4,4′-, 5,5′-, and 6,6′-dimethyl-2,2′-bipyridyls: The structures, phase transitions, vibrations, and methyl group tunneling of their complexes with chloranilic acid

Bator, G.; Sawka‐Dobrowolska, W.; Sobczyk, L.; Grech, E.; Nowicka‐Scheibe, J.; Pawlukojć, A.; Wuttke, Joachim; Baran, J.; Owczarek, Magdalena

doi:10.1063/1.3613640

Cited by 22 publications

(20 citation statements)

References 21 publications

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“…The schematic crystal structure at room temperature is shown in Figure 1(a), where alternating O-H···N and N-H···O hydrogen bonds form a one-dimensional chain along the b-axis. 23 We note that the positional order of the protons We note that the crystal-growth temperature of this material is room temperature, which is well within the ferroelectric phase. Thus, the as-grown ferroelectric domain structure can be dominated by the crystal-growth kinetics.…”

Section: The Materials Investigated In This Study Is the Uniaxial Ferrmentioning

confidence: 63%

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Polarization Switching Ability Dependent on Multidomain Topology in a Uniaxial Organic Ferroelectric

et al. 2013

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The switching of electric polarization induced by electric fields, a fundamental functionality of ferroelectrics, is closely associated with the motions of the domain walls that separate regions with distinct polarization directions. Therefore, understanding domain-walls dynamics is of essential importance for advancing ferroelectric applications. In this Letter, we show that the topology of the multidomain structure can have an intrinsic impact on the degree of switchable polarization. Using a combination of polarization hysteresis measurements and piezoresponse force microscopy on a uniaxial organic ferroelectric, α-6,6′-dimethyl-2,2′-bipyridinium chloranilate, we found that the head-to-head (or tail-to-tail) charged domain walls are strongly pinned and thus impede the switching process; in contrast, if the charged domain walls are replaced with electrically neutral antiparallel domain walls, bulk polarization switching is achieved. Our findings suggest that manipulation of the multidomain topology can potentially control the switchable polarization.

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Section: The Materials Investigated In This Study Is the Uniaxial Ferrmentioning

confidence: 63%

“…23 The α-form, which consists of dark red elongated-plate crystals, was obtained through repetitive recrystallizations from an acetonitrile solution of a 1:1 stoichiometric mixture of purified H 2 ca and 6,6'-dmbp.…”

Section: Methods Sample Preparationmentioning

confidence: 99%

Polarization Switching Ability Dependent on Multidomain Topology in a Uniaxial Organic Ferroelectric

et al. 2013

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“…17 The structure is isostructural to that of 55DMBPH 2 ia at room temperature 5 but is different from that of 55DMBPH 2 ca. 4,9 The unit cell is nearly the same size as that of 55DMBPH 2 ia. The molecules of 55DMBP and H 2 ba are alternately connected through H bonds and form one-dimensional chains.…”

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confidence: 99%

New Organic Ferroelectrics: Cocrystal of 5,5′-Dimethyl-2,2′-bipyridine and Bromanilic Acid

et al. 2011

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Cocrystal 55DMBPH 2 ba was synthesized and characterized. The crystal structure is isostructural to cocrystal 55DMBP H 2 ia with iodanilic acid. The heat capacity, dielectric permittivity, and polarizationelectric field hysteresis showed that the 55DMBPH 2 ba undergoes a paraelectricferroelectic phase transition at 253 K on cooling. The transition mechanism is discussed through the analysis of isotropic temperature factors of atoms.Recently, organic ferroelectrics having a hydrogen bond (H bond), e.g., phenazinechrolanilic acid 1 (PhzH 2 ca), have been paid increasing attention.2,3 In those compounds, dielectric properties depend on a combination of H-bond donor and acceptor.2 A representative series is cocrystals between 5,5¤-dimethyl-2,2¤-bipyridine (55DMBP) and H 2 xa: 55DMBPH 2 ca is antiferroelectric 4 whereas 55DMBPH 2 ia (iodanilic acid) ferroelectic.5 Since both ferroelectricity and antiferroelectricity are found, the series is very important for understanding the mechanism that determines the dielectric nature of such organic complexes. However, there has been no report on 55DMBP H 2 ba (bromanilic acid) so far. In this letter, we report its synthesis, structure, and properties.Single crystals of 55DMBPH 2 ba were grown by diffusion using dehydrated acetone (Wako, >99.5%) as a solvent. Commercial 55DMBP (Aldrich, 98%) and H 2 ba (TCI, >98%) were purified by fractional sublimation in vacuum before dissolving them in dehydrated acetone. The growth took about 2 months. The yield was very low (15%) even in successful cases. Due to the difficulty in crystal growth, only a limited number of single crystals were available for measurements of physical properties. This prevented the authors from performing precise characterization at the highest level.Structure analyses were performed using a SMART APEX diffractometer (Bruker AXS KK). Data collections were performed at room temperature (295 K) and 200 K. Unit-cell refinement and data reduction were carried out using SAINT.

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“…regarding 6,6′‐dimethyl‐2,2′‐bipyridinium chloranilate [H‐66dmbp][Hca] (Figure 1). 6 This compound, which has the longest hydrogen bond length among organic ferroelectric supramolecules, was firstly reported by Bator et al 7. A spontaneous polarization P s of 7–8 μC cm −2 was about half of that of croconic acid (ca.…”

Section: Introductionmentioning

confidence: 85%

Structure–Property Relationship of Supramolecular Ferroelectric [H‐66dmbp][Hca] Accompanied by High Polarization, Competing Structural Phases, and Polymorphs

Kobayashi

Horiuchi

Ishibashi

et al. 2014

Chemistry A European J

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Three polymorphic forms of 6,6'-dimethyl-2,2'-bipyridinium chloranilate crystals were characterized to understand the origin of polarization properties and the thermal stability of ferroelectricity. According to the temperature-dependent permittivity, differential scanning calorimetry, and X-ray diffraction, structural phase transitions were found in all polymorphs. Notably, the ferroelectric α-form crystal, which has the longest hydrogen bond (2.95 Å) among the organic acid/base-type supramolecular ferroelectrics, transformed from a polar structure (space group, P21) into an anti-polar structure (space group, P21/c) at 378 K. The non-ferroelectric β- and γ-form crystals also exhibited structural rearrangements around hydrogen bonds. The hydrogen-bonded geometry and ferroelectric properties were compared with other supramolecular ferroelectrics. A positive relationship between the phase-transition temperature (TC ) and hydrogen-bond length () was observed, and was attributed to the potential barrier height for proton off-centering or order/disorder phenomena. The optimized spontaneous polarization (Ps ) agreed well with the results of the first-principles calculations, and could be amplified by separating the two equilibrium positions of protons with increasing . These data consistently demonstrated that stretching is a promising way to enhance the polarization performance and thermal stability of hydrogen-bonded organic ferroelectrics.

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4,4′-, 5,5′-, and 6,6′-dimethyl-2,2′-bipyridyls: The structures, phase transitions, vibrations, and methyl group tunneling of their complexes with chloranilic acid

Cited by 22 publications

References 21 publications

Polarization Switching Ability Dependent on Multidomain Topology in a Uniaxial Organic Ferroelectric

Polarization Switching Ability Dependent on Multidomain Topology in a Uniaxial Organic Ferroelectric

New Organic Ferroelectrics: Cocrystal of 5,5′-Dimethyl-2,2′-bipyridine and Bromanilic Acid

Structure–Property Relationship of Supramolecular Ferroelectric [H‐66dmbp][Hca] Accompanied by High Polarization, Competing Structural Phases, and Polymorphs

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