Determination of the dehydration pathway in a flexible metal-organic framework by dynamic in situ x-ray diffraction.

Understanding guest exchange processes in metal-organic frameworks is an important step toward the rational design of functional materials with tailor-made properties. The dehydration of the flexible metal-organic framework [Co(AIP)(bpy)0.5(H2O)]•2H2O was studied by novel in situ dynamic x-ray diffraction techniques. The complex mechanism of dehydration, along with the as-yet unreported metastable structures, was determined. The structural information obtained by the application of these techniques helps to elucidate the important guest-host interactions involved in shaping the structural landscape of the framework lattice and to highlight the importance of utilizing this technique in the characterization of functional framework materials.

Hybrid organic-inorganic crystal structure of 4-(di-methyl-amino)-pyridinium di-methyl-ammonium tetra-chlorido-lead(II).

The title compound, (C2H8N)(C7H11N2)[PbCl4], is a hybrid organic-inorganic material. It crystallizes in the space group C2/c and contains one half of a mol-ecule of lead chloride, 4-(di-methyl-amino)-pyridinium, and di-methyl-ammonium in the asymmetric unit. The crystal structure exhibits chains of lead chloride capped by 4-(di-methyl-amino)-pyridinium and di-methyl-ammoium by hydrogen bonding. This creates a one-dimensional zipper-like structure down the a axis. The crystal structure is examined and compared to a similar structure containing lead chloride and di-methyl-benzene-1,4-diaminium.

Solvent exchange in a metal-organic framework single crystal monitored by dynamic in situ X-ray diffraction.

Understanding the processes by which porous solid-state materials adsorb and release guest molecules would represent a significant step towards developing rational design principles for functional porous materials. To elucidate the process of liquid exchange in these materials, dynamic in situ X-ray diffraction techniques have been developed which utilize liquid-phase chemical stimuli. Using these time-resolved diffraction techniques, the ethanol solvation process in a flexible metal-organic framework [Co(AIP)(bpy)0.5(H2O)]·2H2O was examined. The measurements provide important insight into the nature of the chemical transformation in this system including the presence of a previously unreported neat ethanol solvate structure.