Nonstoichiometric copper chalcogenides for photo-activated alkyne/azide cycloaddition

Article abstract of DOI:10.1039/c7cp00724h

Nonstoichiometric copper chalcogenides with heavy copper vacancies can be used as an effective photo-activated catalyst for the Huisgen [3+2] cycloaddition reaction as Cu(I) can be released corresponding to holes (Cu-defects) under light irradiation. These strategies expand new possibilities for carrying out prototypical click chemistry in the presence of functional groups.

Full text of DOI:10.1039/c7cp00724h

View Article Online
View Journal
PCCP
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: H. Y. Zou, M. X.
Gao, T. Yang, Q. L. Zeng, X. X. Yang, F. Liu, M. T. Swihart, N. Li and C. Z. Huang, Phys. Chem. Chem. Phys.,
2017, DOI: 10.1039/C7CP00724H.
This is an Accepted Manuscript, which has been through the
Volume 18 Number
1 7 January 2016 Pages 1–636
Royal Society of Chemistry peer review process and has been
accepted for publication.
PCCP
Accepted Manuscripts are published online shortly after
Physical Chemistry Chemical Physics
www.rsc.org/pccp
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
author guidelines.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the ethical guidelines, outlined
in our author and reviewer resource centre, still apply. In no
event shall the Royal Society of Chemistry be held responsible
for any errors or omissions in this Accepted Manuscript or any
consequences arising from the use of any information it contains.
ISSN 1463-9076
PERSPECTIVE
Darya Radziuk and Helmuth Möhwald
Ultrasonically treated liquid interfaces for progress in cleaning and
separation processes
rsc.li/pccp

Please do not adjust margins
Physical Chemistry Chemical Physics
Page 1 of 5
View Article Online
DOI: 10.1039/C7CP00724H
Journal Name
COMMUNICATION
Nonstoichiometric Copper Chalcogenides for Photo-activated
Alkyne/Azide Cycloaddition
Hong Yan Zou,a‡ Ming Xuan Gao,b‡ Tong Yang,a Qiao Ling Zeng,a Xiao Xi Yang,a Feng Liu,c Mark T.
Swihart,*d Na Li,*c and Cheng Zhi Huang*ab
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
www.rsc.org/
Nonstoichiometric copper chalcogenide nanocrystals (CuCNCs,
Cu2−xSySe1−y NCs) can exhibit both size-dependent interband
absorption at UV-visible wavelengths and localized surface plasmon
resonance (LSPR) absorption at near-infrared wavelengths with the
latter arising from degenerate p-doping produced by copper
vacancies.8 The Cu(II) and Cu(I) coexist in these nanocrystals (NCs).
The Cu(I)/Cu(II) ratio, and thus the free hole concentration,
depends on the concentration of copper vacancies.9 Previous
studies of CuCNCs have focused on their potential for use in
photovoltaics10 and photothermal therapy.11 Our group has verified
their good catalytic abilities in the enhancement of
chemiluminescence and surface functionalization of carbon
quantum dots.12 However, the expanding use of CuCNCs still needs
to be explored.
Nonstoichiometric copper chalcogenides with heavy copper
vacancies can be used as effective photo-activated catalyst for the
Huisgen [3+2] cycloaddition reaction as Cu(I) can be released
corresponding to the holes (Cu-defect) under light irradiation.
These strategy explands new possibilities for carrying out
prototypical click chemistry in the presence of functional groups.
The Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition (CuAAC)
reaction between terminal azides and alkynes is perhaps the most
elegant example of “click” chemistry developed by the groups of
Sharpless and Meldal.1 This click reaction has a powerful impact on
organic synthesis and drug discovery, as well as biological and
electrochemical applications.2 However, the common approach of
producing catalytic Cu(I) via the combination of Cu(II) salt with a
reducing agent (often sodium ascorbate or metallic copper)3 suffers
from formation of by-products. Even when Cu(I) complexes can be
used directly as catalysts, expensive Cu(I) releasing ligands are
required to accelerate the cycloaddition.4 Therefore, an alternative
approach that eliminates the need for a reducing agent or radical
initiator would be highly advantageous. UV or visible light can
photo-reduce Cu(II) and release Cu(I) to catalyse the reaction,5 but
less attention has been paid to reducing the amount of copper salt
or employing nanomaterials as catalysts.6 And the latter can
potentially be very efficient and potent.7 Reducing the catalyst dose
and improving catalyst recovery from products are important for
both biological and industrial applications.
Herein, we reported that copper deficient CuCNCs can
efficiently catalyze azide–alkyne cycloadditions under different light
irradiation. It showed that the ability to release Cu(I) species under
illumination was associated with the presence of free holes (Cu
vacancies) in these nanomaterials. The released Cu(I) can effectively
catalyze the Huisgen 1,3-dipolar cycloaddition, enabling efficient
photo-activated terminal azide–alkyne cycloaddition (Scheme 1)
even in the presence of some functional groups.
A
series of nonstoichiometric copper chalcogenide
nanocrystals (CuCNCs, Cu2−xSySe1−y NCs) were prepared by a one-pot
aqueous procedure at room temperature (Section 1.1 and 1.2 in
Supporting Information). The stoichiometry of CuCNCs was tuned
by changing the molar ratios of sulfur (Na2S) and selenium (SeO2)
precursors (samples N1−N5, Table 1). Transmission electron
microscopy (TEM) showed that the Cu2−xSySe1−y NCs were 20 to 40
Cu2-xSySe1-
y
N
0.028 mol%
N
+
R1 N3
R2
R1
N
rt, air, hv
R2
1
2
3
Scheme
1 A representative Huisgen 1,3-dipolar cycloaddition
reaction catalysed by photo-activated Cu(I) from nonstoichiometric
copper chalcogenide nanocrystals.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 1
Please do not adjust margins

Please do not adjust margins
Physical Chemistry Chemical Physics
Page 2 of 5
View Article Online
DOI: 10.1039/C7CP00724H
COMMUNICATION
Journal Name
to 1.86 with increment of selenium content. Powder X-ray
diffraction (XRD) analysis (Fig.1h) confirmed that the structure of
the as-prepared NCs evolved from covellite for N1 (Cu2−xS) to
berzelianite for N5 (Cu2−xSe)14 and the covellite (110) peak shifted to
lower angle with increasing Se content.15 Cu2−xSySe1−y NCs exhibited
near-infrared LSPR absorption band, along with interband
absorption in the UV-vis region. The bandgap (Eg) increased from
1.17 to 2.02 Ev with increasing Se content (Table 1, Fig. S3†). The
concentration of free holes, calculated using the Mie-Drude model
(Table 1, eq. (S2-S6) and Fig. S4†), decreased with increasing Se
content as anticipated based upon the decreasing in copper
deficiency (increasing in cation to anion ratio) with increasing Se
content.9
Table 2. Optimization of the Reaction Conditionsa
Cu2-xSySe1-y
0.028 mol%
N3
N
N
N
+
rt, air, hv
1a
3a
2a
Figure 1 Characterization of the Cu2−xSySe1−y NCs. (a−b) TEM and
HRTEM images of the Cu1.12S0.55Se0.45 NCs prepared with Se/S ratio
of 1:1 (sample N3 in Table 1). (c−f) Combined (c) and separated
elemental maps of Cu (d), S (e) and Se (f) of typical Cu1.12S0.55Se0.45
NCs (g) SEM-EDXS spectra of Cu1.12S0.55Se0.45 NCs. (h) XRD patterns
for Cu2−xSySe1−y NCs prepared using different Se/S ratios: 0:1, 1:2,
1:1, 2:1, 1:0 (N1−N5, Table 1). For TEM and SEM-EDXS of other
Cu2−xSySe1−y NCs, see Fig. S1, S2†).
