A bifunctional polyazamacrocyclic chelating agent of the formula (I): wherein: and the variables A, L, Q, Q1, X, Y, Z, Z1, m, n and r are as defined in the description of the present application. Also described is a complex of the above chelating agent to an ion of a metal ion, such as an ion of 90Y, 111Li or 177Lu； a conjugate of the complex covalently attached to a biological carrier； and a pharmaceutical composition containing the conjugate. A method of therapeutic treatment of a mammal involving administration of the pharmaceutical composition is also described.
