Columnar assembled pyridyl bis-urea macrocycles 1 provide a strong 1D supramolecular synthon to construct hierarchical assemblies. These 1D pillars contain ditopic symmetrical acceptors in the form of basic oxygen lone pairs. Herein, we probe this synthon with a series of activated halogen bond donors, the regio-isomers of diiodotetrafluorobenzenes, which vary the relative orientation of the halogen bond formers. Irrespective of the initial stoichiometry, each donor only formed one type of co-crystal with 1. In each case, similar strong pillars of assembled 1 were observed that organize the donors through the CO⋯I interaction, which were significantly shorter than the sum of the van der Waals radii of the atoms involved and among the shortest reported for neutral organic molecules. X-ray photoelectron spectroscopy characteristic core level shifts strongly indicated the formation of halogen bonding interactions.These studies suggest that this synthon can utilize both hydrogen and halogen bonding orthogonally to build complex structures.

Gas-phase ion-mobility spectrometry provides a unique platform to study the effect of mobile charge(s) or charge location on collisional cross section and ion separation. Here, we evaluate the effects of cation/anion adduction in a series of xylene and pyridyl macrocycles that contain ureas and thioureas. We explore how zinc binding led to unexpected deprotonation of the thiourea macrocyclic host in positive polarity ionization and subsequently how charge isomerism due to cation (zinc metal) and anion (chloride counterion) adduction or proton competition among acceptors can affect the measured collisional cross sections in helium and nitrogen buffer gases. Our approach uses synthetic chemistry to design macrocycle targets and a combination of ion-mobility spectrometry mass spectrometry experiments and quantum mechanics calculations to characterize their structural properties. We demonstrate that charge isomerism significantly improves ion-mobility resolution and allows for determination of the metal binding mechanism in metal–inclusion macrocyclic complexes. Additionally, charge isomers can be populated in molecules where individual protons are shared between acceptors. In these cases, interactions via drift gas collisions magnify the conformational differences. Finally, for the macrocyclic systems we report here, charge isomers are observed in both helium and nitrogen drift gases with similar resolution. The separation factor does not simply increase with increasing drift gas polarizability. Our study sheds light on important properties of charge isomerism and offers strategies to take advantage of this phenomenon in analytical separations.

Porous organic crystals with one dimensional channels facilitate stereoselective polymerization to produce trans-1,4-polyisoprene with low PDI under mild UV-irradiation.