Synthesis with coordinated ligands: biomolecule attachment to cage amines

Abstract

Conventional procedures can be used to obtain derivatives of carboxylic acid groups pendent to a cage amine complex. Polyamines (spermine, 323 tet) with both primary and secondary N-centres react predominantly at the former to give cage-substituted straight-chain amines carrying particularly high charges in aqueous solutions. Branched derivatives are obtained in reactions with tris(2-aminoethyl)amine (tren), though under the conditions associated with the use of an acyl chloride rather than an ester as the activated form of the reactant complex, poor yields of orthoamide species are obtained with this polyamine. Activation using the peptide-forming reagent EDC (1-(3-dimethylaminopropyl)-3-ethylcarbodiimide) enables ready coupling of the cage to phenylalanine.