Structural analysis of bis(pyridyl)diimines: Factors affecting the molecular geometry and supramolecular packing

Abstract

Systematic analysis of structural features of a series of bis(pyridyl)diimines is done to have an understanding on the effect of different types of interactions in modulating the molecular geometry and final packing of the molecules in the solid state. Supramolecular synthons that may result from weak interactions such as CH···N and aromatic interactions are difficult to predict and hence analyzing homologous series of compounds, which can organize only by weak interactions will lead to generating data sets on various possibilities of synthons. In the series of bis(pyridyl)diimines, small variation in the molecular features such as position of nitrogen on pyridyl ring, presence of hydrogen or methyl group on imine carbon and changing the alkyl spacer length is being related to the observed changes in the occurrence of non-covalent interactions and finally in the crystal packing in the solid state. Cooperative effect of intermolecular interactions and steric factors decide the final structural arrangement, which is being inferred by observing the solid state arrangement of the compounds. Crystallization induced emission of the bis(pyridyl)diimines is also studied and correlated with their structural features and the overall supramolecular architecture.