Influence of terminal halogen moieties on the phase structure of short-core achiral hockey-stick-shaped mesogens: design, synthesis and structure–property relationship

Kaur, Supreet; Mohiuddin, Golam; Satapathy, Pragnya; Nandi, Rajib; Punjani, Vidhika; Prasad, S. Krishna; Pal, Santanu Kumar

doi:10.1039/c8me00027a

Cited by 18 publications

(18 citation statements)

References 74 publications

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“…This observation of diffuse peaks in both small-and wide-angle regions confirmed the presence of ad isordered mesophase. In the XRD scan of 1-10 upon cooling, the intensity of the small-angle peak was greater than that of the wide-angle peak, [60,61]…”

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

confidence: 94%

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

confidence: 94%

“…General Details of the characterization techniques have been published elsewhere. [47,60] Briefly,the instrumental details are as follows. Structural characterization of the compound was performed through a combination of 1 Ha nd 13 CNMR spectroscopy (Bruker Biospin Switzerland AvanceIII 400 MHz).…”

Section: Methodsmentioning

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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“…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%

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

et al. 2022

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“…The instrumental details for structural characterization are similar to as mentioned in our previous papers [46,47,49] and briefed here for the reader's convenience. “Structural characterization of the compounds was carried out with a combination of Attenuated total reflectance (ATR; FTIR Bruker‐ALPHA Bruker‐1227‐3513), UV‐Vis‐NIR spectrophotometer (LABINDIA UV‐Vis Spectrophotometer 3000+), High Resolution Mass Spectrometry (Waters synapt g2s), 1 H NMR and 13 C NMR (Bruker Biospin Switzerland Avance III 400 MHz and 100 MHz spectrometers, respectively).…”

Section: Methodsmentioning

confidence: 99%

Photo‐Responsive Behavior of Azobenzene Based Polar Hockey‐Stick‐Shaped Liquid Crystals

et al. 2021

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A study on the photoswitching behavior of azobenzene‐based polar hockey‐stick‐shaped liquid crystals (HSLCs) has been presented. Two new series of five phenyl rings based polar HSLCs have been designed and synthesized. Solution state photoisomerization of the synthesized materials was investigated thoroughly via UV‐visible and 1H NMR spectroscopic techniques, whereas solid‐state photochromic behavior was elucidated via physical color change of the materials, solid‐state UV‐visible study, powder XRD, and FE‐SEM techniques. The materials exhibited decent photochromic behavior for different potential applications. The thermal phase behavior of the superstructural assembly has been characterized via polarizing optical microscopy (POM), differential scanning calorimetry (DSC), and temperature‐dependent small and wide‐angle X‐ray scattering (SAXS/WAXS) studies. Depending upon the length of the terminal alkyl chain, nematic (N) and partially bilayer smectic A (SmAd) phases were observed. DFT calculations revealed the favorable anti‐parallel arrangement of the polar molecules that substantiate the formation of SmAd phase.

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Influence of terminal halogen moieties on the phase structure of short-core achiral hockey-stick-shaped mesogens: design, synthesis and structure–property relationship

Abstract: An extensive study on the effect of terminal halogens on the structure–property relationship of polar L-shaped mesogens has been elucidated.

Cited by 18 publications

References 74 publications

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

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

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

Photo‐Responsive Behavior of Azobenzene Based Polar Hockey‐Stick‐Shaped Liquid Crystals

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