Solar-driven tandem photoredox nickel-catalysed cross-coupling using modified carbon nitride

Article abstract of DOI:10.1039/d0sc02131h

Nickel-catalysed aryl amination and etherification are driven with sunlight using a surface-modified carbon nitride to extend the absorption of the photocatalyst into a wide range of the visible region. In contrast to traditional homogeneous photochemical methodologies, the lower cost and higher recyclability of the metal-free photocatalyst, along with the use of readily available sunlight, provides an efficient and sustainable approach to promote nickel-catalysed cross-couplings. This journal is

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Solar-driven tandem photoredox nickel-catalysed cross-coupling
using modified carbon nitride
a
a
a
a
a
Yangzhong Qin, † Benjamin C. M. Martindale, † Rui Sun, Adam J. Rieth and Daniel G. Nocera*
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
Nickel-catalysed aryl amination and etherification are driven with
sunlight using a surface-modified carbon nitride to extend the
absorption of the photocatalyst into a wide range of the visible
region. In contrast to traditional homogeneous photochemical
methodologies, the lower cost and higher recyclability of the metal-
free photocatalyst, along with the use of readily available sunlight,
provides an efficient and sustainable approach to promote nickel-
catalysed cross-couplings.
Introduction
Photoredox chemistry has expanded the toolbox of chemical
transformations owing to the ability to generate high energy
and reactive radical intermediates with facility under mild
conditions.1-6 Despite significant progress in the development of
selective bond-breaking and -forming reactions resulting from
Scheme 1. Summary of previous and current work on nickel-catalysed cross-
coupling.
photoredox-driven transformations using nickel, iron and
copper complexes,7 many of these contemporary methods metric for quantifying the sustainability of chemical processes
-12
rely on homogeneous photocatalysts based on iridium or in addition to the more commonly used Process Mass Intensity
2
4-26
ruthenium, which are expensive and potential sources of toxic (PMI = mass of input material/mass of product),
which only
contaminants.1 Moreover, blue or UV light is often required considers the material input. For photocatalytic processes,
3-16
to drive many photocatalytic reactions due to the limited energy and materials costs for generating photons,
1
7-21
absorption range of the common photocatalysts,
which can photocatalysts and products accounted for by including EI with
result in off-pathway side reactions due to the competing PMI. Additionally, costs are accounted for associated with
excitation of other photoactive species present in solution. For removing toxic residues of the photocatalysts and their
instance, bipyridine-ligated nickel aryl halide complexes, often subsequent processing as chemical waste, the failure of which
formed in nickel-catalysed cross-couplings, can absorb UV and may result in detrimental consequences for the environment
2
7-29
blue light and result in unproductive homocoupling and and public health.
For example, the tolerable amount of
dehalogenation.2
2,23
metallic residues (e.g. platinum, iridium and ruthenium) in
Although photoredox catalysis provides powerful strategies pharmaceuticals is strictly regulated. Therefore, strategies to
and new capabilities for synthesis, the cost of the photocatalyst drive chemical reactions with sustainable, recyclable and non-
and light source, as well as the environmental footprint of the toxic materials are in high demand for improved energy
synthetic method and catalyst recovery have been infrequently efficiency, cost-effectiveness and minimal environmental
considered. To address this shortcoming, Energy Intensity (EI = impact.
total process energy/mass of final product) is an essential
Solar-driven chemical reactions are inherently sustainable
3
,30-32
and conducive towards a high EI.
sunlight at sea level is relatively high, on the order of 1000 W/m
Although the power of
2
a.
Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford
(
based on ASTM G-173-03 standard), the energy is
spectroscopically spread over a wide range from the UV region
Street, Cambridge, Massachusetts 02138, United States of America.
Email: dnocera@fas.harvard.edu
†These authors contribute equally.
to the IR. Hence, an efficient photocatalyst that can maximally
Electronic Supplementary Information (ESI) available: [Details about methodologies absorb broadband sunlight remains an unmet goal in
and Measurements]. See DOI: 10.1039/x0xx00000x
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Table 1. Testing C–O cross-coupling reactions with various heterogeneous
a
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DOI: 10.1039/D0SC02131H
photocatalysts.
