Effect of N,N′-dimethylformamide solvent on structure and thermal properties of lanthanide(III) complexes with flexible biphenyl-4,4′-dioxydiacetic acid

• Published in: Journal of thermal analysis and calorimetry 2022-01, Vol.147 (2), p.1187-1200
• Main Authors: Głuchowska, Halina, Łyszczek, Renata, Jusza, Anna, Piramidowicz, Ryszard
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Carbonyls; Chemical analysis; Chemistry; Chemistry and Materials Science; Coordination compounds; Diffraction; Diffraction patterns; Dimethylformamide; Europium; Fourier transforms; Heating; Infrared analysis; Infrared spectroscopy; Inorganic Chemistry; Measurement Science and Instrumentation; Nitrogen; Optical properties; Oxygen atoms; Physical Chemistry; Polymer Sciences; Rare earth metals; Solvents; Thermal analysis; Thermal decomposition; Thermal properties; Thermal stability; Thermodynamic properties; Water chemistry; X-rays; Ytterbium
• ISSN: 1388-6150; 1588-2926
• DOI: 10.1007/s10973-020-10435-1

The N,N′-dimethylformamide (DMF) was used in the microwave-assisted (MW) solvothermal method for the preparation of lanthanide(III) complexes with biphenyl-4,4′-dioxydiacetic acid (H 2 L) of the formula Ln 2 L 3 · x DMF⋅ y H 2 O where Ln = lanthanide(III) ions from La(III) to Lu(III) with the Pm(III) exception x  = 1.5–3; y  = 2 for Yb and Lu or 0 for the remaining complexes and L = C 14 H 12 O 2 (COO) 2 2− . The obtained complexes were characterized by the elemental analysis, infrared spectroscopy (ATR-FTIR), X-ray diffraction patterns and different methods (TG-DSC and TG-FTIR) of thermal analysis. Crystalline complexes contain N,N′-dimethylformamide molecules in their structures. Additionally, water molecules are present in the structures of Yb(III) and Lu(III) complexes. Coordination of lanthanide ions occurs through carboxylate oxygen atoms from the biphenyl-4,4′-dioxydiacetate ligand and most probably carbonyl oxygen atom from N,N′-dimethylformamide. The investigated compounds exhibit different thermal stability, and removal of solvent molecules takes place in a more complex way in the group of heavy lanthanide complexes. Their desolvated forms are an unstable [except Yb(Lu) 2 L 3 compounds], and their further heating leads to the formation of suitable lanthanide oxides (air atmosphere). Thermal stability of the investigated compounds is higher in nitrogen atmosphere. The TG-FTIR methods allowed to propose way of thermal decomposition of investigated compounds through identification of volatile products such as: DMF, H 2 O, CO 2 , CO and CH 4 evolved during heating of complexes. The luminescent properties of terbium(III) and europium(III) complexes were also investigated.