A visible-light-photocatalytic water-splitting strategy for sustainable hydrogenation/deuteration of aryl chlorides

Article abstract of DOI:10.1007/s11426-019-9672-8

Hydrogenation/deuteration of carbon chloride (C?Cl) bonds is of high significance but remains a remarkable challenge in synthetic chemistry, especially using safe and inexpensive hydrogen donors. In this article, a visible-light-photocatalytic watersplitting hydrogenation technology (WSHT) is proposed to in-situ generate active H-species (i.e., H_ad) for controllable hydrogenation of aryl chlorides instead of using flammable H₂. When applying heavy water-splitting systems, we could selectively install deuterium at the C?Cl position of aryl chlorides under mild conditions for the sustainable synthesis of high-valued added deuterated chemicals. Sub-micrometer Pd nanosheets (Pd NSs) decorated crystallined polymeric carbon nitrides (CPCN) is developed as the bifunctional photocatalyst, whereas Pd NSs not only serve as a cocatalyst of CPCN to generate and stabilize H (D)-species but also play a significant role in the sequential activation and hydrogenation/deuteration of C?Cl bonds. This article highlights a photocatalytic-WSHT for controllable hydrogenation/deuteration of low-cost aryl chlorides, providing a promising way for the photosynthesis of high-valued added chemicals instead of the hydrogen evolution.

Full text of DOI:10.1007/s11426-019-9672-8

SCIENCE CHINA
Chemistry
•ARTICLES•
https://doi.org/10.1007/s11426-019-9672-8
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A visible-light-photocatalytic water-splitting strategy for
sustainable hydrogenation/deuteration of aryl chlorides
Xiang Ling1, Yangsen Xu1, Shaoping Wu2, Mofan Liu2, Peng Yang3, Chuntian Qiu1,
Guoqiang Zhang1, Hongwei Zhou4 & Chenliang Su1*
1International Collaborative Laboratory of 2D Materials for Optoelectronic Science & Technology, Engineering Technology Research Center
for 2D Materials Information Functional Devices and Systems of Guangdong Province, Institute of Microscale Optoeletronics, Shenzhen
University, Shenzhen 518060, China;
2School of Pharmacy; Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of
Education; Biomedicine Key Laboratory of Shaanxi Province, Northwest University, Xi’an 710069, China;
3Yunnan Key Laboratory for Micro/nano Materials & Technology, the School of Materials Science and Engineering, Yunnan University,
Kunming 650000, China;
4College of Biological, Chemical Science and Engineering, Jiaxing University, Jiaxing 314001, China
Received November 26, 2019; accepted December 24, 2019; published online February 17, 2020
Hydrogenation/deuteration of carbon chloride (C–Cl) bonds is of high significance but remains a remarkable challenge in
synthetic chemistry, especially using safe and inexpensive hydrogen donors. In this article, a visible-light-photocatalytic water-
splitting hydrogenation technology (WSHT) is proposed to in-situ generate active H-species (i.e., Had) for controllable hydro-
genation of aryl chlorides instead of using flammable H2. When applying heavy water-splitting systems, we could selectively
install deuterium at the C–Cl position of aryl chlorides under mild conditions for the sustainable synthesis of high-valued added
deuterated chemicals. Sub-micrometer Pd nanosheets (Pd NSs) decorated crystallined polymeric carbon nitrides (CPCN) is
developed as the bifunctional photocatalyst, whereas Pd NSs not only serve as a cocatalyst of CPCN to generate and stabilize H
(D)-species but also play a significant role in the sequential activation and hydrogenation/deuteration of C–Cl bonds. This article
highlights a photocatalytic-WSHT for controllable hydrogenation/deuteration of low-cost aryl chlorides, providing a promising
way for the photosynthesis of high-valued added chemicals instead of the hydrogen evolution.
