The　photodynamic　activities　against　Candida　albicans　have　been　evaluated　for　seven　silicon　(IV)　phthalocyanines　modified　axially　by　different　functional　groups.　The　effects　of　the　axial　substituents　on　the　spectroscopic,　photochemical,　cellular　uptake,　and　photobiological　properties　of　these　silicon　phthlaocyanines　have　been　revealed.　The　dicationic　compounds　2　and　4,　having　two　quaternary　ammonium　groups　at　the　axial　positions,　exhibit　the　highest　antifungal　photocytotoxicity　with　an　IC90　of　61-66　mu　M,　which　can　be　ascribed　to　their　high　singlet　oxygen　quantum　yield,　non-aggregation　nature,　effective　cellular　uptake,　and　intracellular　distribution　pattern　(localizing　preferentially　in　the　mitochondria).　By　comparison,　compounds　2　and　4　show　a　higher　photodynamic　inactivation　of　C.　albicans　cells　than　methylene　blue　(MB),　a　known　antifungal　photosensitizer.　The　IC90　values　against　C　albicans　for　2　and　4　are　ca.　8　times　lower　than　that　for　MB.　These　results　indicate　that　the　dicationic　silicon　phthalocyanines　2　and　4　are　interesting　candidates　as　antifungal　photosensitizers　for　future　studies.　(C)　2012　Elsevier　Ltd.　All　rights　reserved.