Tunable Porous Organic Crystals: Structural Scope and Adsorption Properties of Nanoporous Steroidal Ureas
Open Access
- 5 November 2013
- journal article
- research article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 135 (45), 16912-16925
- https://doi.org/10.1021/ja405701u
Abstract
Previous work has shown that certain steroidal bis-(N-phenyl)ureas, derived from cholic acid, form crystals in the P6(1) space group with unusually wide unidimensional pores. A key feature of the nanoporous steroidal urea (NPSU) structure is that groups at either end of the steroid are directed into the channels and may in principle be altered without disturbing the crystal packing. Herein we report an expanded study of this system, which increases the structural variety of NPSUs and also examines their inclusion properties. Nineteen new NPSU crystal structures are described, to add to the six which were previously reported. The materials show wide variations in channel size, shape, and chemical nature. Minimum pore diameters vary from ~0 up to 13.1 Å, while some of the interior surfaces are markedly corrugated. Several variants possess functional groups positioned in the channels with potential to interact with guest molecules. Inclusion studies were performed using a relatively accessible tris-(N-phenyl)urea. Solvent removal was possible without crystal degradation, and gas adsorption could be demonstrated. Organic molecules ranging from simple aromatics (e.g., aniline and chlorobenzene) to the much larger squalene (M(w) = 411) could be adsorbed from the liquid state, while several dyes were taken up from solutions in ether. Some dyes gave dichroic complexes, implying alignment of the chromophores in the NPSU channels. Notably, these complexes were formed by direct adsorption rather than cocrystallization, emphasizing the unusually robust nature of these organic molecular hosts.Keywords
This publication has 90 references indexed in Scilit:
- Second‐Order Nonlinear Optical Activity Induced by Ordered Dipolar Chromophores Confined in the Pores of an Anionic Metal–Organic FrameworkAngewandte Chemie-International Edition, 2012
- Hydrocarbon Separations in a Metal-Organic Framework with Open Iron(II) Coordination SitesScience, 2012
- Bimolecular Reaction via the Successive Introduction of Two Substrates into the Crystals of Networked Molecular CagesJournal of the American Chemical Society, 2011
- Nanoporous Organic AlloysAngewandte Chemie-International Edition, 2011
- Molecular Doping of Porous Organic CagesJournal of the American Chemical Society, 2011
- Predicting Inclusion Behaviour and Framework Structures in Organic CrystalsChemistry – A European Journal, 2009
- Nitrogen and Hydrogen Adsorption by an Organic Microporous CrystalAngewandte Chemie-International Edition, 2009
- Structure–Activity Relationships in Cholapod Anion Carriers: Enhanced Transmembrane Chloride Transport through Substituent TuningChemistry – A European Journal, 2008
- Meldola Lecture: understanding the properties of urea and thiourea inclusion compoundsChemical Society Reviews, 1997
- A microcalorimetric comparison of the adsorption of various gases on two microporous adsorbents: a model aluminophosphate and a natural clayThermochimica Acta, 1992