deuteration, water-splitting, aryl chlorides, Pd nanosheets, carbon nitride
Citation:
Ling X, Xu Y, Wu S, Liu M, Yang P, Qiu C, Zhang G, Zhou H, Su C. A visible-light-photocatalytic water-splitting strategy for sustainable
hydrogenation/deuteration of aryl chlorides. Sci China Chem, 2020, 63, https://doi.org/10.1007/s11426-019-9672-8
1 Introduction
donors (amines, alcohols, and Hantzsch ester) as hydrogen
transfer reagents [1–13]. These processes suffer from the
undesired side reactions, the limited reaction scopes and the
risks involved using flammable gas at high pressure, or op-
erating air and moisture-sensitive metal hydride reducing
agents. Consequently, it is an urgent to develop sustainable
processes for the dechlorination of chlorides with low-cost
and readily available hydrogen donors. Being clean and
abundant, water is an ideal hydrogen donor. Moreover, the
processes using aqueous chemistry are preferred due to re-
Carbon chloride bonds widely exist in natural products and
various significant organic compounds [1]. Activation of
C–Cl bonds has attracted significant interest due to the in-
herent fundamental challenge [2]. Conventional dechlorina-
tion strategies mainly include metal halogen exchange, metal
hydride reagents, or radical-induced reduction with organic
*Corresponding author (email: chmsuc@szu.edu.cn)
© Science China Press and Springer-Verlag GmbH Germany, part of Springer Nature 2020
chem.scichina.com link.springer.com

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Ling et al. Sci China Chem
duced likelihood of side reactions and simplified work-up
procedures [14,15].
measured by inductively coupled plasma-optical emission
spectrometry (ICP-OES, Agilent 700). The high-perfor-
mance mass spectrometry (MS) was conducted by a Q Ex-
active GC Orbitrap GC-MS/MS (Thermo Scientific).
Nuclear magnetic resonance (NMR) spectra were recorded
on Bruker Nanobay spectrometers 500, 600 MHz (Ger-
many). In CDCl3, proton chemical shifts (δ) are reported
relative to the residual protonated solvent (δ=7.26 ppm). The
photocatalytic reaction systems were irradiated by Kessil
LED lights (PR160–427 nm).
Although using hydrogen generated from water [16–18] is
extremely attractive from the view of sustainable develop-
ment, the activation of water molecules to generate hydrogen
is challenging due to the high dissociation energy of O–H
bonds [19]. Most recently, our group has demonstrated a
photocatalytic water splitting technology [20–24] for hy-
drogenation (deuteration) reactions of iodides and carbon-
carbon multibonds [23,24]. Compared with iodides, chlor-
ides are much lower-cost and exist in a larger number of
natural products and pharmaceutically important molecules.
Thus, the development of an environmental benign strategy
for effective hydrogenation/deuteration of more inert carbon-
chloride bonds with sustainable H-donors (i.e., water) is
highly attractive but still remains challenges for producing
high-value-added fine chemicals as well as heavy drugs,
which is currently a significantly important topic in phar-
maceutical fields [25–30].
In this article, we demonstrated an efficient and sustainable
visible light-induced C–Cl activation for hydrogenation/
deuteration of aryl/heteroaryl chlorides based on the photo-
catalytic water-splitting hydrogenation technology (WSHT)
over submicrometer Pd nanosheets decorated by the crys-
talline polymeric carbon nitrides (denoted as Pd NSs/
CPCN). A series of aryl/heteroaryl chlorides were effectively
hydrogenated/deuterated in aqueous solution under mild
conditions (room temperature, ambient tolerance). The ul-
trathin Pd NSs as the cocatalyst employed herein not only
promote the hydrogen generation and stabilization, but also
play a critical role in the activation of C–Cl bonds.
2.2 Preparation of Pd NSs
Pd(acac)2 (50 mg) was added into a glass-pressure vessel
with oleyamine (8 mL) and N,N-dimethylformamide (DMF)
(2 mL). The vessel then was purged with 1 atm CO and
heated at 90 °C for 3 h. After being cooled to room tem-
perature, the obtained products was precipitated with acet-
one, centrifuged and further washed with ethanol for twice.
The precipitate was re-dispersed into DMF (40 mL) for the
further use.
