A series of 1-D lanthanide coordination polymers based on [Ln₄(μ₃-OH)₄] (Ln = Er, Tb, Gd) cluster units

A series of 1-D lanthanide coordination polymers [Ln(μ₃-OH)(pybz)(pa)]_n (Ln = Er (1), Tb (2), Gd (3), Hpybz = 4-pyridin-4-yl-benzoic acid, Hpa = 2-picolinic acid) based on [Ln₄(μ₃-OH)₄] cluster units have been hydrothermally synthesized and characterized by single crystal X-ray diffraction, IR, elemental analysis, and thermogravimetric analysis. X-ray crystal structure analyses reveal that 1-3 are isomorphous with tetragonal space group P 4̄2_1c and comprise tetranuclear Ln-O clusters, in which four Ln³⁺ centers are joined together by four μ₃-bridging hydroxyl groups to form cubane-like [Ln₄(μ₃-OH)₄]⁸⁺ cores that are further linked by four μ₃-pa^- ligands to produce 1-D chains along the c-axis.