A Small Lattice Change Induces Significant Dynamic Changes of CH3NH3+ Caged in Hybrid Perovskite Crystals: Toward Understanding the Interplay between Host Lattices and Guest Molecules

Article abstract of DOI:10.1021/acs.inorgchem.9b00497

Two perovskite-type compounds, (MA)₂[B′Co(CN)₆] (MA = methylammonium, B′ = K(I) and Na(I)), have very similar structures, but exhibit marked differences in the phase and dielectric transitions. Solid state ²H NMR studies reveal the detailed dynamic changes of the caged methylammonium (MA) cations before and after the phase transitions, which are correlated with the different dielectric states of the compounds. Using solid state ⁵⁹Co NMR, the dynamic changes of the host lattices before and after the transitions, which accompany the changes in the dynamics of the caged MA cations, are unveiled, demonstrating the intriguing interplay between the MA cations and the host lattices. On the basis of these observations, the molecular origins of the dielectric transitions are discussed in detail.

Full text of DOI:10.1021/acs.inorgchem.9b00497

Article
Cite This: Inorg. Chem. XXXX, XXX, XXX−XXX
pubs.acs.org/IC
A Small Lattice Change Induces Significant Dynamic Changes of
+
CH NH Caged in Hybrid Perovskite Crystals: Toward
3
3
Understanding the Interplay between Host Lattices and Guest
Molecules
†
,§
†,§
‡
†
†
†
†
Jiachen Wang, Xi Zhang, Robert Graf, Yi Li, Guang Yang, Xiao-Bin Fu, Jia-Qi Ma,
,
†
and Ye-Feng Yao*
†Physics Department & Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Materials Science, East China
Normal University, North Zhongshan Road 3663, Shanghai 200062, P. R. China
‡
Max-Planck-Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
*
S Supporting Information
ABSTRACT: Two perovskite-type compounds, (MA)2-
[
B′Co(CN) ] (MA = methylammonium, B′ = K(I) and
6
Na(I)), have very similar structures, but exhibit marked
differences in the phase and dielectric transitions. Solid state
2
H NMR studies reveal the detailed dynamic changes of the
caged methylammonium (MA) cations before and after the
phase transitions, which are correlated with the different
5
9
dielectric states of the compounds. Using solid state Co
NMR, the dynamic changes of the host lattices before and
after the transitions, which accompany the changes in the
dynamics of the caged MA cations, are unveiled, demonstrat-
ing the intriguing interplay between the MA cations and the
host lattices. On the basis of these observations, the molecular
origins of the dielectric transitions are discussed in detail.
INTRODUCTION
materials with desired properties. Many studies, both
theoretical and experimental, have been devoted to correlating
molecular structure and motions with macroscopic proper-
■
Molecular motions are a key to understanding the microscopic
origins and subsequent evolution of a series of properties and
functions of various materials. Design and manipulation of
local motions are the core issues regarding molecular
8
,18−21
ties.
However, it becomes apparent that, although the
structure of perovskite-type compounds can be precisely
adjusted to attain the desired purposes, the molecular motions
1
,2
machines. In particular, the molecular motions often play
22−30
are not always well controlled.
In many cases, the strong
an essential role in triggering, switching, and driving the system
of a molecular machine. In the hybrid perovskite (MA)[PbI ]
MA = methylammonium), the local motion of the MA cation
3
interplay between the host lattice and the caged molecules
makes the motions of the caged molecules become much more
complicated than initially thought. Without a deep under-
standing of the interplay between the host lattice and the caged
molecules, to effectively predict and design perovskite-type
materials with desired properties is very difficult.
3
(
caged in the host lattice is closely related to its eye-catching
4
−9
photovoltaic property.
In responsive dielectric perovskite-
type compounds, the motions of the organic polar cations can
induce dipolar reorientation, and thus different macroscopic
dielectric states of materials.
Although challenging, understanding and manipulating the
molecular motions and, in turn, establishing a correlation
between molecular motions and macroscopic properties of
material are becoming the main objectives of crystal engineer-
ing. In varied host−guest materials, perovskite-type com-
pounds are good candidates as their structures can be easily
tailored by substituting atoms in the host lattice and/or
10−14
On probing molecular dynamics in varied functional
materials, solid state NMR (SSNMR) has been proven to be
31,32
a particularly powerful technique.
The main merit of solid
state NMR is its capability of monitoring the molecular
motions over a wide frequency range from less than Hz to over
33
2
MHz. Moreover, some NMR methods such as wide line H
NMR and chemical shift anisotropy (CSA) analysis can
provide not only the information on the motion frequency but
14−17
changing the size/shape of the caged cations.
This high
structural flexibility provides material scientists a large
Received: February 28, 2019
imaginary space to design and prepare new perovskite-type
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.inorgchem.9b00497
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
also the geometry of molecular motion that is often strongly
associated with the local environment of the probed molecule
structures were solved by direct methods and successive Fourier
synthesis and then refined by full-matrix least-squares refinements on
2
3
4−36
F using the SHELXTL software package.
or group.
Analyzing the origin of the characteristic
2
Solid State NMR (SSNMR) Experiments. The wide line H and
Co NMR studies were performed on a Bruker Avance III 300
motional geometry thus can offer an opportunity to unveil the
delicate interplay between the molecular motion and the local
environment, which usually cannot be obtained by the other
analytical techniques such as X-ray diffraction or electron
microscopy techniques such as scan electronic microscopy
5
9
2
spectrometer operating at 46.07 MHz for H and 70.84 MHz for
59
Co. A Bruker two-channel static PE probe with a homemade 2.5
2
59
2
mm coil was used to record the H and Co spectra. The H spectra
were acquired using the solid echo sequence (90° − τ − 90° − τ −
2
(
SEM) and transmission electron microscopy (TEM).
