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Exploring the Catalytic Potential of DNA/x-DNA Base−Gold Nanocluster ComplexAuthors: Sandhya Rai,Harjinder Singh,U Deva Priyakumar Conference: The 14 th Theoretical Chemistry Symposium (TCS 2014 2014) Location CSIR-NCL Pune Date: 2014-12-18 Report no: IIIT/TR/2014/67 AbstractIn pursuit of exploring new nanotechnological applications of gold clusters and their complexes with biomolecules, use of modified analogues of DNA as templates for growing nanoparticle complexes has increased significantly in recent years. Towards this larger goal, investigation of gold nanoclusters tagged with natural and size–expanded nucleic acid base pairs has generated considerable interest. In this work, our density functional theory (DFT) based study explores the possibilities of using complexes of DNA bases (adenine (A), thymine (T), guanine (G), and cytosine (C)) and their size- expanded counterparts with gold cluster Au3/4 as model catalyst system for oxidation of CO to CO 2. We first study the interaction of natural and size–expanded bases and base pairs, to shed light on the nature of interaction between the base/base pair and gold cluster (Au 3/4), as well as the effect of these interactions on the hydrogen bonding patterns of the base pair. It was found that the nature of anchoring bond formed between N/O–Au is non-covalent which is also supported by the atoms-in-molecule (AIM) calculations. The complexes are energetically stable, and the calculated binding energies of the gold cluster−DNA base complexes are found to match closely with the experimentally obtained heat of desorption of DNA bases on Au films. Our results on the catalytic activity of these complexes also reveal that the oxidation of CO on these complexes takes place via an Eley−Rideal (E-R) type of mechanism whereas both E-R and Langmuir- Hinshelwood (L-H) mechanisms for this reaction are observed for bare Au3/4 clusters. More interestingly, the CO oxidation reaction on the gold cluster (in the complexes) is found to be more facile, with a lesser activation barrier and higher heat of formation of the products, as compared to that of a pristine Au3/4 cluster. Our results suggest that DNA base−gold cluster complexes can be an attractive and efficient catalytic model system that can have wider applications. Since the nanoscale gold is already known as a potential catalyst for a variety of chemical reactions, our approach will richly supplement to the expanding horizons of catalysis involving gold. Full paper: pdf Centre for Computational Natural Sciences and Bioinformatics |
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