VB
Potential
CB
Yield
Potential
(%)
Band Gap
eV)
Photocatalyst
(
(V)
(V)
SiC
3.0
2.7
2.7
2.3
1.4
1.5
1.8
0.8
1.2
0.7
–1.5
–0.9
–1.9
–1.1
–0.7
14
92
0
NH2CN
ZnSe
GaP
x
24
3
Figure 1. (A) A mechanistic scheme of the photoredox nickel-catalysed cross-
coupling reaction. Q stands for quencher. (B) Cyclic voltammetry measurements
CdTe
of 2.5 mM (dtbbpy)NiCl
2
in the presence of 5 mM quinuclidine, and 12 mM
a
Reactions were run on a 2-mL scale with 8 mg of photocatalyst. The bandgap, valence
quinuclidine in acetonitrile. (C) Absorption spectra of unmodified carbon nitride
band (VB) and conduction band (CB) potentials were taken from ref. 14, and all
referenced to NHE at pH = 0.
NH2
NCN
(
CN
x
x
) and modified carbon nitride ( CN ). The inset shows a posited unit
NCN
x
structure of CN .
state rather than an on-cycle catalyst.49 These studies
thoroughly explored the reaction conditions as well as the
mechanism, which allowed us to employ optimized reaction
conditions (see Table 1), and provide an underpinning for
developing heterogeneous photocatalysts with attractive
energy intensity.
photoredox catalysis. In contrast to homogeneous
photocatalysts, semiconductors, such as GaAs and CdTe, can
harness a broader wavelength of incident light; such materials
appear to be promising photocatalysts for sustainable
3
3-36
photocatalytic reactions.
Nonetheless, the use of inorganic
A suite of heterogeneous catalysts comprising SiC, carbon
semiconductor colloids to harness sunlight and directly drive
chemical reactions has remained challenging due to a variety of
factors, including, but not limited to, surface passivation, charge
recombination, materials instability and the balance between
electron-transfer kinetics from the conduction and valence
bands.36,37
nitride (NH2CN
gaps ranging from 3.0 eV to 1.4 eV.
), ZnSe, GaP and CdTe was surveyed with band
x
5
0-53
Table 1 illustrates the
efficacy of the photocatalysts for C–O coupling under 40 W blue
LED light (Figure S1) illumination. The product yield was
1
determined by H NMR spectroscopy using 1,3-benzodioxole as
NH2
an internal standard. We found that
x
CN gave the highest
Cross-coupling between nucleophiles and aryl halides is a
reaction that has employed both homogeneous and
yield of product (92%) after 24 hours of illumination. ZnSe,
NH2
3
8-46
x
possessing nearly the same band gap (2.7 eV) as CN , yielded
heterogeneous photocatalysts.
To date, these reactions
no product even though the conduction band is more reducing
have required intense light sources and/or prolonged
NH2
illumination.1
-6,17-21
than that of CN
x
(–1.9 V vs. –0.9 V as referenced to NHE at pH
We now demonstrate that nickel-catalysed
5
1,52
=
0, Table 1).
Although they possess similar band gaps, the
aryl amination (C–N) and etherification (C–O) may be directly
driven by solar light using a surface-modified carbon nitride
valence band potential of ZnSe is 0.9 V as compared to 1.8 V for
NH2
x
CN , suggesting that the less oxidizing valence band of ZnSe
(Scheme 1), which extends absorption into a wide range of the
may prevent it from driving photocatalysis. Consistent with this
contention, GaP and SiC, which have higher oxidation potentials
for their valence bands (1.2 V and 1.5 V, respectively) than that
of ZnSe, showed modest conversion yields of 24% and 14%,
respectively, after 24 hours of illumination under blue light. To
provide further insight as to the reaction disparity among
heterogeneous photocatalysts, we examined, by cyclic
visible region thus making it amenable for solar photoredox
catalysis. Additionally, besides being metal-free, the modified
carbon nitride is nontoxic, inexpensive, easily synthesized and
easily separated from product mixtures.
