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TADDOLs with Unprecedented Helical Twisting Power in Liquid Crystals. Preliminary communication
Author(s) -
Kuball HansGeorg,
Weiß Bernhard,
Beck Albert K.,
Seebach Dieter
Publication year - 1997
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19970800818
Subject(s) - chemistry , dopant , liquid crystal , mesophase , sign (mathematics) , benzonitrile , crystallography , stereochemistry , organic chemistry , condensed matter physics , doping , mathematical analysis , physics , mathematics , phase (matter)
A large number of TADDOL (α,α,α′, α′‐ t etraaryl‐1,3‐ d ioxolan‐4,5‐ d imethan ol ) derivatives has been tested as chiral dopants for inducing conversion of nematic to cholesteric phases. With the Merck liquid‐crystal materials ZLI‐1695 and K15 , it was demonstrated that some TADDOLs have unprecedentedly high helical twisting powers (HTP). Thus, the TADDOL with four 9‐phenanthryl α‐substituents has a HTP in the achiral mesophase 4‐(4‐pentylphenyl)benzonitrile of 405 μm −1 between 24 and 34°. The temperature‐dependent HTP measurements have been performed by analyzing Grandjean textures microscopically ( Cano method). The structure‐dependent HTP of various types of TADDOL dopants is discussed. There are similarities between size and sign of HTP on the one hand, and between degree and relative topicity of enantioselectivity in reactions, on the other hand, as caused by TADDOLs and by 1,1′‐binaphthols.