Metal-organic　frameworks　are　a　class　of　attractive　materials　for　fluorescent　sensing.　Improvement　of　hydrolytic　stability,　sensitivity,　and　selectivity　of　function　is　the　key　to　advance　application　of　fluorescent　MOFs　in　aqueous　media.　In　this　work,　two　stable　MOFs,　[Zr6O4(OH)(8)(H2O)(4)(L-1)(2)]　(BUT-14)　and　[Zr6O4(OH)(8)(H2O)(4)(L-2)(2)]　(BUT-15),　were　designed　and　synthesized　for　the　detection　of　metal　ions　in　water.　Two　new　ligands　utilized　for　construction　of　the　MOFs,　namely,　5＇,5＂＇-bis　(4-carboxypheny1)-[1,1＇:3＇,1　＇＇:4　＇＇,1＇＇＇:3＇＇＇,1＇＇＇＇-quinquepheny1]-4,4＇＇＇＇-dicarboxylate　(L-1)　and　4,4＇,4　＇＇,4　＇＇-(4,4＇-(1,4-phenylene)bis(pyridine-6,4,2-triy1))-tetrabenzoate　(L-2),　are　structurally　similar　with　the　only　difference　being　that　the　latter　is　functionalized　by　pyridine　N　atoms.　The　two　MOFs　are　isostructural　with　a　sqc-a　topological　framework　structure,　and　highly　porous　with　the　Brunauer-Emmett-Teller　(BET)　surface　areas　of　3595　and　3590　m(2)　g(-1),　respectively.　Interestingly,　they　show　intense　fluorescence　in　water,　which　can　be　solely　quenched　by　trace　amounts　of　Fe3+　ions.　The　detection　limits　toward　the　Fe3+　ions　were　calculated　to　be　212　and　16　ppb,　respectively.　The　efficient　fluorescent　quenching　effect　is　attributed　to　the　photoinduced　electron　transfer　between　Fe3+　ions　and　the　ligands　in　these　MOFs.　Moreover,　the　introduced　pyridine　N　donors　in　the　ligand　of　BUT-15　additionally　donate　their　lone-pair　electrons　to　the　Fe3+　ions,　leading　to　significantly　enhanced　detection　ability.　It　is　also　demonstrated　that　BUT-15　exhibits　an　uncompromised　performance　for　the　detection　of　Fe3+　ions　in　a　simulated　biological　system.