Structural study on four co-crystals of N-containing heteroaromatics with iodofluorobenzene

Abstract

N-Containing heteroaromatics 1,2,4,5-tetra(pyridin-3-yl)benzene[1,2,4,5-T(3-PY)B] and 1,2,4,5-tetra-(pyridin-4-yl)benzene[1,2,4,5-T(4-PY)B] were each co-crystallized with 1,2-diiodo-tetrafluoro-benzene(1,2-DITFB), or 1,4-diiodo-tetrafluoro-benzene(1,4-DITFB), respectively, generating four co-crystals, namely, (1,2-DITFB)4·[1,2,4,5-T(3-PY)B](1), (1,2-DITFB)4·[1,2,4,5-T(4-PY)B](2), (1,4-DITFB)2·[1,2,4,5-T(3-PY)B]·CHCl3(3), and (1,4-DITFB)·[1,2,4,5-T(4-PY)B]·2CHCl3(4). This study takes aim at providing an insight into the relative importance of fundamental solid state halogen bonding interactions(i.e., halogen⋯N, halogen⋯halogen, and halogen⋯π) in systems. The effects of the donor and acceptor on supramolecular assembly and the crystal structure determined interactions were discussed. The N⋯I halogen bonds are the main directing interactions responsible for the observed structures. In compounds 1 and 2, the donors exhibited lower-than-expected supramolecular connectivity. In spite of this, co-crystal 2 exhibits polymeric structures consisting of infinite one-dimensional(1D) double-zigzag chains of alternating electron donor and acceptor. The basic structure of co-crystals 3 and 4 is also infinite 1D chain. Therefore, the 1D halogen bonded supramolecular assemblies can be obtained by matching the appropriate donor and acceptor.