A new 3-D coordination polymer as a precursor for CuI-based thermoelectric composites

Article abstract of DOI:10.1039/c8dt03219j

Two complexes, [Cu₆I₆(L1)₃]_n (I) and [Cu₄I₄(L2)₂]_n (II) (L1 = 1,4-bis(phenylthio)but-2-yne; L2 = 1,4-bis(phenylthio)butane), as precursors for thermoelectric composite

Full text of DOI:10.1039/c8dt03219j

Dalton
Transactions
View Article Online
View Journal | View Issue
PAPER
A new 3-D coordination polymer as a precursor for
CuI-based thermoelectric composites†
Cite this: Dalton Trans., 2018, 47,
16292
Shi-Qiang Bai, *a Ivy Hoi Ka Wong,a Nan Zhang,a Karen Lin Ke,a Ming Lin,
a
David James Young a,b and T. S. Andy Hor*c
Two complexes, [Cu6I6(L1)3]n (I) and [Cu4I4(L2)2]n (II) (L1 = 1,4-bis(phenylthio)but-2-yne; L2 = 1,4-bis
(phenylthio)butane), as precursors for thermoelectric composites were prepared using a literature pro-
cedure. During the preparation of I, an unexpected 3-D polymorph [Cu4I4(L1)2]n (1) with a triclinic space
group and an infinite [CuI]n staircase structure was obtained. This new polymorph (1) exhibited the same
structure at both room temperature and 173 K. Complexes 1 and II were therefore pyrolysed to compo-
sites 2 and 3, respectively, at 400 °C under a nitrogen gas flow. Composite 3 was pale in color with a low
carbon content (0.05 wt%) and easily disassembled during handling. By comparison, the high carbon
containing (10.2 wt%) composite 2 can be compressed into a robust, light pellet (density 3.58 g cm−3),
which showed a moderate to high Seebeck coefficient (543–1308 μV K−1) over the temperature range
70–240 °C.
Received 7th August 2018,
Accepted 1st October 2018
DOI: 10.1039/c8dt03219j
rsc.li/dalton
materials either have complex structures or require laborious
fabrication conditions.8–10 For example, high performance Bi-
Introduction
Thermoelectric materials have attracted global attention doped PbSeTe/PbTe nanostructured materials are grown by
because of their unique ability of directly converting waste molecular beam epitaxy9 whereas BiSbTe alloys are fabricated
heat to electricity.1–3 Their clean energy conversion contributes by melt spinning and a spark plasma sintering process.11 The
to both local cooling and improves the energy conversion brittle nature and inherent toxicity of some materials may also
efficiency of electricity generation from fossil fuels.4–6 limit their potential applications or large-scale fabrication.
Significant effort has been devoted to the development of Organic polymer based thermoelectric materials have the
efficient thermoelectric materials such as Bi2Te3, PbTe, SnSe advantage of easier fabrication using wet chemistry methods.
and BiCuSeO.7 Thermoelectric efficiency is evaluated based on However, they generally exhibit a low thermoelectric stability
the equation, zT = S2σT/κ. The dimensionless figure of merit zT and efficiency (the highest zT value to date is ∼0.42).12–16
is reliant on the collective influence of electrical conductivity
The practical application of a material for thermoelectric
(σ), Seebeck coefficient (S), and thermal conductivity (κ). current generation or cooling depends on its power factor
However, material performance optimisation is challenging as (PF = S2σ). The electron thermal diffusion rate is directly
the interdependence of these parameters is complex and not related to the electrical conductivity of a given material and is
well understood. Typically, inorganic thermoelectric materials also crucial to the Seebeck coefficient. Hybrid thermoelectric
show high zT values (up to about 3). However, most of these materials could potentially show high values by having the
advantages of both inorganic and organic components.
