126957-44-6Relevant articles and documents
An unusual conformation of α-haloamides due to cooperative binding with zincated porphyrins
Tanasova, Marina,Yang, Qifei,Olmsted, Courtney C.,Vasileiou, Chrysoula,Li, Xiaoyong,Anyika, Mercy,Borhan, Babak
supporting information; experimental part, p. 4242 - 4253 (2011/02/25)
CD and NMR spectroscopic evidence of cooperative binding between an α-halogen atom and a carboxamide group with a zinc porphyrin leads to an unprecedented conformation for the determination of the absolute stereochemistry of α-haloamides (α-halocarboxylic acids derivatized with 1,4-phenylenediamine) through the use of exciton-coupled circular dichroism (ECCD). With the use of chiral lactams, whose rotomeric contributions are minimized, both ECCD and NMR spectroscopy demonstrate that the porphyrin favors binding to the side of the sterically more demanding halogen atom as compared to the smaller hydrogen atom. In all, the data is strongly suggestive of an unusual conformation not observed before for α-chiral amides. A mnemonic for determining the absolute stereochemistry of α-halogenated carboxylic acids is provided.
Synthesis and Ferroelectric Properties of 2,5-Diphenylpyrimidines with Different α-Fluorocarboxylic Acids
Boemelburg, Jan,Heppke, Gerd,Ranft, Andreas
, p. 1127 - 1131 (2007/10/02)
Chiral esters of 2--5-pyrimidine and 2--5-pyrimidine with four different α-fluorocarboxylic acids have been synthesized.The spontaneous polarization and the tilt angles in the smectic C* phase were measured as a function of temperature.All compounds exhibit wide range smectic C* phases, the highest values of the spontaneous polarization being about 400 nC/cm2.Additionally the spontaneous polarization in a higher ordered smectic phase was determined, the values ranging up to about 600 nC/cm2.The spontaneous polarization/tilt angle ratio strongly increases with decreasing temperature. - Keywords: Liquid Crystals, Smectic Liquid Crystals, Ferroelectric Properties, Chiral α-Fluorocarboxylic Acid Esters, 2,5-Diphenylpyrimidines