Entry Cat.
Solvents
Time
Lightb
Yieldc(%)
1
2
3
4
5
6
7
N1
N2
N3d
N4
N5
N3
N3
water
water
water
water
water
water
water
6h
UV
UV
UV
UV
UV
LED
>95
>95
>95
90
6h
6h
6h
6h
86
Table 1 Physical characteriation of Cu2−xSySe1−y NCs as tuned by
12h
12h
88
changing the Se/S ratio.
Natural 61
light
a
No.
Se/S
Stoichiometry
Eg (eV)
Nhb(×1022cm−3
)
8
9
N3
N3
water
12h
Dark
UV
57
93
PBS (pH=7.4)
6h
N1
N2
N3
N4
N5
0:1
1:2
1:1
2:1
1:0
Cu0.97
S
1.17
1.24
1.72
1.84
2.02
19.4
7.34
4.52
4.17
1.72
Cu1.08S0.54Se0.46
Cu1.12S0.55Se0.45
Cu1.73S0.37Se0.63
Cu1.86Se
10
11
N3
N3
ethyl alcohol
ethyl alcohol:
12h
12h
UV
UV
90
93
water=1:1
methanol
12
13
14
N3
N3
N3
12h
12h
12h
UV
UV
UV
88
85
89
aThe bandgaps of copper chalcogenide NCs were estimated from
their extinction spectra (Supporting Information, section 2.1†). bThe
copper defect density (Nh) can be quantitatively interpreted
according to the quasi-static approximation of the Mie-Drude
model (Supporting Information, section 2.2†).
butyl alcohol
butyl alcohol:
Water=1:1
15
16
17
N3
N3
N3
DMSO
12h
12h
12h
UV
UV
UV
84
56
/
n-Heptane
ethyl acetate
nm in diameter (Fig. 1a, Fig.S1†). High-resolution TEM (HRTEM)
images showed that they were single-crystalline with well-resolved
lattice spacing of 0.20 ±0.02 nm corresponding to (110) planes of
hexagonal Cu2−xSySe1−y (Fig. 1b).13 The nanoscale elemental mapping
showed that Cu, S and Se were distributed uniformly throughout
the nanocrystals (Fig. 1c−f). The elemental analysis by energy
dispersive X-ray spectroscopy in the scanning electron microscopy
(SEM-EDXS) (Fig. 1g, Table 1 and Fig. S2†) indicated that the NCs
were copper-deficient with cation-to-anion ratios ranging from 0.97
aAll the reactions were carried out at room temperature using 0.25
mmol of azide, 0.45 mmol (1.8 equiv) of alkyne in the presence of
0.028 mol% Cu2−xSySe1−y NCs (about 0.07 µmol of Cu2−xSySe1−y
formula units). bUV (254 nm, ~100 mW/cm2); LED (~100 mW/cm2).
cIsolated yields by column chromatography (silica gel, mixtures of
aether petrolei/ethyl acetate=5:1). dN3, namely, Cu1.12S0.55Se0.45 was
selected for use in subsequent experiments based on its high
catalytic efficiency and relatively low Nh.
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
Physical Chemistry Chemical Physics
Page 3 of 5
View Article Online
DOI: 10.1039/C7CP00724H
Journal Name
The catalytic activity of the Cu2−xSySe1−y NCs was tested by
COMMUNICATION
using benzyl azide (1a) and phenyl acetylene (2a) as model
substrates under different conditions (Table 2). The desired product
3a (Fig. S5−S7†) was obtained successfully in a better yield (>95%)
for Cu2−xSySe1−y NCs with the higher carrier densities (N1-N3, Nh
>4.52x1022 cm-3) under UV illumination (entries 1-5). The light
irradiation was crucial for the reaction, which affected the yields of
3a dramatically. It was worth noting that the reaction can be
performed even in the dark (57%). But with UV light irradiation, the
quantitative yields of product 3a (entries 3, 6−8) were greatly
improved (>95%). Meanwhile, screening of solvents indicated that
the super result was obtained in water. All these results
demonstrated that Cu2−xSySe1−y NCs were a type of highly efficient
photo-activated catalyst, and suggested that the catalytic activity
was related to the copper deficiency in the Cu2−xSySe1−y NCs.