Inspired by the design principle of “electron crystal and
phonon glass”,10,17 chemical modification and physical pro-
cesses have been developed to prepare optimized and eco-
aInstitute of Materials Research and Engineering, A*STAR (Agency for Science,
Technology and Research), 2 Fusionopolis Way, #08-03, Innovis, Singapore 138634,
friendly hybrid thermoelectric materials. Inorganic–organic
Republic of Singapore. E-mail: bais@imre.a-star.edu.sg
bFaculty of Science, Health, Education and Engineering,
hybridization, doping, nanocompositing and electrochemical
deposition are recently developed fabrication methods for
these composites.18–23
Coordination compounds can exhibit fascinating topologies
and polymorphism, with potential applications as porous,
luminescent, electrical, magnetic or catalytic materials.24–29
They can be discrete small molecules, clusters, 1D chains, 2D
University of the Sunshine Coast, Maroochydore DC, Queensland, 4558, Australia
cDepartment of Chemistry, University of Hong Kong, Pokfulam Road,
Hong Kong SAR, China. E-mail: andyhor@hku.hk
†Electronic supplementary information (ESI) available: Materials and methods;
synthesis of L1 and L2; synthesis of coordination polymer 1; synthesis of compo-
sites 2 and 3; Fig. S1; Fig. S2; references. CCDC 1855099 (1). For ESI and crystal-
lographic data in CIF or other electronic format see DOI: 10.1039/c8dt03219j
16292 | Dalton Trans., 2018, 47, 16292–16298
This journal is © The Royal Society of Chemistry 2018

View Article Online
Dalton Transactions
Paper
layers, 3D frameworks or metal–organic frameworks (MOFs) versus 2D polymeric structures, and hexagon prismatic [Cu6I6]
depending on the type of ligand and metal centre. Synthetic versus cubane [Cu4I4] CuI-secondary building units (SBUs)
conditions such as temperature, solvent, metal–ligand ratio (Scheme 1). They can be prepared easily in high yields (76 and
etc. will also influence the product outcome. Recently, coordi- 72%, respectively).42
nation compounds have been used as precursors for the prepa-
The synthesis of these coordination polymers followed a lit-
ration of nano- and composite materials for energy erature procedure. Typically, a mixture of ligand L1 and CuI
applications.30–33 In the quest for high performance super- (1 : 2 molar ratio) in acetonitrile was stirred for 30 min. The
capacitance, nitrogen-doped carbon/graphene has been fabri- white precipitate was collected by vacuum filtration and
cated from pyrolysis of a composite of graphene oxide and a washed with acetonitrile, ethanol and diethyl ether and dried
nitrogen–ligand supported coordination polymer.31 Similarly, at 60 °C. Microanalytical data of the powder sample matched
single-atom iron implanted N-doped porous carbon for well with the calculated formula of I. However, the powder
efficient oxygen reduction catalysis has been prepared directly XRD pattern (Fig. 1, 1E) of bulk materials did not match the
from Fe-porphyrin based MOFs.32 Pyrolysis of a Cu-based MOF calculated pattern (Fig. 1, IT) based on the published single-
has been used to fabricate a hollow CuO/C electrode material crystal structure (173 K) of I (Fig. 1). The synthesis was
for lithium-ion batteries.33 Lanthanide dithiocarbamate com-
plexes have also been used as pyrolytic precursors to form rare
earth sulfides, which are potential n-type thermoelectric
materials.34,35
Copper iodide (CuI) is an eco-friendly thermoelectric
material possessing p-type semiconductivity with a broad
band gap (∼3.1 eV), high Earth abundance and relatively low
toxicity.36 A transparent thin film of CuI with room tempera-
ture zT value of 0.21 has been reported37,38 and a transparent
thermoelectric module has recently been fabricated.39 CuI has
also been used as a dopant in polycrystalline In4Se3−δ(CuI)x to
improve the thermoelectric performance.40 We have reported
the synthesis of a robust and thermally stable thermoelectric
CuI/C composite with a relatively high Seebeck coefficient
value (∼900 μV K−1 at 204 °C) prepared by pyrolysis of a well-
defined 2D coordination polymer.41
In the current work, we have extended this study to other
CuI-based coordination polymer precursors. We were inter-
ested in using two coordination polymers ([Cu6I6(L1)3]n (I) and
Fig. 1 Powder X-ray diffraction (XRD) patterns of I, II and 1 (T = theore-
[Cu4I4(L2)2]n (II)) to compare the effects of using a rigid di-
thioether spacer (L1) versus a flexible counterpart (L2), 3D
tical profile referenced to the experimentally determined single-crystal
XRD pattern; E = experimental data).
