A　rare　3D　porous　chiral　polyoxoniobate　framework,　[Cu(en)(2)(H2O)](2){[Cu(en)](4)[Cu(en)(2)](5){[Cu(en)(2)KNb24O72H10](2)}center　dot　6en　center　dot　70H(2)O(1)　(en　=　ethylenediamine)　based　on　two　types　of　isomeric　{Cu(en)(2)KNb24O72H10}　clusters　(alpha-CuKNb(24)and　beta-CuKNb24)　has　been　synthesized　by　a　hydrothermal　reaction.　Interestingly,　the　alpha-CuKNb(24)and　beta-CuKNb(24)clusters　are　connected　by　cupric　complexes　to　form　chiral　helical　pillars　with　left-handedness　(L-alpha-CuKNb24)　and　right-handedness　(R-beta-CuKNb24).　To　our　knowledge,　compound1is　the　first　polyoxometalate-based　MOF　with　a　4-connected　neb-type　topology　structure　within　polyoxometalate　chemistry.　This　compound　also　exhibits　proton　conduction　and　strong　water　vapor　adsorption　properties.