Extending the halogen-bonded supramolecular synthon concept to 1,3,4-oxadiazole derivatives

Abstract

A series of five crystal structures of 1 : 1 halogen-bonded complexes were obtained from 4-[5-(4-alkoxyphenyl)-1,3,4-oxadiazole-2-yl]pyridine and 1,3,5-trifluorotriiodobenzene. Electronic structure calculations show that the N (oxadiazole) ⋯I interaction in the new synthon is as strong as the classic N (pyridine) ⋯I interaction. Oxygen to sulfur atom subsitution on the oxadiazole ring results in a different supramolecular packing where the N (pyridine) ⋯I interaction is favored, which could be rationalized by the changes in the molecular electrostatic potential predicted from the theoretical calculations.

Pillars of assembled pyridyl bis-urea macrocycles: a robust synthon to organize diiodotetrafluorobenzenes

“…3b). This is remarkably linear and directional compared to that of 1·(o-DITFB) 2 , which shows that a linear symmetric halogen bond Table 1 Crystallographic data and structure refinement parameters of co-crystals 1·(o-DITFB) 2 , 1·(m-DITFB) 2 ·DMSO, and 1·p-DITFB donor easily favours the formation of linear long chain assemblies propagated by C-I⋯O halogen bonds. Co-crystallization of 1 with m-DITFB consistently formed a three component crystal with a 1 : 2 : 1 ratio of 1 : m-DITFB : DMSO, regardless of the initial stoichiometry.…”

“…The most symmetrical XB donor p-DITFB gave rise to a 1 : 1 donor-acceptor co-crystal utilizing the CO⋯I synthon. On the other hand, o-DITFB and m-DITFB isomers resulted in 1 : 2 donor-acceptor co-crystals {1·(o-DITFB) 2 and 1·(m-DITFB) 2 ·DMSO} where both CO⋯I and type I/II iodine-iodine interactions were observed. DMSO in the structure of 1·(m-DITFB) 2 ·DMSO acted as a second XB acceptor molecule.…”

“…Hydrogen atoms bonded to carbon were located in difference maps before being included as riding atoms. In 1·(o-DITFB) 2 and 1·(m-DITFB) 2 ·DMSO the urea hydrogens were located in difference maps and refined isotropically with their N-H distances restrained to be approximately equal. However, in 1·p-DITFB the urea hydrogens were located in difference maps and refined freely.…”

“…1 The C-X⋯N supramolecular synthon is the most widely studied among the halogen bond supramolecular synthons, often used in the engineering of organic co-crystals due to its robustness. 2 The N⋯I halogen bond has been frequently used to drive the self-assembly of solid-state architectures, which are stable at room temperature and in air. 3 Typical examples include the alignment of stilbene and diacetylene derivatives through crystal engineering to favor topochemical [2 + 2] photodimerization 4 in the solid-state and topotactic polymerization.…”

Noncovalent Interactions between 1,3,5-Trifluoro-2,4,6-triiodobenzene and a Series of 1,10-Phenanthroline Derivatives: A Combined Theoretical and Experimental Study

“…In a recent study, Hidalgo et al reported a series of five crystal structures of 1:1 halogen-bonded complexes between TFTIB and 4-[5-(4-alkoxyphenyl)-1,3,4-oxadiazole-2-yl]pyridine. In each of the five crystal structures, one TFTIB molecule formed three C−I• • • N halogen bonds with neutral halogen atom acceptors [26]. Unfortunately, the latter two studies did not discuss the factors controlling the formation of multiple halogen bonds with a single TFTIB molecule.…”