2,2'-Bipyridine Derivatives as Halogen Bond Acceptors in Multicomponent Crystals

Abstract

In this work, we present a systematic study of the halogen bonding potential of different 2,2'-bipyridine derivatives in the synthesis of cocrystals by using selected perfluorinated iodobenzenes and N-haloimides as halogen bond donors. These halogen bond acceptor molecules were chosen to explore how different substituents on 2,2'-bipyridine affect halogen bond formation. Out of 24 combinations, we obtained only 8 cocrystals by using two methods, liquid-assisted grinding and crystallization from the solution. Of those 8 cocrystals, one has already been described in the literature. 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 are I···N or Br···N halogen bonds, while in the one remaining cocrystal it is the I···C(π) halogen bond.

Scheme 1. Structures of Halogen Bond (XB) Donor and Acceptor Molecules Used in This Study

Figure 1

Calculated values in kJ mol^–1e^–1 of the molecular electrostatic potential mapped to the electron density isosurfaces (ρ = 0.001 au) corresponding to the optimized geometries of bipyridine derivatives (m062x/def2tzvp level of theory).

Figure 2

Parts of crystal structures of 2,2′-bipyridine derivative cocrystals with perfluorinated iodobenzenes.

Figure 3

Parts of the crystal structures of cocrystals with N-haloimides as halogen bond donors. Bending of the bipyridine moiety is visualized using blue planes and torsional angle values.