Four new lanthanide(iii) coordination polymers (1–4) have been synthesized by using 2,5-dihydroxybenzene-1,4-dicarboxylate (Dhbdc, C8H6O62−) as a ligand and characterized by elemental analysis, infrared spectroscopy, TGA-DSC (Thermogravimetric Analysis-Differential Scanning Calorimetry) and single crystal X-ray diffraction studies. The isolated complexes include; [Ce(Dhbdc)(H2O)3Cl]n (1) and [Ln(Dhbdc)1.5(H2O)2]n·3n(C2H6O)·nH2O [Ln = Eu (2), Gd (3) and Tb (4)]. The structural analysis reveals that compound 1 is a two-dimensional polymer in which the cerium atoms are coordinated by six oxygen and two bridging chloride ions adopting a dodecahedral geometry. The compounds 2–4 are isomorphous and their extended structures consist of three-dimensional supramolecular frameworks encapsulating  channels occupied by the guest water and ethanol molecules. The metal atoms in 2–4 exhibit a square antiprism geometry. All these compounds have O–H⋯O hydrogen bonds originating from the coordinated water and solvent molecules that help to consolidate the structures. The compounds 1, 3 and 4 were investigated for magnetic properties and they exhibited weak antiferromagnetic coupling interactions between the lanthanides as per the Curie Weiss law. Anisotropic nature of 3 and 4 has been depicted as per magnetization versus field plots. Complex 4 behaves as a soft magnetic material as compared to 3. The luminescence studies indicate that compounds 2, 3 and 4 show ligand-centred fluorescence, which is significantly enhanced in the case of 4.
Bibliographical noteFunding Information:
Prof X. Chen acknowledges National Natural Science Foundation of China (Grants No. 21771057 and U1804253) for the financial support. S. Hussain is thankful to the Henan Normal University for postdoctoral support. The author from King Khalid University also acknowledge the financial and technical support of Deanship of Scientific Research (DSR) at King Khalid University of Saudi Arabi.
- COORDINATION POLYMERS
- LUMINESCENT PROPERTIES
- HYDROTHERMAL SYNTHESIS