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Updated: Aug 12, 2025
From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding
Published on: March 24, 2018
Boat and Chair Shaped Hexahalogen Synthons
P E Swathi Krishna1, Hruidya C Babu1, Nanditha G Nair1
1School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram (IISER TVM), 695551, Thiruvananthapuram, Kerala, India.
Abstract:
Non-covalent halogen bonding interactions are quintessential in crystal engineering for the construction of distinctive supramolecular synthons. Here, we report the first crystalline evidences of unique boat and chair shaped cyclic hexahalogen synthons in the crystal structures of α,α,α',α',4-pentabromo-o-xylene (PBX) and α,α,α',α',4,5-hexabromo-o-xylene (HBX) respectively. Nature and stability of constituent interactions in the supramolecular synthons are scrutinized with the help of quantum-chemical calculations. Pendás' interacting quantum atoms approach confirmed the stability of Br⋅⋅⋅Br interactions leading to boat and chair shaped synthons with major contribution from exchange-correlation. Although both the molecules are achiral in nature, the packing forces guide PBX to crystallize in the chiral space group P21 with a helix-like orientation while HBX packs in a centrosymmetric P21 /n space group. The extended furcations in the pentabromo derivative construct a molecular framework consisting of macrocycles realized through halogen bonding.
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