The design of compounds with novel and improved physico-chemical properties as advanced functional materials with a specific application spectrum requires the knowledge about possible supramolecular packing motifs and their experimental control in crystalline lattice. Besides the structure of the individual molecule, non-covalent interactions play a significant role in the determination of molecular conformation, along with the formation of three-dimensional supramolecular architecture in a crystal as a requirement for molecular recognition processes, and the related bioactivity. Involvement of functional groups will contribute to the formation of a predefined packing motif due to their well-defined interactions. The strength and directionality of these interactions create characteristic packing motifs, which can be used for the design of supramolecular arrangements by the development of appropriate strategies for the precise control of their topology. Most relevant of these non-covalent interactions are stacking interactions and hydrogen bonds, which have been subjects of extensive study in the last two decades. In recent literature, substantial efforts have been put in by various researchers towards the understanding of interactions involving organic fluorine and the role they play in generating different packing motifs which guides assembling of molecules in the crystal lattice.

The validity of the newly proposed ‘carbon bonding’, an interaction where a carbon atom acts as an electrophilic site towards a variety of nucleophiles, has been investigated in the solid state. X-ray charge density analysis provides experimental evidence for this hitherto unexplored interaction and unravels its nature and strength.

Co-crystallization is the supramolecular phenomenon of aggregation of two or more different chemical entities in a crystalline lattice through non-covalent interactions. It encompasses the study of the manifestation of multi-component crystalline solids as well as their design. The chemistry community and the literature suggest cocrystals with reference to co-crystallization products and multi-component crystalline solids. Over the last decade cocrystals have become very popular as a potential new/alternate solid form of pharmaceuticals. However, there is no consensus on what exactly a cocrystal means and what it constitutes across academia, industry and regulatory bodies. On the other hand, cocrystals have been endorsed to the extent that the following facts have been obscured: (1) cocrystals are only one of the putative outcomes of co-crystallization, if at all, and (2) their application goes way beyond pharmaceuticals. Solvates, solid solutions, eutectics, salts, ionic liquids, solid dispersions, supramolecular gelators etc. are among the multifarious products of co-crystallization. The manifestation of these supramolecular/non-covalent crystalline adducts is controlled by the inherent nature of the system (the components involved) besides the surroundings (temperature, solvent, pH etc.); in effect it is a thermodynamic outcome. Each of these adducts, including cocrystals, are unique, exhibit varied physicochemical properties and are amenable to design and therefore have, and potentially find, manifold applications in diverse fields such as organic synthesis & separation, green chemistry, energy storage, solar cells, electronics, luminescent and smart materials, apart from pharmaceuticals. This article highlights the diversity of crystal forms and the utility of small molecule supramolecular combinations.

The enigmatic type II C–F⋯F–C and C–F⋯S–C interactions in pentafluorophenyl 2,2′-bithiazole are shown to be realistic “σ-hole” interactions based on high resolution X-ray charge density analysis.