can be
201609989.
Angew. Chem. Int. Ed. 2017, 56, 1 – 6
ꢀ 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1
These are not the final page numbers!

Angewandte
Communications
Chemie
Scheme 1. Light controls the reactivity of open (1o–4o) and closed
1c–4c) diarylethene isomers, carrying aromatic and aliphatic alde-
(
hyde/ketone groups, respectively, towards amines resulting in either
imines (1i–4i) or benzothiophene rearrangement products (1r–4r). o:
open, c: closed, i: imine, r: rearranged. Bn=Benzyl, TMS=trimethyl-
silyl.
repeated for several cycles (see Figure S20 in the Supporting
Information and Figures S15–S19 for thermal stability). The
reactivity of the two DAE isomers towards amines was
initially investigated by HNMR spectroscopy (Figure 1,
bottom). Irradiation of a colorless millimolar solution of 1o
Figure 1. Top: Proposed mechanism for the amine-induced decolora-
tion of aldehyde-substituted DAEs. Bottom: Selected regions of the
1
HNMR spectra (CD CN, 298 K) of a) 1o; b) mixture of 1o and 1c
3
1
corresponding to the PSS after 30 min irradiation with 350 nm light;
c) mixture of 1o and 1c corresponding to the PSS of 1o after 30 min
irradiation with 350 nm light +1 equiv BA; d) pure N-benzylforma-
mide.
with light at 350 nm for 30 min produces a deep violet solution
1
with a HNMR spectrum containing diagnostic signals for the
open and closed isomers in a ratio close to that of the PSS as
À5
determined by UPLC for the 4 ꢁ 10 m solution. The addition
of 1.0 equiv of benzylamine (BA) to the irradiated DAE
mixture immediately causes decoloration of the solution.
1
After 30 min, the HNMR signals of 1o remain unaf-
fected, indicating that the open DAE isomer is completely
unreactive towards the amine. In contrast, in the case of the
the closed isomer 1c the proton signals change. The aldehyde
signal of 1c disappears, suggesting that the nucleophilic
addition of the amine to the aldehyde group took place
selectively only in the closed isomer. Similar results are
obtained by UV/Vis absorption spectroscopy. The addition of
BA to a solution of 1o, irradiated at 365 nm to achieve the
PSS, results in a gradual decay of the band centered at lmax
=
5
64 nm in the visible region of the spectrum and a hypsochro-
mic shift of the band in the UV region is observed, resulting in
a yellowish solution (Figure 2a). Once no further changes of
the absorption spectra were observed, the sample was
irradiated again with 365 nm light but no further spectral
changes occurred. In view of these results, we conclude that
Figure 2. a) Left: Evolution of the UV/Vis absorption spectrum corre-
1
c reacts selectively with BA in the presence of 1o and in an
À5
sponding to the PSS of 1 (2.4ꢂ10 m) after the addition of BA
irreversible manner to generate reaction product 1r, which is
photoinactive. In order to elucidate the structure of 1r, we
isolated the closed isomer 1c, which was subsequently treated
with 1.0 equiv of BA (further details are given in the
À2
(
1.7ꢂ10 m). Right: Gradual decay of the band at 564 nm correspond-
ing to the formation of 1r. b) X-ray crystal structure of 1r; gray C,
white H, green F, red O, yellow S. Ellipsoids represent the 50% proba-
[
18]
bility level. Hydrogen atoms are shown as spheres of arbitrary radii.
2
www.angewandte.org
ꢀ 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2017, 56, 1 – 6
These are not the final page numbers!

Angewandte
Communications
Chemie
Supporting Information). X-ray diffraction analysis of pure 1r
Table 1: First-order rate constants (k) determined for the rearrangement
reaction of DAEs 1c and 3c with various amines.
revealed that the DAE core rearranges into a benzothiophene
[18]
[
a]
[b]
[b]
scaffold, causing the decomposition of the thiophene ring
opposite to the aldehyde, generating a photochemically
unreactive compound (Figure 2b).
Amine
Structure
k(1c)/min
k(3c)/min
SPER
1.67
2.66
The presence of N-benzylformamide as a by-product in
the HNMR experiments provides further insight into
CAD
DAP
OA
0.30
0.49
0.12
0.033
0.50
1.58
0.13
0.025
1
a reasonable mechanism for the observed rearrangement
reaction. Initially, the nucleophilic attack of the amine at the
highly reactive, aliphatic aldehyde of the closed DAE isomer
produces the corresponding hemiaminal intermediate. Sub-
sequently, this intermediate rearranges to the more stable
compound 1r with elimination of N-benzylformamide
BA
MBA
BMA
0.002
0.0012
0.0010
n.r.