2.3 Preparation of CPCN
According to the typical procedure [31], melamine (3.0 g)
was ground with KBr (2.0 g) in 3 mL EtOH and 1 mL glycol
in an agate mortar. After drying at 65 °C, the resultant
mixture was heated to 550 °C for 3 h at a rate of 3.3 °C min−1
in a tube furnace (inner diameter is 5 cm) with open two ends
in an air atmosphere. After it was cooled to room tempera-
ture, the bright yellow green product was washed with
boiling deionized water several times and collected by fil-
tration, followed by drying at 60 °C under vacuum.
2 Experimental
2.4 Synthesis of Pd NSs/CPCN
2.1 General information
Common reagents were commercially available and used as
received without any further purification unless stated
otherwise. Pd(acac)2, melamine and KBr were purchased
from commercial sources (Sigma-Aldrich and Alfa Aesar,
USA) and used as received. Transmission electron micro-
scope (TEM) images were taken using a Tecnai F30 (FEI)
and Titan Cubed Themis G2 300 (FEI). X-ray diffraction
(XRD) patterns were performed on Rigaku Ultima IV using
Cu Kα irradiation at a scan rate of 2o min−1 with the target
voltage of 40 kV and the current of 40 mA. The UV-Vis
absorption spectra were recorded on a UV-3600 UV-Vis-NIR
scanning spectrophotometer (Carry 5000, Agilent, USA).
The chemical compositions were analyzed using X-ray
photoelectron spectroscopy (XPS, Thermo Escalab 250,
USA, a monochromatic Al Kα X-ray source. All binding
energies were referenced to the C 1s peak (284.6 eV) arising
from adventitious carbon). The content of palladium was
226 mg CPCN and 100 mL DMF was stirred overnight and
then sonicated for 1 h. The Pd NSs in 40 mL DMF described
above were added into the dispersion and stirred for about
12 h. Finally, the mixture was centrifuged and washed with
ethanol for twice and dried under vacuum. By varying the
amount of CPCN, Pd NSs/CPCN with different Pd contents
was prepared.
2.5 Photocatalytic H2 evolution
The photocatalytic water splitting was carried out in a
150 mL Pyrex flask reactor (Labsolar VIAG, Perfectlight
Technology Co., Ltd., China) via top-irradiation with a
300 W xenon lamp (Perfect Light Company Solaredge
300C) with a UVCUT-420 nm filter (Newport). The tem-
perature of the reaction system (10 °C) was controlled by the
circulated water. Typically, the PdNSs/CPCN photocatalyst

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Ling et al. Sci China Chem
(20 mg) was suspended in an aqueous solution containing
3 Results and discussion
10 vol% triethanolamine (TEOA) solution. The evolved gas
was quantified online using a gas chromatograph (GC, Fuli
9890II, China) equipped with a thermal conductivity detector
(TCD) with argon as the carrier gas.
To synthesize sub-micrometer Pd NSs, Pd(acac)2 was dis-
solved in DMF and reduced by CO in the presence of
oleyamine at 90 °C for 3 h. The color of the reaction mixture
turned to blue-black from the initial light yellow as the re-
action progressed. After being cooled to room temperature,
the mixture was precipitated with acetone and centrifuged.
The obtained Pd NSs were washed twice with ethanol and re-
dispersed in DMF for further use. The TEM image in Figure
1(a) reveals that the as-prepared Pd NSs are hexagonal
morphology with a size of over 100 nm (the long diagonal of
the hexagon). The high-resolution TEM (HRTEM) image of
the individual Pd nanosheet (Figure 1(b)) exhibits the lattice
fringes with an interplanar spacing of 0.24 nm, correspond-
ing to 1/3(422) fringes of face centered cubic (fcc) Pd [32].
The fcc structure of Pd NSs was further determined by X-ray
diffraction (XRD) pattern (Figure 2(a)). The result indicates
that the (111) facet of Pd NSs is the basal planes, which is
consistent with the previous reports [32,33].
2.6 Apparent quantum yield (AQY) calculations of H2
production
The 100 mg of Pd NSs/CPCN photocatalyst is placed into a
100 mL pure water in a closed gas circulation system. The
catalyst solution was irradiated by a 300 W Xe lamp ap-
plying band pass filters (centered at 400, 420, 475, 500 and
550 nm) for 2 h. The average intensity of irradiation is de-
termined by a FZ-A spectroradiometer (Photoelectric In-
strument Factory of Beijing Normal University).
