Circular dichroism spectra of the achiral guest N-aryl-N-nitrosamines included in the crystal host matrices of cholic acid.

The crystalline inclusion complexes of cholic acid with three symmetric N-aryl-N-nitrosamines were prepared, and their X-ray structures were solved. As a result of chiral conformations adopted by the enclathrated guest nitrosamines, the solid-state CD spectra were measured in KBr disks. The observed Cotton effect sign, corresponding to the n-pi* transition, was correlated with the helicity of the twisted nitrosamine chromophore conjugated with the N-aryl substituent. In addition, the absolute configuration of the enantiomorphous crystals of N-benzyl-N-nitroso-4-chloroaniline was established on the basis of the solid-state CD and X-ray crystallographic results.