The present invention relates to new compounds comprising a siderophore moiety as well as a core structure able to chelate a metal ion. Optionally, the compounds may have additionally a moiety with a functional element including a marker molecule, a bioactive agent, an activity based probe suitable to monitor the aberrant expression or activity of proteins involved in the initiation and progression of bacterial infection, or a compound useful for bacterial inhibition. In a further aspect, the present invention provides a pharmaceutical composition containing said compound, for example, said pharmaceutical composition is an antibiotic. Additionally, the present invention relates to the use of said compounds in diagnostic methods, in particular, imaging methods including SPEC, PET or MRI. In an embodiment of the present invention, the compound is part of a theranostic composition having both, therapeutic as well as diagnostic activities.
