کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5222440 1383454 2009 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Synthesis and thermal properties of liquid crystal trimers comprising cyanobiphenyl and salicylaldimine anisometric segments
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
Synthesis and thermal properties of liquid crystal trimers comprising cyanobiphenyl and salicylaldimine anisometric segments
چکیده انگلیسی

The synthesis and mesomorphism of a series of liquid crystal trimers made by covalently linking two cyanobiphenyl moieties with a central salicylaldimine core through two flexible spacers are reported. Nine different oxyalkyleneoxy spacers varying in the number of carbon atoms and thus, methylene units from 3 to 11 were used to understand structure-mesomorphic property correlations. The optical microscope and differential scanning calorimeter were employed to evaluate their phase transitional behavior. All the trimers exhibit an enantiotropic uniaxial nematic phase over a wide thermal range (>80 °C) while a homolog comprising an octamethylene (even-parity) spacer displays, additionally, a metastable smectic phase. The nematic-isotropic transition temperatures critically depend on the parity of the spacer with the values for the odd-parity spacer containing homologs being lower than those of the even members, a feature generally observed in oligomesogens.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Tetrahedron - Volume 65, Issue 32, 8 August 2009, Pages 6403-6409
نویسندگان
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