5519-23-3Relevant academic research and scientific papers
Synthesis and characterization of biphenyl-based azo liquid crystals and its optical properties: effect of lateral and tail group
Thakor, Akshay,Dwivedi, Durgesh J.,Desai, Vipul,Jadeja, Upendra H.,Sharma, Vinay S.,Patel
, p. 8 - 26 (2021/07/06)
An azo ester-based biphenyl substituted rod-shaped azo-based material has been synthesized and well-characterized and further studied their mesogenic, optical, and thermal properties. All the synthesized derivatives displayed enantiotropical nematic and SmC phases with good temperature range of mesophase which is further influence by the variation of alkyl chain. The present synthesized derivatives having left terminally substituted phenyl ring by -OR inbuilt with ester azo group and right terminally dodecyloxy tail (-OC12H25) at the right terminal end. The mesomorphism is measured by using POM, DSC, and high-temperature XRD technique, and the photophysical behavior was measured by UV-Vis spectroscopy.
Synthesis and mesomorphic properties of bis ester derivatives of coumarin containing chalcone linkage
Shah, Priyanka,Soni, Rina,Soman, Shubhangi S
, (2021/05/04)
Bis ester derivatives of coumarin containing chalcone linkage with various terminal alkoxy groups were designed, synthesized and characterized. Compounds 11a-m were studied for their mesomorphic properties using polarizing optical microscope & differential scanning calorimetry and photophysical properties using UV-vis & fluorescence spectroscopy. In this particular homologous series, compounds having lower flexible alkoxy chains showed very good mesogenic property with nematic mesophase formation, while analogues with higher chains failed to show any liquid crystalline property. Compound 11a with methoxy group showed very good absorbance and fluorescence as compared to higher chain length analogues.
Synthesis, mesomorphic properties and biological evolution of calamitic-shaped chalcone-based LCs: effect of lateral and terminal group
Dwivedi, Durgesh J.,Thakor, Akshay,Desai, Vipul,Sharma, Vinay S.,Patel
, p. 16 - 32 (2021/05/26)
The mesomorphic properties of linear shaped homologous series based on two linkage group have been designed and synthesized with different side chain substituents (-OR) on the one end of terminal side with presence of lateral nitro group and second terminal iodo substituted group. Novel series consists thirteen members (C1 to C8, C10, C12, C14, C16, C18). Compounds (C1 to C6) showed nonliquid crystalline properties while compound (C7 to C18) displayed smectic and nematogenic mesophase properties. The textures of smectic C and nematic phase are fan, schlieren and droplets type. All these compounds were characterized by spectroscopic techniques such as [FTIR] and 1H Nuclear magnetic resonance [NMR] spectroscopy. The mesomorphic properties of these compounds were observed by POM and further confirmed by DSC and XRD. Chalconyl ester based compounds (C3 to C12) shows good antibacterial as well as antifungal activity compared with corresponding standard drugs.
Influence of different linkages on the mesomorphic properties of aromatic ring system liquid crystals
Al-Hamdani, Uhood J.,Shihabaldain, Nezar L.,Al-Mayah, Duaa S.,Jassem, Ahmed M.
, p. 13 - 24 (2021/07/06)
In order to study the effect of the central linkage on the mesomorphic behaviour of aromatic ring liquid crystals we have synthesized two homologues groups, group A includes compounds 1a-d and group B includes compounds 2a-e. Group A has azo, azomethine,
λ-shaped to T-shaped azo diester mesogens having methyl (–CH3)/methoxy(–OCH3) terminal substituents with trisubstituted benzene
Duan, Yongtao,Koshti, Rohit R.,Kumar Ameta, Rakesh,Patel, H. N.,Sangani, Chetan B.,Tarpada, Umesh P.,Vyas, Akshay,Yao, Yongfang
, (2021/07/12)
A two new homologous series of λ-shape to T-shape mesogenic azo diesters were synthesized, and their thermotropic properties were studied by differential scanning calorimetry and a hot-stage polarizing optical microscope. The difference between these two series is in the structure of terminal substituents methyl (–CH3) for series I and methoxy (–OCH3) for series II at one terminus. Structure variation from λ-shape to T-shape as we go from lower members to higher members is discussed. In the series I, methoxy to n-pentyloxy derivatives are non-mesogenic. n-hexyloxy derivative exhibits only monotropic nematic mesophase. n-heptyloxy to n-dodecyloxy derivatives exhibit monotropic smectic C mesophase. n-tetradecyloxy derivative exhibits enantiotropic SmA mesophase, whereas n-hexadecyloxy derivatives exhibit monotropic Smectic A mesophase. In series II, methoxy to n-hexyloxy derivatives are non-mesogenic. n-heptyloxy and n-octyloxy derivatives exhibit monotropic smectic C mesophase. Smectic A mesophase commences from the n-decyloxy derivative as a monotropic and persists up to the last member synthesized. The mesomorphic properties of the present series were compared with each other and with the structurally related mesogenic homologous series to evaluate the effect of methyl (–CH3)/methoxy (–OCH3) substituents as well as variation in the shape of the molecule by varying the alkoxy chain length of the bulky lateral substituent on mesomorphism.
Synthesis and mesomorphic characterization of some novel steroidal mesogens: A structure–property correlation
Bhat S, Vanishree,Kumar, Sandeep,Raghunathan, V. A.