Scheme 1 Overview of this work including the formation of coordination polymers I, 1 and II from ligands L1 and L2 and CuI; the formation of
composites 2 and 3 by pyrolysis with sample images; thermoelectric performance evaluation of composite 2.
This journal is © The Royal Society of Chemistry 2018
Dalton Trans., 2018, 47, 16292–16298 | 16293

View Article Online
Paper
Dalton Transactions
repeated with a reproducible powder XRD pattern (Fig. 1, 1E).
This pointed to a different solid-state structure of the material
Results and discussion
that was prepared in our laboratory. We proceeded to grow Ligands L1, L2 and compound II were synthesized using litera-
single crystals of the coordination complex from CuI and ture procedures for thioether formation42,46 (ESI†). Complex 1
ligand L1 to study the structure of the product. Colourless was produced on a gram scale in reasonable yield (72%) using
crystals were obtained from slow evaporation of a sample solu- ligand L1 with CuI in a 1 : 2 molar ratio in acetonitrile. The
tion over a week at room temperature (Fig. 2). These single- infrared spectra of 1 revealed strong vibration peaks at 735 and
crystals were air stable and their X-ray diffraction data were 686 cm−1, which correspond to C–S stretching. The room
collected at r.t. and refined. This study revealed a new 3-D temperature spectrum of 1 at an excitation wavelength of
coordination polymer [Cu4I4(L1)2]n (1).43 Its powder XRD pat- 405 nm revealed broad luminescence at ∼587 nm and
terns simulated from the single-crystal XRD data matched well ∼633 nm with the latter as maxima (Fig. S1, ESI†). The high-
with the powder XRD patterns of the bulk sample seen earlier energy peak at ∼587 nm became dominant as the temperature
(Fig. 1, 1T and 1E). The X-ray diffraction pattern of the same reached 120 K and below (Fig. S1, ESI†).
single crystal of 1 was measured at 173 K and gave similar
Room-temperature, single-crystal X-ray diffractometry
unit cell parameters, thus suggesting no structural transform- revealed that 1 crystallized in the triclinic centrosymmetric
ˉ
ation. These results mean that the coordination polymer 1 space group P1 with two Cu(I) centres in the asymmetric unit
does not undergo any solid-state phase transition between (Fig. 2). The cell volume was 928.7 Å3 at 173 K and no phase
room temperature and 173 K. This structural analysis of 1 transition with temperature was observed. Complex 1 is a
revealed that it is a new 3-D coordination polymer with an infi- neutral three-dimensional coordination polymer incorporating
nite 1-D [CuI]n ladder as the SBUs (Scheme 1). The spacer infinite [CuI]n staircases along the a direction (Fig. 2). Each
serves as a bridging ligand using its two sulfur donors. It is a [CuI]n ladder is linked to four neighbouring ladders through
polymorph of the previously reported compound I, which bridging ligand L1 using the two thioether sulfur (S–S) donors
composes hexagonal [Cu6I6] SBUs. This form of polymorphic (Scheme 1, Fig. 2). The coordination polymers 1 and I are poly-
ˉ
ˉ
variation is fairly common in coordination polymers, and morphs with different crystalline space groups (P1 and R3) and
sometimes with unpredictable outcomes.44,45 The room temp- secondary building units ([CuI]n staircase in 1 and [Cu6I6]
erature powder XRD pattern of a bulk sample of II obtained cluster in I). The Cu–S bond lengths in 1 are 2.34 and 2.36 Å,
from ligand L2 and CuI matched well with its simulated which are similar to 2.37 Å recorded in I. There is no chemical
powder XRD pattern from the single crystal structure data col- interaction between the copper centers and the triple bond
lected at 173 K (Fig. 1, IIT,E). We herein report the isolation (CuC) of L1. The neighboring Cu⋯Cu separations within each
and characterization of this new coordination polymer 1 and [CuI]n staircase are 2.70, 3.14 and 2.78 Å. The Cu⋯Cu distance
the pyrolysis of 1 and II to generate CuI/C composites with from the neighboring [CuI]n staircases separated by ligand L1
quite different properties.
is about 10.4 Å.
