Urea inclusion compounds interactions

Brustolon, M. Maniero, A.L. Segre, U. Guest-guest interactions in urea inclusion compounds. J. Chem. Soc., Perkin trans., II 1997, 2521. 

Welberry. T.R. Mayo, S.C. Diffuse x-ray scattering and Monte Carlo study of guest-host interactions in urea inclusion compounds. J. Appl. Crystallogr. 1996. 29. 353-364. 

As mentioned in Section 13.5.1, the transient species [BO(OH)2]-has been stabilized by hydrogen-bonding interactions with the nearest urea molecules in the host framework of the inclusion compound [(CH3)4N]+[B0(0H)2]--2(NH2)2C0-H20. A perspective view of the crystal structure along the [010] direction is presented in Fig. 20.4.16. The host lattice consists of a parallel arrangement of unidirectional channels whose cross section has the shape of a peanut. The diameter of each spheroidal half is about 704 pm, and the separation between two opposite walls at the waist of the channel is about 585 pm. The well-ordered tetramethylammonium cations are accommodated in double columns within each channel. 

Host — A - molecular entity that forms an -> inclusion complex with organic or inorganic -> guests, or a - chemical species that can accommodate guests within cavities of its crystal structure. Examples include cryptands and crowns (where there are -> ion-dipole interactions between heteroatoms and positive ions), hydrogen-bonded molecules that form clathrates (e.g., hydroquinone and water), and host molecules of inclusion compounds (e.g., urea or thiourea). The - van der Waals forces and hydrophobic interactions (- hydrophobic effect) bind the guest to the host molecule in clathrates and inclusion compounds. 

Brown, M.E. Chaney, J.D. Santarsiero, B.D. Hollingsworth, M.D. Superstructure topologies and host-guest interactions in commensurate inclusion compounds of urea with bis(methyl ketone)s. Chem. Mater. 1996, 8, 1588. 

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