0.0007
n.r.
DMBA
(
Figure 1, top). To confirm the proposed mechanism for the
À2
À5
formation of 1r, we synthesized the imine derivative 1i
starting from the open DAE 1o. As expected, 1i can be
switched between the open and the closed isomers by
alternating UV- and visible-light irradiation in a reversible
fashion and without generation of 1r (Scheme 1, see Fig-
ure S35 in the Supporting Information). This is in agreement
with the proposed mechanism for the formation of 1r, which
requires the intermediacy of the hemiaminal derivative
[
a] 1ꢂ10 m in CH CN. [b] 2ꢂ10 m in CH CN.
3
3
Supporting Information); afterwards a specific amount of
amine was added. We monitored the variation of optical
density at the maximum of the visible absorption band
belonging to the closed isomer. This region was chosen since
the absorption of the rearrangement products 1r–4r is
minimal and the absorbance change thereby maximized.
The rate constants were determined by fitting the UV/Vis
spectral changes with a first-order reaction. As expected from
the proposed mechanism, tertiary amines are not reactive.
Secondary amines react much slower than primary ones as
indicated by comparing the rates of BMA with BA. This
discrimination is presumably due to the increased steric
hindrance of the secondary amines. For similar reasons BA
reacts faster than MBA. Purely aliphatic amines are about
one order of magnitude more reactive than BA. Finally,
aliphatic oligoamines, such as DAP, CAD, and SPER react
faster than what would be expected by simply correcting for
the number of amino groups present in the corresponding
molecules. Clearly, neighboring group effects play an impor-
tant role in these cases.
(
Figure 1, top). Similar experiments were performed using
1
switches 2–4. UV/Vis absorption and HNMR spectra con-
firmed the transformation of the investigated switches into
products that show the same central scaffold as 1r, and differ
only in the substitution pattern (for further details see the
Supporting Information). The main difference in the amine-
induced rearrangements of DAEs 1c–4c is the reaction time,
which reflects the reactivity of the carbonyl moiety. As
expected, the reactivity follows the order 3c > 1c ꢀ 2c > 4c
(
for the UV/Vis spectra see the Supporting Information). This
order can be rationalized considering that the less reactive
ketone 4c forms the hemiaminal intermediate more slowly
than the aldehydes, of which 3c is the fastest as it contains no
electron-donating methoxy group. Note that the effect of
substitution on the thiophene ring is smaller than that
resulting from a slight change in the amine structure, high-
lighting the degree of chemoselectivity for sensing amines.
After serendipitously discovering this unique rearrange-
ment reaction of the closed, carbonyl-substituted DAE
isomers, we engaged in a systematic spectroscopic investiga-
tion in order to 1) quantify the rate constant for the reaction
of all four switches with a variety of amines and to
When considering these reactivity data, particular atten-
tion should be paid to 3c, which displays better photoswitch-
ing performance (high PSS), excellent thermal stability (see
Figure S18 in the Supporting Information), and also higher
reactivity. According to the data obtained for CAD, the
rearrangement of 3c occurs 1.6 times faster than that of 1c
À5
and a limiting concentration of 2.0 ꢁ 10 m was determined,
2
) determine the lowest concentration range for which an
with a 50% decrease of the absorption at 580 nm within
110 min (see Figure S57 in the Supporting Information).
To optimize the conditions for sensing of the amines we
studied the influence of the pH on the kinetics of the reaction
(see Section 6.1. in the Supporting Information). The optimal
rate was obtained upon addition of 10 equiv of p-toluenesul-
evolution of the spectral bands takes place over a reasonable
time frame (up to 2 h).
