Improving the Singlet Oxygen Photosensitization Activity of Fluorenone-Based Materials

Area of Science:

• Materials Science
• Inorganic Chemistry
• Photochemistry

Background:

• Coordination polymers are advanced materials with tunable properties.
• Thioether fluorenones are novel organic ligands with potential applications in optoelectronics.
• Understanding the photophysical properties of metal-iodide complexes is crucial for developing new functional materials.

Purpose of the Study:

• To synthesize and characterize novel coordination polymers using copper(I) iodide and new thioether fluorenone ligands.
• To investigate the photophysical properties, including luminescence and photosensitization capabilities, of the synthesized compounds.
• To correlate the ligand design with the observed optical and electronic properties using experimental and computational methods.

Main Methods:

• Synthesis of coordination polymers (UDS-7, UDS-8, UDS-9) using copper(I) iodide and thioether fluorenone ligands (L7, L8, L9).
• Structural characterization using X-ray diffraction techniques.
• Photophysical analysis including steady-state and time-resolved spectroscopy, excitation power-dependent photoluminescence, and near-infrared photoluminescence spectroscopy.
• Computational studies using density functional theory (DFT) and time-dependent DFT (TD-DFT).

Main Results:

• Three coordination polymers (UDS-7, UDS-8, UDS-9) were successfully synthesized and characterized.
• The compounds exhibit ligand-centered 1,3LC emissions, deviating from expected metal-to-ligand charge-transfer behavior.
• Singlet oxygen (1O2) photosensitization was observed, with enhanced performance in UDS-7 and UDS-9 compared to UDS-8.
• Excitation power-dependent studies revealed singlet-singlet and triplet-triplet annihilation, indicating efficient exciton migration.

Conclusions:

• The rational design of thioether fluorenone ligands allows for the development of novel copper(I) iodide coordination polymers with unique photophysical properties.
• The synthesized materials display ligand-centered luminescence and act as efficient photosensitizers for singlet oxygen generation.
• The findings provide insights into structure-property relationships, paving the way for the design of advanced functional materials for applications in areas like photodynamic therapy or sensing.