Intramolecular hydrogen bonding in ortho-substituted arylamide oligomers: a computational and experimental study of ortho-fluoro- and ortho-chloro-N-methylbenzamides.

As a part of our systematic study of foldamer structural elements, we analyze and quantify the conformational behavior of two model compounds based on a frequently used class of aromatic oligoamide building blocks. Combining computational and NMR approaches, we investigate ortho-fluoro- and ortho-chloro-N-methylbenzamide. Our results indicate that the -F substituent in an ortho position can be used to fine-tune the rigidity of the oligomer backbone.

Hydrogen bonds in ionic liquids revisited: (35/37)Cl NMR studies of deuterium isotope effects in 1-n-butyl-3-methylimidazolium chloride.

Detailed knowledge of the structure, dynamics, and interionic interactions of ionic liquids (ILs) is critical to understand their physicochemical properties. In this letter, we show that deuterium isotope effects on the chloride ion 35/37Cl NMR signal represent a useful tool in the study of interionic hydrogen bonds in imidazolium chloride ILs. Sizable Delta35/37Cl(H,D) values obtained for the model system 1-n-butyl-3-methylimidazolium chloride ([C4mim]Cl) upon deuteriation of the imidazolium C-2 and C-2,4,5 positions, of nearly 1 and 2 ppm, respectively, show that the approach can readily identify and differentiate Cl.