A pair of homochiral trinuclear Zn(ii) clusters exhibiting unusual ferroelectric behaviour at high temperature

Article abstract of DOI:10.1039/C9CE00034H

Molecular ferroelectrics as a class of promising information storage materials have triggered widespread attention owing to their light weight, easy processing and mechanical flexibility. However, reports of molecular ferroelectrics with high-temperature ferroelectric behaviour and higher spontaneous polarization are mainly focused on organic-inorganic perovskites, which are scarce in coordination compound avenues. Here, a pair of homochiral trinuclear Zn(ii) clusters formulated as R-[Zn₃(R-L)₂(CH₃COO)₄] (R-1) and S-[Zn₃(S-L)₂(CH₃COO)₄] (S-1) were successfully constructed with zinc(ii) and the enantiomeric chiral Schiff-base ligands (R/S)-HL (HL = 2-methoxy-6-[(1-phenyl-ethylimino)-methyl]-phenol) through a solvent diffusion method. The solid-state circular dichroism (CD) spectra perfectly illustrate the enantiomeric characteristics of R-1 and S-1. Interestingly, the trinuclear Zn(ii) cluster (R-1) exhibits unusual high-temperature ferroelectric behaviour at 503 K, when the external electric field is 12 KV cm^?1, and the remnant polarity (P_r) and spontaneous polarization (P_s) of R-1 can reach up to 5.4 μC cm^?2 and 8.45 μC cm^?2, respectively, which are comparable with organic-inorganic perovskite ferroelectrics in the literature. To the best of our knowledge, it is the first example of a high-temperature ferroelectric possessing higher spontaneous polarization in Zn-based molecular ferroelectrics.

Full text of DOI:10.1039/C9CE00034H

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DOI: 10.1039/C9CE00034H
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ARTICLE
A Pair of Homochiral Trinuclear Zn (II) Clusters Exhibiting Unusual
Ferroelectric Behaviour at High-Temperature
Meiying Liu, Haiyang Yu and Zhiliang Liu*
Received 00th January 20xx,
Accepted 00th January 20xx
Molecular ferroelectrics as a class of promising information storage materials have triggered widespread attention owing
to their light weight, easy processing and mechanical flexibility. However, reports of molecular ferroelectrics with high-
temperature ferroelectric behaviour and the higher spontaneous polarization are mainly focus on organic−inorganic
perovskites, and which is scarce in coordination compound avenues. Here, a pair of homochiral trinuclear Zn (II) clusters
formulated as R-[Zn3(R–L)2(CH3COO)4] (R-1) and S-[Zn3(S–L)2(CH3COO)4] (S-1), were successfully constructed with zinc (II)
and the enantiomeric chiral Schiff-base ligands (R/S)-HL (HL = 2-methoxy-6-[(1-phenyl-ethylimino)-methyl]-phenol)
through solvent diffusion method. The solid-state circular dichroism (CD) spectra perfectly illustrate the enantiomeric
characteristic of R-1 and S-1. Interestingly, the trinuclear Zn (II) cluster (R-1) exhibits unusual high-temperature
ferroelectric behaviour at 503 K, when external electric field is 12 KV/cm, remnant polarity (Pr) and spontaneous
polarization (Ps) of R-1 can reach up to 5.4 μC/cm2 and 8.45 μC/cm2, respectively, which can be comparable with
organic−inorganic perovskite ferroelectrics in the literatures. To the best of our knowledge, it is the first example of high-
temperature ferroelectric possessing the higher spontaneous polarization in Zn-based molecular ferroelectrics.
