Non-covalent structure-forming bonding of 2-aryhydrazone thiazolo[3,2-a]pyrimidines in the crystalline phase

Currently, hydrazones are promising building blocks for the creation of various supramolecular architectures, since they can undergo conformational and configuration changes under the influence of external conditions. Thus, from the point of view of supramolecular chemistry, the potential use of compounds containing a hydrazone functional group for the design of molecular switches, as well as for the creation of new materials, has been demonstrated.

This work is devoted to the synthesis and study of 2-arylhydrazone thiazolo[3,2-a]pyrimidine derivatives structures in the crystalline phase.

The obtained derivatives are characterized using a complex of physico-chemical (IR-, NMR ¹H- and ¹³C-spectroscopy, ESI-MS spectrometry, and X-ray diffraction) analyses.

It was confirmed that arylhydrazones are in the Z-isomer form in the crystalline phase. Additionally, it was established that non-covalent intramolecular and intermolecular interactions play the main role in supramolecular organization in crystals. So, the formation of hydrogen-, chalcogen-, π-π-bonded racemic dimers, and halogen-bonded homochiral chains was shown.

The structure of arylhydrazones containing halogen substituents in aryl fragments has also been studied. The embedding of a sterically inaccessible halogen substituent, blocked for the formation of intermolecular interactions, into one of two aryl fragments that switch off the action of structure-forming halogen bonding in one position and switch on in the second one, together leads to different self-assembly in the crystalline phase.

Thus, the synthesis and study of the supramolecular organization of 2-arylhydrazone thiazolo[3,2-a]pyrimidine derivatives in the solid phase were successfully carried out, and the possibility of implementing various supramolecular ensembles was discovered.