Staring from l-lactide and ε-caprolactone, the corresponding lactic-caprolactone cooligomer with hydroxyl and carboxylic acid groups were synthesized. These oligomers were connected with chelating groups through a long chain tether, ready for transition metal binding. Coordination of organometallic rhenium (I) and technetium (I) complexes generated the conjugates in high yield and short time, satisfying the requirements for short-lived ...