Phthalocyanines are a group of synthetic molecules derived from porphyrin compounds. For decades, phthalocyanine molecules have been a very important object of study for the scientific community. Not only because of their ability to bind to a wide variety of metals and non-metals at the core of their structure, but also because of their recognised photochemical activity to generate reactive oxygen species (ROS), such as ¹O₂ and O₂^.-, via energy transfer and electron transfer reactions, respectively. These oxygen species have the ability to cause damage to bacterial cells, as well as assist in the elimination of malignant and tumour cells during the development of diseases such as cancer. In our study, we have synthesised via microwave several unsubstituted phthalocyanine molecules linked to different metals of the first transition series: Zn, Cu, Ni, Co, Fe and Mn. For this study several unsubstituted phthalocyanine molecules bound to different metals of the first transition series were synthesized via microwave. It was analyzed how the photochemical activity is modulated (UV-VIS spectrum, fluorescence, quantum yields of 1O2, free radicals, etc.) depending on the size and electronic configuration of the central metal. For this purpose, we have performed some theoretical calculations related to the energies of the excited states, and correlated them with the experimental results. Finally, the photobiological activity of phthalocyanines in DNA was carried out by using bacterial plasmid pBR-322 in agarose gel electrophoresis. This allowed us to obtain a general idea about which metals can provide the highest photosensitising ability in possible applications of Photodynamic Therapy.