Here, an example is presented of how, in well-designed
acquire). The H pulse width was 2 μs at an RF field strength of γB /
1
2π = 125 kHz. The refocusing delays, τ, range from 16 to 30 μs. The
2
hybrid perovskite crystals, a small change in the host lattices
can induce significant dynamic changes of the caged cations
and, in turn, different macroscopic dielectric states. The
samples two hybrid organic−inorganic perovskite (HOIP)
compounds, (MA) [B′Co(CN) ] (B′ = K(I), 1; Na(I), 2),
H patterns were simulated using the Weblab software (http://
3
2
59
weblab.mpip-mainz.mpg.de/weblab/). The Co spectra were
acquired using the EASY pulse sequence. The Co excitation
37
59
pulse width was 0.5 μs at an RF field strength of γB /2π = 100 kHz.
1
2
6
RESULTS AND DISCUSSION
Summary of the Crystal Structures of 1 and 2. Details
of the single-crystal structure study were reported previously.
were designed to have the same caged cations (i.e., the MA
cations) and very similar host lattices. The only structural
difference between the two compounds is the alkali metal ion
■
27
+
+
+
in the host lattices, that is, K in 1 and Na in 2. Replacing K
As a background, we would like to summarize the key points of
the structures of 1 and 2. Both of the compounds have the
same double perovskite structures (Figure 1, Tables S1 and
+
with Na results in a different lattice size, which is anticipated
to cause changes in the motions of the caged MA cations and
27
dielectric transition behaviors. In the previous work, Shi et al.
solved the crystal structures of 1 before and after the transition.
For 2, only the crystal structure in the high-temperature phase
has been solved, while the crystal structures in the
intermediate- and low-temperature phases still remain
2
7
unknown. In this work, first, we tried to solve the crystal
structures of 2 in the intermediate- and low-temperature
2
phases. Then, using solid state H NMR, the dynamics of the
caged MA cations before and after the transitions were
revealed in detail and correlated with the different dielectric
states. Using solid state 59Co NMR, the dynamic changes in
the host lattices before and after the transitions that
accompany the changes in the caged MA cation dynamics
were unveiled, demonstrating the intriguing interplay between
the motions of the MA cations and the host lattices. On the
basis of these observations, the molecular origins of the
different dielectric transitions are discussed in detail.
EXPERIMENTAL SECTION
■
Sample Preparation. An aqueous solution (50 mL) containing
Na [Co(CN) ] (2.84 g, 10 mmol) and (MA)Cl (2.03 g, 30 mmol)
3
6
was evaporated to produce pale-yellow block crystals of 2. Compound
was prepared by the same method.
: Yield 88% (based on K [Co(CN) ]). Theoretical composition
1
1
3
6
calculated (%) for C H CoKN (318.29): C 30.19, H 3.80, N 35.21;
8
12
8
measured composition: C 30.38, H 3.80, N 34.90.
: Yield 82% (based on Na [Co(CN) ]). Theoretical composition
2
Figure 1. Schematic illustration of the cage structures of 1 and 2 in
different phases. The C atom of the totally disordered MA cation
above Ttr1 is refined as N atom (a model to show facial
reorientations). Hydrogen atoms are omitted for clarity. The
temperature scale is arbitrary.
3
6
calculated (%) for C H CoN Na (302.18): C 31.80, H 4.00, N
8
12
8
3
7.08; measured composition: C 32.18, H 4.19, N 36.18.
For deuterated samples, deuterated (MA)Cl was first prepared by
H/D exchange of MA cations in deuterated water (repeated five times
via a dissolution−drying process). Then the deuterated (MA)Cl was
used with D O (99.8 atom % D, Sigma-Aldrich) to prepare 1-d and
2
3
2
-d3.
S2), but show strikingly different phase transitions and
dielectric transition properties. 1 exhibits only one phase
transition at Ttr1 = 423 K, whereas 2 undergoes two phase
transitions at Ttr2 = 200 K and Ttr1 = 260 K (see Figures S1
Dielectric Measurements. Complex dielectric permittivity was
measured on crystalline powdered samples in the Ag|pellet|Ag
sandwich with an Agilent 4294A impedance analyzer at 1 MHz
frequency with an applied electric field of 0.5 V.
and S2). Above T , the X-ray data show that both the
tr1
X-ray Diffraction Experiments. X-ray diffraction experiments
+
̅
compounds adopt the cubic space group Fm3m. The anionic
were carried out at various temperatures using a Rigaku Saturn 724
cage [B′ Co (CN)A ] is regular with an edge length (Co−
diffractometer with a Mo−Kα radiation source (λ = 0.71075 Å) or a
4
4
12
CN−B′) of 5.727 Å for 1 at 463 K and 5.502 Å for 2 at 293
K. The MA cation confined in the cage shows a highly
orientation disorder and is refined with a face ([100]
Bruker D8 Venture diffractometer with a Cu−Kα radiation source (λ
=
1.54178 Å). Data collection, cell refinement, and data reduction
were performed using the CrystalClear software package. The
B
DOI: 10.1021/acs.inorgchem.9b00497
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
orientations) model, similar to the one in the room-
of about 42 kHz. This quadrupolar splitting value indicates that
the MA cations undergo an axial rotation along the C−N axis
(see Figure S3). The horns of the pattern show a slight
bending. This can be attributed to the local wiggling motion
temperature phase of (MA)[PbI ]. Below T , 1 undergoes a
3
tr1
drastic change in structure to the monoclinic space group C2/
c. The anionic cage is highly distorted due to the tilting of the
rigid Co(CN) component, accompanied by the distortion of
along the axis Cn1 with an open angle of θ (see Model I in
6
1
the relatively labile KN octahedron. In particular, the MA
cation becomes totally ordered.