As Cu in the Cu2−xSySe1−y NCs had Cu(I)/Cu(II) character, light
irradiation was likely to excite Cu dopants releasing Cu(I) ions into
the solution. Taking Cu1.12S0.55Se0.45 (N3) as an example, after
irradiation, the Cu2p peaks were broadened and underwent
splitting with pronounced satellite formation due to the presence of
paramagnetic Cu(II) (Fig. S8a,b†).16The changed intensity of peaks
with a slight shift for oxide species (SOxy−) and S2− suggested that
oxide formed upon exposure of Cu1.12S0.55Se0.45 to UV irradiation
(Fig. S8c,d†).17 A shift of the of Se3d peaks from 54.8 eV to 59.2 eV
showed that Se was present in multiple oxidation states ranging
from selenide to the oxide species (Fig. S8e,f†).16These phenomena
suggested that Cu(I) on the surface of CuCNCs was oxidized to Cu(II)
upon exposure to oxygen and UV light, thereby forming a chemical
potential gradient driving diffusion of Cu(I) from the particle core to
the surface (Fig.S8−S12†). During the catalytic process, S2− and
selenide on the NC surface were slowly photo-oxidized to SOxy– and
SeO32−, allowing the release of Cu(I) to catalyse the azide/alkyne
click cycloaddition reaction between benzyl azide and phenyl
acetylene. The coupled plasma-atomic emission spectroscopic (ICP-
AES) analysis measurements showed that the amount of Cu species Figure
2
Dynamic monitoring of the Huisgen 1,3-dipolar
(Cu(I), Cu(II), or both) released under illumination was at least 3 cycloaddition reaction between azides and terminal alkynes under
times that released in the dark (Table S1†), demonstrating the light- 254 nm UV light irradiation. (a) Real time 1H NMR spectra of photo-
initiated release of Cu species.5b Sensitive spirolactam ring CuAAC reaction between 0.25 mmol of benzyl azide and 0.45 mmol
remained unopened when the CuCNCs were added to the (1.8 equiv) of phenyl acetylene in water catalysed by 0.07 µmol of
rhodamine B hydrazide solution, indicating that Cu(I) was the main Cu1.12S0.55Se0.45 (N3) under 100 mW/cm2 irradiation by 254 nm light.
species released form the NCs under illumination, because Cu(II) (b) Reaction kinetics analysed using Eq. (S7, S8†), (Supporting
was reported to open the spirolactam ring (Scheme S1 and Fig. S13- Information, section 3.8.1†).
15†).18The release of Cu(I) species was also verified by its
enhancement of the room temperature electron spin resonance triazole product formation, indicating that a photo-activation stage
(ESR) signal of hydroxide radicals (OH•, Fig. S16†) generated from was required for the catalysis.21 Under UV illumination, the rapid
19
dimethyl pyridine N-oxide in the presence of H2O2 and by the activation of the CuAAC reaction without an induction period was
ability to catalyse the Huisgen1,3-dipolar cycloaddition reaction consistent with the rapid release of Cu(I) observed by ICP-AES
between azides and terminal alkynes.1
above. After four cycles of catalytic cycloaddition in water using
The kinetics of the photo-activated Cu(I)-catalyzed azide– Cu1.12S0.55Se0.45 (N3), the recovered product yield remained as high
alkyne cycloaddition (Fig. 2, Fig. S17−S19†) were studied by as 86ꢀ%, indicating that the catalyst can be reused multiple times
1
monitoring the azide-to-triazole ratio using H NMR spectra.3,20Two without regeneration (Fig. S20†).