DOI: 10.1039/x0xx00000x
www.rsc.org/
more competitive than perovskite ferroelectrics, because they
can be synthesized through moderate chemistry approach,
and exhibit plentiful molecular structures, tuneable chemical
Introduction
For decades, polynuclear complexes or clusters have already
intrigued chemists’ attention owing to their underlying
applications in sensors, magnetism, optics, chirality and
ferroelectric or dielectric materials.1-12 In the scope of
ferroelectric materials, bifunctional systems integrating
ferroelectric properties with optical activity, chirality,
magnetism, fluorescence, dielectric or piezoelectric properties
have been reported.13-20 In order to attain versatile
multifunctional ferroelectric materials, it is necessary to
rationally design and controllably synthesize the specific
complexes or clusters. In light of that chiral space groups and
polar point groups are the essential conditions for ferroelectric
materials, it may be an optimal choice to utilize homochiral
ligand to synthesize ferroelectric polynuclear clusters
with the addition of other potential properties such as circular
dichroism, fluorescence, magnetism and so on. Among chiral
ligands, chiral Schiff-base ligand is an extremely popular
candidate due to its unique advantages such as extensive
coordination sites, abundant coordination modes and simple
synthetic methods.21 What’s more, polynuclear cluster
ferroelectrics as an emerging class of ferroelectrics will be
and physical properties. For example, Jérôme Long et al
reported a high-temperature molecular ferroelectric Zn/Dy
cluster exhibiting single-ion-magnet behaviour and lanthanide
luminescence.17 Thomas. C. W. Mak et al researched a chiral
3D Metal−Organic Framework presenting ferroelectric
switchable behaviour through fast reversible re/adsorption of
water spirals.22 Therefore, it may be a great research area
using clusters to explore multifunctional properties such as
chirality, ferroelectricty, fluorescence, magnetism and so on.
Based on aforementioned considerations, we have successfully
synthesized a pair of homochiral trinuclear Zn (II) clusters
which were fabricated through a pair of enantiomerically chiral
Schiff-base ligands with divalent zinc salt using solvent
diffusion method. The chiral Schiff-base ligands (Scheme 1),
stemmed from the condensation of 2-hydroxy -3-
methoxybenzaldehyde and R/S-2-amino-3-phenyl-1- propanol,
will be beneficial to clusters crystallized in the polar point
groups compatible with the structural necessity of
ferroelectrics. As rarely reported multifunctional ferroelectric
materials, first, fluorescent properties of R-1 and S-1 have
been researched displaying blue-green light emission by solid
fluorescence spectra. Then, the solid-state circular dichroism
(CD) spectra perfectly explain the enantiomeric characteristic
of R-1 and S-1. Finally, the trinuclear Zn (II) clusters belong to
polar space group that it is an indispensable requirement for
ferroelectric. It's striking that the trinuclear Zn (II) cluster (R-1)
exhibits well-shaped hysteresis loop at high-temperature of
Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth
Materials, School of Chemistry and Chemical Engineering, Inner Mongolia
University, Hohhot 010021, P.R. China. E-mail: cezlliu@imu.edu.cn. Fax/Tel:
+86-471-4994375.
†Electronic Supplementary Information (ESI) available: [details of any
supplementary information available should be included here]. See
DOI: 10.1039/x0xx00000x
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503K, which is extremely unusual high-temperature Synthesis of Schiff-base ligand (R/S)-HL
View Article Online
The Schiff-base ligand was synthesizDeOdI: 1b0y.10t3h9/eC9fCoEl0lo0w03i4nHg
method. R/S-(±)-1-Phenylethylamine (10 mmol, 0.89 g) was
dissolved in methanol solution (5 mL), and then the methanol
solution (5 mL) including o-vanillin (10 mmol, 1.52 g) was
added under refluxing. After 2 hours, the light-yellow solution
containing required product was obtained and used without
further purification.
ferroelectric behaviour in coordination compound perspective.
Simultaneously, the spontaneous polarization (Ps) reaches to
8.45 μC/cm2 at high-temperature of 503 K, which can be
competitive
with
organic−inorganic
perovskite-type
ferroelectrics reported in the literatures.23 ， 24 As far as we
know, this is the first example of high-temperature
ferroelectric possessing the higher spontaneous polarization in
Zn-based molecular ferroelectrics.
Synthesis of R-[Zn3(R–L)2(CH3COO)4] (R-1)
The Schiff-base ligand (R)-HL (1.0 mmol) was added in ethanol
(10 mL) including triethylamine (1.0 mmol, 140 μL), and then
Zn(CH3COO)2·2H2O (0.5 mmol, 0.10 g) was added. The mixture
was stirred for 30 min at room temperature, next to the
mixture was filtered. The filtrate was transferred to the tube
and diffused across the n-hexane. Yellow block crystals were
attained after about 4 days, which were collected through
filtering
and
air-drying.
Yield:
50%
(based
on
Zn(CH3COO)2·2H2O). Elemental analysis calcd for R-1
(C40H44N2O12 Zn3): C, 51.06%, H, 4.71% and N, 2.98%. Found: C,
50.56%, H, 4.22%, and N, 2.89%. IR (KBr pellet, cm-1): 3442s,
2976m, 2378s, 1623s, 1455w, 1407w, 1310w, 1244m, 1215m,
1090m, 977w, 859w, 738w, 702m, 669m.
