Highly active subnano palladium clusters embedded in i-motif DNA

Area of Science:

• Nanotechnology
• Catalysis
• Biomaterials

Background:

• Sub-nanoscale metal clusters offer unique catalytic properties.
• DNA nanotechnology provides precise control over material synthesis.
• Developing efficient and stable catalysts is crucial for chemical processes.

Purpose of the Study:

• To synthesize highly active sub-nanoscale palladium (Pd) clusters using i-motif DNA as a template.
• To investigate the structure-activity relationship of Pd clusters stabilized by i-motif DNA.
• To explore the potential of DNA scaffolds for designing advanced catalysts.

Main Methods:

• Synthesis of Pd clusters using i-motif DNA template at varying Pd/base ratios.
• Characterization using Electrospray Ionization Mass Spectrometry (ESI MS), Dynamic Light Scattering (DLS), X-ray Photoelectron Spectroscopy (XPS), UV-visible spectroscopy, and Fourier-Transform Infrared Spectroscopy (FTIR).
• Catalytic activity assessment via the reduction of 4-nitrophenol.
• Density Functional Theory (DFT) calculations to elucidate the interaction between Pd and DNA.

Main Results:

• Controlled formation of Pd clusters (Pd1-Pd5, Pd8-Pd9) and nanoparticles ( 2.6 nm) by adjusting the Pd/base ratio.
• I-motif-stabilized Pd8-Pd9 clusters demonstrated high catalytic activity (relative rate constant of 2034 min⁻¹ (mM Pd)⁻¹).
• DFT revealed that i-motif DNA ligates Pd ions at cytosine N3 sites, forming metallic and positively charged Pd species that activate the substrate.

Conclusions:

• I-motif DNA serves as an effective template for synthesizing highly active sub-nanoscale Pd catalysts.
• The unique structure of i-motif DNA, with hemiprotonated C·C pairs, facilitates efficient Pd ligation and enhances catalytic performance.
• Programmable DNA scaffolds offer a promising strategy for developing next-generation sub-nanoscale metal catalysts with superior activity.