different kinetic regimes were observed, using Cu1.12S0.55Se0.45under
With the optimized reaction conditions in hand, we next
254 nm UV (Fig. 3) and white light LED irradiation (Fig. S17†). These focused on broadening the scope of functional group for azides and
results contrasted with observations of the rate in the dark (Fig. alkynes as shown in Fig. 3 and Table 3. The catalysts showed great
S18†) and the ambient light (Fig. S19†), for which three different versatility toward alkynes installed with different functional groups
stages were distinguished and an induction period preceded
(3b-3f) gave good yields of the corresponding products in our new
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
Physical Chemistry Chemical Physics
Page 4 of 5
View Article Online
DOI: 10.1039/C7CP00724H
COMMUNICATION
Journal Name
F
N
OH
because of the relative low cytotoxicity) and high catalytic
effectiveness achieved by release of very small quantities of Cu(I).
N
N
N
N
N
N
O
N
N
O
Acknowledgements
3c
3d
3b
This study was financially supported by the National Natural
Science Foundation of China (NSFC, Grant No. 21375109, 21535006),
Fundamental Research Funds for the Central Universities
(XDJK2016C177) and Doctoral Scientific Research Foundation
(SWU116006).
O
N
O
N
N
N
H
N
N
O
N
N
S
O
N
O
N
O
References
3f
3e
1
(a) H. C. Kolb, M. G. Finn and K. B. Sharpless, Angew. Chem.
Int. Ed. 2001, 40, 2004–2021; b) V. Rostovtsev, L. G. Green,
V. V. Fokin and K. B. Sharpless, Angew. Chem. Int. Ed. 2002,
41, 2596–2599; (c) M. T. Meldal and C. W.Tornøe, In
proceedings of the second international and the
seventeenth American peptide symposium, 2001, 263; (d)
C. W. Tornøe, C. Christensen and M. Meldal, J. Org. Chem.
2002, 67, 3057–3064.
Figure 3 Products included in Table 3.
Table 3 Scope of the Photocatalytic CuAACa
Entry
Cat.
Time
Solvent
Yield(%)
3b
3c
3d
3e
3f
N3
N3
N3
N3
N3
6h
water
water
water
water
94
80
58
93
72
2 (a) C. L. Wang, D.L. Ikhlef, , S. Kahlal, J. Saillard and D. Astruc,
Coord. Chem. Rev. 2016, 316, 1–20; (b) K. Kacprzak, I.
Skiera, M. Piasecka and Z. Paryzek, Chem. Rev. 2016, 116
6h
,
12h
6h
5689–5743; (c) V. K. Tiwari, B.B. Mishra, K.B. Mishra, N.
Mishra, A.S. Singh, X. Chen, Tornøe and C. Christensen,
Chem. Rev. 2016, 116, 3086–3240.
(a) L. Shi, C. Jing, W. Ma, D.W. Li, J. E. Halls, F. Marken and
Y.T. Long, Angew. Chem. Int. Ed. 2013, 52, 6011–6014; (b)
Y.H. Li, W. Wu, J.F. Yang, L. Yuan, C. H. Liu, J. Zheng and R.H.
10h
methanol
3
aPerformed under the optimal conditions. Isolated yield of product
3.
Yang, Chem. Sci. 2016,
Adogla, H. Guan, Y. Lin and Q. Wang,
2015, 26, 1868 1872.
X. W. Yan, Y. C. Luo, Z. B. Zhang, Z. X. Li, Q. Luo, L. M. Yang, B.
Zhang, H. F. Chen, P. M. Bai, Q. Q. Wang, Angew. Chem. Int.
Ed., 2012, 51, 3358–3363.
7
, 1920–1925;(c) X. Zhao, L. Cai, E. A.
B
ioconjugate Chem.
