Search

The article describes the self-assembly of the mixture of 1,1-dihydroperfluorooctyl (HPFO) end-capped polystyrene (HPFO-PS) and the corresponding HPFO end-capped polybutylmethacrylate (HPFO-PBMA). Transmission electron microscopy shows that 1/1 (w/w) blends of the mixture form block copolymer-like lamellar structures. The authors explain the film of the 1/1 (w/w) blended HPFO end-functionalized polymers was transparent above 340 nm, while the corresponding homopolymers was opaque below 1000 nm.

The introduction of the CF3 group on the C9 atom in quinidine can significantly increase the conformational interconversion barrier of the cinchona alkaloid scaffold. With this modification the conformational behavior of cinchona alkaloids in various solvents can be conveniently investigated via 19F NMR spectroscopy. Based on the reliable conformational distribution information obtained, the accuracy of both theoretical (PCM) and empirical (Kamlet—Taft) solvation models has been assessed using linear free energy relationship methods. The empirical solvation model was found to provide accurate prediction of solvent effects, while PCM demonstrated a relatively low reliability in the present study. Utilizing similar empirical solvation models along with Karplus-type equations, the conformational behavior of quinidine and 9-epi-quinidine has also been investigated. A model SN2 reaction has been presented to reveal the important role of solvent-induced conformational behavior of cinchona alkaloids in their reactivity. [ABSTRACT FROM AUTHOR]

The trifluoromethyl substituent has been incorporated into quinidine as a conformational stabilizer and a probe to provide straightforward insight into the conformational behavior of cinchona alkaloids. By significantly decreasing the rotation rate of the quinoline-carbinol bond, the relatively bulky CF3 group enables the NMR signals of the syn and anti conformers to be differentiated at room temperature. In addition to the stabilizing effect, the introduction of the fluorinated moiety also facilitates the application of 19F NMR spectroscopy, thereby allowing conformational studies under various conditions without the use of deuterated solvents. [ABSTRACT FROM AUTHOR]