Treatment　of　3-　or　4-nitrophthalonitrile　with　1,2:5,6-di-O-isopropylidene-　α-d-glucofuranose　or　1,2:3,4-di-O-isopropylidene-α-d-galactopyranose　in　the　presence　of　K2CO3　gave　the　corresponding　glycosubstituted　phthalonitriles.　These　precursors　underwent　self-cyclisation,　or　mixed-cyclisation　with　the　unsubstituted　phthalonitrile,　to　afford　the　tetra-　or　mono-glycosylated　zinc(ii)　phthalocyanines,　respectively.　As　shown　by　absorption　spectroscopy,　these　compounds　were　not　significantly　aggregated　in　organic　solvents,　giving　a　weak　to　moderate　fluorescence　emission.　Upon　irradiation　these　compounds　could　sensitise　the　formation　of　singlet　oxygen　in　DMF,　with　quantum　yields　in　the　range　of　0.40-0.66.　The　in　vitro　photodynamic　activities　of　these　compounds　against　HepG2　human　hepatocarcinoma　and　HT29　human　colon　adenocarcinoma　cells　were　also　studied.　The　mono-glycosylated　phthalocyanines　exhibited　significantly　higher　photocytotoxicity　compared　with　the　tetra-α-glycosylated　analogues,　having　IC50　values　down　to　0.9　μM.　The　tetra-β-glycosylated　counterparts　were　essentially　inactive.　The　lower　photocytotoxicities　of　the　tetra-glycosylated　phthalocyanines　are　in　line　with　their　lower　cellular　uptake　and/or　higher　aggregation　tendency　as　reflected　by　weaker　intracellular　fluorescence,　and　lower　efficiency　at　generating　intracellular　reactive　oxygen　species.　For　the　mono-glycosylated　phthalocyanines,　the　higher　uptake　can　be　attributed　to　their　hydrophilic　saccharide　units,　which　increase　the　amphiphilicity　of　the　macrocycles.　©　The　Royal　Society　of　Chemistry　2008.