1429432-76-7Relevant academic research and scientific papers
Molecular, spectroscopic and thermal studies on catechol, 4,5-dibromocatechol, resorcinol, hydroquinone and 4-4′-dihydroxybiphenyl derivatives armed with benzothiazole moieties
Alshargabi, Arwa,Yeap, Guan-Yeow,Mahmood, Wan Ahmad Kamil,Samikannu, Rakesh
, p. 189 - 196 (2013)
A new series of catechol, 4,5-dibromocatechol, resorcinol, hydroquinone and 4-4′-dihydroxybiphenyl derivatives possessing two benzothiazole moieties at respective positions of 1,2, 1,3, 1,4 and/or 4,4′ has successfully been synthesized. The molecular structures were fully elucidated by spectroscopic techniques (1H NMR, 13C NMR and two dimensional COSY, HMBC, HMQC, DEPT-135 and DEPT-90). The connectivity study between the cause of using different core systems in the target compounds and the anisotropic behavior as inferred from phase transition temperature and relevant morphology studies has led to some unique features arising from this series. Compounds with ortho substituent exhibit enantiotropic N and SmA phases. The analogues containing resorcinol and 4,4′-disubstituentbiphenyl show enanotiotropic nematic behavior while the hydroquinone derivative induces the formation of monotropic nematogen. An extensive study to further substantiate the relationship between the stability of the nematic phase and associated transition temperatures due to different core systems is also reported.
Synthesis and liquid crystalline studies of disc-shaped molecule on azo-bridged benzothiazole-phenyl ethers
Yeap, Guan-Yeow,Abdul Rahim, Mursyida,Lin, Chien-Min,Lin, Hong-Cheu,Maeta, Nobuyuki,Ito, Masato M.
, p. 734 - 740 (2016)
A new series of triphenylene core attached by six peripheral arms containing benzothiazole-azo with terminal ethoxy unit have successfully been synthesized and their liquid crystalline properties were characterized. The members in this series differ by the length of the methylene unit of [sbnd](CH2)n[sbnd], where n, varied following ascending order from 5 to 10. The molecular structure was characterized by elemental (C, H and N) analysis and spectroscopic methods including Fourier Transform Infrared (FT-IR) and Proton Nuclear Magnetic Resonance (1H NMR). The texture and the phase transition temperatures were investigated by using polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). The disc-shape molecule with shorter spacer (n?=?5) showed monotropic nematic phase. The higher homologues with n?=?8–10 exhibited enantiotropic nematic phase and monotropic smectic C phase. The XRD diffraction studies further confirm the presence of smectic C without any discotic columnar phase.
Synthesis and terminal chain effect on the phase transition behavior of azo-bridged benzothiazole-phenyl ethers
Alshargabi, Arwa,Yeap, Guan-Yeow,Takeuchi, Daisuke,Ito, Masato M.
, p. 128 - 139 (2013/06/27)
A series of azo-bridged benzothiazole-phenyl ethers 4-((6- ethoxybenzothiazol-2-yl)diazenyl)bromoalkoxybenzene in which an exocyclic N=N group is situated between an ethoxy-substituted benzothiazole and a bromoalkoxyphenyl have been synthesized and characterized. The phase transition behavior of these compounds have been correlated against the variation of the flexible alkyl chain with n methylene units (CH2), ranging from 5 to 12. The thermal stability as reflected by the transition temperature range of the present homologues is found to be strongly dependent on the length of the CH2 units. All the members of this series exhibit enantiotropic nematic phases. However, upon further cooling, the compounds with n = 9-12 also behave as smectogens.
