Polymorphs and stoichiometric variants of crown ether-based molecular complexes: exploring the landscape of conformational flexibility and supramolecular interactions†

Abstract

Leveraging supramolecular interactions, we explored the structural diversity of molecular complexes formed from crown ethers and dithiooxamide (DTX) or 3,5-dinitroaniline (DNA). In our attempts to obtain ternary systems, co-crystallization was done in the presence or absence of halogenated compounds to utilize the orthogonality of the supramolecular interactions—hydrogen and halogen bonds. Nevertheless, binary complexes predominated but in diverse crystal forms. Though not present in the crystal lattice, the halogenated compounds, as scaffolds, are critical in attaining the conformational diversity in the crown ethers. The structural diversity in the multi-component systems highlights the versatility of interactions and the conformational flexibility of crown ethers. The adaptable nature of crown ethers facilitated interactions with coformers, resulting in complexes of varied stoichiometries. Experimental and computational analyses reveal distinct conformational motifs favoured by these molecules, influencing interaction profiles and crystal forms. This study underscores the importance of understanding molecular flexibility and diverse interactions for material synthesis and molecular design.