Evolution of Circularly Polarized Luminescence in Atomically Precise Silver Nanoclusters with Intrinsic Chirality

Area of Science:

• Nanomaterials Science
• Chiroptical Spectroscopy
• Photochemistry

Background:

• Circularly polarized luminescence (CPL) probes excited-state chiroptical properties.
• Silver nanoclusters (Ag29 NCs) exhibit intrinsic chirality.
• Post-synthetic modification can alter NC properties.

Purpose of the Study:

• To investigate the evolution of excited-state chiroptical properties in Ag29 NCs using CPL.
• To understand how post-synthetic modification affects CPL activity.
• To demonstrate the excited-state dependent CPL property of Ag29 NCs.

Main Methods:

• Synthesis of racemic Ag29 NCs using 1,3-benzenedithiol (BDT) and triphenylphosphine (PPh3).
• Separation of Ag29 NC enantiomers via chiral column chromatography.
• Post-synthetic modification with a cationic silver(I) complex.
• Circularly polarized luminescence (CPL) and circular dichroism (CD) measurements.
• Picosecond photoluminescence (PL) decay studies and low-temperature CPL measurements.

Main Results:

• Racemic Ag29 NCs with exterior cage chirality were synthesized and separated.
• Post-synthetic modification enhanced near-infrared (NIR) photoluminescence (PL).
• CPL activity was dramatically enhanced post-modification, with |g_lum| increasing significantly.
• CPL activity demonstrated an excited-state dependent property.

Conclusions:

• The study demonstrates the evolution of excited-state chiroptical properties in Ag29 NCs.
• Post-synthetic modification significantly enhances CPL activity, highlighting excited-state dependence.
• Time-resolved CPL measurements suggest a dynamic evolution of CPL activity.