The halogen bonding proclivity of the ortho-methoxy-hydroxy group in cocrystals of o-vanillin imines and diiodotetrafluoro-benzenesElectronic supplementary information (ESI) available: Details on mechanochemical and solution synthesis, PXRD patterns for all relevant materials and SCXRD data. CCDC No. 1549339 - (ov1an)(13tfib), 1558825 - (ov1an)(14tfib), 1558860 - (ovadm)(12tfib), 1558871 - (ovadm)2(14tfib) and 1558834 - ovadm contain the crystallographic data for this paper. For ESI and crystall

In this work, we describe novel halogen bonded o -vanillin imine cocrystals. As cocrystal coformers, we selected perfluorinated diiodobenzenes, 1,2-, 1,3- and 1,4-diiodotetrafluorobenzene, as halogen bond donors. To explore the halogen bonding proclivity of the o -vanillin ortho -methoxy-hydroxy group, two imines were produced by condensation of o -vanillin with amines containing hydrophobic residues that have no additional potential halogen bond acceptor sites other than the o -vanillin oxygen atoms. We have prepared four cocrystals by both one-pot three-component solvent-free synthesis and the conventional solution-based method. The results of our work show that the ortho -methoxy-hydroxy group of the o -vanillin moiety is a good halogen bond acceptor and is capable of forming predictable halogen-bonded synthons. In the studied cocrystal structures, a wide range of varieties of this synthon were observed, including bonds with a single acceptor (either the methoxy O atom - in two structures, or the hydroxy O atom - in one), 'slightly bifurcated' bonds with a dominant (hydroxy) and ancillary (methoxy) acceptor, and a geometrically unusual asymmetrical bifurcated bond. Novel halogen bonded o -hydroxy imine cocrystals with 1,2-, 1,3- and 1,4-diiodotetrafluorobenzene have been synthesized. We present an insight into the halogen bond acceptor potential of the ortho -methoxy-hydroxy group of the o -vanillin moiety.