NEW TRITHIA-MACROCYCLE AND DITHIOXA-MACROCYCLE WITH BIPHENYL FUSED INTO THE BACKBONE - STRUCTURES, AND MOLECULAR MODELING STUDIES

Two novel thiamacrocycles have been synthesised with a biphenyl unit a nd SCCSCCS or SCCOCCS linkers in the ring backbone. Their crystal stru ctures have been determined, showing the trithia ligand to have both S CCS torsions anti (a) whilst the dithioxa ligand has both its SCCO tor sions in a plus gauche (g+) conformation. Molecular dynamics simulatio ns of these two ligands at several temperatures again show differences , the trithia being more rigid; in addition, the conformations predomi nating in the dynamics simulations of the dithioxa ligand are differen t from that of the crystal structure. No conformation occurred with an y frequency which could be considered to have potential as a tridentat e ligand (all-endo sulfurs or oxygens). Derivatives built with additio nal o-Me substituents were also examined. The cavity size provided by two of the ligands (operating as tridentate ligands) was calculated, a nd the implications for coordination of the new ligands are considered .