Results and discussion
Photoredox nickel-catalysed aryl etherification was first voltammetry (CV), the reduction of the nickel complex,
reported with a polypyridyl iridium photocatalyst that is excited (dtbbpy)NiCl (dtbbpy = 4,4′-di-tert-butyl-2,2′-dipyridyl), in the
2
by blue LED light.38 The mechanism was further studied by our presence of quinuclidine as the base, as well as the oxidation of
group and revealed to involve a sustained productive Ni(I/III) the quinuclidine itself. Owing to the (quasi)irreversibility of the
dark cycle initiated by a one electron reduction of the Ni(II) oxidation wave observed in CVs (Figure 1B), a standard
4
7,48
precatalyst (Figure 1A).
Significantly, our recent study shows thermodynamic potential cannot easily be assigned for either
that the photoredox reaction can also be realized by replacing species. However, the onsets of the nickel reduction wave at
the photocatalyst and photon source with a sub-stoichiometric ‒0.6 V as well as the quinuclidine oxidation wave at 1.1 V are in
amount of Zn metal,48 suggesting that the photocatalytic cycle line with our proposal that the potentials of the valence and
serves as an electron source to return an off-cycle Ni(II) complex conduction bands must be balanced to allow both cathodic and
to the active Ni(I) catalyst. This observation is consonant with anodic processes to occur. Consequently, among all the
the recent observation that Ni(II) resides off-cycle in a resting
2
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Figure 3. The product yield of nickel-catalysed aryl amination and etherification
NCN
driven by broadband sunlight with
x
CN as the photocatalyst. The reactions
remain active even after applying a series of long pass filters with increasing
cutting wavelength up to 590 nm. AM1.5 Global solar spectrum based on ASTM
G-173-03 is shown at the top for reference.
Figure 2. (A) Reaction conditions for nickel-catalysed aryl amination and
etherification. (B) The product yield using photocatalyst CN or CN under
x x
illumination with either white or orange LED lamps.
In analogy to aryl etherification, we posited that nickel-
catalysed photoredox aryl amination could also proceed
through a Ni(I/III) dark cycle given the similarity in reaction
NH2
NCN
3
8,39
conditions.
A larger-than-one quantum yield (QY = 2.7 ± 0.1)
heterogeneous photocatalysts tested, metal-free NH2CN
exhibits the best performance for C–O cross-coupling.
x
was also reported for the C–N cross-coupling with [Ir(dF-CF -
3
4
8
ppy) (dtbbpy)][PF ] as the photocatalyst, confirming the
2
6
To utilize broadband sunlight, we next sought to extend the presence of a Ni(I/III) cycle, analogous to the mechanism of aryl
NH2CN
absorption by its chemical modification.
35,54,55
x
etherification. We note that, unlike aryl etherification catalysis,
NCN
Specifically, cyanamide-modified carbon nitride ( CN
x
) shows aryl amination does not require dtbbpy since the amine
not only wider absorption in the visible region than that of substrate can act as a ligand to stabilize the nickel centre.
NH2
56
CN
x
(Figure 1C) but also long-lived electrons in the
Accurate quantum yield measurements are challenging for
conduction band, which cause the material to turn blue after these heterogeneous reactions owing to scattering.
5
7
reductive quenching of the hole upon photolysis. These long- Consequently, we performed external quantum yield
lived electrons offer a continuous source of redox equivalents measurements (EQY = number of product / number of incident
to reduce the Ni(II) complexes and drive the productive Ni(I/III) photons) for both C–N and C–O cross-coupling (see Figure 2A)
NCN
NCN
dark cycle.
CN
x
was synthesized from two inexpensive using
x
CN as the photocatalyst at low incident powers.
4
7,48
precursors (melamine and potassium thiocyanate) according to Consistent with previous observations,
a previously reported procedure (see section C in the SI). The excess of unity (2.2  0.2 and 2.4  0.1 for C–N and C–O cross-
absorption edge of
we obtained EQYs in
5
6
NCN
x
CN is red-shifted compared to that of coupling, respectively) under illumination with monochromic
NH2
58
CN , and the Tauc plot shows a minor change of 60 mV in light at 435 nm (Section F.6 in the SI). EQY values in excess of 1
x
the band gap (see Figure S2). This change is likely due to a slight unequivocally support the existence of dark cycle, as we have
movement of the conduction band potential while maintain the previously observed. Note that the actual quantum yields
5
3
same valence band potential. Successful surface NCN should be higher because the incident photons in the EQY
functionalization was confirmed by Fourier Transform Infrared measurements are not all absorbed by the heterogeneous
Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy photocatalyst due to scattering.
