Luminescence from the trans-dioxotechnetium(V) chromophore

Area of Science:

• Inorganic Chemistry
• Photochemistry
• Materials Science

Background:

• Technetium (Tc) complexes are known for their unique electronic properties.
• Excited-state luminescence in Tc complexes has been limited, especially at room temperature.
• Understanding luminescence in Tc complexes is crucial for developing new functional materials.

Purpose of the Study:

• To describe the luminescence properties of novel technetium complexes.
• To investigate the first observation of room temperature excited-state luminescence in Tc complexes.
• To compare the luminescence of Tc complexes with their rhenium (Re) analogues.

Main Methods:

• Synthesis and characterization of trans-[TcO2(L)4]+ and trans-[TcO2(CN)4]3- complexes.
• Luminescence spectroscopy at room and low temperatures (8 K).
• Density Functional Theory (DFT) and Time-Dependent DFT (TDDFT) calculations.

Main Results:

• Observed room temperature excited-state luminescence in Tc complexes for the first time, with emission maxima from 745 to 780 nm.
• Low-temperature spectra showed characteristic progressions of O=Tc=O and Tc-L stretching modes, similar to Re analogues.
• DFT/TDDFT calculations predicted Tc emission to be 0.41 eV lower in energy than Re analogues.
• Low-temperature lifetimes (8 K) ranged from 15 to 1926 μs, consistent with Re complexes.

Conclusions:

• The study successfully demonstrated room temperature excited-state luminescence in technetium complexes.
• The findings provide a foundation for further research into Tc-based luminescent materials.
• The observed properties suggest potential applications in areas requiring light-emitting technetium compounds.