Architectures in Copper Metal-Organic Frameworks from 4-Substituted Anionic 1,2,4-Triazoles

Three new metal-organic frameworks, [Cu₃(L1)₂(OH)₄]_n (1), [Cu(L1)(Cl)]_n (2), and [Cu(H₂O)(L2)(Cl)]_n (3), were synthesized under hydrothermal conditions by reaction of 4-substituted 1,2,4-triazole derivative ligands (L1 = 4-(1,2,4-triazol-4-yl)ethanesulfonate; L2 = 4-(1,2,4-triazol-4-yl)benzenesulfonate) with Cu²⁺ salts. The different geometry and chemical features of the ligands have yielded unique crystal structures with different dimensionalities. The magnetic properties of the three compounds have been analyzed, all of which show antiferromagnetic interactions: J1 = –130 cm^–1 and J2 = –370 cm^–1 (1), J = –12.3 (2), and –216 cm^–1 (3) (convention used H = –J). The nature and the magnitude of the antiferromagnetic super exchange are correlated with the crystal structure and the distinct bridging modes between spin carriers in the solid state.