Anatoliy N. Sokolov

Supramolecular Catalysis in the Organic Solid State through Dry Grinding

[Figure Presented] Chemical mechanics: Hydrogen-bonddriven self-assembly and mechanochemistry are used to facilitate supramolecular catalysis in the solid state. Mortar-andpestle grinding proves to be an efficient means to achieve co-crystal formation and turnover using a physical mixture composed of an olefin and catalytic amounts of a ditopic template (see scheme).

Conformational polymorphism in a heteromolecular single crystal leads to concerted movement akin to collective rack-and-pinion gears at the molecular level

We describe a heteromolecular single crystal that exhibits three reversible and concerted reorganizations upon heating and cooling. The products of the reorganizations are conformational polymorphs. The reorganizations are postulated to proceed through three motions: (i) alkyl translations, (ii) olefin rotations, and (iii) rotational tilts. The motions are akin to rack-and-pinion gears at the molecular level. The rack-like movement is based on expansions and compressions of alkyl chains that are coupled with pinion-like 180° rotations of olefins. To accommodate the movements, phenol and thiophene components undergo rotational tilts about intermolecular hydrogen bonds. The movements are collective, being propagated in close-packed repeating units. This discovery marks a step to understanding how organic solids can support the development of crystalline molecular machines and devices through correlated and collective movements.