This invention describes a first report on the synthesis of certain <124>I-labelled photosensitizers related to chlorines and bacteriochlorins with long wavelength absorption in the range of 660-800 nm. In preliminary studies, these compounds show a great potential for tumor detection by positron emission tomography (PET) and treatment by photodynamic therapy (PDT). The development of tumor imaging or improved photodynamic therapy agent(s) itself represent an important step, but a dual function agent (PET imaging and PDT) provides the potential for diagnostic body scan followed by targeted therapy.