As for 2, it adopts the same cubic system above Ttr1 (293 K)
Figure 2 and Figure S4). With increasing temperature, the
patterns gradually develop into a typical Pake line shape with a
further reduction in quadrupolar splitting, indicating that the
MA cations have gained more motional freedom. Analyzing the
line shape of the patterns above 395 K yields asymmetry
parameters, η, all equal to 0, indicating that the MA cations
have gained some additional motions. In the pattern
simulation, a processional motion for MA (i.e., an axial
6
as 1. The crystal structure of 2 at above T was reported in the
tr1
2
7
literature. However, its structures in the intermediate- and
low-temperature phases were not resolved previously probably
due to crystal quality deterioration. In this study, we solve the
tentative structures for the two phases. Between Ttr1 and Ttr2,
at 220 K, 2 adopts the monoclinic space group with C2/c and
cell parameters of a = 10.8938(3) Å, b = 11.0012(3) Å, c =
rotation with an open angle, θ , between the C−N bond and
2
the rotation axis C ) (see Model I in Figure 2, and Figures S5
n2
and S6) was introduced. The simulated patterns (the gray
lines) fit well with the experimental ones. But note that the
processional motion model is not a unique model that can
1
0.9958(4) Å, and β = 89.9970(3)°, very close to those
obtained above T . Below T , 2 undergoes another drastic
tr1
tr2
change in structure in the monoclinic space group C2/c with
cell parameters of a = 13.1956(19) Å, b = 8.0426(11) Å, c =
average η to 0, and the value of the angle, θ , in the
2
processional motion model varies with the η value. At 395 K, a
small, but clear, sharp signal starts to appear in the middle of
the pattern. This signal can be attributed to the fast isotropic
tumbling motion of the MA cation. The coexistence of the
sharp signal and the wide Pake pattern in the spectrum
indicates that a portion of the MA cations in 1 start to undergo
a fast isotropic tumbling motion before transition. This can be
related to the pretransition phenomenon in the dielectric
7
.4220(11) Å, and β = 124.2300° at 190 K. The distorted
structure is the result of tilting of the rigid Co(CN) unit. In
6
both structures, the caged MA cation becomes ordered with
certain orientations. Note that the present structures are
probably not the final correct ones and they would better be
treated as references to the following dynamic SSNMR study.
Motions of MA Cation in 1-d . To obtain a better
3
understanding of the phase transitions and the dielectric
transitions of 1 and 2, the molecular dynamics of the caged
MA cations were investigated by wide-line H NMR. This
NMR method can determine the geometry and frequency of
rotational motions on a time-scale ranging from 10 to 10
s.
12
transition.
2
High-Temperature Phase (T ≥ T ). A sudden change is
tr1
observed in the pattern after the transition (T = 425 K), where
−
4
−8
the Pake line shape disappears completely and only the sharp
3
2,38
signal remains. This indicates that all of the MA cations in 1-d3
Two deuterated samples, 1-d and 2-d , in which the
3 3
39,40
have a fast isotropic tumbling motion.
This transition
−
NH group of MA is deuterated, were prepared for the study.
3
2
temperature is very close to the temperature observed in DSC
and dielectric measurements, suggesting the same molecular
origin for these transitions.
Figure 2 demonstrates the temperature dependent H NMR
patterns of 1-d . By analyzing the patterns, detailed
information on the reorientation processes of MA in 1-d3
was obtained.
3
Motions of MA Cations in 2-d . Figure 3 demonstrates
3
2
the temperature dependent H NMR patterns of 2-d . Marked
3
Low-Temperature Phase (T < T ). At temperatures below
tr1
2
changes are observed in the patterns, indicating the significant
reorientation of MA cations at different temperatures.
Ttr1 (e.g., T = 295 K), the static H line shows almost a
characteristic Pake pattern shape with a quadrupolar splitting
Low-Temperature Phase (T ≤ T ). At 140 K, the patterns
tr2
of 2-d show a Pake line shape spanning ca. 42 kHz in width,
3
indicating that the MA cations undergo axial rotation along the
C−N axis. A slight bending in the horns of the pattern can be
attributed to the wiggling of the MA cations (Model II).
Analysis of the line shape shows that the asymmetric
parameter, η, is not equal to 0, indicating that the processional
motion from Model I most likely is not present in 2-d3.
Intermediate Phase (Ttr2 < T < T ). When the temperature
tr1
is between Ttr2 and Ttr1 (e.g., T = 210 K), the pattern shows a
clear change in the line shape compared to that before the first
transition. The patterns in this temperature range can be
simulated with a model considering that the MA cations
undergo a 2-site jump about the C axis inclined to the C−N
n
bond at an angle of 48°, with a jump angle of 90° (see Model
III). On the basis of Model III, we have successfully simulated
the patterns (the gray lines) as they match very well with the
experimental ones. From the simulation, we are able to obtain
the jump rates, k. The Arrhenius plot of the jump rates, k = k0
Figure 2. Simulated (gray line) and experimental (black line) solid
2
2
state H NMR patterns of 1-d from 295 to 425 K. The H patterns
3
exp(−E /RT), yields an activation energy E = 33.2 kJ/mol and
were simulated using the NMR Weblab (http://weblab.mpip-mainz.
mpg.de/weblab/). The cartoon picture on the left illustrates the
motion model of the MA cations. The MA hydrogen atoms are
omitted for clarity.
a
a
1
3
−1
a pre-exponential factor k = 1.66 × 10 s .
