Intermolecular interactions in polymorphs of the cyclic trimeric perfluoro-ortho-phenylene mercury from geometric, energetic and AIM viewpoints: DFT study and Hirshfeld surface analysis

Abstract

Macrocyclic polydentate Lewis acids are of ongoing interest owing to their ability for molecular recognition of anions; however, deep understanding of the nature of supramolecular bonding in their crystals is still lacking. To solve this problem, we have analysed four polymorphic modifications A-D of cyclic trimeric perfluoro-ortho-phenylene mercury (1) by quantum chemical calculations of intermolecular pair interactions energy. In all polymorphs, the main structural motif is stacked columns, which are further connected to a three-dimensional structure with either ladder-shape interactions between parallel macrocycles or T-shape interactions between nearly perpendicular macrocycles. Both arrangements contribute almost equally to the stabilization of the crystal structure. According to DFT computational study of isolated dimers that correspond to the most energetically favourable molecular pairs, and topological analysis of electron density distribution, the stabilization of these dimers is governed by HgÁÁÁC and CÁÁÁC interactions.Significant contribution also comes from FÁÁÁC and HgÁÁÁF interactions, while the role of mercurophilic interactions and FÁÁÁF contacts seems negligible. Statistical analysis of crystal structures of host-guest complexes of the macrocycle 1 using Voronoi polyhedra and Hirshfeld surfaces showed the same types of intermolecular interactions to be responsible for stabilization of its polymorphs and cocrystals.

Polymorphism of 3-(5-phenyl-1,3,4-oxadiazol-2-yl)- and 3-[5-(pyridin-4-yl)-1,3,4-oxadiazol-2-yl]-2H-chromen-2-ones

“…The presence of an extended -system creates preconditions for the formation of stacking interactions which is soft enough to provide a shift of the stacked molecules. Such molecules are capable of forming a large number of polymorphic modifications (Shtukenberg et al, 2017;Dolgushin et al, 2016;Shishkina et al, 2019).…”

“…This approach has proved to be more informative in studying the structure of crystals and the role of intermolecular interactions of different types in their formation. This approach is the most useful in comparing polymorphic modifications (Dolgushin et al, 2016;Shishkina et al, 2019).…”

Intermolecular Interactions in Functional Crystalline Materials: From Data to Knowledge

“…A comparison of polymorphs, solvates, and co-crystals of such compounds gives a key for better understanding of these factors. For example, an analysis of 88 crystal structures containing trimeric perfluoro-ortho-phenylen mercury (TPPM) revealed only four motifs of their packing with Lewis bases, governed mainly by Hg...C and π...π interactions [80]. It was shown that the type of supramolecular motif strongly correlates with the nature of a co-former.…”

“…For example, the binary stacks of TPPM and aromatic molecules can be found in a series of co-crystals with luminescent properties [72]. This motif, one of four typical for TPPM co-crystals [80], can be constructed from a TPPM molecule and two aromatic C 6 rings situated above and below the TPPM meanplane ( Figure 3a). The Crystal Packing Feature search allows us to extract from the CSD other examples of such potentially luminescent co-crystals, and to compare the distances between the meanplanes of planar molecules as a measure of charge transfer from electron-rich aromatic molecules to anticrowns.…”

“…The results of the comparison are grouped in accord with the number of neighbors forming molecular clusters (from 1 to 2 for different structures to all 14 for pseudo-isostructural compounds), and the groups can also be compared with each other to reveal synthons and associates common for different groups. Such grouping reflects the fact that similar motifs found in polymorphs and solvates typically keep similar intermolecular connectivity and energy of pair interactions [80,101]. The result of such analysis is the dendrogram visualizing crystal packing similarity between different groups of crystal structures.…”