(XPS) (Figures S3 and S4), which showed a cyanamide stretch
The C–N and C–O coupling photocatalysis of the two carbon
and the presence of potassium, respectively, consistent with nitrides was examined using white LED and orange LED
5
6
previous reports. As we expected, the modified carbon nitride excitation (see the inset in Figure 2B and section E in the SI)
NCN
NH2
(
CN
x
) performs better as a photocatalyst than CN
x
under under the reaction conditions shown in Figure 2A, which are
all irradiation conditions (Table S1).
similar to the optimized conditions reported previously with
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Figure 4. The NCNCN
x
. photocatalyst was reused for multiple cycles over which no
decrease in product yields was observed for either aryl amination or aryl
etherification.
Figure 5. Applicability of nickel-catalysed aryl amination and etherification driven
NCN
1
3
8,39
by sunlight and CN
1
x
. Yields were determined by H NMR signal referenced to
homogeneous photocatalysts.
For both cross-coupling
, especially as the
,3-benzodioxole. Reaction heated to 55 C. b Different reaction condition, see
a
NCN
outperforms NH2CN
excitation source is shifted into the red side of the visible
absorption region. The white light LED has a spectrum peak at
reactions,
CN
x
x
c
section B in the SI. 40 hours illumination.
pass filter, product yields of 20% were achieved for both cross-
couplings after 20 hours. These results are of particular
significance since sunlight spans a broad spectrum where only a
small fraction falls within the blue and UV region (see Figure 3,
x
top panel). Thus CN is able to harness an extended spectral
range of sunlight (up to 590 nm) for photoredox cross-coupling
reactions.
An additional advantage offered by heterogeneous
4
60 nm in addition to a broadband emission centred at 600 nm,
whereas the orange light only has the 600 nm band with no
emission below 500 nm (see Figure S1). Notably, neither of the
LEDs exhibit emission in the UV region. This is particularly
important, because depending on the light intensity and the
absorption spectrum of the photocatalyst, even a small portion
of UV or blue light may be responsible for the majority of the
observed activity in the presence of more intense but
unproductive red light. For example, in a recent report on
photoredox cross-coupling with carbon nitride, the white and
green light sources both contained contributions from the UV
region, which appears to be responsible for the observed
reactivity based on the results reported here. After 20 hours of
illumination under our UV-free white light, CN resulted in
x
product yields of 63% and 55% for the C—N and C—O couplings,
respectively, in contrast to the 98% and 92% product yields
(Figure 2B). Moreover, after 20-hour
illumination with the orange LED light source,
provided a trace amount of product (3% and 1%), whereas
CN delivered 67% and 52% conversion for C—N and C—O
x
couplings, respectively. These results clearly demonstrate the
NCN
photocatalysts is their facile recyclability, which is confirmed for
CN in Figure 4. The photocatalyst was recovered by
x
subjecting it to three rounds of washing and centrifugation
NCN
4
3
followed by drying at 130 C in air (see section D in the SI). The
NCN
recovered
x
CN showed no loss in activity after 5 cycles.
5
9,60
NH2
Consistent with this result as wells as with previous reports
that establish the NCN surface modification to be photostable,
FTIR measurements showed that the NCN surface modification
was retained with photocycling (Figure S3). To further
investigate whether the activity observed using recycled
photocatalyst was due to residual nickel deposited on
NCN
observed for
CN
x
NH2
x
CN only
NCN
x
CN ,
NCN
NCN
we performed photoreactions with recycled
x
CN (after 5
2
+
cycles) in the absence of Ni complexes. For these control
experiments, we observe 4% and 0% product yield for aryl
amination and etherification, respectively. Consistent with
previous reports, the results of these control experiments
show that photocatalysis in recycling experiments is not due to
NCN
enhanced photoactivity of CN
broad band absorption.
x
under orange light due to its
4
6
Having demonstrated the improved photoactivity of the
NCN
x
surface-modified carbon nitride CN in the visible region, the
NCN
nickel deposition on the CN
Finally, the general applicability of NCNCN
x
photocatalyst.
was examined for
cross-coupling reactions were examined under one sun
irradiance provided by a solar simulator (Newport Sol2A ABA
class) with an AM1.5 filter (see section E in the SI); a 345 nm
x
the solar-driven nickel-catalysed cross-coupling between
different aryl bromides and nucleophiles. For aryl amination
(Figure 5), we consistently obtained the expected products with
high yields for various secondary (3, 4) and primary (5) amines.
