Fiddling with metal atoms

Organic ions or molecules that bind to the surface of noble metal nanoclusters are known as ligands. Usually, these ligands are modified to allow for tailoring the nanoclusters leading to potential practical applications. 

So far, however, it has not been well understood how modifying the ligand alters the electronic and optical properties of the metal nanoclusters. 

In a new study published in Inorganic Chemistry¹, scientists from Saudi Arabia and the US demonstrate how surface-bound mercaptonitrobenzoic acid molecules can alter the electronic and optical properties of silver nanoclusters. 

They were able to induce such change by tweaking the pH chemistry of such systems.  

At pH levels higher than 13, the surface-bound organic acids lose hydrogen ions, in turn forming soluble and stable silver nanoclusters in aqueous solutions. 

When pH was lowered from 13 to 7, two adjacent acid molecules on the surface of the nanoclusters formed chemical structures called dimers, each one consisting of two identical molecules of the acids. 

These dimers are responsible for changing the electronic structure of the nanoclusters as well as their optical properties. 

“This research offers a simple and efficient tool for tuning optical and electronic properties of metal nanoclusters which are potentially useful for making photo-active catalysts and biomedical sensors,” says lead scientist Omar Mohammed from the King Abdullah University of Science and Technology (KAUST), Saudi Arabia.

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