, (2021/08/25)
The steroidal derivatives are found to be extremely good mesogens since their inception. Because of their inherent chirality, they have the potential to induce a wide variety of liquid crystalline phases, including frustrated phases depending upon the structure of the steroidal skeleton and the substituents attached. In this report, a series of novel monoalkoxy and dialkoxy benzoate derivatives of ergosterol and a few monoalkoxy derivatives of stigmasterol have been synthesized and their mesomorphic property has been investigated. The derivatives exhibited various mesophases including SmA, SmC*, N*, TGB and blue phases. Also, the gelation ability of some of these derivatives with various organic solvents has been examined. Furthermore, the mesomorphism of these derivatives has been compared with the analogous cholesteryl counterparts.
Photoconductive bent-core liquid crystalline radicals with a paramagnetic polar switchable phase
Shivakumar, Kilingaru I.,Pociecha, Damian,Szczytko, Jacek,Kapu?ciński, Szymon,Monobe, Hirosato,Kaszyński, Piotr
supporting information, p. 1083 - 1088 (2020/02/05)
A series of self-organizing bent-core derivatives 1[12,n], containing a highly π-delocalized stable radical as the central angular structural element, is described. The planarity of the open-shell core permits efficient π-π stacking, which results in the formation of B2 and soft crystalline phases above 100 °C. Optical, XRD and dielectric analyses of 1[12,12] indicate that the ground state of the observed B2 phase is polar antiferroelectric of type SmCAPA exhibiting tristable electro-optical switching. SQUID and EPR measurements revealed strong antiferromagnetic spin-spin exchange interactions below the isotropic phase, which have been estimated at θ = -46 cm-1 with the Curie-Weiss law. Transient photoconductivity was observed in the B2 phase with a hole carrier mobility μh of 1.4 × 10-4 cm2 V-1 s-1
Synthesis of novel liquid crystalline and fire retardant molecules based on six-armed cyclotriphosphazene core containing Schiff base and amide linking units
Guan-Seng, Tay,Jamain, Zuhair,Khairuddean, Melati
, p. 28918 - 28934 (2020/08/25)
Nucleophilic substitution reaction between 4-hydroxybenzaldehyde and hexachlorocyclotriphosphazene, HCCP formed hexakis(4-formlyphenoxy)cyclotriphosphazene, 1. Intermediates 2a-e was formed from the alkylation reaction of methyl 4-hydroxybenzoate with alkyl bromide which further reduced to form benzoic acid intermediates. Further reaction of 2a-e and other substituted benzoic acid formed 3a-h, which then reduced to give subsequent amines, 4a-h. Other similar reaction was used to synthesis 4i. Condensation reaction between 1 and 4a-i yielded hexasubstituted cyclotriphosphazene compounds, 5a-i having Schiff base and amide linking units, and these compounds consist of different terminal substituents such as heptyl, nonyl, decyl, dodecyl, tetradecyl, hydroxy, carboxy, chloro, and nitro groups, respectively. Compound 5j with amino substituent at terminal end was formed from the reduction of 5i. All the intermediates and compounds were characterized using Fourier Transform Infrared (FT-IR), Nuclear Magnetic Resonance (NMR) and CHN elemental analysis. Mesophase texture of these compounds were determined using Polarized Optical Microscope (POM) and their mesophase transition were further confirmed using Differential Scanning Calorimetry (DSC). Only compounds 5a-e with alkoxy chains exhibited smectic A phase while other intermediates (1, 2a-e, 3a-h, and 4a-i) and final compounds (5f-j) are found to be non-mesogenic with no liquid crystal behaviour. The confirmation of the identity of the SmA phase was determined using XRD analysis. The study on the structure-properties relationship was conducted in order to determine the effect of the terminal group, length of the chains and linking units to the mesophase behaviour of the compounds. Moreover, the fire retardant properties of these compounds were determined using Limiting Oxygen Index (LOI) testing. Polyester resin with LOI value of 22.53% was used as matrix for moulding in the study. The LOI value increased to 24.71% when this polyester resin incorporated with 1 wt% of HCCP. Generally, all the final compounds showed a positive results with LOI value above 27% and the highest LOI value was belonged to compound 5i with 28.53%. The high thermal stability of the Schiff base molecules and the electron withdrawing group of the amide bonds and nitro group enhanced the fire retardant properties of this compound.
Hydrogen bonding and the design of twist-bend nematogens
Crawford, Catriona A.,Gorecka, Ewa,Imrie, Corrie T.,Pociecha, Damian,Storey, John M. D.,Walker, Rebecca
, (2020/02/13)
The phase properties of equimolar mixtures consisting of a hydrogen bond donor, a 4-alkoxybenzoic acid (nOBA), and one of two different stilbazole-based hydrogen bond acceptors, either 4-[(E)-2-(4-{[6-(4′-methoxy[1,1′-biphenyl]-4-yl)hexyl]oxy}phenyl)-ethenyl]-pyridine (1OB6OS) or 4-[(E)-4′-(6-{4-[(E)-2-(pyridin-4-yl)ethenyl]phenoxy}hexyl)-[1,1′-biphenyl]-4-carbonitrile (CB6OS) are reported. Neither hydrogen bond acceptor exhibits liquid crystal behaviour whereas the nOBA compounds show smectic and/or nematic behaviour depending on the length of the alkyloxy chain. For the complexes of an nOBA with n = 1–5, both conventional nematic and twist-bend nematic phases were observed, while for n ≥ 6 smectic phases emerged and the twist-bend nematic phase was extinguished. The CB6OS-nOBA mixtures may exhibit the heliconical smectic CTB phase. The local molecular arrangement in the two sets of mixtures are similar and changes on increasing n but this is not reflected in the nematic-isotropic transition temperatures. Birefringence studies of the mixtures are reported. In general the behaviour of the hydrogen-bonded mixtures is similar to that of their covalently bonded counterparts.
