What we can learn about fast chemical processes from slow diffraction experiments

A single-crystal-to-single-crystal Diels–Alder reaction with mixed topochemical and topotactic behaviour

During a SCSC solid-state Diels–Alder reaction, voids are created, followed by conformational change and crystal annealing that lead to the formation of new weak interactions.

New results for phase transitions from catastrophe theory

Catastrophe theory predicts that in certain limits universal relations should exist between barrier heights, curvatures and the positions of local maxima and minima on a potential or free energy surface. In the present work we investigate these relations for both first- and second-order phase transitions, revealing that the ideal ratios often hold quite well over a wide range of conditions. This elementary catastrophe theory is illustrated for the melting transition of an atomic cluster, the isotropic-to-nematic transition in a liquid crystal, and the ferromagnetic-to-paramagnetic phase transition in the two-dimensional Ising model.