Ganesan Paramasivam

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Detection of [Au25(PET)18(O2)n]− (n = 1, 2, 3) Species by Mass Spectrometry

The Journal of Physical Chemistry C, 2018

Au 25 (SR) 18 ]nanoclusters have been tested as a model catalyst in multiple oxidation reactions ... more Au 25 (SR) 18 ]nanoclusters have been tested as a model catalyst in multiple oxidation reactions involving CO, alkenes, cyclohexane, and alcohols. Oxygen is used as an oxidizing agent in most of the reactions. Hence, O 2 activation is of great interest in catalysis. The mechanism of these reactions, the role of intact nanoclusters as catalytically active species and the utility of such nanoclusters as homogeneous catalysts, etc., are not completely clear. Herein, we investigate the interaction of [Au 25 (SR) 18 ]in solution with O 2 using electrospray ionization mass spectrometry (ESI MS) and density functional theory (DFT) calculations. Up to three O 2 molecules attach to an [Au 25 (SR) 18 ]in dichloromethane (DCM) when O 2 gas is passed through a solution of the former. Oxygen addition to the nanocluster leads to its decomposition. The nanocluster is most stable in toluene and least stable in THF when kept under a continuous flow of O 2 , where no O 2 adduct peaks are observed. It shows intermediate stability in DCM in the presence of O 2 and the decomposition products, in this case, are of a different type compared to the former solvents. The appearance of O 2 adducts and the variation in the stability of the nanocluster in different solvents is assumed to be due to the difference in oxygen solubility in these solvents. DFT calculations suggest that the first two O 2 molecules interact with the surface Au atoms through the cavities formed by the ligands and staples in the nanocluster and the third O 2 interacts only with 2phenylethane thiol (PET) ligands.

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ACS nano, Jan 27, 2018

We report the formation of supramolecular adducts between monolayer-protected noble metal nanoclu... more We report the formation of supramolecular adducts between monolayer-protected noble metal nanoclusters and fullerenes, specifically focusing on a well-known silver cluster, [Ag(BDT)], where BDT is 1,3-benzenedithiol. We demonstrate that C molecules link with the cluster at specific locations and protect the fragile cluster core, enhancing the stability of the cluster. A combination of studies including UV-vis, high-resolution electrospray ionization mass spectrometry, collision-induced dissociation, and nuclear magnetic resonance spectroscopy revealed structural details of the fullerene-functionalized clusters, [Ag(BDT)(C) ] ( n = 1-9). Density functional theory (DFT) calculations and molecular docking simulations affirm compatibility between the cluster and C, resulting in its attachment at specific positions on the surface of the cluster, stabilized mainly by π-π and van der Waals interactions. The structures have also been confirmed from ion mobility mass spectrometry by comparin...

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Atomically Precise Nanocluster Assemblies Encapsulating Plasmonic Gold Nanorods

Angewandte Chemie (International ed. in English), 2018

We present the self-assembled structures of atomically precise, ligand-protected noble metal nano... more We present the self-assembled structures of atomically precise, ligand-protected noble metal nanoclusters leading to encapsulation of plasmonic gold nanorods (GNRs). Unlike highly sophisticated DNA nanotechnology, our approach demonstrates a strategically simple hydrogen bonding-directed self-assembly of nanoclusters leading to octahedral nanocrystals encapsulating GNRs. Specifically, we use the p-mercaptobenzoic acid (pMBA) protected atomically precise nanocluster, Na4[Ag44(pMBA)30] and pMBA functionalized GNRs. High resolution transmission and scanning transmission electron tomographic reconstructions suggest that the geometry of the GNR surface is responsible for directing the assembly of silver nanoclusters via H-bonding leading to octahedral symmetry. Further, use of water dispersible gold nanoclusters, Au~250(pMBA)n and Au102(pMBA)44 also formed layered shells encapsulating GNRs. Such cluster assemblies on colloidal particles present a new category of precision hybrids with di...

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