The present invention relates to chelates resulting from the complexation of picolinate cross-bridged cyclams of formula (I), wherein the substituents L1-L4 and R1-R4 are defined as in the claims, with metallic cations. The invention further relates to picolinate cross-bridged cyclam ligands of formula (I). Another object of the invention is the use of chelates of the invention in nuclear medicine and the use of ligands of the invention in cations detection or epuration of effluents.