Scheme 1 The enantiomeric Schiff-base ligands (R/S)-HL
Synthesis of S-[Zn3(S–L)2(CH3COO)4] (S-1)
S-1 was synthesized in the same condition with R-1, except
that the Schiff-base ligand (S)-HL (1.0 mmol) was used to
instead of the Schiff-base ligand (R)-HL (1.0 mmol). Yield: 52%
(based on Zn(CH3COO)2·2H2O). Elemental analysis calcd for R-1
(C40H44N2O12 Zn3): C, 51.06%, H, 4.71% and N, 2.98%. Found: C,
50.53%, H, 4.18%, N, 2.83%. IR (KBr pellet, cm-1): 3441s,
2978m, 2376s, 1622s, 1456w, 1408w, 1311w, 1245m, 1216m,
1091m, 978w, 859w, 738w, 702m, 670m.
Experiment
Materials and Measurements
All chemicals were purchased from commercial sources and
used without further purification. Elemental analyses of C, H
and N were tested on a Perkin-Elmer 2400 elemental analyzer.
Infrared spectra were collected by the FT-IR spectrometer
using KBr pellets under the range of 4000–400 cm-1. Power X-
ray diffraction (PXRD) patterns were measured on an
EMPYREAN PANALYTICAL apparatus with single crystals power
in the range of 5–80° using Cu-Kα radiation. Circular dichroism
spectra were conducted on a JASCO J-810 Spectropolarimeter
in KBr tables in the wavelength range of 200–650 nm. TG
curves were attained with a NETZSCH STA409pc apparatus
under a heating rate of 10°C/min from 20 to 1300°C in the
nitrogen protection. Fluorescence spectra for R-1 and S-1 were
recorded on an Hitachi F-7000 FL Spectrophotometer
equipped with a 150 W xenon lamp as the excitation and
emission source at room temperature, and the slit width of
ligand’s fluorescence spectra both are 5.0 nm in the excitation
and emission, and that of Zn-clusters are 5.0 nm in the
excitation and 2.5 nm in the emission. Fluorescence decay
lifetimes were carried out by Edinburgh FLS920
spectrophotometer. The P–E hysteresis loop and leakage
current curves were performed at high temperature using a
Premier II ferroelectric instrument and 9010 Temperature
Controller. Temperature dependence of the dielectric constant
was measured through E4980A Precision impedance analyzer.
The high temperature electric polarization, dielectric constant
and leakage current curves were measured using pellet, which
was pressed using crystal power, coated with silver paste on
two opposite surfaces.
Crystal data collection and refinement
Crystallographic datas of R-1 and S-1 were collected on a
Bruker Apex II diffractometer equipped with a CCD area
detector andgraphite-monochromatic Mo-Kα radiation (λ =
0.71073 Å). Absorption corrections were applied using the
SADABS program. Structures were solved by direct methods
and refined by the full-matrix least-squares method on F2. All
non-hydrogen atoms were refined with anisotropic thermal
parameters, while all hydrogen atoms were added to
appropriate positions in theory and refined with isotropic
thermal parameters by a riding model. Crystallographic data
have been deposited at the Cambridge Crystallographic Data
Center with the deposition numbers CCDC 1813074 for R-1
and CCDC 1813076 for S-1.
Results and discussion
Description of the structures
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DOI: 10.1039/C9CE00034H
Fig.1 Molecular structure of trinuclear Zn (II) clusters S-1 (a) and R-1 (b), packing view of trinuclear Zn(II) clusters S-1 (c) and R-1 (d), displaying four
crystallographically independent cluster. Hydrogen atoms are omitted for clarity, Zn (yellow), N (blue), O (red), C (gray)
Single-crystal X-ray diffraction analysis verified that R-1 and S-1
are enantiomeric crystallizing in monoclinic space group P21
belonging to polar point group, which proves the chirality has
been effectively transferred from the chiral ligand to clusters.