Consistent with previous results, cross-coupling of heterocyclic
aryl bromides proved to be more challenging, but heating to
55 C furnished product in good yields (6, 7). Similarly, for aryl
etherification, methanol and isopropanol furnished product
long pass filter was employed to eliminate any deep UV light. As
NCN
shown in Figure 3,
x
CN drove quantitative conversions for
both cross-coupling reactions. By gradually red-shifting the cut-
off wavelength of the long pass filter, we observed a decrease
3
9
in the product yields commensurate with the diminished
NCN
absorption of
x
CN . Nonetheless, even with a 590 nm long
4
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yields of over 90% (8, 9). Surprisingly, water can be cross- 15 A. H. Bonardi, F. Dumur, G. Noirbent, J. Lalevee aVniedwDA.rtiGcliegOmnleinse,
Beilstein J. Org. Chem., 2018, 14, 3025-30D4O6I.: 10.1039/D0SC02131H
6 B. M. Hockin, C. F. Li, N. Robertson and E. Zysman-Colman, Catal.
Sci. Technol., 2019, 9, 889-915.
coupled with 99% yield under slightly modified conditions (10)
see section B in SI). Heterocyclic aryl bromides were also
coupled successfully in good yields with a reaction time of 40
1
1
1
1
2
2
2
(
7 W. B. Liu, J. B. Li, P. Querard and C. J. Li, J. Am. Chem. Soc., 2019,
hours (11, 12).
1
41, 6755-6764.
8 C. H. Lim, M. Kudisch, B. Liu and G. M. Miyake, J. Am. Chem. Soc.,
018, 140, 7667-7673.
9 J. He, C. Y. Chen, G. C. Fu and J. C. Peters, ACS Catal., 2018, 8,
1741-11748.
Conclusions
2
We have demonstrated that surface-modified carbon nitride,
1
NCNCN
x
, with its extended absorption in the visible region, can
0 S. Ruccolo, Y. Qin, C. Schnedermann and D. G. Nocera, J. Am.
Chem. Soc., 2018, 140, 14926-14937.
1 L. K. G. Ackerman, J. I. M. Alvarado and A. G. Doyle, J. Am. Chem.
Soc., 2018, 140, 14059-14063.
2 B. J. Shields, B. Kudisch, G. D. Scholes and A. G. Doyle, J. Am.
Chem. Soc., 2018, 140, 3035-3039.
directly utilize broadband sunlight to drive nickel-catalysed aryl
amination and etherification. In contrast to UV- and blue-light
driven photoredox processes, the method disclosed herein
enables highly efficient bond formation at high energy intensity
(EI) while avoiding competing photoexcitations of other
chemical species frequently encountered in dual photocatalytic 23 S. I. Ting, S. Garakyaraghi, C. M. Taliaferro, B. J. Shields, G. D.
processes. Owing to its increased efficiency in solar light
Scholes, F. N. Castellano and A. G. Doyle, J. Am. Chem. Soc., 2020,
42, 5800-5810.
24 F. G. Calvo-Flores, ChemSusChem, 2009, 2, 905-919.
1
absorption, metal-free nature, facile separation, ready
NCN
recyclability, and straightforward synthesis,
x
CN is an
2
2
2
5 F. Roschangar, R. A. Sheldon and C. H. Senanayake, Green Chem.,
015, 17, 752-768.
6 C. Jimenez-Gonzalez, D. J. C. Constable and C. S. Ponder, Chem.
Soc. Rev., 2012, 41, 1485-1498.
