Two　inorganic-organic　hybrid　isopolyoxoniobates　(1　and　2)　based　on　new　high-nuclearity　{Nb54O151}　clusters　have　been　synthesized　under　hydrothermal　conditions.　In　particular,　the　combination　of　the　unique　{Nb54O151}　clusters　with　copper-amine　complexes　has　led　to　rare　helical　nanotubes,　which　are　further　linked　by　alkali　metal　cations　or　copper-amine　complexes　into　two　2D　similar　bamboo-raft-like　layered　networks　(1　and　2),　respectively.　Compound　1　exhibits　effective　base-catalytic　decomposition　of　chemical　warfare　agent　simulants　dimethyl　methylphosphonate　(DMMP)　and　diethyl　cyanophosphonate　(DECP).　©　The　Royal　Society　of　Chemistry