0
High-Temperature Phase (T ≥ T ). Above T , the
tr1
tr1
patterns exhibit a sudden change in the line shape. The
C
DOI: 10.1021/acs.inorgchem.9b00497
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
36,41
significantly to the dielectric response.
Below T , the
tr1
polar MA cations of 1 are ordered in the cages. The axial
rotation of MA around the C−N bond cannot induce dipolar
reorientation and thus makes no contribution to the dielectric
response. The gradual, but continuous, increase in the
dielectric value below Ttr1 is likely from the electronic and
ionic displacements and the local motions (e.g., the wiggling
motion and the processional motion) of MA, which can result
in the oscillation of the dipolar moment in the plane
perpendicular to the C axis (see Figure 5a). Right below
n
Figure 3. (a) The three motion models for the MA cations. The MA
hydrogen atoms are omitted for clarity. (b) Simulated (gray line) and
2
experimental (black line) solid state H NMR patterns of 2-d from
3
1
40 to 400 K. Below T , the patterns can be simulated using Model
tr2
II. Between Ttr2 and T , the patterns can be simulated using Model
tr1
III. To obtain the best fit, an additional component based on Model
II was added into the signal. Above T , the patterns can be simulated
tr1
2
using Model IV. The H patterns were simulated using the NMR
Weblab. (c) The Arrhenius plot of the 2-site jump rates, k. The jump
2
rates were obtained from the H pattern simulation.
significantly reduced signal width indicates that the MA cations
undergo fast dynamics. However, the characteristic splitting in
the patterns indicates that the motions of the MA cations are
still not isotropic. To fit the patterns, we introduced Model IV,
where the MA cations perform a 4-site jump motion (or an
Figure 5. Depictions of (a) the wiggling motion of an MA cation and
the resultant oscillation of the dipolar moment; (b) the 2-site jump
motion of an MA cation and the resultant oscillation of the dipolar
moment; and (c) the 4-site jump motion of an MA cation and the
resultant oscillation of the dipolar moment. Left: The red arrows
denote the dipolar moment of MA. Right: The red arrows denote the
projection of the dipolar moment of MA under each motion.
axial rotation) about the C axis inclined to the C−N bond at
n
an angle, θ. By varying θ, the patterns acquired above T can
tr1
be simulated.
Correlating the Motions of MA Cations with
Dielectric Transitions. On the basis of the NMR
observations, we were able to correlate the motions of MA
cations with the dielectric transitions of 1 and 2 (see Figure 4).
It is known that dipolar reorientation can contribute
Ttr1, a portion of the MA cations become disordered by
undergoing a fast isotropic tumbling motion. These activated
MA cations may also contribute to the increase in the dielectric
values before the transition. Above T , all of the MA cations
tr1
undergo the fast isotropic tumbling motion. Reflecting this big
change in the state of the MA cations, the dielectric value
jumps to the high-dielectric state.
Unlike 1, 2 has two phase transitions. The first one has a
transition temperature of Ttr2 = 200 K. Below T , the MA
tr2
cations exhibit the local wiggling and might partially contribute
to the slight increase in the dielectric values (see Figure 5a).
Above T , the MA cations start to exhibit the 2-site jump
tr2
motion. This motion can induce dipolar reorientation and thus
may contribute to the increase in the dielectric values (see
Figure 5b). With increasing temperature, more and more MA
cations start to exhibit this type of jump motion, resulting in a
Figure 4. Temperature dependence of the real part of the dielectric
constant of powder samples: (a) 1 and (b) 2 in the heating and
cooling modes. The frequency is 1 MHz.
clear increase in the dielectric values between Ttr2 and T . At
tr1
Ttr1, all of the MA cations start to exhibit 4-site jump motion
D
DOI: 10.1021/acs.inorgchem.9b00497
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
or an axial rotation), resulting in the dipolar reorientation of a
large amplitude (see Figure 5c) and consequently the dielectric
switching at Ttr1.
The origin of different dynamics of MA cations in 1 and 2
during the dielectric transitions can be attributed to the
different geometric restrictions on the MA cations caused by
the different accessible volume in the host lattice. Take the
cubic phase of 1 and 2 above Ttr1 for example. The NMR
Article
(
315 to 450 K. Below Ttr1 (315−415 K), the signals show the
characteristic quadrupole line shape, whereas the signal line
shape suddenly changes into a sharp and almost isotropic one
when the temperature is above Ttr1. A similar change is also
observed in 2-d (see Figure 6b): below Ttr2 (LT phase), the
3
signal line shape shows two edges with one horn in the middle,
which are typical features of an unsymmetrical tensor. When
the temperature is between Ttr2 and Ttr1 (intermediate phase),
the line shape shows the features close to those of an axially
symmetric tensor. When the temperature is above Ttr1 (HT
phase), the signals show a clear narrowing in the width and the
line shape approaches an isotropic one.
results show that, above T , the MA cations in 2 undergo 4-
tr1
site jump motion, whereas those in 1 immediately experience
an isotropic tumbling motion. The different size in the cubic
cage between 1 and 2 provides a hint for the origin of this
5
9
The Co NMR signal is strongly influenced by the
difference. The X-ray results show that, above T , the lattice
tr1
quadrupole coupling and the chemical shift anisotropy, both
parameters are a = b = c = 11.454(6) Å for 1 (T = 463 K), and
a = b = c = 11.003(4) Å for 2 (T = 293 K). The side length of
4
2−44
of which depend on the site symmetry of Co.