Thermogravimetric analysis (TGA) of 1 was conducted from
room temperature to 900 °C under air and nitrogen flows with
a heating rate of 30 °C per min (Fig. 3). Coordination polymer
1 was stable up to about 180 °C in both air and nitrogen. The
first weight loss stages between 180–565 °C (in air) and
180–615 °C (in N2) correspond to the loss of ligand L1.
Compound 1 then loses iodide at higher temperature and
probably converts to CuO in air and remains as metallic
Fig. 2 (a) Molecular structure of 1. (b) Single-crystal of 1 with orien-
tation directions. (c) Three-dimensional structure of 1.
Fig. 3 Thermal stability of coordination polymer 1 in both air and nitro-
gen gas flows.
16294 | Dalton Trans., 2018, 47, 16292–16298
This journal is © The Royal Society of Chemistry 2018

View Article Online
Dalton Transactions
Paper
copper in nitrogen. Guided by its TGA data, a white powder cubic phase CuI (PDF No. 00-006-0246) (Fig. 4a). No carbon
sample of 1 was thermally treated at 400 °C for 1 h in a box diffraction peaks were detected in composite 2 which has a
furnace under a nitrogen flow. The pyrolysis gave black compo- high amount (∼10 wt%) of carbon, indicating the amorphous
site 2 containing 10.17 wt% of carbon, and no sulfur (micro- nature of this carbon. The thermal stabilities of composites 2,
analysis). The pyrolysis of coordination polymer II using the 3 and pure CuI were evaluated in a flow of N2. Composites 2
same conditions as for 1 afforded pale composite 3 with only a and 3 were less thermally stable than the control sample CuI,
trace amount of carbon (0.05 wt%). The density of a pellet of and composite 2 was less stable than 3 (Fig. S2, ESI†). The
sample 2 formed under 10 bar pressure was 3.58 g cm−3
which is slightly lower than a CuI/C composite (4.24 g cm−3
,
)
higher weight percentage of carbon in 2 was also reflected in
the reduced density of a pellet formed at 10 bar. This pellet
with about 4.25 wt% of carbon recently fabricated by us from a was robust, compared to the corresponding pellet of 3 which
2-D coordination polymer.41 The pellet of composite 3 formed easily disassembled during handling and no further character-
under the same pressure disassembled easily, which is similar ization was conducted. Composite 2 was conductive and reflec-
to that of pure copper iodide.41 These results indicate that the tance UV-vis spectroscopy revealed a moderate band gap
residue (mainly carbon) may act as a binder and that the energy (2.93 eV) (Fig. 4b), calculated using the cut-off wave-
amount of binder may be crucial to stabilizing the pellet. Both length. This value indicated that composite 2 is a semi-
composites 2 and 3 exhibited dominant CuI X-ray diffraction conductor and within the band gap range reported for CuI
peaks, which are consistent with the standard pattern for based materials.36
Fig. 4 (a) Powder XRD patterns of composites 2 and 3. (b) UV-vis reflectance spectroscopy of composite 2.
Fig. 5 Low-magnification field emission scanning electron microscopy (FESEM) images of composite 2 (a, b). Elemental mapping of iodine and
copper in composite 2 (c–e).
This journal is © The Royal Society of Chemistry 2018
Dalton Trans., 2018, 47, 16292–16298 | 16295

View Article Online
Paper
Dalton Transactions
The low-magnification scanning electron microscopy
images of 2 revealed crystalline nano-/micro-sized particles
(Fig. 5a and b). Elemental mapping indicated dominant iodide
and copper in the composite (Fig. 5c–e). X-ray photoelectron
spectroscopy (XPS) confirmed the presence of C, Cu and I
(Fig. 6). A high-resolution Cu 2p spectrum (Fig. 6a) shows two
relatively strong peaks centred at 932.6 and 952.5 eV corres-
ponding to Cu 2p3/2 and Cu 2p1/2, respectively. Similarly, the I
3d spectrum (Fig. 6b) contained two peaks centred at 619.8
and 631.5 eV, which correspond to I 3d5/2 and I 3d3/2, respect-
ively. These values are consistent with the binding energies of
CuI nanoparticles and composite materials.47–49
A pressed pellet sample of composite 2 was evaluated for its
electrical conductivity and Seebeck coefficient using a ZEM3
system. Six cycle measurement experiments were conducted
for stability and reproducibility (Fig. 7). Each cycle included
eight relative high temperature points (75, 100, 125, 150, 175,
200, 225 and 250 °C) together with four temperature gradients
(5, 10, 15 and 20 °C). The thermoelectric behaviour in the first
cycle was quite different from that observed in the 2nd to 6th
cycles. We observed a similar pattern in our previous study
and regard the first cycle as sample optimization. Overall, the
electrical conductivity values were low and increased with
temperature over a very narrow range (0.000045–0.00035 S
cm−1) from 70 to 240 °C during the 2nd and 6th cycles (Fig. 7a).