A collection of eight different amines was studied in
combination with the synthesized DAE switches (Table 1 and
the Supporting Information). Amines were chosen to repre-
sent different classes, such as tertiary amines (N,N-dimethyl-
benzylamine (DMBA)), secondary amines (N-benzylmethyl-
amine (BMA)), bulky primary amines (benzylamine and (S)-
fonic acid to a solution of 3c in CH CN followed by the
3
addition of 10 equiv of CAD. This resulted in a 40-fold rate
increase as compared to the rate in the absence of the acid
catalyst. A larger excess of acid led to decreasing rates. This
observation points to the classic scenario of an optimal,
(
À)-a-methylbenzylamine (MBA)), primary linear aliphatic
amines (octylamine (OA)), primary diamines (1,3-diamino-
propane (DAP) and cadaverine (CAD)), and aliphatic tris-
[
19]
slightly acidic pH window, where a small amount of acid
increases the electrophilicity of the carbonyl group yet too
large amounts lead to protonation of the amine, thereby
reducing its nucleophilicity.
amines (spermidine (SPER)). In a typical experiment, a
2
its PSS (for the PSS values of the DAEs see Table S2 in the
À5
ꢁ 10 m solution of the DAE was irradiated until it reached
Angew. Chem. Int. Ed. 2017, 56, 1 – 6
ꢀ 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
3
These are not the final page numbers!

Angewandte
Communications
Chemie
Once the reaction conditions for amine sensing had been
optimized, we focused on applying this methodology by using
simple and inexpensive platforms. Initially, we decided to
create a colorcode assay, which makes it possible to detect
amines with the “naked eye” quickly and easily. Different
quantities of amines were added to a 16-well microplate filled
with a solution of 3 (CH CN, l = 365 nm). This resulted in
the characteristic color change from deep violet to yellow at
different rates. Manipulation of the pictures taken during the
colorimetric assay allowed us to create a palette of colors that
can be used to estimate the amine concentration in a solution
within a short time interval (see Figures S62 and 63 in the
Supporting Information).
amine sensing. Importantly, this methodology allowed us to
sense vapors of cadaverine down to a threshold of 12 ppbv
(parts per billion in volume) in 30 s (see Figures S65 and S66
in the Supporting Information).
In conclusion, we have described a simple method for the
detection of amines in solution and in the gas phase. Our
colorimetric assay is based on aldehyde-substituted DAE
scaffolds, which can be activated by exposure to UV light.
Only the on-demand-generated closed isomer can react with
amines, leading to a decolorized rearrangement product (and
an amide). Kinetic studies involving facile UV/Vis absorption
monitoring allowed us to discriminate a wide variety of
amines and revealed rapid reaction in the presence of primary
aliphatic amines, while secondary amines react more slowly,
and tertiary amines do not react at all. In contrast to other
methodologies based on multicomponent systems or bimo-
lecular cascade reactions, which require two different sensing
molecules, our strategy involves only one. Here, the two
sequential events occur simultaneously in the same sensing
unit, providing extremely rapid responses. The low reactivity
of the open isomer towards amines and the possibility of
activating the DAE sensors by irradiation on defined areas of
surfaces make them ideal for the development of a new
generation of smart yet low-cost sensing devices. Current
work in our laboratories is focused on
3
irr
In order to prove the versatility of our sensing strategy we
moved from studies in solution to the preparation of amine-
sensitive solid supports. A filter paper was coated with the
colorless inactive DAE 3o (Figure 3a). After that, the surface
1
) Enhancing the reactivity of the closed form for the
rearrangement by implementing electron-accepting sub-
stituents to stabilize the thiolate leaving group (see
mechanism Figure 1, top);
2
3
) Implementing fluorescence as a more sensitive readout;
) Achieving high photoconversion in the PSS upon expo-
sure to sunlight to ease the use in developing countries.
Beyond amine detection, we are aiming to develop this
promising new transformation into a light-triggered acyl
transfer reaction for bioconjugation.
Figure 3. Amine sensing with light-activated filter paper: a) Filter paper
coated with a solution of 3o; b) in situ activation by irradiating at
3
65 nm for 2 min with a UV lamp after the surface had been covered
with a photomask (printed on transparent plastic sheet with
a common laser printer); c) color evolution after exposure of the filter
paper to CAD vapors for 5 min; d) after removal of the CAD, the non-
irradiated areas (residual 3o) can be activated by irradiating at 365 nm
for 2 min, creating the “negative” of picture (b); e) color evolution
when the filter paper is exposed again to CAD vapors for 5 min.
Acknowledgements
We thank Dr. Beatrice Cula Braun for the X-ray crystallo-
graphic data and Michael Kathan for helpful discussions.
Generous support by the European Research Council (ERC
via ERC-2012-STG_308117 “Light4Function”), the Euro-
pean Commission (via MSCA-ITN “iSwitch” GA No.
