Restricted Photoinduced Conformational Change in the Cu(I) Complex for Sensing Mechanical Properties

Area of Science:

• Materials Science
• Photochemistry
• Polymer Science

Background:

• Polymer matrices significantly influence chromophore photophysical properties.
• Photophysical responses can vary with the surrounding medium, such as crystalline glass versus solution.

Purpose of the Study:

• To quantitatively probe polymer matrix viscosity using excited state dynamics.
• To establish a correlation between excited state lifetime, emission wavelength, and viscosity.

Main Methods:

• Utilized the copper complex [Cu(dmp)2]+ (dmp = 2,9-dimethyl-1,10-phenanthroline) as a photoluminescent probe.
• Investigated changes in excited state dynamics within different supramolecular polymer materials.
• Correlated photoluminescence properties (lifetime, emission wavelength) with matrix viscosity.

Main Results:

• Observed a direct correlation between excited state lifetime and emission wavelength with polymer viscosity.
• Attributed observed effects to restricted photoinduced structural distortion of the copper complex in stiffer matrices.
• Demonstrated a photoluminescence sensor with a 6-order-of-magnitude dynamic range for viscosity sensing.

Conclusions:

• The photophysical properties of [Cu(dmp)2]+ serve as an effective indicator of polymer matrix viscosity.
• This approach offers a sensitive method for probing macromolecular environments.
• The developed sensor exhibits a broad dynamic range and enhanced sensitivity compared to existing probes.