42 research outputs found
Trapping virtual pores by crystal retro-engineering
Stable guest-free porous molecular crystals are uncommon. By contrast, organic molecular crystals with guest-occupied cavities are frequently observed, but these cavities tend to be unstable and collapse on removal of the guests—this feature has been referred to as ‘virtual porosity’. Here, we show how we have trapped the virtual porosity in an unstable low-density organic molecular crystal by introducing a second molecule that matches the size and shape of the unstable voids. We call this strategy ‘retro-engineering’ because it parallels organic retrosynthetic analysis, and it allows the metastable two-dimensional hexagonal pore structure in an organic solvate to be trapped in a binary cocrystal. Unlike the crystal with virtual porosity, the cocrystal material remains single crystalline and porous after removal of guests by heating
Supramolecular Architectures Constructed from Piperazine and Substituted Benzoic Acids
The shape of the halogen atom—anisotropy of electron distribution and its dependence on basis set and method used
Hydrogen-bonding contributions to the lattice energy of salts for 2nd Harmonic-Generation
A combination of X-ray single-crystal diffraction and Monte Carlo structure solution from X-ray powder diffraction data in a structural investigation of 5-bromonicotinic acid and solvates thereof
Crystal structures of the coordination polymers formed between 1,2-bis(3′-pyridyl)ethyne and silver(I) trifluoromethanesulfonate
The development of carbamazepine-succinic acid cocrystal tablet formulations with improved in vitro
Synthesis, structural characterization, Hirshfeld surface analysis, spectroscopic and ferroelectric properties studies of 4-methylbenzylammonium sulfate
Identification of a new co-crystal of salicylic acid and benzamide of pharmaceutical relevance
Raman spectroscopy, X-ray powder diffraction/X-ray crystallography and differential scanning calorimetry have been used to study the phenomenon of co-crystal formation in stoichiometric mixtures of salicylic acid with benzamide. Raman spectroscopy was particularly useful for the characterization of the products and was used to determine the nature of the interactions in the co-crystals. It was observed that little change in the vibrational modes associated with the phenyl groups of the respective reactants took place upon co-crystal formation, but changes in intensities of the vibrational modes associated with the amide and the carboxylic acid groups were observed upon co-crystal formation. Several new vibrational bands were identified in the co-crystal which were not manifested in the physical mixture of both components and could be used as diagnostic features of co-crystal formation. © 2009 Springer-Verlag