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Chiral supramolecular hosts comprising urea-modified l-phenylalanines and achiral primary amines were developed, which facilitated enantioselective inclusion of alkyl aryl sulfoxides (3) up to 89% ee owing to the formation of ternary inclusion crystals. From the structural optimization of the components, the combination of N-(phenylcarbamoyl)-l-phenylalanine (1a) and benzhydrylamine (2e) showed the best inclusion ability among the considered supramolecular hosts. The type of the hydrogen-bonding network of ammonium-carboxylate salts 1a·2 was dependent on the steric bulk of combined primary amine 2. The rigid phenylurea moiety of 1a and moderate steric bulk of 2e played an important role in their high inclusion ability. Host 1a·2e afforded two ternary polymorphic inclusion crystals with the inclusion of acetonitrile. Furthermore, the crystal structures of 1a·2e·3 revealed that the inclusion of 3 was assisted by hydrogen bonding to the host and that stereoselectivity reversal occurred for larger sulfoxides, which was attributed to packing variations of one-dimensional hydrogen-bonding networks. [ABSTRACT FROM AUTHOR]

The solubility and phase behavior of linear polymethacrylate polymers, primarily poly(phenylalkyl methacrylate)s, in imidazolium-based ionic liquids (ILs) were systematically studied by changing the structure of each component. Solutions of polymethacrylates in 1-alkyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide ([Cnmim][NTf2]) showed lower critical solution temperature (LCST) phase behavior, and the phase separation temperature (Tc) could be varied by selecting an appropriate combination of a polymer and an IL. An increase in alkyl chain length between the phenyl and ester groups in the polymer side chain decreased the Tc; alternatively, substitution of the imidazolium cation with a longer alkyl chain increased the Tc. When the same anion was used, the miscibility of the polymer/IL system was mainly determined by the alkyl chain length. Tccould also be varied by mixing two ILs in an appropriate ratio. In addition, the kinetics of the reversible phase transition phenomena exhibited by these polymers were examined. Redissolution kinetics were largely controlled by the magnitude of the difference between Tcand the glass transition temperature (Tg) of the polymer (Tc− Tg), in addition to the mutual affinity between the polymer and the IL. [ABSTRACT FROM AUTHOR]

The systematic investigation of supramolecular host systems consisting of a primary amine/carboxylic acids has been performed upon changing the molecular length of the component. The combinations of enantiopure erythro-2-amino-1,2-diphenylethanol (1) and achiral benzoic acid derivatives (2a−e) were found to be effective for the inclusion of 1-phenylethanol derivatives (3a−d) with chiral recognition. X-ray crystallographic analyses revealed that a one-dimensional (1D) helical columnar architecture was commonly constructed in the ternary inclusion crystals. However, there were two types of arrangements of the columns, anti-parallel and parallel, depending on the relative molecular length of 2/3. Similarity in molecular lengths between 2and 3resulted in an anti-parallel alignment of the columns, while a parallel alignment was achieved when one of the two components was much longer than the other; the 1D helical columns tend to align in an anti-parallel manner to cancel their dipole; however, the alignment switches to a parallel manner to avoid the formation of large voids between the columns. [ABSTRACT FROM AUTHOR]