The AQY was calculated from the equation:
2×the number ofevolved H2molecules
AQY =
× 100%
the numberofincidentphotos
The Pd NSs/CPCN nanocomposite was constructed via the
electrostatic adsorption in DMF through stirring Pd NSs
described above and CPCN for over 12 h. After being
homogeneously mixed, the color of Pd NSs/CPCN disper-
sion changed from yellow (CPCN) to dark blue, and the
composite was obtained after centrifugation and drying.
Three Pd NSs/CPCN catalysts with different contents of Pd
were prepared by varying the amount of CPCN, named as Pd
NSs/CPCN-1, Pd NSs/CPCN-2 and Pd NSs/CPCN-3, re-
spectively. The color of the three resulting Pd NSs/CPCN
nanohybrids is deepening to blackish green, as shown in
Figure S1 (Supporting Information online). The contents of
Pd of Pd NSs/CPCN-1, Pd NSs/CPCN-2 and Pd NSs/CPCN-
3 were measured to be approximately 1.9%, 5.8% and 9.1%
2.7 General procedure of photocatalytic reactions
A silica tube containing the catalyst, substrate (0.2 mmol),
TEOA (0.9 mL), H2O (8.1 mL) and ethanol (1 mL), was
sealed in a glovebox and transferred outside. Then the
mixture was irradiated under the LED light (427 nm) with
stirring for 24 h. Ether acetate (5 mL) was added to the
mixture and the upper organic phase was collected. The yield
was calculated by GC-MS with the standard curve and by
NMR. For photocatalytic stability evaluation, the catalyst
was re-collected by centrifugation, washed with ethanol and
dried under vacuum. For deuteration, D2O and CH2CH2OD
were used instead of water and ethanol.
Figure 1 (a, b) TEM and HRTEM images of Pd NSs. The inset in (b) is the FFT pattern from the marked yellow square. (c) TEM image of Pd NSs/CPCN-
2. (d) The HAADF-STEM image of Pd NSs/CPCN-2. (e–h) The HAADF-STEM images and element mapping patterns of Pd NSs/CPCN-2 (color online).

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Ling et al. Sci China Chem
Figure 2 (a) XRD patterns of Pd NSs, CPCN and Pd NSs/CPCN-2. (b) UV-Vis-NIR diffuse reflectance spectra of CPCN and Pd NSs/CPCN-2 (color
online).
(Table S1, Supporting Information online) by ICP-OES, re-
spectively. As illustrated in Figure 2(a), the slightly de-
creased peak intensity of Pd NSs/CPCN-2 could be ascribed
to the interaction between Pd NSs and CPCN in Pd NSs/
CPCN-2, which might be beneficial to improve the photo-
catalytic activity. The light absorption edge shows negligible
difference of Pd NSs/CPCN-2 compared with CPCN in the
UV-Vis-NIR diffuse reflectance spectra (Figure 2(b)) ran-
ging from 300 to 500 nm. The increased absorption of Pd
NSs/CPCN-2 in the range of 500 to 1,200 nm is attributed to
the intrinsic absorption of Pd NSs. To observe the structure
of Pd NSs/CPCN and the distribution of Pd NSs in Pd NSs/
CPCN, the spherical aberration-corrected scanning trans-
mission electron microscopy in high angle annular dark field
mode (CS-corrected STEM-HAADF) was conducted on the
sample Pd NSs/CPCN-2. As shown in Figure 1(c, d), Pd NSs
were dispersed rather well on the surface of CPCN. The
energy-dispersive X-ray spectroscopy (EDS) elemental
mapping images (Figure 1(e–h)) further confirmed the good
dispersion of Pd NSs on surface of CPCN. XRD was further
employed to characterize the crystal structure of Pd NSs/
CPCN-2. In Figure 2(a), the decorated Pd NSs only reduce
the peak intensity of CPCN.