−
catalytic system (Fig.S21−30†). It is worth noting that the CuCNCs
presented high specificity and therefore allowed the use of azide
rhodamine-type molecules with this click chemistry.22 Both Cu(II)
ions and reducing agents such as ascorbic acid can open the
spirolactam ring in rhodamine B derivatives,18 which dramatically
limits the use of these derivatives with implementation of this
conventional click chemistry reactions. However, using CuCNCs as
4
5
(a) B. J. Adzima, Y. H. Tao, C. J. Kloxin, C. A. DeForest, K. S.
Anseth and C. N. Bowman, Nat. Chem. 2011, 3, 256–259;
(b) J. C. Bear, N. Hollingsworth, P. D. McNaughter, A. G.
Mayes, M. B. Ward, T. Nann, G. Hogarth and I. P. Parkin,
Angew. Chem. Int. Ed. 2014, 53, 1598–1601; (c) B. W. Wang,
J. Durantini, J. Nie, A. E. Lanterna, J. C. Scaiano, J. Am. Chem. Soc.
2016, 138, 13127−13130.
(a) S. Díez-González and S. P. Nolan, Angew. Chem. Int. Ed.
2008, 47, 8881–8884; (b) M. R. Decan, S. Impellizzeri, M. L.
Marin and J. C. Scaiano, Nat. Commun. 2014, 5, 4612–4620.
the catalyst, click reactions involving azide rhodanmine
B
derivatives could be very successful (Fig. S24−S30†). For example,
with a low loading of CuCNCs, the reaction of N-(Rhodamine-B)
lactam-ethyl-2-azideacetamide (11) with phenylacetylene produced
the expected product(N-(Rhodamine-B)lactam-ethyl-2-(4-phenyl-
1H-1,2,3-triazol-1-yl)acetamide (3f)) with a yield up to 72% (Fig.
S24−30†). Furthermore, these CuCNCs have very low cytotoxicity
(Fig. S31†) at these loadings, which can reduce the need for
expensive copper-free click chemistry reagents,23 greatly reducing
costs and expanding applications of click reaction for biosensing
and bioimaging.
6
7
8
V. O. Rodionov, S. I. Presolsky, S. Gardinier, Y. H. Lim and M.
G. Finn, J. Am. Chem. Soc. 2007, 129, 12696–12704.
(a) Y. X. Zhao, H. C. Pan, Y. B. Lou, X. F. Qiu, J. J. Zhu and C.
Burda, J. Am. Chem. Soc. 2009, 131, 4253–4261; (b) J. M.
Luther, P. K. Jain, T. Ewers and A. P. Alivisatos, Nat. Mater.
2011, 10, 361–366; (c) F. Scotognella, D. V. Giuseppe, R. S.
K. Ajay, D. Dirk, Z. Margherita, C. Matteo, M. Karol, C.
Alberto, K. Kseniya, L. Guglielmo, M. Liberato and T.
Francesco, Nano Lett. 2011, 11, 4711–4717.
In conclusion, we have presented a new type of catalyst for the
Huisgen 1,3-dipolar cycloaddition, which enables efficient photo-
activated click chemistry without the use of Cu(II) salts or reducing
agents. The nonstoichiometric CuCNCs developed in this work was
demonstrated to act as the catalyst by releasing Cu(I) into solution
under illumination. These CuCNCs open up exciting new possibilities
for carrying out this prototypical click chemistry with broad
functional groups especially for the spirolactam ring in rhodamine B
derivatives, that are sensitive to Cu(II) and/or the reducing agents.
These catalysts have great potential for further applications in
biochemistry, block copolymer synthesis and surface modification
and may be particularly valuable in biologically related applications
9
(a) X. Liu and M. T. Swihart, Chem. Soc. Rev. 2014, 43,
3908–3920; (b) D. Dorfs, T. Härtling, K. Miszta, N. C. Bigall,
M. R. Kim, A. Genovese, A. Falqui, M. Povia and L. Manna, J.
Am. Chem. Soc. 2011, 133, 11175–11180; (c) I. Kriegel, C. Y.