7 R. P. Schwarzenbach, B. I. Escher, K. Fenner, T. B. Hofstetter, C. A.
Johnson, U. von Gunten and B. Wehrli, Science, 2006, 313, 1072-
attractive heterogeneous photocatalyst for environmentally
benign and sustainable solar synthesis.
2
Acknowledgements
We want to thank Prof. Christine Caputo at University of New
Hampshire for confirming the UV-vis diffuse reflectance
spectrum. This work is supported by the National Science
Foundation under grant CHE-1855531.
1
077.
2
8 X. M. Liu, Q. J. Song, Y. Tang, W. L. Li, J. M. Xu, J. J. Wu, F. Wang
and P. C. Brookes, Sci. Total Environ., 2013, 463, 530-540.
9 D. G. J. Larsson, Philos. Trans. R. Soc. B, 2014, 369, 20130571.
0 D. G. Nocera, Inorg. Chem., 2009, 48, 10001-10017.
2
3
Conflicts of interest
There are no conflicts to declare.
31 D. G. Nocera, Acc. Chem. Res., 2017, 50, 616-619.
3
3
2 M. Oelgemoller, Chem. Rev., 2016, 116, 9664-9682.
3 W. Y. Teoh, J. A. Scott and R. Amal, J. Phys. Chem. Lett., 2012, 3,
6
29-639.
4 X. J. Lang, X. D. Chen and J. C. Zhao, Chem. Soc. Rev., 2014, 43,
73-486.
5 X. C. Wang, S. Blechert and M. Antonietti, ACS Catal., 2012, 2,
596-1606.
Notes and references
3
3
3
4
1
J. M. R. Narayanam and C. R. J. Stephenson, Chem. Soc. Rev.,
011, 40, 102-113.
J. Xuan and W. J. Xiao, Angew. Chem. Int. Ed., 2012, 51, 6828-
838.
2
1
2
6 X. Li, J. G. Yu, J. X. Low, Y. P. Fang, J. Xiao and X. B. Chen, J. Mater.
Chem. A, 2015, 3, 2485-2534.
7 Y. Q. Qu and X. F. Duan, Chem. Soc. Rev., 2013, 42, 2568-2580.
8 J. A. Terrett, J. D. Cuthbertson, V. W. Shurtleff and D. W. C.
MacMillan, Nature, 2015, 524, 330-334.
9 E. B. Corcoran, M. T. Pirnot, S. S. Lin, S. D. Dreher, D. A. DiRocco,
I. W. Davies, S. L. Buchwald and D. W. C. MacMillan, Science,
2
0 E. R. Welin, C. Le, D. M. Arias-Rotondo, J. K. McCusker and D. W.
C. MacMillan, Science, 2017, 355, 380-384.
1 M. S. Oderinde, M. Frenette, D. W. Robbins, B. Aquila and J. W.
Johannes, J. Am. Chem. Soc., 2016, 138, 1760-1763.
2 Q. M. Kainz, C. D. Matier, A. Bartoszewicz, S. L. Zultanski, J. C.
Peters and G. C. Fu, Science, 2016, 351, 681-684.
3 C. Cavedon, A. Madani, P. H. Seeberger and B. Pieber, Org. Lett.,
6
3
4
D. M. Schultz and T. P. Yoon, Science, 2014, 343, 1239176.
M. H. Shaw, J. Twilton and D. W. C. MacMillan, J. Org. Chem.,
3
3
2
016, 81, 6898-6926.
N. A. Romero and D. A. Nicewicz, Chem. Rev., 2016, 116, 10075-
0166.
E. C. Gentry and R. R. Knowles, Acc. Chem. Res., 2016, 49, 1546-
556.
C. K. Prier, D. A. Rankic and D. W. C. MacMillan, Chem. Rev., 2013,
13, 5322-5363.
M. D. Levin, S. Kim and F. D. Toste, ACS Cent. Sci., 2016, 2, 293-
01.
5
6
7
8
9
1
1
3
1
016, 353, 279-283.
1
4
4
4
4
4
4
4
1
3
L. Marzo, S. K. Pagire, O. Reiser and B. Konig, Angew. Chem. Int.
Ed., 2018, 57, 10034-10072.
0 A. Hossain, A. Bhattacharyya and O. Reiser, Science, 2019, 364,
eaav9713.