In
compounds lacking high symmetry at the Co site, the large
1
(see Figure 1) is 0.451 Å longer than that of 2. On one hand,
electric field gradients (EFGs) may result in large second order
the longer side length indicates that the MA cations residing in
the cage of 1 have more space to move, providing a qualitative
understanding of the different dynamics of MA cations in the
cubic phases of 1 and 2. On the other hand, the relatively small
side length of 2 indicates that the caged MA cations in 2 have
closer contact with the host lattice, a clue to the interplay
between the host lattice and the caged MA cation, which will
be discussed in the next section. Reflecting the influence of
such an interplay, 1 and 2 have different Goldschmidt
tolerance factors and thus different cubic-disordered phase
4
5
quadrupole broadening of the central transition. This
explains the origin of the wide signals in the low symmetric
phases of the samples (the LT phase for 1-d , and the LT and
the intermediate phase for 2-d ). In principle, analysis of the
line shape can provide the information on the quadrupole
interaction and the chemical shift anisotropy, which can be
further used to extract detailed dynamic information on the
Further experimental study using the
Co NMR in different external magnetic fields as well as a
simulation study of the pattern line shape is the subject of
ongoing studies in our laboratory. In the cubic phases of 1-d3
3
3
3
−
46,47
[
Co(CN)6] anions.
5
9
27
transition temperatures.
Interplay between the Motions of MA Cations and
the Host Lattices. Reflecting the interplay between the caged
cation and the host lattice, the [Co(CN)6]3 anions in the host
lattice of the samples show intriguing dynamic changes that
accompany the motional changes of MA cations. Figure 6a
and 2-d , the high symmetry of the Co sites results in a
3
−
significant attenuation of both the quadrupole coupling and the
chemical shift anisotropy. This explains the origin of the
narrow signals of 1-d and 2-d in the high-temperature phases.
Reflecting the symmetry change of the Co sites during the
phase transitions, the changes in the Co NMR spectra in
Figure 6 clearly indicate that the [Co(CN)6] anions undergo
delicate adjustments during the phase transitions. The
Co(CN)6] anion is the key linker of the host lattice. The
3
3
5
9
exhibits the static Co (I = 7/2) NMR spectra of 1-d from
59
3
3
−
3−
[
3
−
adjustments in [Co(CN)6]
thus clearly evidence the
dynamic changes of the host lattice. At the same time, the
5
9
similar transition temperatures obtained from the Co NMR
3
−
2
of [Co(CN)6] and the H NMR of MA cations indicate the
coupling between the caged cation and the host lattice. But so
far, we have not been able to tell whether the motions of MA
cations initiate the adjustment of the host lattices, or inversely,
the adjustment of host lattices initiates the motions of MA
cations, or if the motions of MA cations just coincide with the
adjustment of the host lattices.
The knowledge of the interplay between the host lattice and
the caged MA cation provides a deep understanding of the
origin of the dielectric permittivity of 1 and 2. From the point
of view of charge distribution, the host lattices of 1 and 2 both
have an equivalent negative charge which balances the positive
charge of the caged MA cations. If the center of the equivalent
negative charge from the host lattice does not completely
overlap with the center of the positive charge of the MA cation,
an additional dipole moment between the positive charge and
the equivalent negative charge may exist. When changing
temperature, it is very likely that the interplay between the host
lattice and the caged MA cation will induce the change in the
additional dipole moment, thus contributing to the dielectric
permittivity of the sample. Therefore, the interplay between
the host lattice and the caged MA cation indicates that not
only the reorientation of the dipole moment of the MA cation
Figure 6. Temperature dependent 59Co NMR powder patterns of (a)
1
-d and (b) 2-d . These spectra were acquired at a 300 MHz NMR
3 3
instrument. The chemical shift scale was calibrated using a 1M
K [Co(CN) ] aqueous solution (δ = 0 ppm). LT phase: Low-
3
6
temperature phase. HT phase: High-Temperature phase.
E
DOI: 10.1021/acs.inorgchem.9b00497
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
but also the accompanying change in the host lattice can
contribute to the dielectric permittivity.
(2) Schliwa, M. Molecular Motors. In Encyclopedic Reference of
Genomics and Proteomics in Molecular Medicine; Springer: Berlin, 2006;
pp 1160−1174.
(3) Pijper, D.; Feringa, B. L. Molecular Transmission: Controlling
CONCLUSIONS
Dynamic changes of the caged MA cations and the host lattice
■
the Twist Sense of a Helical Polymer with a Single Light-Driven
Molecular Motor. Angew. Chem., Int. Ed. 2007, 46 (20), 3693−3696.
