MOLECULAR RECOGNITION BY PROTONATED O-BISDIEN AND ITS METAL-COMPLEXES

The protonated forms of the basic ligand 1,4,7,13,16,19-hexaaza-10,22-dioxacyclotetracosane or [24]ane-N6O2 (O-BISDIEN) recognize certain anions. The compounds studied are malonic acid, phosphoric acid, glycine, acetohydroxamic acid, and potassium phosphorous formate (KOOCPH(O)(OK)) in their various protonated and anionic forms. Detailed formation constants measuring this recognition are reported for all species found. [24]-ane-N6O2 also forms 1:1 and 1:2 ligand to divalent transition metal ion complexes, with a variety of protonated species and one dinuclear hydroxo bridged form. All of these cationic complexes of O-BISDIEN exhibit recognition toward the same substrates. The quantitative formation constants for the species formed are also reported. Finally, equilibria and kinetics are reported for the formation of dioxygen complexes of selected O-BISDIEN-dicobalt-substrate systems. All the H-bonded and metal ion coordinated species formed are discussed in the light of the principles of molecular recognition.