Characterization of Intermolecular Interactions in a Disordered Solid via a One-Dimensional Patterson Synthesis

Abstract

We report the application of a one-dimensional Patterson analysis of diffuse X-ray scattering from the 1,8diiodooctane/urea inclusion compound to obtain information on the intermolecular interaction between the iodine end groups of adjacent 1,8-diiodooctane guest molecules within the urea tunnel host structure in this inclusion compound. One aspect of the X-ray scattering from the guest component in this incommensurate inclusion compound comprises diffuse sheets perpendicular to the host tunnel axis, and we consider measurements of the intensity, I(l g ), obtained from one-dimensional scans perpendicular to the diffuse sheets in reciprocal space (each diffuse sheet is specified by integer l g ). The one-dimensional Patterson map constructed from I(l g ) has a dominant peak at ca. 3.94 Å, which is interpreted as the projection, on to the tunnel axis, of the intermolecular I‚‚‚I distance. This value of D z (I‚‚‚I) is shown to be consistent with a model in which the iodine end groups are in van der Waals contact with the I f I vector lying essentially parallel to the tunnel axis. We emphasize that this well-defined structural information has been obtained despite the substantial disorder in this system.

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Structural Properties of Carboxylic Acid Dimers Confined within the Urea Tunnel Structure: An MD Simulation Study

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