were evaluated through XPS spectra. As shown in Figure 3
(a), the peaks at 336 and 341.2 eV in Pd NSs are assigned to
Pd 3d5/2 and Pd 3d3/2 of Pd(0), respectively. However, the
binding energy of Pd 3d in Pd NSs/CPCN exhibits an ob-
vious decrease of 0.5 eV compared with Pd NSs. Corre-
spondingly, the binding energy of N 1s in Pd NSs/CPCN-2
displays 0.4 eV increase compared with the pure CPCN
(Figure 3(b)). This result indicates that the strong metal-
support interaction (SMSI) [34,35] appears at the interfaces
between Pd NSs and CPCN. This might be due to the in-built
amino groups in the CPCN skeleton that could act as the
binding sites to interact with Pd NSs. Accordingly, the
electron cloud density surrounding the interface between Pd
NSs and CPCN increases. This would finally affect the
catalytic performance of the Pd NSs/CPCN.
The photocatalytic water splitting is a process of decom-
posing the O–H bonds of water, resulting in the generation of
active H-species (Had) which subsequently form hydrogen
molecules. Hence, the H2 production activity of Pd NSs/
CPCN-2 was evaluated by carrying out the visible light-
induced hydrogen evolution assay on the Pd NSs/CPCN-2.
As shown in Figure 4(a), Pd NSs/CPCN exhibits an excellent
photocatalytic activity. The hydrogen evolution rate of Pd
NSs/CPCN reaches up to 2.53 mmol h−1 g−1 with a quantum
The chemical states of Pd NSs, CPCN and Pd NSs/CPCN
Figure 3 Pd 3d (a) and N 1s (b) XPS spectrum of Pd NSs and Pd NSs/CPCN-2 (color online).

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Ling et al. Sci China Chem
Figure 4 (a) Photocatalytic H2 evolution over Pd NSs/CPCN-2 and Pd NSs/CPCN-2 after three cycles of hydrogenated dichlorination process under visible
light (λ≥420 nm). (b) Photocatalytic stability of Pd Ns/CPCN-2 towards hydrogenation of 2-chloro-benzonitrile (color online).
efficiency of approximate 2.4% in the initial hour. By re-
placing water with heavy water, the active D-species could
be obtained by this technology for the further deuteration.
The H2 evolution result indicates that Pd NSs/CPCN might
be able to achieve the aim by using the in-situ generated
active D-species as D donors for the subsequent deuteration
of inert aryl chlorides. In this proposed process, Pd not only
serves as cocatalysts for heavy water splitting to generate and
stabilize D-species, but also plays a major role in the se-
quential activation and deuteration of C–Cl bonds. The high
atom utilization ratio and specific surface area of Pd NSs
employed in the Pd NSs/CPCN could enlarge the contact
area between Pd and CPCN to enhance the electron transfer
on the interface as well as increase the adsorption ability of
the photogenerated active D-species and chloride substrates.
Since the core of our strategy described above is utilizing
the in-situ generated active D (H) species to achieve the
deuterium (hydrogen) incorporation in the aryl/heteroaryl
ring via the C–Cl bond cleavage, we chose the hydrogenated
dechlorination of inert aryl chlorides as the initial model
reaction to study the transformation of C–Cl bonds. As
shown in Table S2, a series of control experiments were
carried out with 2-chloro-benzonitrile as the model substrate
to optimize reaction conditions and confirm the synergistic
effect of Pd NSs/CPCN during the hydrogenated di-
chlorination process. First, in the case of only pure water in
the system with Pd NSs/CPCN-2 (40 mg) as the catalyst
(entry 1) under blue light irradiation (427 nm) for 24 h, only
trace amount of the product was detected by the GC-MS. In
Table S2 entry 2, the yield increased dramatically to 94.2%
when TEOA used as a sacrificial agent was added into the
system. The highest yield was obtained because the hydro-
philic solvent ethanol was used to enhance the solubility of
substrates in water (Table S2, entry 3). Hence, the TEOA/
H2O/ethanol system was determined to be the optimal re-
action system. Then catalytic performances of various cata-
lysts (Pd NSs/CPCN-1, Pd NSs/CPCN-2 and Pd NSs/CPCN-
3) with different Pd amounts were evaluated with the TEOA/
H2O/ethanol system shown in Table S2 entry 4–6. From the
obtained results, Pd NSs/CPCN with a Pd content of 5.8%
(Pd NSs/CPCN-3) are chosen as the optimal catalyst.
