Condensation products of formylcamphor with diamines : Structures in alcoholic solutions as derived from uv absorption and circular dichroism spectroscopy

The condensation products of optically active diamines with two molecules of formylcamphor have been investigated in methanolic solutions, where the formylcamphor chromophore is known to exist in the anti or (E) configuration. UV absorption and circular dichroism spectra are rationalised within an exciton formalism to give information about the absolute configuration.As with chloroform solutions, where the chromophore exists in the syn configuration, it is demonstrated that the title compounds may achieve the low energy conformation in seemingly different ways depending on substituents. Because of the different structure of the molecule when the chromophore is in the anti configuration as compared with the syn configuration, rotational conformations with respect to the substituted ethylene bridge in the same compound may be different in CH₃OH and CHCl₃.Finally “chelating solvation” in hydrogen bonding media is demonstrated through dissolution of the compounds in various alcohols.