Three 3D lanthanide anionic metal-organic frameworks {K-5[Ln(5)-(IDC)(4)(OX)(4)]}(n)center dot(20H(2)O)(n) with 1D channels were synthesized under hydrothermal conditions [Ln = Gd (1), Tb (2), and Dy (3)]. The K+ ions within the 1D channel are easily exchanged with various cations. The emission intensities of Tb-III in 2 increased significantly upon the addition of Ca2+ ions, while the introduction of other metal ions caused the intensities to be either unchanged or weakened.