Layered supramolecular compounds containing different patterns of hydrogen bonds, [C₄H₁₂N₂]- (HL)₂ (I) and [YL(HL)(H₂O)₃]•2H₂O (II) (H₂L＝O₂NC₆H₃(CO₂H)₂, 3-nitrophthalic acid) have been synthesized and characterized by elemental analysis, IR spectra and X-ray single crystal diffraction. Compound I consists of one diprotonated piperazine cation and two 2-carboxy-6-nitrobenzoate anions. The anions are linked by the strong O—H…O hydrogen bonds into infinite chains, which further extend to sheets by the N—H…O interactions between the anion chains and cations. The 2D layers are assembled into 3D supramolecular network via the weak forces from the adjacent layers. Complex II also has a layered supramolecular architecture packed by the 2D layers, which are constructed by the dinuclear rare-earth complexes with 3-nitrophthalate via intermolecular hydrogen bonds. There are two crystallization water molecules filling up each of the rhombic pores of the network. Compound I crystallizes in the monoclinic system, space group P2₁/c with parameters a＝1.3176(3) nm, b＝1.1096(2) nm, c＝0.75950(15) nm, b＝97.14(3)°, V＝1.1017(4) nm³, Z＝4, m＝0.129 mm^－1, D_c＝1.533 Mg/m³. Complex II crystallizes in triclinic system, space group P-1 with a＝0.81262(16) nm, b＝0.86942(18) nm, c＝1.5011(3) nm, α＝99.84(3)°, β＝91.26(3)°, γ＝104.55(3)°, V＝1.0091(4) nm³, Z＝1, m＝2.983 mm^－1, D_c＝1.910 Mg/m³.

Key words: hydrogen bond, supermolecule, 3-nitrophthalic acid, rare-earth complex, crystal structure