Two novel binuclear lanthanide complexes, [Ln(3-Cl-4-MOBA)(3)(5,5'-DM-2,2'-bipy)](2)(5,5'-DM-2,2'-bipy) (Ln = Eu(1), Gd(2)), 3-Cl-4 MOBA = 3-chloro-4-methoxybenzoate; 5,5'-DM-2,2'-bipy = 5,5'-dimethy-2,2'-bipyridine) have been successfully synthesized under hydrothermal conditions. The complexes are characterized by single-crystal X-ray diffraction and elemental analysis. Complexes 1 and 2 are isomorphous, and each metal center is eight-coordinated with a distorted square-antiprism coordination geometry. The binuclear units are assembled into 1D, 2D and 3D supramolecular structures by weak hydrogen bonds (C-H center dot center dot center dot O and C-H center dot center dot center dot Cl) and pi-pi stacking interactions. Thermal behavior of the complexes 1 and 2 was determined by TG/DSC-FTIR techniques. Heat capacities of the complexes are measured by a DSC instrument in the temperature range of 283.15-393.15 K. Based on the heat capacities date, the thermodynamic functions (H-T-H-298(.)15K) and (S-T-S-298(.)15K) were obtained. The activation energy E values of the first decomposition stage for complexes 1 and 2 were calculated by integral iso-conversional nonlinear (NL-INT) method. The fluorescence spectra and lifetime of complex 1 (Eu3+ ion) were studied in depth. (C) 2018 Elsevier Ltd.