PROPERTIES OF THE GUEST MOLECULES IN THE 1,10-DIBROMODECANE UREA INCLUSION COMPOUND - A MOLECULAR-DYNAMICS SIMULATION STUDY

A molecular dynamics (MD) simulation of the 1,10-dibromodecane/urea in clusion compound has been carried out at a temperature of 300 K to inv estigate various local structural properties of the 1,10-dibromodecane guest molecules within the urea tunnel structure. The bromide radial distribution function determined from the MD simulation indicates a br oad distribution for the intermolecular Br...Br distance, but consider ably narrower distributions for intramolecular Br...C distances. This supports information determined experimentally via bromine K-edge EXAF S spectroscopy. The MD simulation provides evidence that a small propo rtion of the 1,10-dibromodecane molecules contain a gauche end-group, and provides direct evidence for the interconversion between gauche an d trans end-group conformations on a timescale of the order of picosec onds. The MD simulation indicates that there is substantial dynamic di sorder of the 1,10-dibromodecane guest molecules within the urea tunne l structure. These local structural properties and dynamic properties of the 1,10-dibromodecane guest molecules, determined from the MD simu lation, are compared directly with corresponding information establish ed via experimental approaches.