Three new divalent metal(II) aminodiphosphonates with a layered structure have been synthesized by hydrothermal reactions, namely, Zn(H 2 L 1 ) (1), Cd 2 (L 1 ) (2) (H 4 L 1 Zbutyl-N(CH 2 PO 3 H 2 ) 2 ), and Zn 3 (HL 2 ) 2 $1.5H 2 O (3), (H 4 L 2 Zcyclo-hexyl-N(CH 2 PO 3 H 2 ) 2 ). The h100i 2D zinc(II) phosphonate layer in Zn(H 2 L 1 ) 1 is built from ZnO 4 tetrahedra interconnected by aminodiphosphonate ligands. One phosphonate group of the ligand is tridentate whereas the other one is 1H-protonated and unidentate. The amine group is also protonated. In Cd 2 (L 1 ) 2, one Cd(II) ion is octahedrally coordinated by one nitrogen atom and five phosphonate oxygen atoms from four L 1 anions, whereas the other one is five-coordinated by five phosphonate oxygen atoms in a distorted square pyramidal geometry. The aminodiphosphonate ligand is fully deprotonated, and acts as a undecadentate metal linker. The CdO 5 N and CdO 5 polyhedra are interconnected via edge-and corner-sharing into a 1D chain along b-axis, and such chains are bridged by the diphosphonate ligands into a h200i metal phosphonate layer. The hK101i and hK202i metal phosphonate layers in Zn 3 (HL 2 ) 2 $1.5H 2 O (3) are based on ZnO 4 tetrahedra crosslinked by bridging aminodiphosphonate ligands. Both phosphonate groups of the aminodiphosphonate ligand have been deprotonated and are tridentate metal linkers. The amine group remains 1H-protonated. All three compounds exhibit broad emission band in the blue light region.