Zhang, J. Rodríguez-Fernández, R. D. Schaller, D. V. Talapin,
E. Como and J. Feldmann, J. Am. Chem. Soc. 2012, 134
,
1583–1590; (d) Y. Xie, A. Riedinger, M. Prato, A. Casu, A.
Genovese, P. Pablo Guardia, S. Sottini, C. Sangregorio, K.
Miszta, S. Ghosh, T. Pellegrino and L. Liberato Manna, J.
Am. Chem. Soc. 2013, 135, 17630–17637.
10 Y. X. Zhao and C. Burda, Energy Environ. Sci. 2012,
5576.
11 (a)X. Liu, W.C. Law, M. Jeon, X. Wang, M. Liu, C. Kim, P.
5, 5564–
N.Prasad and M. T. Swihart, Adv. Healthcare Mater. 2013,
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
Physical Chemistry Chemical Physics
Page 5 of 5
View Article Online
DOI: 10.1039/C7CP00724H
Journal Name
, 952–957;(b) S.H.Zhang, C.X.Sun, J. F. Zeng, Q.Sun,
COMMUNICATION
2
G.L.Wang, Y. Wang, Y. Wu, S.X.Dou, M.Y.Gao and Z. Li, Adv.
Mater. 2016, 28, 8927–8936.
12 (a) S. Q. Lie, D. M. Wang, M. X. Gao and C. Z. Huang,
Nanoscale, 2014, 6,10289–10296; (b) M. X. Gao, L. Yang, Y.
Zheng, X. X. Yang, H. Y. Zou, J.Han, Z. X. Liu, Y. F. Li and C. Z.
Huang, Chem. Eur. J. 2017, 23, 1–9.
13 J. J. Wang, D. J. Xue, Y. G. Guo, J. S. Hu and L. J. Wan, J. Am.
Chem. Soc. 2011, 133, 18558–18561.
14 M. X. Liu, X. Z. Xue, C. Ghosh, X. Liu, Y. Liu, E. P. Furlani, M.
T. Swihart, P. N. Prasad, Chem. Mater. 2015, 27, 2584–2590.
15 (a) X. Liu, X. L. Wang and M. T. Swihart, Chem. Mater. 2013,
25, 4402–4408; (b) K. Miszta, R. Brescia, M. Prato, G.
Bertoni, S. Marras, Y. Xie, S. Ghosh, M. R. Kim and L.
Manna. J. Am. Chem. Soc. 2014, 136, 9061–9069;
16 S. C. Riha, D. C. Johnson and A. L. Prieto, J. Am. Chem. Soc.
2010, 133, 1383–1390.
17 A. Parker, C. Klauber, A. Kougianos, H. R. Watling, W. van
Vronswijk, Hydrometallurgy, 2003, 71, 265–276.
18 V. Dujols, F. Ford and A. W. Czarnik, J. Am. Chem. Soc. 1997,
119, 7386–7387.
19 P. Xiao, F. Dumur, J. Zhang, J. P. Fouassier, D. Gigmes and J.
Lalevée, Macromolecules 2014, 47, 3837–3844.
20 V. O. Rodionov, V. V.Fokin and M. G. Finn, Angew. Chem.
2005, 117, 2250–2255.
21 (a) V. O. Rodionov, S. I. Presolski, D. Díaz Díaz, V. V. Fokin
and M. G. Finn, J. Am. Chem. Soc. 2007, 129, 12705–12712;
(b) G. C. Kuang, P. M. Guha, W. S. Brotherton, J. T.
Simmons, L. A. Stankee, B. T. Nguyen, R. J. Clark and L. Zhu,
J. Am. Chem. Soc. 2011, 133, 13984–14001.
22 T. J. L. Mustard, D. J. Mack, J. T. Njardarson and P. H. Y.
Cheong, J. Am. Chem. Soc. 2013, 135, 1471–1475.
23 J. C. Jewett and C. R. Bertozzi, Chem. Soc. Rev. 2013, 39
1272–1279.
,
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
Please do not adjust margins