Absorption Properties of a Porous Organic Crystalline Apohost Formed by a Self-Assembled Bis-Urea Macrocycle

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• 作者：Mahender B. Dewal ; Michael W. Lufaso ; Andrew D. Hughes ; Stevan A. Samuel ; Perry Pellechia ; Linda S. Shimizu
• 刊名：Chemistry of Materials
• 出版年：2006
• 出版时间：October 3, 2006
• 年：2006
• 卷：18
• 期：20
• 页码：4855 - 4864
• 全文大小：460K
• 年卷期：v.18,no.20(October 3, 2006)
• ISSN：1520-5002

文摘

We report herein the characterization and binding properties of a microporous crystalline host formedby the self assembly of a bis-urea macrocycle 1. Bis-urea macrocycle 1 has been designed to crystallizeinto stacked hollow columns. The self-assembly process is guided primarily by hydrogen bonding andaromatic stacking interactions that yield crystals of filled host 1·acetic acid (AcOH). The AcOH guestsare bound in the cylindrical cavities of the crystal. The guest AcOH can be removed by heating to forma stable crystalline apohost 1. Apohost 1 displays a type I gas adsorption isotherm with CO₂ that isconsistent with an open framework microporous material. Apohost 1 binds a range of small moleculeguests with specific stoichiometry. The formation of these inclusion complexes does not destroy thecrystal framework and therefore apohost 1 can be reused, much like a zeolite. We investigated the structureof apohost 1 and its inclusion complexes by powder X-ray diffraction. The ability of guests to bind andtheir stoichiometry could be rationalized on the basis of the size, shape, and polarity of the guest molecules.Finally, the shape selectivity of these self-assembled porous materials was demonstrated in competitionstudies in which apohost 1 preferentially bound p-xylene from a mixture of xylene isomers.