Likewise, the Seebeck coefficients values between 70 and
240 °C were constant in a relatively narrow range (543–1308
μV K−1). The highest Seebeck coefficient (1308 μV K−1) was
observed at 94 °C from the 6th cycle (Fig. 7b). The power factor
Fig. 7 Temperature-dependent thermoelectric properties of composite
2 evaluated using six-cycle measurements: (a) electrical conductivity, (b)
Seebeck coefficient, and (c) power factor.
was calculated from the equation PF = S2σ over the tempera-
ture range 70 to 240 °C and found to be in a relatively narrow
range (0.006–0.03 μW m−1 K−2) (Fig. 7c).
There are few CuI-based thermoelectric materials reported
in the literature, despite the potential advantages of this sub-
stance. Molten CuI demonstrates constant electrical conduc-
Fig. 6 High-resolution XPS spectra of Cu 2p (a) and I 3d (b) of compo-
site 2. (c) XPS survey spectrum of composite 2.
16296 | Dalton Trans., 2018, 47, 16292–16298
This journal is © The Royal Society of Chemistry 2018

View Article Online
Dalton Transactions
Paper
tivity (∼1
(620–890 μV K−1) over the range ∼900–1150 K.50 Transparent
CuI thin films exhibit good electrical conductivity (283 S cm−1
S
cm−1
)
and high Seebeck coefficients
Conflicts of interest
)
There are no conflicts of interest to declare.
with a moderate room temperature Seebeck coefficient value
(∼237 μV K−1).37–39 Moreover, CuI has also been doped into Se
vacancies of polycrystalline In4Se3−δ(CuI)x to improve its elec-
trical conductivity.40,51 Although our CuI-based composites
obtained from coordination polymers demonstrated relatively
low electrical conductivity due to the high proportion of amor-
phous carbon,41 they have relatively high Seebeck coefficient
values (>1300 μV K−1) over a moderate temperature range.
Moreover, this coordination polymer precursor approach offers
the possibility of tuning the carbon concentration of the ther-
moelectric composites formed under relatively mild conditions.
The pellet of composite 2 was robust during the multicycle
measurements, whereas composite 3 obtained from the 2D
coordination polymer II readily disassembled. By comparison,
pyrolysis of a 2D coordination polymer [Cu4I4(L3)2]n formed
from a flexible SNS ligand (L3 = bis(2-(cyclohexylthio)ethyl)
amine) and CuI afforded a robust composite pellet with 4 wt%
of carbon.41 Of the various structural parameters, including
the ligand, CuI SBU motif and dimensionality (0–3D), the
ligand could play the most important role in controlling the
nature of the resulting composite. We have extensively studied
and reported the use of chemically related spacers and metals
to generate structurally distinctive soft materials, mainly
coordination oligomers and polymers.44,45,52–54 Carbon
species have previously been used for tuning the thermoelec-
tric performance of core–shell C@PbTe. The amorphous
carbon sphere was reported to enhance the thermoelectric per-
formance.55 A reduced Seebeck coefficient was previously
observed for carbon nanotubes and amorphous carbon doped
Bi2Te3 composites. By comparison, amorphous carbon can
have a positive influence on p-type materials.56
Acknowledgements
Funding support from the Institute of Materials Research
and Engineering (A*STAR) (SERC Grant No. 1527200020) is
gratefully acknowledged. The authors thank Miss Hong Anh
Nguyen of National Junior College, Singapore for her assist-
ance with partial synthesis of coordination polymers.