(4) Burschka, J.; Pellet, N.; Moon, S.-J.; Humphry-Baker, R.; Gao,
in two perovskite-type compounds, (MA) [B′Co(CN) ] (B′ =
2
6
2
K and Na), were investigated in great detail by solid state H
P.; Nazeeruddin, M. K.; Gratzel, M. Sequential deposition as a route
̈
5
9
and Co NMR. It was found that the two compounds exhibit
marked differences in MA dynamics during the phase and
dielectric transitions despite having highly similar crystal
structures. The MA cation in the K compound undergoes a
dynamic change from local wiggling motion to fast isotropic
tumbling motion, whereas, in the Na compound, the MA
cation undergoes dynamic changes from local wiggling to 2-site
jump and then 4-site jump, in addition to the ever-present C−
N axial rotation. This is strikingly different from the K
compound. Accompanying the motions of MA cations, the
host lattices of 1 and 2 show dynamic changes coincidentally
occurring at the same transition temperatures, demonstrating
the intriguing interplay between the crystal lattice and the
motions of caged cations. This information on the interplay
between the caged cations and the host lattices of 1 and 2
provides new insights into the dielectric transition behaviors of
compounds on a molecular level.
to high-performance perovskite-sensitized solar cells. Nature 2013,
499 (7458), 316−319.
(5) Kojima, A.; Teshima, K.; Shirai, Y.; Miyasaka, T. Organometal
halide perovskites as visible-light sensitizers for photovoltaic cells. J.
Am. Chem. Soc. 2009, 131 (17), 6050−6051.
(
6) Kubicki, D. J.; Prochowicz, D.; Hofstetter, A.; Pec
́
hy, P. t.;
zel, M.; Emsley, L. Cation Dynamics in
Zakeeruddin, S. M.; Grat
̈
Mixed-Cation (MA) (FA)1−xPbI3 Hybrid Perovskites from Solid-
x
State NMR. J. Am. Chem. Soc. 2017, 139 (29), 10055−10061.
(7) Liu, M.; Johnston, M. B.; Snaith, H. J. Efficient planar
heterojunction perovskite solar cells by vapour deposition. Nature
013, 501 (7467), 395−398.
8) Sanchez, R. S.; Gonzalez-Pedro, V.; Lee, J.-W.; Park, N.-G.;
2
(
Kang, Y. S.; Mora-Sero, I.; Bisquert, J. Slow dynamic processes in lead
halide perovskite solar cells. Characteristic times and hysteresis. J.
Phys. Chem. Lett. 2014, 5 (13), 2357−2363.
(9) Snaith, H. J.; Abate, A.; Ball, J. M.; Eperon, G. E.; Leijtens, T.;
Noel, N. K.; Stranks, S. D.; Wang, J. T.-W.; Wojciechowski, K.;
Zhang, W. Anomalous hysteresis in perovskite solar cells. J. Phys.
Chem. Lett. 2014, 5 (9), 1511−1515.
ASSOCIATED CONTENT
Supporting Information
■
(10) Du, Z. Y.; Xu, T. T.; Huang, B.; Su, Y. J.; Xue, W.; He, C. T.;
*
S
Zhang, W. X.; Chen, X. M. Switchable Guest Molecular Dynamics in
a Perovskite-Like Coordination Polymer toward Sensitive Thermor-
esponsive Dielectric Materials. Angew. Chem., Int. Ed. 2015, 54 (3),
914−918.
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.inorg-
chem.9b00497.
(11) Shi, C.; Han, X.-B.; Wang, Y.; Zhang, W. Tuning dielectric
DSC curves, temperature dependent dielectric measure-
2
transitions by B′-site mixing in hybrid double perovskite crystals
ments, simulated H NMR patterns, and crystallographic
(
2
CH NH ) [K Rb Co(CN) ] (x= 0.23−0.62). Inorg. Chem. Front.
3
3
2
1−x
x
6
data and structural refinement details (PDF)
016, 3 (12), 1604−1608.
(12) Zhang, W.; Ye, H.-Y.; Graf, R.; Spiess, H. W.; Yao, Y.-F.; Zhu,
Accession Codes
R.-Q.; Xiong, R.-G. Tunable and switchable dielectric constant in an
CCDC 1878215 and 1878216 contain the supplementary
crystallographic data for this paper. These data can be obtained
free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by
emailing data_request@ccdc.cam.ac.uk, or by contacting The
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
amphidynamic crystal. J. Am. Chem. Soc. 2013, 135 (14), 5230−5233.
(13) Zhang, X.; Shao, X. D.; Li, S. C.; Cai, Y.; Yao, Y. F.; Xiong, R.
G.; Zhang, W. Dynamics of a caged imidazolium cation-toward
understanding the order-disorder phase transition and the switchable
dielectric constant. Chem. Commun. 2015, 51 (22), 4568−4571.
(14) Du, Z.-Y.; Sun, Y.-Z.; Chen, S.-L.; Huang, B.; Su, Y.-J.; Xu, T.-
T.; Zhang, W.-X.; Chen, X.-M. Insight into the molecular dynamics of
guest cations confined in deformable azido coordination frameworks.
Chem. Commun. 2015, 51 (86), 15641−15644.
AUTHOR INFORMATION
Corresponding Author
E-mail: yfyao@phy.ecnu.edu.cn.
ORCID
Ye-Feng Yao: 0000-0002-6274-2048
Author Contributions
These authors contributed equally to this work.
■
(
15) Kubicki, D. J.; Prochowicz, D.; Hofstetter, A.; Saski, M.; Yadav,
*
P.; Bi, D.; Pellet, N.; Lewins
́
ki, J.; Zakeeruddin, S. M.; Gratzel, M.;
̈
Emsley, L. Formation of Stable Mixed Guanidinium-Methylammo-
nium Phases with Exceptionally Long Carrier Lifetimes for High-
Efficiency Lead Iodide-Based Perovskite Photovoltaics. J. Am. Chem.