Considering the structures of R-1 and S-1 are basically the
similar, R-1 was selected as representative to describe the
specific crystal structure in detail. As shown in Fig. 1, in the
asymmetric unit, there are three independent Zn(II) ions which
adopts two different coordination fashions. Both Zn1 and Zn3
are four-coordinated with quadrihedron coordination
geometry, ligated by one nitrogen atom and one oxygen atom
from one (R)-L － ligand, and two oxygen atoms from two
different carboxyl groups. The Zn1–O/N bond distances are in
the range of 1.934(3)–2.020(5) Å and the O–Zn1/3–O and O–
Zn1/3–N bond angles are 95.05(17)–115.63(18)°, which is
comparable to these Zn (II) complexes in other literatures.25, 26
Zn2 adopts a distorted octahedral geometry, coordinated by
two oxygen atoms from two different (R)-L－ ligands, and four
oxygen atoms from four different carboxyl groups. The Zn2–
O/N bond lengths ranging from 2.357(4)–2.427(4) Å, the O–
Zn2–O and O–Zn2–N bond angles are 74.60(13)-159.63(15)°,
all of that are comparable to these in other reported Zn(II)
compounds.27, 28 The adjacent Zn (II) ions are bridged by two
μ2-η1 : η1 carboxylate group and one μ2-phenol-oxygen,
forming a linear trinuclear structure. The distances between
the central Zn (II) ion and two terminal Zn (II) ions are
3.5327(10) Å and 3.5075(11) Å, respectively, and which is
similar to the analogous Zn (II) complexes.29 The coordination
fashions of S-1 and R-1 are basically similar with analogue
complex in literatures, which are six-coordinated with
octahedron geometry, five-coordinated with square pyramid
configuration or four-coordinated with quadrihedron
coordination geometry. The packing diagram of analogue Zn
(II) complexes almost are 2D or 3D structure,25-29 while the
packing diagram of trinuclear Zn (II) clusters exhibits the linear
stacked arrangement as shown in Fig.1(c) and Fig.1(d). The
Fig. 2 PXRD patterns for S-1 and R-1 (a), PXRD patterns of R-1 at different
temperatures (b)
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reason of that may be caused by the difference of ligands. presenting ferroelectricity.30 In light of the enantiomeric
View Article Online
DOI: 10.1039/C9CE00034H
Crystallographic data and structure refinement parameters for nature of R-1 and S-1, R-1 was selected to research
S-1 and R-1 are listed in Table S1, the main bond lengths (Å) ferroelectric and dielectric properties. Dielectric measurement
and bond angles (°) for S-1 and R-1 are listed in Table S2 and of R-1 was carried out on pellet pressed by utilizing crystal
Table S3. In Fig.2(a), all of main patterns of as-synthesized powder under the temperature range of 300 – 550 K (Fig.4a),
Zn(II) clusters are basically consistent with the simulated the dielectric constant doesn’t exhibit obviously abnormal in
patterns, though there exists some small patterns unwell
corresponded to the simulation. The phenomenon might be
explained by following reasons. ( ⅰ) There is little impurity in
crystal power. ( ⅱ) The crystal is weathering in some extent.
( ⅲ) Some solvent molecules might volatilize in the surface of
crystal. ( ⅳ) The simulation of Zn-cluster is obtained by the
Single-crystal X-ray diffraction analysis utilizing the single-
crystal, while the PXRD of that is measured using the power
grinded by single-crystal. The tiny difference of single-crystal
and crystal power may cause the distinction between the
simulated patterns and PXRD of as-synthesized sample.
CD spectra and Thermal stability study
To prove optical activity and enantiomeric nature, solid-state
circular dichroism (CD) spectra of R-1 and S-1 were measured.
As shown in Fig.3, the spectra of R-1 and S-1 are roughly
mirror images of each other, which clearly illustrate the
characters of a pair of optical enantiomeric. The spectra of R-1
displays a negative Cotton effect around 333 and 414 nm,
while S-1 presents a positive Cotton effect at the same
wavelength. The thermogravimetric analysis (TGA) was tested
to inspect the stability of R-1 (Fig.S3). There is about 2.5%
weight loss in the range of 300-528 K. After analysis and
calculation, there is no free solvent molecule in the crystal
lattice. Therefore, it may be caused by minor impurity
adhering to the surface of crystal. When the temperature is
above 528 K, the curve start quickly decreasing, illustrating
the structure of R-1 starts disintegrated. Moreover, the R-1
can remain greatly structural stability until decomposition,
which is vertified by PXRD at different temperature (Fig.2b).
When the temperature increases, the PXRD of R-1 almost
remain unchanged until it was destroyed.
