A europium (III) complex tested for deoxyribonucleic acid-binding, bovine serum albumin binding, and antibacterial activity

Abstract

An original complex with europium is fabricated and characterized using infra-red spectroscopy, ultraviolet–visible spectroscopy, and elemental analysis as well as an Extended X-ray Absorption Fine Structure (EXAFS) for europium absorption edge at 6977 eV energy. The ligands were completely coordinated regarding the metal with four nitrogen sites for [Eu(dafone)2Cl2.(H2O)2]Cl·H2O, such that dafone is 4,5-diazafluoren-9-one. Close-neighbor correlations from nitrogen atoms on macrocyclic cages are evident within the EXAFS spectrum. Distorted octahedral structures of the europium (III) complex were examined by utilizing EXAFS and XANES methods. The final resulted bond-length for Eu atom with O, N, and Cl are 2.36±0.05Å, 2.52±0.08Å, and 2.76±0.06Å, respectively. The coordination number for O, N, and Cl atoms are 1.94, 4.48, and 1.89, where the total coordination number is 8.31 for the central Eu atom. The binding properties of the europium samples with bovine serum albumin (BSA) and deoxyribonucleic acid (DNA) were also evaluated. The interaction mode of DNA and the complex in this work was studied based on the UV–Vis absorption titration, fluorescence titration, circular dichroism spectroscopy, viscometric assessment, thermodynamic study, ionic strength measurement and competitive binding test. The outcomes show that the complex binds to fish salmon DNA at adequate intercalation. Also, this study reveals an excellent binding property of this complex with BSA proteins. The in vitro fish salmon DNA binding activity of the samples was studied to determine the antibacterial effect of the Eu-complex on an on several gram-negative and gram-positive bacteria.