Solution Equilibria of Enantiopure Helicates: The Role of Concentration, Solvent and Stacking Interactions in Self-Assembly

✍ Scribed by Christophe Provent; Elisabeth Rivara-Minten; Sujatha Hewage; Gerhard Brunner; Alan F. Williams

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 198 KB
• Volume: 5
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/(sici)1521-3765(19991203)5:12<3487::aid-chem3487>3.0.co;2-4

✦ Synopsis

The formation of helicates between silver(i) and a series of enantiopure ligands (L 1 ± L 4 ) containing the bis(oxazolyl) pyridine unit has been studied in solution. Ligands L 1 and L 2 form [AgL 2 ] and double-helical [Ag 2 L 2 ] 2 . L 3 and L 4 show more complicated behaviour, forming [AgL 2 ] , [Ag 2 L 2 ] 2 , [Ag 2 L 3 ] 2 and [Ag 3 L 3 ] 3 . The relative concentrations of the complexes may be modified by changing the total concentration or the solvent. For L 3 the trinuclear species is believed to be stabilised by interligand p-stacking interactions which are enhanced in L 4 , leading to almost exclusive formation of [Ag 3 L 3 ] 3 . All complexes appear to be labile on an NMR time scale at room temperature, and racemic mixtures of ligands undergo exclusive homochiral association.