References
1 S. Li, X. Li, Z. Ren and Q. Zhang, J. Mater. Chem. A, 2018, 6,
2432–2448.
2 J. He and T. M. Tritt, Science, 2017, 357, eaak9997.
3 G. J. Snyder and A. H. Snyder, Energy Environ. Sci., 2017, 10,
2280–2283.
4 M. S. Dresselhaus, G. Chen, M. Y. Tang, R. Yang, H. Lee,
D. Wang, Z. Ren, J.-P. Fleurial and P. Gogna, Adv. Mater.,
2007, 19, 1043–1053.
5 J.-P. Brantut, C. Grenier, J. Meineke, D. Stadler, S. Krinner,
C. Kollath, T. Esslinger and A. Georges, Science, 2013, 342,
713–715.
6 Y. Pei, H. Wang and G. J. Snyder, Adv. Mater., 2012, 24,
6125–6135.
7 G. Tan, L.-D. Zhao and M. G. Kanatzidis, Chem. Rev., 2016,
116, 12123–12149.
8 L.-D. Zhao, G. Tan, S. Hao, J. He, Y. Pei, H. Chi, H. Wang,
S. Gong, H. Xu, V. P. Dravid, C. Uher, G. J. Snyder,
C. Wolverton and M. G. Kanatzidis, Science, 2016, 351, 141–
144.
9 T. C. Harman, M. P. Walsh, B. E. Laforge and G. W. Turner,
J. Electron. Mater., 2005, 34, L19–L22.
10 G. J. Snyder and E. S. Toberer, Nat. Mater., 2008, 7, 105–
114.
Conclusions
We have produced gram-scale quantities of air stable and tri- 11 W. Xie, X. Tang, Y. Yan, Q. Zhang and T. M. Tritt, Appl.
clinic 3D coordination polymer 1 possessing a [CuI]n staircase Phys. Lett., 2009, 94, 102111.
structure. Complex 1 is a polymorph of known 3D coordi- 12 G.-H. Kim, L. Shao, K. Zhang and K. P. Pipe, Nat. Mater.,
nation polymer I that crystallises in the highly-symmetric
2013, 12, 719–723.
ˉ
space group R3 and contains [Cu6I6] SBUs. Complex 1 does not 13 E. M. Thomas, B. C. Popere, H. Fang, M. L. Chabinyc and
undergo a solid-state phase transition at low temperature
R. A. Segalman, Chem. Mater., 2018, 30, 2965–2972.
(173 K). The thermogravimetric analysis of 1 indicated a rela- 14 S. N. Patel, A. M. Glaudell, K. A. Peterson, E. M. Thomas,
tively broad ligand decomposition temperature range
K. A. O’Hara, E. Lim and M. L. Chabinyc, Sci. Adv., 2017, 3,
(180–615 °C) under nitrogen. The direct pyrolysis of 1 at a
e1700434.
moderate temperature (400 °C) gave a robust, semi-conductive, 15 E. Lim, K. A. Peterson, G. M. Su and M. L. Chabinyc, Chem.
thermoelectric composite 2 with a relatively high Seebeck Mater., 2018, 30, 998–1010.
coefficient. This work bridges the fields of coordination 16 N. Saxena, J. Keilhofer, A. K. Maurya, G. Fortunato,
polymer self-assembly, polymorphism and the application of
well-defined coordination polymer precursors to the synthesis
J. Overbeck and P. Müller-Buschbaum, ACS Appl. Energy
Mater., 2018, 1, 336–342.
of thermoelectric composite materials. The different behaviour 17 S. Mukhopadhyay, D. S. Parker, B. C. Sales, A. A. Puretzky,
of composites derived from different coordination compound M. A. McGuire and L. Lindsay, Science, 2018, 360, 1455–1458.
precursors indicates that ligand composition significantly 18 E. Jang, A. Poosapati and D. Madan, ACS Appl. Energy
influences the nature of the resulting CuI-based composite.
Mater., 2018, 1, 1455–1462.
