Antimicrobial　photodynamic　therapy　(aPDT)　is　an　effective　way　to　combat　infectious　diseases　and　antibiotic　resistance.　Photosensitizer　is　a　key　factor　of　aPDT　and　has　triggered　extensive　research　interest.　In　this　study,　a　new　asymmetric　Zn(II)　phthalocyanine　mono-substituted　with　a　triazatricyclodecane　moiety　(compound　3)　and　its　cationic　N-methylated　derivative　(compound　4)　were　synthesized.　Their　photodynamic　antimicrobial　activities　were　evaluated　using　bioluminescent　bacterial　strains.　Compound　3　showed　phototoxicity　only　toward　the　Gram-positive　bacteria,　whereas　the　cationic　derivative　compound　4　exhibited　strong　anti-bacterial　activity　against　both　Gram-positive　and　Gram-negative　strains.　These　bacterial　species　were　eradicated　(＞　4.0　logs　or　99.99%　killing)　at　appropriate　concentrations　of　compound　4　with　12.7　J/cm(2)　of　red　light,　demonstrating　compound　4　as　a　potent　aPDT　agent.