1 M. N. Hopkinson, B. Sahoo, J. L. Li and F. Glorius, Chem. Eur. J.,
2
019, 21, 5331-5334.
4 I. Ghosh, J. Khamrai, A. Savateev, N. Shlapakov, M. Antonietti and
B. Konig, Science, 2019, 365, 360-366.
5 Y. Y. Liu, D. Liang, L. Q. Lu and W. J. Xiao, Chem. Commun., 2019,
2
014, 20, 3874-3886.
1
1
2 J. K. McCusker, Science, 2019, 363, 484-488.
3 K. Teegardin, J. I. Day, J. Chan and J. Weaver, Org. Process Res.
Dev., 2016, 20, 1156-1163.
5
5, 4853-4856.
6 B. Pieber, J. A. Malik, C. Cavedon, S. Gisbertz, A. Savateev, D. Cruz,
T. Heil, G. G. Zhang and P. H. Seeberger, Angew. Chem. Int. Ed.,
2
1
4 C. B. Kelly, N. R. Patel, D. N. Primer, M. Jouffroy, J. C. Tellis and G.
A. Molander, Nat. Protoc., 2017, 12, 472-492.
019, 58, 9575-9580.
This journal is © The Royal Society of Chemistry 2020
Chem. Sci., 2020, 11, 1-5 | 5
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PleaseC dh oe mn oi ct a al dS cj ui es nt cme argins
Page 6 of 7
ARTICLE
Chem. Sci.
4
4
4
5
5
5
5
7 R. Sun, Y. Z. Qin, S. Ruccolo, C. Schnedermann, C. Costentin and
D. G. Nocera, J. Am. Chem. Soc., 2019, 141, 89-93.
8 R. Sun, Y. Qin and D. G. Nocera, Angew. Chem. Int. Ed., 2020, 59,
View Article Online
DOI: 10.1039/D0SC02131H
2
-9.
9 P. A. Payard, L. A. Perego, I. Ciofini and L. Grimaud, ACS Catal.,
018, 8, 4812-4823.
2
0 Y. J. Cui, Z. X. Ding, P. Liu, M. Antonietti, X. Z. Fu and X. C. Wang,
Phys. Chem. Chem. Phys., 2012, 14, 1455-1462.
1 Q. P. Lu, Y. F. Yu, Q. L. Ma, B. Chen and H. Zhang, Adv. Mater.,
2
016, 28, 1917-1933.
2 J. Zhao, X. Wang, Z. C. Xu and J. S. C. Loo, J. Mater. Chem. A, 2014,
, 15228-15233.
2
3 H. Yu, R. Shi, Y. Zhao, T. Bian, Y. Zhao, C. Zhou, G. I. N.
Waterhouse, L. Z. Wu, C. H. Tung and T. Zhang, Adv. Mater., 2017,
2
9.
4 Y. Wang, X. C. Wang and M. Antonietti, Angew. Chem. Int. Ed.,
012, 51, 68-89.
5 S. W. Cao, J. X. Low, J. G. Yu and M. Jaroniec, Adv. Mater., 2015,
7, 2150-2176.
5
5
5
2
2
6 V. W. Lau, I. Moudrakovski, T. Botari, S. Weinberger, M. B. Mesch,
V. Duppel, J. Senker, V. Blum and B. V. Lotsch, Nat. Commun.,
2
016, 7, 12165.
5
7 H. Kasap, C. A. Caputo, B. C. M. Martindale, R. Godin, V. W. H.
Lau, B. V. Lotsch, J. R. Durrant and E. Reisner, J. Am. Chem. Soc.,
2
016, 138, 9183-9192.
8 J. Tauc, R. Grigorovici and A. Vancu, Phys. Stat. Sol., 1966, 15, 627-
37.
9 A. Vijeta and E. Reisner, Chem. Commun. (Camb.), 2019, 55,
4007-14010.
5
5
6
6
1
0 V. W. Lau, D. Klose, H. Kasap, F. Podjaski, M. C. Pignie, E. Reisner,
G. Jeschke and B. V. Lotsch, Angew. Chem. Int. Ed. Engl., 2017, 56,
5
10-514.
6
| Chem. Sci., 2020, 11, 1-5
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