The invention relates to compounds according to the general formula (I) or a pharmaceutically acceptable salt of an inorganic or organic acid, a hydrate, a stereoisomer or a solvate thereof, R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11 and R12 being selected independently of one another from hydrogen and alkoxy. The compounds of formula (I) as ligands are suitable for the production of radioactively labelled 68Ga, 64Cu, 67Ga, 111In or 99mTc complexes. The invention further relates to a method for producing the compounds of formula (I) and the radioactively labelled complexes and to the use of the radioactively labelled complexes in imaging methods, such as PET/CT, in particular of the liver.