Dynamic Covalent Spiropyran Exchange for Rapid Structural Diversification.

Here we disclose that spiropyrans are able to undergo dynamic covalent exchange via their corresponding merocyanine isomers. In the latter, the indolinium moieties can be exchanged by a Michael-type addition-elimination sequence, in which a methylene indoline attacks a merocyanine and subsequently the initial indoline fragment is cleaved. The rate and position of the exchange equilibrium strongly depend on the reaction conditions as well as the substitution pattern on the methylene indoline fragments.

MRI findings in six dogs with ependymoma of the brain and spinal cord.

There are few published descriptions of the MRI appearance of canine intracranial or spinal cord ependymoma. In this multicenter, retrospective, secondary analysis, case series study, three veterinary radiologists independently reviewed and recorded imaging characteristics of MRI studies in six dogs with histopathologically confirmed ependymoma (three intracranial and three spinal cord cases). A consensus was reached when there was disagreement on specific features.

Voltage-Gated Switching of Moiré Patterns in Epitaxial Molecular Crystals.

Studying molecular materials at the nanoscale allows us to gain a deeper understanding of supramolecular structure formation and serves as the basis for rationally controlling the resulting interfacial properties. Here, we describe the formation of extended Moiré patterns resulting from the assembly of dipolar π-conjugated molecules on highly oriented pyrolytic graphite at the liquid-solid interface as characterized by scanning tunneling microscopy (STM). By switching the bias of the sample and thus the orientation of the external electric field in the vicinity of the STM junction, structural reorganization of the molecular building blocks and the resulting organic 2D crystal is induced and can conveniently be monitored by the appearance and disappearance of the Moiré patterns.