Soc. 2018, 140 (9), 3345−3351.
§
(
16) Kubicki, D. J.; Prochowicz, D.; Hofstetter, A.; Zakeeruddin, S.
M.; Gratzel, M.; Emsley, L. Phase Segregation in Cs-, Rb- and K-
Doped Mixed-Cation (MA) (FA) PbI Hybrid Perovskites from
Notes
̈
The authors declare no competing financial interest.
x
1−x
3
Solid-State NMR. J. Am. Chem. Soc. 2017, 139 (40), 14173−14180.
ACKNOWLEDGMENTS
(17) Kubicki, D. J.; Prochowicz, D.; Hofstetter, A.; Zakeeruddin, S.
■
M.; Gratzel, M.; Emsley, L. Phase Segregation in Potassium-Doped
̈
This work was supported by the National Natural Science
Foundation of China (21574043) and the Fundamental
Research Funds for the Central Universities. The authors
thank Prof. Wen Zhang at SEU for providing the samples.
3
9
Lead Halide Perovskites from K Solid-State NMR at 21.1 T. J. Am.
Chem. Soc. 2018, 140 (23), 7232−7238.
(18) Xu, Q.; Eguchi, T.; Nakayama, H.; Nakamura, N.; Kishita, M.
Molecular Motions and Phase Transitions in Solid CH NH PbX (X
3
3
3
=
C1, Br, I) as Studied by NMR and NQR. Z. Naturforsch., A: Phys.
Sci. 1991, 46, 240−246.
(19) Franssen, W. M. J.; van Es, S. G. D.; Derviso
REFERENCES
■
(
1) Sauvage, J.-P.; Amendola, V. Molecular Machines and Motors;
Springer Science & Business Media, 2001; Vol. 99.
̧ glu, R.; de Wijs, G.
̆
A.; Kentgens, A. P. M. Symmetry, Dynamics, and Defects in
F
DOI: 10.1021/acs.inorgchem.9b00497
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Methylammonium Lead Halide Perovskites. J. Phys. Chem. Lett. 2017,
(38) Shenderovich, I. G.; Buntkowsky, G.; Schreiber, A.; Gedat, E.;
Sharif, S.; Albrecht, J.; Golubev, N. S.; Findenegg, G. H.; Limbach, H.-
H. Pyridine-15 Na mobile NMR sensor for surface acidity and surface
defects of mesoporous silica. J. Phys. Chem. B 2003, 107 (43), 11924−
11939.
(39) Gedat, E.; Schreiber, A.; Albrecht, J.; Emmler, T.;
Shenderovich, I.; Findenegg, G.; Limbach, H.-H.; Buntkowsky, G.
8
(
(1), 61−66.
20) Even, J.; Pedesseau, L.; Katan, C. Analysis of Multivalley and
Multibandgap Absorption and Enhancement of Free Carriers Related
to Exciton Screening in Hybrid Perovskites. J. Phys. Chem. C 2014,
1
(
18 (22), 11566−11572.
21) Gottesman, R.; Haltzi, E.; Gouda, L.; Tirosh, S.; Bouhadana, Y.;
2
H-Solid-State NMR Study of Benzene-d 6 Confined in Mesoporous
Silica SBA-15. J. Phys. Chem. B 2002, 106 (8), 1977−1984.
40) Rossler, E.; Taupitz, M.; Borner, K.; Schulz, M.; Vieth, H. M. A
Zaban, A.; Mosconi, E.; De Angelis, F. Extremely Slow Photo-
conductivity Response of CH NH PbI Perovskites Suggesting
3
3
3
(
̈
̈
Structural Changes under Working Conditions. J. Phys. Chem. Lett.
014, 5 (15), 2662−2669.
22) Chen, S.; Shang, R.; Wang, B. W.; Wang, Z. M.; Gao, S. An A-
simple method analyzing 2H nuclear magnetic resonance line shapes
to determine the activation energy distribution of mobile guest
molecules in disordered systems. J. Chem. Phys. 1990, 92 (10), 5847−
2
(
Site Mixed-Ammonium Solid Solution Perovskite Series of [(NH2-
5
(
855.
NH ) (CH NH ) ][Mn(HCOO) ](x= 1.00−0.67). Angew. Chem.,
3
x
3
3
1−x
3
41) Zhang, W.; Cai, Y.; Xiong, R. G.; Yoshikawa, H.; Awaga, K.
Int. Ed. 2015, 54 (38), 11093−11096.
Exceptional Dielectric Phase Transitions in a Perovskite-Type Cage
(
23) Jain, P.; Dalal, N. S.; Toby, B. H.; Kroto, H. W.; Cheetham, A.
Compound. Angew. Chem., Int. Ed. 2010, 49 (37), 6608−6610.
K. Order− disorder antiferroelectric phase transition in a hybrid
inorganic− organic framework with the perovskite architecture. J. Am.
Chem. Soc. 2008, 130 (32), 10450−10451.
(
42) Chan, J. C. C.; Au-Yeung, S. C. F. Cobalt-59 NMR
Spectroscopy. In Annual Reports on NMR Spectroscopy; Elsevier,
000; Vol. 41, pp 1−54..
43) Godbout, N.; Oldfield, E. Density functional study of cobalt-59
2
(
(
24) Kundys, B.; Lappas, A.; Viret, M.; Kapustianyk, V.; Rudyk, V.;
Semak, S.; Simon, C.; Bakaimi, I. Multiferroicity and hydrogen-bond
ordering in (C H NH ) CuCl featuring dominant ferromagnetic
nuclear magnetic resonance chemical shifts and shielding tensor
elements in Co (III) complexes. J. Am. Chem. Soc. 1997, 119 (34),
2
5
3
2
4
interactions. Phys. Rev. B: Condens. Matter Mater. Phys. 2010, 81 (22),
24434.
