Researchers from the Department of Chemistry Lidija Posavec, Vinko Nemec, Nikola Bedeković and Dominik Cinčić and a student of the Department of Chemistry Filip Kučas have published an article titled 2,2'-Bipyridine Derivatives as Halogen Bond Acceptors in Multicomponent Crystals in the ACS journal Crystal Growth & Design (IF 3,8).
The manuscript presents a systematic study of the halogen bonding potential of different 2,2’-bipyridine derivatives (4,4'-dimethyl-2,2'-bipyridine, 6,6-dimethyl-2,2'-bipyridine, 4,4'-di-tert-butyl-2,2'-bipyridine and 2,2'-biquinoline) in the synthesis of cocrystals by using selected halogen bond donors (1,4-diiodotetrafluorobenzene, 1,3,5-triiodo-2,4,6-trifluorobenzenr, N-iodosuccinimide, N-bromosuccinimide, N-bromophthalimide and N-bromosaccharin). These halogen bond acceptor molecules were chosen to explore how different substituents on 2,2’-bipyridine affect halogen bond formation. The overall efficiency of cocrystal formation was relatively low (8 out of 24 possible cases, or ca. 33 %), by using two methods, liquid-assisted grinding and crystallization from the solution. As expected, structural data revealed that 2,2’-bipyridine derivatives act as ditopic halogen bond acceptors in all structures. Dominant interactions in 7 of the cocrystals were I···N or Br···N halogen bonds, while in the one remaining cocrystal it was the I∙∙∙C(π) halogen bond. In order to rank 2,2’-bipyridine derivatives as halogen bond acceptors, values of molecular electrostatic potentials were calculated on geometries that were optimized using density functional theory.
This research was performed as part of the project New building blocks for the supramolecular design of complex multi-component molecular crystals based on halogen bonds (HaloBond IP-2019-04-1868), financed by the Croatian Science Foundation
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