Contribution of Solvents to Geometrical Preference in the Z/E Equilibrium of N-Phenylthioacetamide

We studied the Z/E preference of N-phenylthioacetamide (thioacetanilide) derivatives in various solvents by means of ¹H NMR spectroscopy, as well as molecular dynamics (MD) and other computational analyses. Our experimental results indicate that the Z/E isomer preference of secondary (NH)thioamides of N-phenylthioacetamides shows substantial solvent dependency, whereas the corresponding amides do not show solvent dependency of the Z/E isomer ratios. Detailed study of the solvent effects based on molecular dynamics simulations revealed that there are two main modes of hydrogen (H)-bond formation between solvent and (NH)thioacetamide, which influence the Z/E isomer preference of (NH)thioamides. DFT calculations of NH-thioamide in the presence of one or two explicit solvent molecules in the continuum solvent model can effectively mimic the solvation by multiple solvent molecules surrounding the thioamide in MD simulations and shed light on the precise nature of the interactions between thioamide and solvent. Orbital interaction analysis showed that, counterintuitively, the Z/E preference of NH-thioacetamides is mainly determined by steric repulsion, while that of sterically congested N-methylthioacetamides is mainly determined by thioamide conjugation.

Inclusion crystals of V-shaped host molecules having trialkoxybenzene moieties with a carborane or benzoquinone derivative

Crystallization of an o-carborane or benzoquinone derivative with adamantane-based molecules possessing pyrogallol derivatives resulted in the formation of inclusion crystals through CH⋯O or lone pair⋯π interactions.

Co-Inclusion of cyclic ethers and chloroform by a macrocycle with benzophenone-3,3′,4,4′-tetracarboxylic diimide units

Crystallization of a diimide-based macrocycle having adamantane parts and several cyclic ethers in chloroform provided inclusion crystals, where both guests were cooperatively accommodated within inner spaces between the macrocycles.