<p>The development of technologies and the growing scientific interest in compounds with luminescent properties determine the relevance of research on the development of new lanthanide complexes due to their unique optical characteristics. In the work, a new coordination compound of neodymium (III) with β-diketone containing an unsaturated bond in the α-position − 2-methyl-5-biphenylpent-1-ene-3,5-dione, and mixed-ligand complexes with 1,10-phenanthroline and 2,2’-bipyridine based on it were synthesized. Homopolymers of both mono- and mixed-ligand metal complexes, as well as a copolymer of a neodymium sample with methyl methacrylate were obtained by radical polymerization. The synthesized samples were investigated using IR spectroscopy, diffuse reflectance spectroscopy, scanning electron microscopy (SEM), and their thermal and luminescent characteristics were studied. Based on the diffuse reflection spectra, the covalence parameters were calculated. Analysis of the luminescence spectra showed that the emission intensity increases from the monoligand complex [Nd(mbphpd)₃⋅2H₂O]⋅H₂O to the mixed-ligand complex Nd(mbphpd)₃⋅phen (almost 3 times) Nd(mbphpd)₃⋅bpy (5 times). In the case of polymer systems, there is no significant increase in emission characteristics for monoligand and phenanthroline complexes, however, for the [Nd(mbphpd)₃⋅bpy]_n, the relative luminescence intensity increases by 3 times compared to Nd(mbphpd)₃⋅bpy, and by 9 times for [Nd(mbphpd)₃]_n. The increase in the emission of heteroligand compounds is due to the leveling of the quenching effect of the OH groups of water molecules. As can be seen from the micrographs, the structure of the obtained compounds directly affects the emission intensity. Unfortunately, possible oligomerization processes and, accordingly, the heterogeneous structure of the monomeric neodymium complex did not allow obtaining qualitative luminescence indicators in this case, but mixed-ligand metal complexes based on it can be proposed as emissive materials.</p>