Synthesis and properties of pyrazolinone organic compounds and their rare earth complexes

4-Benzoyl-3-methyl-1-phenyl-5-pyrazolinone (HPMBP) was facilely synthesized by Friedel-Crafts acylation reaction of PMP with benzoyl chloride and reacted with Eu(III) and La(III) salts leading to the formation of Eu(HPMBP)4 and La(HPMBP)3·2H2O and characterized by FTIR, 1H NMR, XRD, and X-ray single crystal diffraction. X-ray single crystal diffraction analysis revealed that Eu(III) ions exhibit an eight-coordinated square antiprism geometry through eight oxygen from four HPMBPs, while La(III) ions exhibit an eight-coordinated triangular dodecahedron geometry through six oxygen from three HPMBPs and two waters in the equatorial plane. Hirshfeld surface analysis of the complexes was determined by crystallographic calculation. It is interesting to note that the H···H, C···H and H···C are the main interactions found in the two crystal structures. All these weak intermolecular forces are supported by the overall fingerprint plot obtained in the Hirshfeld surface analysis of the complexes. La(HPMBP)3·2H2O exhibits a green luminescence effect due to the fluorescence of the excited state emitted from the HPMBP. What’s more, the antibacterial activities of the HPMBP, Eu(III), and La(III) coordination complexes to Staphylococcus aureus and Escherichia coli are also investigated, indicating that the antibacterial activity of the two complexes are better than that of HPMBP for E. coli, while for S. aureus, only Eu(HPMBP)4 is better than that of HPMBP. The Eu(HPMBP)4 has a better antibacterial activity to E. coli and S. aureus than La(HPMBP)3·2H2O. Our work preliminarily reveals that the metal ions also have different effects on antibacterial activities of complexes.