Fig.3 CD spectra for S-1 and R-1 at RT in KBr pellets
Fig.4 Temperature dependence of the dielectric constant for R-1 (a), Hysteresis
loop (100 Hz) for R-1 obtained from pellet pressed using crystal powder at
Ferroelectric and dielectric properties
different temperatures (b), Hysteresis loop (100 Hz) for R-1 under different
The structural analysis reveals that both R-1 and S-1 are polar
space group P21, which belongs to one of ten polar point
groups (C1, C2, C1h, C2v, C4, C4v, C3, C3v, C6, C6v) required for
external electric fields at 503 K (c)
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the range of temperature, indicating no phase transition Fluorescence properties of R-1 and S-1
appears before R-1 start decomposing , which is consistent
View Article Online
The fluorescence properties of theDOlIi:g1a0n.1d039/hCa9vCeE00b0e34eHn
researched (Fig.S6), and the sharp emission peak of (S)-HL and
(R)-HL both are at 406 nm (λex = 283 nm). Both S-1 and R-1
exhibit greatly strong blue-green fluorescence under UV
irradiation in the solid state at room temperature. As shown in
Fig.S7, the broad emission peak of S-1 and R-1 both are at 460
nm (λex = 327 nm). Generally, fluorescence can derive from
metal-centered emission (extensively observed in lanthanide
complexes by the so-called antenna effect), organic ligands
excitation (especially from the highly conjugated ligands) and
charge-transfer such as ligand-to-metal charge transfer (LMCT)
and metal-to-ligand charge transfer (MLCT).2 Furthermore, it is
very difficult to oxidize or reduce Zn2+ belonging to the d10
configuration, so the fluorescence of S-1 and R-1 is not charge-
transfer in nature.45-47 Comparing to the emission peak of
ligand and trinuclear Zn (II) clusters, the emission peaks of S-1
and R-1 exhibit red-shift in some degree. Thus, the
fluorescence of S-1 and R-1 may be ascribed to the ligands
fluorescence emissions. What’s more, after coordination
between the ligand and Zn (II) ion, the conjugation effect has
been enhanced leading the stronger emission intensity of S-1
and R-1 than that of (S)-HL and (R)-HL. Moreover, the
fluorescent lifetime of R-1 and S-1 are 2.35 and 2.41 μs,
respectively (Fig.S8). And the quantum yields both are 2.4%.
with the PXRD at different temperature and DSC analysis
(Fig.S4). The hysteresis loop was performed up to 503 K, while
the hysteresis loop of R-1 wasn’t discovered at room
temperature, which may illustrate the electric field required to
efficiently polarize R-1 is too high.17 With temperature rising,
polarity of R-1 gradually increases but still is unsaturated.
When it is up to 503 K, R-1 shows a well-shaped hysteresis
loop (Fig.4b). As shown in Fig.4c, both remnant polarity and
saturated polarity increasingly goes up with increasing applied
electric field. When external electric field is 12 KV/cm,
remnant polarity (Pr) and spontaneous polarization (Ps) of R-1
can reach up to 5.4 μC/cm2 and 8.45 μC/cm2, respectively.
Such a high polarization is significantly higher than that of the
31
classical ferroelectric Rochelle salt (Ps = 0.25 μC/cm2) and
some Zn-based molecular ferroelectrics,20,32-41 but is in the
same order of magnitudes for several perovskite-type
molecular ferroelectrics, such as [MeHdabco]RbI3 (Ps = 6.8
μC/cm2)23 or (3-pyrrolinium)CdBr3 (Ps
=
7.0 μC/cm2).24
Moreover, the low leakage current (less than 10-7 A/cm2) as a
function to further corroborate the P–E hysteresis loops of R-1
originating from the ferroelectricity (Fig.S5).17,42-44 As far as we
know, it is the first Zn-based molecular ferroelectric which
possesses the higher spontaneous polarization and exhibits
high-temperature ferroelectric property (Table 1).