This journal is © The Royal Society of Chemistry 2018
Dalton Trans., 2018, 47, 16292–16298 | 16297

View Article Online
Paper
Dalton Transactions
19 X. Tang, D. Fan, K. Peng, D. Yang, L. Guo, X. Lu, J. Dai, 38 C. Yang, D. Souchay, M. Kneiß, M. Bogner, H. M. Wei,
G. Wang, H. Liu and X. Zhou, Chem. Mater., 2017, 29,
7401–7407.
M. Lorenz, O. Oeckler, G. Benstetter, Y. Q. Fu and
M. Grundmann, Nat. Commun., 2017, 8, 16076.
20 K. Zhao, M. Guan, P. Qiu, A. B. Blichfeld, E. Eikeland, 39 B. M. M. Faustino, D. Gomes, J. Faria, T. Juntunen,
C. Zhu, D. Ren, F. Xu, B. B. Iversen, X. Shi and L. Chen,
G. Gaspar, C. Bianchi, A. Almeida, A. Marques, I. Tittonen
J. Mater. Chem. A, 2018, 6, 6977–6986.
and I. Ferreira, Sci. Rep., 2018, 8, 6867.
21 X. Gao, M. He, B. Liu, J. Hu, Y. Wang, Z. Liang and J. Zhou, 40 Y.-C. Chen, H. Lin and L.-M. Wu, Inorg. Chem. Front., 2016,
ACS Appl. Energy Mater., 2018, 1, 2927–2933. 3, 1566–1571.
22 B. Poudel, Q. Hao, Y. Ma, Y. Lan, A. Minnich, B. Yu, X. Yan, 41 S.-Q. Bai, I. H. K. Wong, M. Lin, D. J. Young and
D. Wang, A. Muto, D. Vashaee, X. Chen, J. Liu, T. S. A. Hor, Dalton Trans., 2018, 47, 5564–5569.
M. S. Dresselhaus, G. Chen and Z. Ren, Science, 2008, 320, 42 M. Knorr, F. Guyon, A. Khatyr, C. Däschlein, C. Strohmann,
634–638.
S. M. Aly, A. S. Abd-El-Aziz, D. Fortin and P. D. Harvey,
23 Y. Sun, L. Qiu, L. Tang, H. Geng, H. Wang, F. Zhang,
Dalton Trans., 2009, 948–955.
D. Huang, W. Xu, P. Yue, Y.-S. Guan, F. Jiao, Y. Sun, 43 X-ray crystallography of 1: Crystal data for C16H14Cu2I2S2
(M = 651.27 g mol−1): triclinic, space group P1, a = 7.3864
(3) Å, b = 12.2916(4) Å, c = 12.5264(4) Å, α = 115.972(1), β =
106.724(1)°, γ = 94.804(1), V = 949.67(6) Å3, Z = 2, T = 296(2)
K, Dcalc = 2.278 g cm−3, 87 927 reflections measured (1.90°
≤ Θ ≤ 40.41°), 11 922 unique (Rint = 0.0312) which were
used in all calculations. The final R1 was 0.0298 (I > 2σ(I))
and wR2 was 0.0793 (all data).
ˉ
D. Tang, C.-A. Di, Y. Yi and D. Zhu, Adv. Mater., 2016, 28,
3351–3358.
24 M. Shivanna, Q.-Y. Yang, A. Bajpai, S. Sen, N. Hosono,
S. Kusaka, T. Pham, K. A. Forrest, B. Space, S. Kitagawa and
M. J. Zaworotko, Sci. Adv., 2018, 4, eaaq1636.
25 X.-Y. Li, H.-F. Su, M. Kurmoo, C.-H. Tung, D. Sun and
L.-S. Zheng, Nanoscale, 2017, 9, 5305–5314.
26 D. Liu, F.-F. Lang, X. Zhou, Z.-G. Ren, D. J. Young and 44 S.-Q. Bai, A. M. Yong, J. J. Hu, D. J. Young, X. Zhang,
J.-P. Lang, Inorg. Chem., 2017, 56, 12542–12550.
27 N.-Y. Li, D. Liu, Z.-G. Ren, C. Lollar, J.-P. Lang and
H.-C. Zhou, Inorg. Chem., 2018, 57, 849–856.
Y. Zong, J. Xu, J.-L. Zuo and T. S. A. Hor, CrystEngComm,
2012, 14, 961–971.