25) Liao, W.-Q.; Zhang, Y.; Hu, C.-L.; Mao, J.-G.; Ye, H.-Y.; Li, P.-
8
(
065−8069.
2
(
44) Zhou, P.; Au-Yeung, S. C.; Xu, X.-P. A DFT and 59Co Solid-
State NMR study of the Second-Sphere Interaction in Polyammo-
nium Macrocycles Cobalt Cyanide Supercomplexes. J. Am. Chem. Soc.
F.; Huang, S. D.; Xiong, R.-G. A lead-halide perovskite molecular
ferroelectric semiconductor. Nat. Commun. 2015, 6, 7338.
1
(
999, 121 (5), 1030−1036.
(
26) Polyakov, A. O.; Arkenbout, A. H.; Baas, J.; Blake, G. R.;
45) Crewdson, P.; Bryce, D. L.; Rominger, F.; Hofmann, P.
Meetsma, A.; Caretta, A.; van Loosdrecht, P. H.; Palstra, T. T.
Coexisting ferromagnetic and ferroelectric order in a CuCl4-based
organic−inorganic hybrid. Chem. Mater. 2012, 24 (1), 133−139.
Application of Ultrahigh-Field 59Co Solid-State NMR Spectroscopy
in the Investigation of the 1, 2-Polybutadiene Catalyst [Co(C H )-
8
13
(
C H )]. Angew. Chem., Int. Ed. 2008, 47 (18), 3454−3457.
4
6
(
27) Shi, C.; Yu, C. H.; Zhang, W. Predicting and screening
59
(
46) Nielsen, U. G.; Jakobsen, H. J.; Skibsted, J. Co chemical shift
dielectric transitions in a series of hybrid organic−inorganic double
perovskites via an extended tolerance factor approach. Angew. Chem.,
Int. Ed. 2016, 55 (19), 5798−5802.
anisotropy and quadrupole coupling for K Co(CN) from MQMAS
3
6
and MAS NMR spectroscopy. Solid State Nucl. Magn. Reson. 2001, 20
(
1−2), 23−34.
(
28) Wang, X.-Y.; Gan, L.; Zhang, S.-W.; Gao, S. Perovskite-like
(47) Ooms, K. J.; Terskikh, V. V.; Wasylishen, R. E. Ultrahigh-field
5
9
−
+
metal formates with weak ferromagnetism and as precursors to
solid-state Co NMR studies of Co(C B H ) and Co(C H )
2 9 11 2 5 5 2
amorphous materials. Inorg. Chem. 2004, 43 (15), 4615−4625.
salts. J. Am. Chem. Soc. 2007, 129 (21), 6704−6705.
(
29) Zhao, X.-H.; Huang, X.-C.; Zhang, S.-L.; Shao, D.; Wei, H.-Y.;
Wang, X.-Y. Cation-dependent magnetic ordering and room-temper-
ature bistability in azido-bridged perovskite-type compounds. J. Am.
Chem. Soc. 2013, 135 (43), 16006−16009.
(
30) Chen, S.; Shang, R.; Hu, K.-L.; Wang, Z.-M.; Gao, S.
2
+
2+
2+
2+
[
NH NH ][M(HCOO) ](M= Mn , Zn , Co and Mg ):
2 3 3
structural phase transitions, prominent dielectric anomalies and
negative thermal expansion, and magnetic ordering. Inorg. Chem.
Front. 2014, 1 (1), 83−98.
(
31) Schmidt-Rohr, K.; Spiess, H. W. Multidimensional Solid-State
NMR and Polymers; Academic Press: London, 1994.
32) Hansen, M. R.; Graf, R.; Spiess, H. W. Solid-State NMR in
(
Macromolecular Systems: Insights on How Molecular Entities Move.
Acc. Chem. Res. 2013, 46 (9), 1996−2007.
(
33) Yao, Y.; Chen, Q. From Helical Jump to Chain Diffusion: Solid-
State NMR Study of Chain Dynamics in Semi-Crystalline Polymers.
In Annual Reports on NMR Spectroscopy; Elsevier, 2010; Vol. 69, pp
1
99−224.
34) Shao, X. D.; Zhang, X.; Shi, C.; Yao, Y. F.; Zhang, W. J. A. S.
Switching dielectric constant near room temperature in a molecular crystal
015, 2 (5), 1500029.
35) Shi, C.; Zhang, X.; Cai, Y.; Yao, Y. F.; Zhang, W. J. A. C. I. E.
Angew. Chem., Int. Ed. 2015, 54 (21), 6206−6210.
36) Shi, C.; Zhang, X.; Yu, C. H.; Yao, Y. F.; Zhang, W. Geometric
(
2
(
(
isotope effect of deuteration in a hydrogen-bonded host−guest
crystal. Nat. Commun. 2018, 9 (52), 481.
(
37) Jaeger, C.; Hemmann, F. EASY: a simple tool for
simultaneously removing background, deadtime and acoustic ringing
in quantitative NMR spectroscopy–part I: basic principle and
applications. Solid State Nucl. Magn. Reson. 2014, 57−58 (1), 22−28.
G
DOI: 10.1021/acs.inorgchem.9b00497
Inorg. Chem. XXXX, XXX, XXX−XXX