Table 1. The list of measured temperature, remnant polarity (Pr) and spontaneous polarization (Ps) in some Zn-based ferroelectrics
Temperature
(K)
Pr
Ps
Compound
Reference
(μC /cm2)
(μC /cm2)
a R-[Zn3(R–L)2(CH3COO)4]
503 K
283 K
283 K
RT
RT
RT
RT
RT
RT
RT
5.4
0.02
0.01
2.9
8.45
0.066
-
6.26
5.27
0.30
15.3
-
0.127
0.25
0.294
0.105
0.51
This work
32
b {[Zn2(TIPA)(btc)(μ2-OH)]·4H2O}n
c [Zn2(X)(CH3CH2OH)]·3H2O
d [Zn2(mtz)(nic)2(OH)]n·0.5nH2O
e [Zn(phtz)(nic)]2n
33
34
34
35
36
37
20
38
2.5
f [Zn (HQA)Br2(H2O)3]n
g R-[Zn4(HL)2(L)2·(CH3OH)2]·(NO3)2
h [Zn2(tib)4/3(L1)2]·DMA
0.16
3.97
0.032
0.058
0.128
0.035
0.033
0.21
i {[Zn6(MIDPPA)3(1,2,4-btc)3(NO2)3(H2O)3](H2O)7}n
j ZnL2(H2O)2
k [Zn(s-nip)2]n
RT
RT
RT
39
40
41
l [Zn3(BIDPE)3(5-OH-bdc)3·4H2O]n
m [Zn(Mitz)Cl]n
a HL = 2-methoxy-6-[(1-phenyl-ethylimino)-methyl]-phenol, b TIPA = tris[4-(1H-imidazol-1-yl)-phenyl]amine, H3btc = 1,3,5-benzenetricarboxylic acid,
c
d
e
H4X = tetrakis[4-(carboxyphenyl)oxamethyl]methane acid, Hmtz = 5-methyltetrazole, Hnic = nicotinic acid, Hphtz = 5-phenyltetrazole, Hnic =
nicotinic acid, f HQA = 6-methoxyl-(8S,9R)-cinchonan-9-ol-3-carboxylic acid, g H2L = 2-[(1-benzyl-2-hydroxy-ethylimino)-methyl]-6-methoxy-phenol,
h
H2L1 = biphenyl-4,4’-dicarboxylic acid, tib = 1,3,5-tris(1-imidazolyl)benzene, MIDPPA = 4,4’-di(4-pyridine)-4 " –imidazoletriphenylamine, 1,2,4-
i
j
k
H3btc
=
1,2,4-benzenetricarboxylic acid,
L
=
1,2,2-trimethyl-3-(pyridin-4-ylcarbamoyl)cyclopentanecarboxylic acid,
s-nip = (S)-2-(1,8-
l
m
naphthalimido)-3-(4-imidazole)propanoate, BIDPE = 4,4’-bis(imidazol-1-yl)diphenyl ether, 5-OH-H2bdc = 5-hydroxy-isophthalic acid, Mitz = 3-
tetrazolyl-6-methyl-5-(4-pyridyl)-2-pyridone
RT = room temperature
trinuclear Zn (II) cluster (R-1) presents excellently thermal
stability up to 528 K. Meanwhile, the trinuclear Zn (II) clusters
Conclusions
(R-1 and S-1) present obvious fluorescence properties,
showing blue-green emission. What’s more, the chirality of the
clusters is demonstrated by solid-state circular dichroism (CD)
spectra. It is worth mentioning that the trinuclear Zn (II) cluster
(R-1) can display well-shaped hysteresis loop at high-
In summary, a pair of homochiral trinuclear Zn (II) clusters,
exhibiting unusual high-temperature ferroelectric behaviour,
has been obtained by assembling the chiral Schiff-base ligands
with divalent zinc salt using solvent diffusion method. The
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17 J. Long, J. Rouquette, J. M. Thibaud, R. A. FVeierwreAirrtaic,le LO.nliDne.
temperature of 503 K, which is extremely scarce high-
temperature ferroelectric behaviour. When external electric
field is 12 KV/cm, remnant polarity (Pr) and spontaneous
polarization (Ps) of R-1 can reach up to 5.4 μC/cm2 and 8.45
μC/cm2, respectively. The spontaneous polarization of R-1 is
much higher than most that of reported Zn-based molecular
ferroelectrics and is on a par with some high-temperature
perovskite-type ferroelectrics. As far as we know, it is the first
example of high-temperature Zn-based molecular ferroelectric
possessing an impressive spontaneous polarization. It can be
seen from the above mentioned that the pair of homochiral
trinuclear Zn (II) clusters facilitate the development of
molecular-based multifunctional materials for ferroelectrics,
fluorescence property and excellent thermal stability
materials.
Carlos, B. Donnadieu, V. Vieru, L. F. Chibotaru, L. Konczewicz,
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Table of Contents Entry
A pair of homochiral trinuclear Zn (II) clusters exhibit unusual ferroelectric
behaviour at high-temperature.