Density Functional Theory Based Studies on Gold Clusters and their Complexes with Biomolecules

Abstract

Interesting physiochemical properties of gold nanoclusters have attracted the scientific community towards their extensive applications in catalysis, biosensing, protein engineering, gene newlinetechnology, etc. The role of gold clusters as catalysts has been of intense interest in recent newlineyears, being regarded as new generation of catalysts due to their unusually high catalytic newlineperformance. The nontoxic and biocompatible nature of gold nanoclusters has put them on newlinethe center stage for designing therapeutic drug delivery vehicles and efficient biosensors. In newlinethe present work, computational studies based on density functional theory (DFT) was performed to study the electronic structure modulation on increasing the size of the gold cluster newlineand how the biomolecular tagging effects the electronic structure and properties of these gold newlineclusters. These modulations exhibit great potential in influencing the catalytic properties and newlinebiosensing mechanism of the gold nanoclusters. In order to choose a reliable level of theory, newlinean extensive benchmarking of DFT functionals was done, based on which PBE0 functional newlinewas employed for carrying out all the calculations related to geometry and electronic modulation of small gold clusters on increasing the system size and also tagging them with natural/synthetic biomolecules. newlineThe work demonstrates how the quantum size effects play an instrumental role in tuning the newlinecatalytic potential of these clusters, in case of CO oxidation. An even odd oscillation is newlinefound in the fragmentation energy of clusters indicating a preferentially higher stability for newlineeven numbered clusters. A correlation between the electronic properties of the clusters and newlinethe activation energy barrier was established, suggesting that modulating the electronic structure is the key to fine-tune the catalytic properties of the cluster. The catalytic properties of newlinethe gold clusters can also be modulated by tagging them with biomolecules. In this respect, newlinecomplexes of nucleobases (natural/size-expanded) tagged to gold cluster (Au