Moreover, no reaction occurs under all conditions (Table S2
entry 7–9) except for using Pd NSs/CPCN as a photocatalyst
under blue light irradiations. This indicates that both the light
and the synergistic photocatalyst are essential for the hy-
drogenated dechlorination reaction. Moreover, the effect of
irradiation sources with different wavelength (λ=510 and
610 nm) was also estimated. As shown in Table S1 entry 10
and 11, the yield of the hydrogenation/deuteration of chlor-
ides decreased dramatically when increasing the wavelength
of the LED lamp. This indicated that H2/D2 evolution effi-
cacy decreased when increasing the wavelength, resulting in
the reduction of the reaction efficiency of the following
hydrogenated dichlorination/deuteration. Subsequently, the
photocatalytic stability of Pd NSs/CPCN was examined with
catalytic Pd NSs/CPCN-2. As shown in Figure 4(b), Pd NSs/
CPCN maintained the excellent activity during the first two
cycles. However, the catalytic ability of Pd NSs/CPCN-2
decreased to 80.9% in the third cycle and further to 61.7% in
the fourth cycle. Moreover, the photocatalytic H2 evolution
performances over Pd NSs/CPCN-2 after three cycle reac-
tion decreased to around 50% (Figure 4(a)). Therefore, it
indicated that the decreased hydrogenation/deuteration
ability of Pd NSs/CPCN could be ascribed to the reduced
photocatalytic H2 evolution performance. To further confirm
this, the Pd NSs/CPCN-2 after three cycles was used to
perform the control experiment, where the hydrogenated
dichlorination of 2-chloro-benzonitrile was conducted in the
TEOA/H2O/ethanol system with the hydrogen gas (1 atm)
but without the light irradiation. The 2-chloro-benzonitrile
was fully converted to the corresponding product at room
temperature as shown in Table S2 entry 12, which further
confirmed that the decreased hydrogenation/deuteration
ability of Pd NSs/CPCN could be attributed to the reduced
photocatalytic H2 evolution performance.
Under the optimal condition, a variety of aryl/heteroaryl
chlorides and two drug chlorides were examined to assess the
universality of photocatalytic hydrogenated dechlorination

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Ling et al. Sci China Chem
Table 2 Deuteration of aryl/heteroaryl chloridesa)
of chlorides with water as the hydrogen source. In Table 1,
the electron-withdrawing group-substituted aryl chlorides
such as cyano or carbonyl groups in various positions (2a–2c
and 2e–2h) efficiently gave the desired hydrogenated pro-
ducts with high yields through the TEOA/H2O/ethanol sys-
tem. Even the electron-donating group-substituted aryl
chlorides such as m- or p-chloro-benzamine (2m and 2n) and
chloro-naphthene (2d) are suitable for this strategy. How-
ever, the TEOA/H2O/ethanol system was not suitable for aryl
chlorides containing the ester groups. When replacing
TEOA/H2O/ethanol with MeOH/H2O, aryl chlorides (2i–2l),
containing the ester groups, could gave the aim products with
excellent yields. The C–F bond cannot be hydrogenated in
this system due to the much higher bond energy. Further-
more, the heteroaryl chlorides (2o–2v) and two bioactive
chlorides (2w and 2x) were also appropriate for our strategy
in the TEOA/H2O/ethanol system, generating the corre-
sponding hydrogenated products with remarkable yields.
Based on the optimal conditions of hydrogenated de-
chlorination, replacing water and ethanol with D2O as the D
source and CH3CH2OD as solvent, respectively, the reaction
scope towards the deuteration of aryl/heteroaryl chlorides
was assessed, where TEOAwithout the D-label was still used
as the sacrificial agent. As illustrated in Table 2, the deu-
teration occurs at the position of C–Cl bonds of aryl/het-
eroaryl chlorides in high yields with good to excellent
deuterium incorporation. Additionally, the functional group
tolerance of our strategy is rather good. However, for 3o,
using 6-chloroquinoline as the substrate, deuteration occurs
a) Chloride substrate (0.2 mmol), TEOA/D2O/CH3CH2OD (0.9 mL/8.1
mL/1.0 mL), Pd NSs/CPCN-2 (40 mg), irradiation 24 h. b) CD3OD/D2O
(5.0 mL/5.0 mL). Yields were calculated from GC-MS measurements using
a standard curve.
