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Monotropic or enantiotropic mesophases? Liquid-crystalline and solid state polymorphism 4-chloro-1,3-phenylene bis-[4-(4-alkyloxyphenylazo)benzoates.
Autorzy
Rok wydania
2014
Czasopismo
Numer woluminu
587
Strony
59-66
DOI
10.1016/j.tca.2014.04.024
Kolekcja
Język
Angielski
Typ publikacji
Artykuł
This article presents a homologous series of bent-core molecules consisting of a 4-chlororesorcinol as a central unit and 4-[(4-alkyloxyphenyl)diazenyl]benzoic acids as wings. With the use of polarizing optical microscopy (POM), thermal analysis (TOA) and differential scanning calorimetry (DSC) the mesogenic properties were detected. Furthermore, the X-ray diffraction (XRD) measurements were also performed for selected samples. Compounds of the above mentioned series form nematic, B6, and smectic C mesophases. An interesting phenomenon in the solid phase polymorphism was observed in some cases. In our experiment one crystalline form (CrI) melts to nematic phase while the second form (CrII) melts at higher temperature directly to isotropic phase. The solid state modification determines whether a monotropic and an enantiotropic mesophase is observed.
Słowa kluczowe
Bent-core liquid crystals, Nematic phase, Azobenzene, Smectic C, B6 phase
Adres publiczny
http://dx.doi.org/10.1016/j.tca.2014.04.024
Strona internetowa wydawcy
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