Structural organization and molecular self-assembly of a new class of polar and non-polar four-ring based bent-core molecules

Kaur, Supreet; Mohiuddin, Golam; Punjani, Vidhika; Khan, Raj Kumar; Ghosh, Sharmistha; Pal, Santanu Kumar

doi:10.1016/j.molliq.2019.111687

Cited by 15 publications

(24 citation statements)

References 61 publications

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“…S1–S17 † ). In our previous report with similar molecular architecture (terminal –CN and –OCH 3 moieties at the molecular short arm), 23 only nematic and SmA phases were observed without any SmC transition, but here, interestingly, we noticed the tilted phase beneath the SmA phase.…”

Section: Methodssupporting

confidence: 74%

“…The bent angle of 147° was in accordance with similar type of molecules. 22,23 The synthetic route for the final compounds is presented in Scheme 1 and the details are included in the ESI (Fig. S1–S17†).…”

Section: Methodsmentioning

confidence: 99%

“…Unsymmetrical bent-core molecules or hockey-stick shaped molecules, renowned for their potential physical properties for device applications, such as nematic ferroelectricity, 21 cybotactic nematic phases, 22–26 formation of a polarization modulated layer undulated phase structure, 27–30 and a long range blue phase with a high Kerr constant, 31 barely exhibit “de Vries-like” behaviour. In the past two decades, miscellaneous hockey-stick shaped mesogens (composed of four or more phenyl rings) have been explored.…”

Section: Introductionmentioning

confidence: 99%

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Observation of “de Vries-like” properties in bent-core molecules

et al. 2022

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Section: Methodssupporting

confidence: 74%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Observation of “de Vries-like” properties in bent-core molecules

et al. 2022

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“…Moreover, the dopant SK 1–8 has a cybotactic nematic phase above the crystal phase. 29 , 30 The summarized data of the optimized DFT structure of the dopants are presented in Table 1 .…”

Section: Experimental Sectionmentioning

confidence: 99%

Flexoelectric Polarization in a Nematic Liquid Crystal Enhanced by Dopants with Different Molecular Shape Polarities

et al. 2022

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Flexoelectricity may have an important impact on the switching properties of nematic and cholesteric liquid crystals due to the linear coupling between the flexoelectric polarization of the liquid crystal and the applied electric field. This coupling is the origin of the extraordinary electro-optic effect in cholesterics aligned in the uniform lying helix texture, resulting in fast switching and field control of both rise and fall times. Therefore, the flexoelectric properties of the liquid crystals have become an important issue when designing and synthesizing liquid crystal materials and/or preparing their mixtures with appropriate flexoelectric compounds (dopants). Here, we report on the flexoelectric polarization of a highly polar nematic liquid crystal host enhanced by doping it with two newly synthesized dopants SK 1–6 and SK 1–8, possessing a hockey stick molecular shape, and comparing their doping effect with the one of the dimeric dopants CB7CB possessing a symmetric bend molecular shape. All dopants were dissolved in small concentration (5 wt %) in the nematic host so that the linear approximation of the dependence of the difference between splay e s and bend e b flexoelectric constants, that is, ( e s – e b ), on the concentration of the dopant in the host material can be applied. In this way, ( e s – e b ) was estimated for the hockey stick dopants SK 1–6 and SK 1–8 to be 0.182 and 0.204 nC/m, respectively. The obtained flexoelectric polarization of these dopants is among the highest reported in the literature so far.

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“…Interestingly,w ewerea ble to successfully grow crystalss uitable for SCXRD experiments (see the Supporting Information for details) of one of the representative examples,c ompound 1-4, to demonstrate the bent angle of the compound, which is an important parameteri nt he field of BCLCs and investigate the elusivec haracteristics of molecular packing (Figure 2a-f). [52][53][54][55][56][57] Compound 1-4 was found to crystallize in the monoclinic Figure 1. Chiral bent-core molecules with a) a ÀCH 3 moiety at the kink position (previously reported in ref.…”

Section: Single-crystal X-ray Diffraction (Scxrd) Studiesmentioning

confidence: 99%

Chiral Bent‐Shaped Molecules Exhibiting Unusually Wide Range of Blue Liquid‐Crystalline Phases and Multistimuli‐Responsive Behavior

Punjani

Mohiuddin

Kaur

et al. 2020

Chemistry A European J

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Recently,a nu nprecedented observation of polar order,t hermochromic behavior,a nd exotic mesophases in new chiral, bent-shapeds ystemsw ith a ÀCH 3 moiety placed at the transverse position of the central core was reported. Herein,ah omologous series of compounds with even-numbered carbonc hains from n = 4t o1 8w ere synthesized, in which ÀCl was substituted for ÀCH 3 at the kink position and ad rastic modification in the phase structure of the bentshaped moleculew as observed. An unusuals tabilization of the cubic blue phase (BP) over aw ide range of 16.4 8Ch as been witnessed. Twoh omologues in this series (1-12 and 1-14) exhibit an interesting phase sequence consisting of BPI/ II, chiraln ematic, twist grain boundary,s mectic A, and smectic X( SmX) phases.T he higher homologues( 1-16 and 1-18) stabilizet he SmX phase enantiotropically over the entire temperature range. Crystal structure analysis confirmed the bent molecular architecture, with ab ent angle of 1488,a nd revealed the presenceo ft wo different molecular conformations in an asymmetric unit of compound 1-4. AD FT study corroborated that the ÀCl moiety at the central core of the molecule led to an increasei nt he dipole momenta long the transverse direction, which, in turn, facilitated the unusual stabilization of frustrated structures.C rystal polymorphism has been evidenced in three homologues( 1-10, 1-12, and 1-14) of the series. On the application of mechanical pressure through grinding, compound 1-10 transformedf rom a brighty ellow crystalline solid to ad ark orange-green amorphouss olid, which reversed upon dropwise additiono fd ichloromethane, indicating reversible mechanochromism in this class of compounds. In addition,e xcellent thermochromic behavior has been observed for compound 1-10w ith a controlled temperature-colorcombination.Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.[a] Cr = crystal;I so = isotropic;N cyb * = chiral nematic phase composed of Sm clusters;T GBA = twist grain boundary phase;S mectic A = SmA; Smectic X = SmX. [b] Phaset ransitionso bserved by meanso fP OM in an ITO-coated planar cell (antiparallelrubbing). [c] Phase transitionso bserved by means of SAXS/WAXS.( 1-14: Cr 1a = amorphous,C r 2b = transition crystalline state, Cr 3c = crystal polymorph.)Chem.E ur.

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Structural organization and molecular self-assembly of a new class of polar and non-polar four-ring based bent-core molecules

Cited by 15 publications

References 61 publications

Observation of “de Vries-like” properties in bent-core molecules

Observation of “de Vries-like” properties in bent-core molecules

Flexoelectric Polarization in a Nematic Liquid Crystal Enhanced by Dopants with Different Molecular Shape Polarities

Chiral Bent‐Shaped Molecules Exhibiting Unusually Wide Range of Blue Liquid‐Crystalline Phases and Multistimuli‐Responsive Behavior

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