Three isostructural Ln-BTB frameworks (Ln = Eu (1), Dy (2), Yb (3)) were synthesized and structurally characterized, in which mononuclear and trinuclear [Ln3] units as nodes construct unprecedented (3,4,10)-connected 3D frameworks with (4·6·8)4(4·8(2))2(4·8(5))(6(2)·8(4))(4(5)·6(8)·8(26)·10(6)) point symbol. The luminescent investigations revealed that compound 1 can sensitively and selectively detect Al(3+), but comparably compound 2 could not detect Al(3+) among various cations. More importantly, 1 as an Al(3+) sensor can be reused at least five times, which represents the first recyclable metal organic framework (MOF)-supported Al(3+) sensor. Additionally, magnetic investigations on 2 also were carried out, showing a single-molecule-magnet behavior.