Lanthanide radii controlled one-dimensional polymer and dinuclear complexes and their fluorescent properties

Area of Science:

• Coordination Chemistry
• Materials Science
• Inorganic Chemistry

Background:

• Lanthanide complexes are crucial for luminescence applications.
• Designing versatile bridging ligands is key to controlling coordination polymer structures.
• Tetramethyl-1,4-phenylene bis(methylene)diphosphonate offers a unique scaffold for lanthanide coordination.

Purpose of the Study:

• To design and synthesize a novel bi-phosphonate ligand.
• To investigate the coordination behavior of the ligand with lanthanide nitrates.
• To characterize the resulting coordination complexes and their photophysical properties.

Main Methods:

• Ligand synthesis and characterization.
• Reaction of bi-phosphonate with lanthanide nitrates.
• Formation of 1D coordination polymers (ribbon, semi-ribbon, zigzag, dinuclear-triligand).
• Characterization using IR spectroscopy, elemental analysis, and X-ray diffraction.
• Photophysical property investigation (fluorescence, quantum yield).

Main Results:

• Successful synthesis of tetraethyl-(2,3,5,6-tetramethyl-1,4-phenylene) bis(methylene)diphosphonate.
• Formation of four distinct 1D coordination complex types (I-IV) dependent on lanthanide ionic radius.
• Characterization confirmed the structures of the synthesized complexes.
• Eu(3+) and Tb(3+) complexes showed strong fluorescence with quantum yields >= 20% upon excitation of Ln(3+) absorption bands.

Conclusions:

• The synthesized bi-phosphonate ligand effectively bridges lanthanide ions.
• Lanthanide ionic radius dictates the formation of diverse 1D coordination polymer architectures.
• The resulting lanthanide complexes possess significant luminescent properties, particularly Eu(3+) and Tb(3+) complexes.