The ability of dibenzo-3n-crown-n ethers (n = 6–12) to form stable adducts in solution with a range of neutral and cationic transition metal complexes is discussed. The concept of second sphere coordination can be enlarged to one of molecular recognition involving the whole gamut of non-covalent bonding interactions. It is described how this research led logically to molecular receptors for the bipyridinium herbicides Diquat and Paraquat. In particular, dibenzo-30-crown-10 forms a highly selective 1:1 complex with Diquat whereas, a constitutional isomer, bispara-phenylene-34-crown-10, is a good molecular receptor for Paraquat.
ASJC Scopus subject areas
- Chemical Engineering(all)