Comparison of helical twisting powers of novel fluorinated amphiphilic enantiomers with their hydrogenated counterparts
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Dosyalar
Tarih
2006
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Academic Press Inc Elsevier Science
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
This is the first report on novel amphiphilic enantiomers as esters of alanine and serine with a partially fluorinated octyl chain (L-APFOE and L-SPFOE), which form intrinsic chiral nematic (N*) phases with water only and exhibit very high helical twisting powers (htps) compared to their hydrogenated counterparts, dodecylesters of L-alanine (L-ADDE) and L-serine (L-SDDE). They also exhibit a wider N* range than those known in the literature. Furthermore, the htps of the chiral dopants mandelic acid (MA) and hexahydromandelic acid (HHMA) in the racemic nernatic phase of DL-SPFOE and DL-APFOE are remarkably higher than those in the hydrogenated counterparts. The tremendous increase in chirality (htps) of the same single chiral center is a new phenomenon in micellar N* phases and is attributed to a "pivot" effect of the fluoroalkyl chain. As a result, a "skewed micelle" model is proposed to explain why the htp value of L-APFOE is higher than that of L-SPFOE, and accordingly how the intermicellar chirality transfer (chiral induction) may be visualized. The simplicity of these binary mixtures and the enlargement in htp of the single chiral centers visualized as the "skewed micelle" model may provide a basis vital for future computer modeling of chiral lyotropics.
Açıklama
Anahtar Kelimeler
Helical Twisting Powers, Fluorinated/Hydrogenated Chiral Amphiphiles, Chiral Lyotropic Phases
Kaynak
Journal Of Colloid And Interface Science
WoS Q Değeri
Q2
Scopus Q Değeri
Q1
Cilt
300
Sayı
1