45 S.-Q. Bai, L. Jiang, A. L. Tan, S. C. Yeo, D. J. Young and
T. S. A. Hor, Inorg. Chem. Front., 2015, 2, 1011–1018.
28 R. J. Comito, Z. Wu, G. Zhang, J. A. Lawrence III,
M. D. Korzyński, J. A. Kehl, J. T. Miller and M. Dincă, 46 M. Konrad, F. Meyer, K. Heinze and L. Zsolnai, J. Chem.
Angew. Chem., Int. Ed., 2018, 57, 8135–8139. Soc., Dalton Trans., 1998, 199–205.
29 T. P. Latendresse, V. Vieru, B. O. Wilkins, N. S. Bhuvanesh, 47 L. Barkat, M. Hssein, Z. El Jouad, L. Cattin, G. Louarn,
L. F. Chibotaru and M. Nippe, Angew. Chem., Int. Ed., 2018,
57, 8164–8169.
N. Stephant, A. Khelil, M. Ghamnia, M. Addou, M. Morsli
and J. C. Bernède, Phys. Status Solidi A, 2017, 214, 1600433.
30 B.-B. Gao, M. Zhang, X.-R. Chen, D.-L. Zhu, H. Yu, 48 M. Kumar, V. Bhatt, O. S. Nayal, S. Sharma, V. Kumar,
W.-H. Zhang and J.-P. Lang, Dalton Trans., 2018, 47, 5780–
M. S. Thakur, N. Kumar, R. Bal, B. Singh and U. Sharma,
5788.
Catal. Sci. Technol., 2017, 7, 2857–2864.
31 J. Luo, W. Zhong, Y. Zou, C. Xiong and W. Yang, ACS Appl. 49 R. Mulla and M. K. Rabinal, Energy Technol., 2018, 6, 1178–
Mater. Interfaces, 2017, 9, 317–326. 1185.
32 L. Jiao, G. Wan, R. Zhang, H. Zhou, S.-H. Yu and 50 K. Nishikawa, Y. Takeda and T. Motohiro, Appl. Phys. Lett.,
H.-L. Jiang, Angew. Chem., Int. Ed., 2018, 57, 8525–8529. 2013, 102, 033903.
33 H.-J. Peng, G.-X. Hao, Z.-H. Chu, C.-L. He, X.-M. Lin and 51 X. Yin, J.-Y. Liu, L. Chen and L.-M. Wu, Acc. Chem. Res.,
Y.-P. Cai, J. Alloys Compd., 2017, 727, 1020–1026. 2018, 51, 240–247.
34 X. Luo, L. Ma, M. Xing, Y. Fu, M. Sun and P. Tao, J. Rare 52 S.-Q. Bai, K. L. Ke, D. J. Young and T. S. A. Hor,
Earths, 2012, 30, 802–806. J. Organomet. Chem., 2017, 849–850, 137–141.
35 C. Wood, A. Lockwood, J. Parker, A. Zoltan, D. Zoltan, 53 S.-Q. Bai, L. Jiang, D. J. Young and T. S. A. Hor, Dalton
L. R. Danielson and V. Raag, J. Appl. Phys., 1985, 58, 1542–
1547.
36 M. Grundmann, F.-L. Schein, M. Lorenz, T. Böntgen,
Trans., 2015, 44, 6075–6081.
54 S.-Q. Bai, J. Y. Kwang, L. L. Koh, D. J. Young and
T. S. A. Hor, Dalton Trans., 2010, 39, 2631–2636.
J. Lenzner and H. von Wenckstern, Phys. Status Solidi A, 55 J. Liu, X. Wang, L. Wang and L. Peng, Mater. Lett., 2014,
2013, 210, 1671–1703. 117, 49–52.
37 C. Yang, M. Kneiβ, M. Lorenz and M. Grundmann, Proc. 56 B. Trawiński, B. Bochentyn, N. Gostkowska, M. Łapiński,
Natl. Acad. Sci. U. S. A., 2016, 113, 12929–12933.
T. Miruszewski and B. Kusz, Mater. Res. Bull., 2018, 99, 10–17.
16298 | Dalton Trans., 2018, 47, 16292–16298
This journal is © The Royal Society of Chemistry 2018