CRYSTAL-STRUCTURE AND MOLECULAR-DYNAMICS SIMULATION OF TRI-O-THYMOTIDE CLATHRATES WITH THIOPHENE AS GUEST MOLECULE

Tri-o-thymotide (TOT) forms a cage-type clathrate with the thiophene g uest molecule in a host:guest ratio of 2:1. This clathrate crystallize s in the trigonal system (space group P3(1)21). The unit cell, of dime nsions a = b = 13.585(4), c = 29.914(12)Angstrom, contains 6 TOT and o ne thiophene molecule. The crystal structure, established by direct me thods (R = 0.053), indicates that the host cavity has an oblate-ellips oid shape with a crystallographic twofold axis parallel to the largest dimension of the cage. The guest molecule within the cavity is disord ered. Molecular dynamics simulations have been performed and indicate that the guest molecules have hindered molecular freedom around the sh ortest ellipsoid axis of the cavity, and may produce a dynamic disorde r in the cage of the TOT clathrate.