Highly intense NIR emissive Cu₄Pt₂ bimetallic clusters featuring Pt(i)-Cu₄-Pt(i) sandwich kernel

Area of Science:

• Materials Science
• Nanotechnology
• Photochemistry

Background:

• Metal nanoclusters (NCs) show promise for bioimaging and phototherapy due to near-infrared (NIR) photoluminescence (PL).
• Limited quantum yield (QY) and emission wavelengths beyond 800 nm hinder the application of current metal NCs.

Purpose of the Study:

• To develop highly luminescent NIR-emitting bimetallic NCs with enhanced QY.
• To investigate the effect of ligand modification on the photoluminescence properties of metal NCs.

Main Methods:

• Synthesis of bimetallic copper-platinum (Cu4Pt2) NCs with a specific ligand structure.
• Systematic modification of ligand substituents (R in R-C≡C-) to tune electronic effects.
• Photoluminescence spectroscopy to measure QY, emission wavelength, and excited state decay lifetime.
• Computational studies to understand structure-property relationships.

Main Results:

• A bright NIR bimetallic Cu4Pt2 NC was synthesized with a high PLQY of 36.7% at ~830 nm and a high yield of 67%.
• Ligand modification effectively modulated PLQY, emission wavelength, and excited state decay lifetime.
• Both experimental and computational results indicated that ligand modification suppresses non-radiative transitions and tunes energy gaps for wavelength adjustment.

Conclusions:

• Ligand modification is a viable strategy for enhancing NIR luminescence intensity and tailoring emission wavelengths in alloy metal NCs.
• This work provides a framework for the rational design of metal NCs with improved photophysical properties for advanced applications.