Three isostructural Ln-BTB frameworks (Ln = Eu (1), Dy (2), Yb (3)) were synthesized and structurally characterized, in which mononuclear and trinuclear [Ln(3)] 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 Al3+, but comparably compound 2 could not detect Al3+ among various cations. More importantly, 1 as an Al3+ sensor can be reused at least five times, which represents the first recyclable metal organic framework (MOF)-supported Al3+ sensor. Additionally, magnetic investigations on 2 also were carried out, showing a single-molecule-magnet behavior.