Abstract The (2-methoxyphenyl) piperazine (MPP) was selected as the functional group and conjugated to dithiocarbamate through different spacers. A series of new MPP derivatives (MPPnDTC, n= 2–6) were synthesized and radiolabelled with 99m Tc-nitrido core or 99m Tc- tricarboxyl core as potential 5-HT1A receptor imaging agents. All the six 99m Tc-labelled complexes were lipophilic and neutral. Biodistribution results showed that those ...