Magneto-structural relationships in paddle-wheel dinuclear copper(II) complexes with tunable dimensionality (0D→1D→2D)

• Four paddle-wheel [Cu₂] complexes with tunable 0D→1D→2D structures were synthesized and retain strong AFM coupling ( J =–144.7 to –176.4 cm⁻¹). • π -conjugated pyz linkers, shorter intra-cluster Cu···Cu distances, and higher dimensionality synergistically enhance AFM coupling in the complexes. • syn - syn carboxylate bridging mediates intracluster AFM exchange, while Cu···Cu distance and τ are key to regulating J . • Ligand choice (DMF vs. pyz) modulates Cu(II) electron density, further tuning the magnetic behavior of the paddle-wheel [Cu₂] systems. • Clear magneto-structural relationships were established and offer a rational design strategy for Cu(II)-based functional magnetic materials. Paddle-wheel dinuclear Cu(II) complexes serve as an ideal platform to elucidate the assembly of coordination clusters into 1D chains or 2D layers while preserving structural integrity. This study reports the synthesis, structural characterization, and magnetic properties of four paddle-wheel dinuclear copper(II) complexes, [Cu₂(dpa)₄(DMF)₂]∙DMF ( 1 , 0D, Hdpa=diphenylacetic acid), [Cu₂(dpa)₄(pyz)₂]ₙ ( 2 , 1D, pyz =pyrazine), [Cu₂(ita)₂(DMF)₂]ₙ ( 3 , 1D, H 2 ita =itaconic acid), and [Cu₂(ita)₂( pyz)₂]ₙ ( 4 , 2D) with tunable dimensionality (0D→1D→2D). By tuning carboxylate ligands (Hdpa vs. H₂ita) and auxiliary linkers (DMF vs. pyz), precise control over framework dimensionality was achieved, with all complexes retaining the paddle-wheel [Cu₂] core featuring syn - syn carboxylate bridging. Single-crystal X-ray diffraction analysis revealed variations in intra-cluster Cu···Cu distances, distortions in coordination geometry (trigonality parameter τ ), and differences in inter-cluster connectivity. Magnetic susceptibility measurements show all complexes exhibit strong antiferromagnetic (AFM) coupling ( J = –144.7 to –176.4 cm⁻¹), with Weiss constants ( θ , reflecting inter-dimer magnetic interactions) ranging from –1.47 K (0D) to –1057 K (2D). Key findings indicate that four factors—shorter intra-cluster Cu···Cu distances, the presence of π-conjugated pyrazine (pyz) linkers, higher structural dimensionality, and reduced distortion in coordination geometries—act synergistically to maximize AFM coupling. This work successfully establishes unambiguous magneto-structural relationships, thereby offering a rational design strategy for the development of copper(II)-based functional magnetic materials. Four paddle-wheel dinuclear Cu(II) complexes with tunable dimensionality (0D→1D→2D) were synthesized, and their magneto-structural relationships show π-conjugated pyz, shorter intra-cluster Cu···Cu distances, and higher dimensionality act synergistically to maximize AFM coupling.