not only at the position of C–Cl bonds (86% D incorporated)
but also at the α active hydrogen of quinoline (95% D in-
corporated). It indicated that when the chloride substrate
possesses active hydrogens, the hydrogen isotope exchange
will take place in the process of chloride deuteration. Thus,
2-chloroquinolin was further used as the substrate, where the
α active position was substituted by the chlorine. Deuteration
only occurs at the position of C–Cl bonds with good deu-
terium incorporation (85%). In general, our strategy is able to
efficiently transform C–Cl bonds of aryl/heteroaryl and
bioactive chlorides to C–D bonds in good deuterium in-
corporation with green and low-cost D-sources under mild
conditions.
Table 1 Dechlorination of aryl/heteroaryl chloridesa)
Accordingly, based on the obtained experimental results
described above, a possible mechanism of the photocatalytic
C–Cl bonds by hydrogenated dechlorination/deuteration was
proposed (Figure 5). First, the inert chlorides are adsorbed on
the surface of Pd NSs and activated by Pd NSs [36]. Upon
the blue light LED irradiation, the excited electrons in CPCN
will transfer to Pd NSs [37,38]. Subsequently, the electrons
will reduce H2O (D2O) to H2 (D2), which further adsorbs on
the surface of Pd NSs. Then, Pd NSs catalyze the hydro-
genated dichlorination/deuteration of C–Cl bonds by use of
the generated H2 (D2). Meanwhile, the generated holes can
oxidize TEOA to [TEOA]+ [39].
4 Conclusions
In conclusion, the efficient and selective transformation of
C–Cl to C–H has been achieved with in-situ generated hy-
drogen active species from aqueous solution under visible
light over Pd NSs decorated CPCN. A variety of aryl and
heteroaryl chlorides were effectively hydrogenated under
mild conditions in remarkable yields with good functional
group tolerance. By replacing H2O with D2O, the in-situ
a) Chloride substrate (0.2 mmol), TEOA/H2O/ethanol (0.9 mL/8.1 mL/
1.0 mL), Pd NSs/CPCN-2 (40 mg), irradiation 24 h. Yields were calculated
from GC-MS measurements using a standard curve. b) Methanol/H2O (5.0
mL/5.0 mL). c) Irradiation 48 h.

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Ling et al. Sci China Chem
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photocatalytic deuteration of inert C–Cl bonds to produce
high-value-added D-chemicals. This work highlights a sus-
tainable strategy utilizing aqueous solutions as the H (D)-
source for the sustainable hydrogenation/deuteration of inert
chlorides, opening the possibility for the efficient and sus-
tainable production/innovation of new heavy drugs with
improved pharmacokinetic and toxicity profiles. Further
applications of WSHT for converting a series of function-
alities, such as C–H, C–OH, C=O, to C–D bonds are cur-
rently ongoing for the controllable synthesis of heavy
chemicals/drugs.
Acknowledgements This work was supported by the National Natural
Science Foundation of China (21972094, 51701127, 21401190), China
Postdoctoral Science Foundation (2017M612709), Guangdong Special
Support Program, Pengcheng Scholar Program, Shenzhen Peacock Plan
(KQJSCX20170727100802505, KQTD2016053112042971), Educational
Commission of Guangdong Province (2016KTSCX126), Foundation for
Distinguished Young Talents in Higher Education of Guangdong
(2018KQNCX221),
Shenzhen
Innovation
Program
(JCYJ
20170818142642395). We are thankful for the support of TEM character-
izations from the Electron Microscopy Center of Shenzhen University and
computational source supplied by the National Supercomputing Center in
Shenzhen (Shenzhen Cloud Computing Center).
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Conflict of interest The authors declare that they have no conflict of
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http://chem.scichina.com and http://link.springer.com/journal/11426. The
supporting materials are published as submitted, without typesetting or
editing. The responsibility for scientific accuracy and content remains en-
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