642196), the German Research Foundation (DFG via SFB
658, project B8), and the Alexander von Humboldt Founda-
tion is gratefully acknowledged.
was covered with a photomask and irradiated with 365 nm
light. In this way we could create a color-patterned surface by
converting DAE 3o into its active form 3c, in precisely
specified areas of the surface (Figure 3b). After the exposure
of the sample to vapors of CAD we observed that only the
areas containing the light-activated sensor 3c were decolored
(
Figure 3c). Moreover, the regions that were previously not Conflict of interest
activated by light can be activated a posteriori (Figure 3d).
This makes patterning possible and the sensor can be used
multiple times through the sequential activation of specific
small areas.
The authors declare no conflict of interest.
Keywords: amines · diarylethenes · photochromism · sensing
This sequential UV activation nicely demonstrates that
the inactive sensing material does not react with the amines
until the moment it is activated by the UV light, ensuring that
the sensor is preserved until the appropriate moment of
4
www.angewandte.org
ꢀ 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2017, 56, 1 – 6
These are not the final page numbers!

Angewandte
Communications
Chemie
[
9] B. Lee, R. Scopelliti, K. Severin, Chem. Commun. 2011, 47,
9639 – 9641.
[
1] a) S. Bardꢂcz, Trends Food Sci. Technol. 1995, 6, 341 – 346; b) A.
Naila, S. Flint, G. Fletcher, P. Bremer, G. Meerdink, J. Food Sci.
[10] J. Lim, O. S. Miljani c´ , Chem. Commun. 2012, 48, 10301 – 10303.
[11] J. H. Jung, S. J. Lee, J. S. Kim, W. S. Lee, Y. Sakata, T. Kaneda,
Org. Lett. 2006, 8, 3009 – 3012.
[12] P. Q. Leng, F. L. Zhao, B. C. Yin, B. C. Ye, Chem. Commun.
2015, 51, 8712 – 8714.
[13] a) N. Shao, J. Y. Jin, S. M. Cheung, R. H. Yang, W. H. Chan, T.
Mo, Angew. Chem. Int. Ed. 2006, 45, 4944 – 4948; Angew. Chem.
2006, 118, 5066 – 5070; b) Y. Shiraishi, K. Adachi, M. Itoh, T.
Hirai, Org. Lett. 2009, 11, 3482 – 3485; c) F. Nourmohammadian,
T. Wu, N. R. Branda, Chem. Commun. 2011, 47, 10954 – 10956;
d) Y. Shiraishi, K. Yamamoto, S. Sumiya, T. Hirai, Phys. Chem.
Chem. Phys. 2014, 16, 12137 – 12142.
2010, 75, R139 – R150.
[
2] a) B. ten Brink, C. Damink, H. M. L. J. Joosten, J. H. J. H.
in’t Veld, Int. J. Food. Microbiol. 1990, 11, 73 – 84; b) A.
Halꢃsz, ꢄ. Barꢃth, L. Simon-Sarkadi, W. Holzapfel, Trends
Food Sci. Technol. 1994, 5, 42 – 49; c) M. H. S. Santos, Int. J. Food
Microbiol. 1996, 29, 213 – 231.
3] a) I. A. Bulushi, S. Poole, H. C. Deeth, G. A. Dykes, Crit. Rev.
Food Sci. Nutr. 2009, 49, 369 – 377; b) C. Y. Chong, F. Abu Bakar,
A. R. Russly, B. Jamilah, N. A. Mahyudin, Int. Food Res. J. 2011,
[
18, 867 – 876.
[
4] a) D. C. Johnson, D. Dobberpuhl, R. Roberts, P. Vandeberg, J.
Chromatogr. A 1993, 640, 79 – 96; b) S. Shesnov, L. Bigler, M.
Hesse, Eur. J. Mass Spectrom. 2002, 8, 1 – 16; c) M. L. Latorre-
Moratalla, J. Bosch-Fustꢅ, T. Lavizzari, S. Bover-Cid, M. T.
Veciana-Noguꢅs, M. C. Vidal-Carou, J. Chromatogr. A 2009,
[14] a) M. Irie, Chem. Rev. 2000, 100, 1685 – 1716; b) H. Tian, S. J.
Yang, Chem. Soc. Rev. 2004, 33, 85 – 97.
