Four new transition metal carboxyphosphonates with 2D and 3D supramolecular structures, namely, Fe₂[(HL)(H₂O)] (1), Fe(H₄L)₂ (2), Zn(H₃L) (3) and Zn₂(HL) (4) (H₅L = 4-HO₂C–C₆H₄–CH₂N(CH₂PO₃H₂)₂), have been synthesized under hydrothermal conditions. For compound 1, {FeO₅N} and {CPO₃} polyhedra are interconnected into a 2D layer in the bc-plane via corner-sharing. Then the adjacent layers are further assembled into a 3D supramolecular structure through π–π stacking interactions. Compound 2 shows a 3D supramolecular structure. {FeO₆} and {CPO₃} polyhedra are interconnected into a 2D layer in the bc-plane via corner-sharing, which is further linked through π–π stacking interactions to form a 3D supramolecular structure. The overall structure of compound 3 can be described as a 2D supramolecular structure. The {ZnO₄} polyhedra are interconnected by {CPO₃} tetrahedra via corner-sharing to form a 1D chain. These neighboring metal phosphonate chains are connected through hydrogen bonding interactions to give rise to a 2D supramolecular structure in the ac-plane. In compound 4, {ZnO₃N} and {ZnO₄} polyhedra are interconnected by {CPO₃} tetrahedra via corner-sharing and edge-sharing to form a 2D inorganic layer in the bc-plane, which is further linked through π–π stacking interactions to form a 3D supramolecular structure. The surface photovoltage properties of compounds 1–2 and luminescence properties of compounds 3–4 have been investigated. More interestingly, compound 4 is selective for sensing DMF and acetone.