Nd3+ and Yb3+ complexes with N-(diphenylphosphoryl) pyrazine-2-carboxamide as UV-NIR radiation converters and single-ion magnets

The increased interest in designing bifunctional magnetic-luminescent compounds stems from their promising application potential. Appropriately designed lanthanide coordination compounds were found suitable for this purpose. This work describes the structural, optical and magnetic properties of photostable lanthanide coordination compounds (Nd, Yb) with N-(diphenylphosphoryl)pyrazine-2-carboxamide (HL) acting as an antenna. Optical properties of the compounds were characterized by IR, high-resolution absorption and emission spectroscopies at 300, 77 and 5 K. The trinuclear coordination compounds (labeled as Na(2)LnL(4)), with a crystal structure stiffened by eight oxygen bridges with eight-coordinated lanthanide ion, as well as sixand seven coordinated Na ions, were found to be excellent converters of UV radiation into the NIR. The ligand-to-metal energy transfer mechanisms in Na2NdL4 were discussed. Na2YbL4 reached the highest (Q(Yb)(L) = 5.8%) overall emission quantum yield among the coordination compounds of Yb3+ with organic ligands in solid state. The static and dynamic magnetic properties of Na2NdL4 and Na2YbL4 were studied, revealing that the compounds exhibit behavior of field-induced Single Ion Magnets (SIMs) with the effective energy barrier value of 27.4 K (Na2NdL4) and 26.2 K (Na2YbL4). The anisotropic barrier was extracted from static magnetism and optical properties analysis, giving an insight into the magneto-optical correlation. We demonstrated that proper design of ligand structure and coordination compound architecture allows to obtain molecular magnets with optimized infrared emission.

Automated summary

The study describes the structural, optical, and magnetic properties of lanthanide coordination compounds with N-(diphenylphosphoryl)pyrazine-2-carboxamide as an antenna, which showed excellent performance in converting UV radiation into near-infrared light. The compounds exhibit behavior of field-induced Single Ion Magnets (SIMs) with high effective energy barrier values, demonstrating potential applications in molecular magnets with optimized infrared emission.