[15] a) D. Wilson, N. R. Branda, Angew. Chem. Int. Ed. 2012, 51,
5431 – 5434; Angew. Chem. 2012, 124, 5527 – 5530; b) M. Kathan,
P. Kova rˇ ꢇ cˇ ek, C. Jurissek, A. Senf, A. Dallmann, A. F. Thꢈne-
mann, S. Hecht, Angew. Chem. Int. Ed. 2016, 55, 13882 – 13886;
Angew. Chem. 2016, 128, 14086 – 14090.
1
216, 7715 – 7720.
5] a) J. Lange, C. Wittmann, Anal. Bioanal. Chem. 2002, 372, 276 –
83; b) B. Bꢂka, N. Adꢃnyi, D. Virꢃg, M. Sebela, A. Kiss,
[
[
[
2
Electroanalysis 2012, 24, 181 – 186; c) S. Leonardo, M. Campꢆs,
Microchim. Acta 2016, 183, 1881 – 1890.
[16] C. Godoy-Alcꢃntar, A. K. Yatsimirsky, J. M. Lehn, J. Phys. Org.
Chem. 2005, 18, 979 – 985.
6] a) N. A. Rakow, A. Sen, M. C. Janzen, J. B. Ponder, K. S. Suslick,
Angew. Chem. Int. Ed. 2005, 44, 4528 – 4532; Angew. Chem.
[17] Thermally induced rearrangements of some DAEs to benzo-
thiophenes have been observed by Kobatake: a) S. Kobatake, H.
Imagawa, H. Nakatani, S. Nakashima, New J. Chem. 2009, 33,
1362 – 1367; b) D. Kitagawa, S. Kobatake, Chem. Lett. 2011, 40,
93 – 95; c) H. Shoji, S. Kobatake, Chem. Commun. 2013, 49,
2362 – 2364.
[18] CCDC 1508362 contains the supplementary crystallographic
data for this paper. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via www.
ccdc.cam.ac.uk/data_request/cif.
2005, 117, 4604 – 4608; b) J. R. Askim, M. Mahmoudi, K. S.
Suslick, Chem. Soc. Rev. 2013, 42, 8649 – 8682.
7] a) T. L. Nelson, C. OꢀSullivan, N. T. Greene, M. S. Maynor, J. J.
Lavigne, J. Am. Chem. Soc. 2006, 128, 5640 – 5641; b) M. S.
Maynor, T. L. Nelson, C. OꢀSulliva, J. J. Lavigne, Org. Lett. 2007,
9, 3217 – 3220; c) T. L. Nelson, I. Tran, T. G. Ingallinera, M. S.
Maynor, J. J. Lavigne, Analyst 2007, 132, 1024 – 1030; d) M. Cai,
S. L. Daniel, J. J. Lavigne, Chem. Commun. 2013, 49, 6504 – 6506.
8] a) S. Nieto, J. M. Dragna, E. V. Anslyn, Chem. Eur. J. 2010, 16,
[
[19] R. G. Kallen, W. P. Jencks, J. Biol. Chem. 1966, 241, 5864 – 5878.
2
27 – 232; b) J. M. Dragna, G. Pescitelli, L. Tran, V. M. Lynch,
E. V. Anslyn, L. Di Bari, J. Am. Chem. Soc. 2012, 134, 4398 –
407; c) P. Metola, E. V. Anslyn, T. D. James, S. D. Bull, Chem.
4
Manuscript received: October 12, 2016
Revised: November 18, 2016
Final Article published: && &&, &&&&
Sci. 2012, 3, 156 – 161; d) Y. T. Zhou, Y. L. Ren, L. Zhang, L.
You, Y. F. Yuan, E. V. Anslyn, Tetrahedron 2015, 71, 3515 – 3521.
Angew. Chem. Int. Ed. 2017, 56, 1 – 6
ꢀ 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
5
These are not the final page numbers!

Angewandte
Communications
Chemie
Communications
Colorimetric Detection of Amines
Turn on the detector: Upon activation by
UV light, diarylethenes carrying an inter-
nal aldehyde group undergo a rearrange-
ment reaction in the presence of biogenic
amines, which facilitates their colori-
metric detection (see scheme).
V. Valderrey, A. Bonasera, S. Fredrich,
S. Hecht*
&&& — &&&
Light-Activated Sensitive Probes for
Amine Detection
6
www.angewandte.org
ꢀ 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2017, 56, 1 – 6
These are not the final page numbers!