The effect of terminal substituents on crystal structure, mesophase behaviour and optical property of azo-ester linked materials

Karim, Md. Rabiul; Sheikh, Md. Rezaul Karim; Yahya, Rosiyah; Salleh, Noordini M.; Lo, Kong Mun; Mahmud, Habibun Nabi Muhammad Ekramul

doi:10.1080/02678292.2016.1216620

Cited by 57 publications

(9 citation statements)

References 40 publications

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“…Weight loss of the polymers demonstrates three stages with respect to the temperature. The first one occurs within 298–316 °C, which corresponds to the azo groups’ and aliphatic units’ decomposition . The second one, within the range of 330–504 °C, is connected with the azomethine groups’ decomposition.…”

Section: Resultsmentioning

confidence: 96%

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Photoactive Fluorinated Poly(azomethine)s with Azo Groups in the Main Chain for Optical Storage Applications and Controlling Liquid Crystal Orientation

Kovalchuk

Kobzar

Ткаченко

et al. 2019

ACS Appl. Polym. Mater.

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Polymer multicomponent materials containing conjugated fragments (such as azo- or azomethine groups) have attracted significant attention due to their possible use in the efficient reversible stimuli-responsive, light-responsive devices. Light-responsive polyazomethines with azo groups in the backbone (Azo-Pams) are synthesized by polycondensation of tetrafluorobenzene- or octafluorobiphenylene-based bis-hydroxybenzaldehydes with hexamethylenediamine. The polymers feature the simultaneous combination of azo and azomethine groups inside one conjugated block. The synthesized polymers can be solution cast into flexible solid films with tensile strength of about 24 MPa. We found that the obtained Azo-Pam polymers have an amorphous structure (T g ∼ 134 °C) and high thermal stability (up to 300 °C). Their optical spectra depend on the solvent type and its pH which influence the dynamical equilibrium between the tautomeric forms. It also determines the balance between the main (azo form) and the ionized form in the solvent and allows to purposefully regulate the absorption maxima. We demonstrate the ability to record optical information using Azo-Pam films in the form of polarization gratings (holograms) with a regulated diffraction efficiency. A uniform orientation of liquid crystal is achieved by a polarized UV irradiation of glass substrates covered with the polymer Azo-Pam-II. The obtained data show that the synthesis strategy of the Azo-Pam polymers is an effective instrument for designing a wide range of stimuli-responsive and optical active materials.

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Section: Resultsmentioning

confidence: 96%

“…The single broad peak (amorphous halo) at 2θ ∼ 20.6° with the d -spacing of about 0.33 nm was observed for each polymer sample. The measured distance can be attributed to the space between efficiently packed polymer chains …”

Section: Resultsmentioning

confidence: 99%

Photoactive Fluorinated Poly(azomethine)s with Azo Groups in the Main Chain for Optical Storage Applications and Controlling Liquid Crystal Orientation

Kovalchuk

Kobzar

Ткаченко

et al. 2019

ACS Appl. Polym. Mater.

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“…The existence of mesophases near room temperature is very important for potential applications; consequently, lateral moieties are incorporated into the molecular architecture to lower the melting temperature [ 26 ]. On the other hand, polar terminal substituents and linking moieties were both important factors for the designed compounds, in terms of the formation, kind, thermal stability, and range of the observed mesophase [ 5 , 12 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ].…”

Section: Introductionmentioning

confidence: 99%

Synthetic, Mesomorphic, and DFT Investigations of New Nematogenic Polar Naphthyl Benzoate Ester Derivatives

et al. 2021

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Four new non-symmetrical derivatives based on central naphthalene moiety, 4-((4–(alkoxy)phenyl) diazenyl)naphthalen–1–yl 4–substitutedbenzoate (In/x), were prepared, and their properties were investigated experimentally and theoretically. The synthesized materials bear two wing groups: an alkoxy chain of differing proportionate length (n = 6 and 16 carbons) and one terminal attached to a polar group, X. Their molecular structures were elucidated via elemental analyses and FT-IR and NMR spectroscopy. Differential scanning calorimetry (DSC) and polarized optical microscopy (POM) were carried out to evaluate their mesomorphic properties. The results of the experimental investigations revealed that all the synthesized analogues possess only an enantiotropic nematic (N) mesophase with a high thermal stability and broad range. Density functional theory (DFT) calculations were in accordance with the experimental investigations and revealed that all prepared materials are to be linear and planar. Moreover, the rigidity of the molecule increased when an extra fused ring was inserted into the center of the structural shape, so its thermal and geometrical parameters were affected. Energy gap predictions confirmed that the I16/c derivative is more reactive than other compounds.

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“…Sardon et al (2021) synthesized compounds 40 (a–d) and compared them with a compound studied back in 2016 by Karim et al, labeled as compounds 41 (b–c) [ 49 , 50 ]. The result of this observation is illustrated in Table 1 .…”

Section: Structure–property Relationshipmentioning

confidence: 99%

Liquid Crystals Investigation Behavior on Azo-Based Compounds: A Review

Razali

Jamain

2021

Polymers

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Liquid crystal is an intermediate phase between the crystalline solid and an isotropic liquid, a very common substance in our daily lives. Two major classes of liquid crystal are lyotropic, where a liquid crystal is dissolved in a specific solvent under a particular concentration and thermotropic, which can be observed under temperature difference. This review aims to understand how a structure of a certain azo compound might influence the liquid crystal properties. A few factors influence the formation of different liquid crystals: the length of the alkyl terminal chain, inter/intra-molecular interaction, presence of spacer, spacer length, polarization effects, odd-even effects, and the presence of an electron-withdrawing group or an electron-donating group. As final observations, we show the compound’s different factors, the other liquid crystal is exhibited, and the structure–property relationship is explained. Liquid crystal technology is an ideal system to be applied to products to maximize their use, especially in the electronic and medical areas.

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The effect of terminal substituents on crystal structure, mesophase behaviour and optical property of azo-ester linked materials

Abstract: Table SI1: FT-IR vibrational frequencies for main functional groups and 1 H NMR chemical shifts of different type of protons present in compounds C1-C6 Wavenumber (cm -1 ) Functional groups (CH, aliphatic) (C=O in ester) (C=C, vinyl) (C=C, aromatic) (N=N)

Cited by 57 publications

References 40 publications

Photoactive Fluorinated Poly(azomethine)s with Azo Groups in the Main Chain for Optical Storage Applications and Controlling Liquid Crystal Orientation

Photoactive Fluorinated Poly(azomethine)s with Azo Groups in the Main Chain for Optical Storage Applications and Controlling Liquid Crystal Orientation

Synthetic, Mesomorphic, and DFT Investigations of New Nematogenic Polar Naphthyl Benzoate Ester Derivatives

Liquid Crystals Investigation Behavior on Azo-Based Compounds: A Review

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