Search results for "ta116"

Electronic Structure and Optical Properties of the Intrinsically Chiral 16-Electron Superatom Complex [Au20(PP3)4]4+

2014

The recently solved crystal structure of the [Au20(PP3)4]Cl4 cluster (PP3: tris(2-(diphenylphophino)ethyl)phosphine) is examined using density functional theory (DFT). The Au20 core of the cluster is intrinsically chiral by the arrangement of the Au atoms. This is in contrast to the chirality of thiolate-protected gold clusters, in which the protecting Au-thiolate units are arranged in chiral patterns on achiral cores. We interpret the electronic structure of the [Au20(PP3)4]Cl4 cluster in terms of the superatom complex model. The 16-electron cluster cannot be interpreted as a dimer of 8-electron clusters (which are magic). Instead, a superatomic electron configuration of 1S(2) 1P(6) 1D(6) …

Symmetry breaking in ligand-protected gold clusters probed by nonlinear optics

2016

The first hyperpolarizabilities of [Au25(SR)18](-1/0) and Au38(SR)24 clusters were determined by Hyper-Rayleigh Scattering. A strong dependence on the molecular symmetry was observed, and we explore two strategies to destroy the center of inversion in [Au25(SR)18](-1/0), protection by chiral ligands and alloying of the cluster with silver. This may open new avenues to applications of Au : SR clusters in second-order nonlinear optics.

Force Distribution Analysis of Mechanochemically Reactive Dimethylcyclobutene

2013

Internal molecular forces can guide chemical reactions, yet are not straightforwardly accessible within a quantum mechanical description of the reacting molecules. Here, we present a force-matching force distribution analysis (FM-FDA) to analyze internal forces in molecules. We simulated the ring opening of trans-3,4-dimethylcyclobutene (tDCB) with on-the-fly semiempirical molecular dynamics. The self-consistent density functional tight binding (SCC-DFTB) method accurately described the force-dependent ring-opening kinetics of tDCB, showing quantitative agreement with both experimental and computational data at higher levels. Mechanical force was applied in two different ways, namely, exter…

A DFT Study of Linear Gold–Thiolate Superclusters Absorbing in the Therapeutic NIR Window

2015

A series of linear clusters up to an aspect ratio of 1:6, formed as multimers of smaller clusters with an icosahedral Au13(5+) core having an eight-electron superatom configuration, are computationally predicted to have a greatly enhanced size-dependent absorption in the near-infrared (NIR) region extending to the biologically important NIR window. A novel structural model is presented for the previously isolated thiol-stabilized Au54(SR)30 cluster, where the metal core is formed as a heterodimer of the cores of the known Au25(SR)18(-/0) and Au38(SR)24 clusters.

One-pot synthesis and characterization of subnanometre-size benzotriazolate protected copper clusters

2012

A simple one-pot method for the preparation of subnanometre-size benzotriazolate (BTA) protected copper clusters, Cu(n)BTA(m), is reported. The clusters were analyzed by optical and infrared spectroscopy, mass spectrometry and transmission electron microscopy together with computational methods. We suggest a structural motif where the copper core of the Cu(n)BTA(m) clusters is protected by BTA-Cu(i)-BTA units.

The Role of the Anchor Atom in the Ligand of the Monolayer-Protected Au25(XR)18– Nanocluster

2015

We present a density functional theory (DFT) investigation on the role of the anchor atom and ligand on the structural, electronic, and optical properties of the anionic Au25(XR)18– nanocluster (X = S, Se, Te; R = H, CH3, and (CH2)2Ph). Substituting the anchor atom with other group 16 elements induces subtle changes in the Au–Au and Au–X bond lengths and polarization of the covalent bond. The changes in the electronic structure based on substituting both the anchor and R groups are presented through careful analysis of the density of states and theoretical determined optical spectra. We give a detailed side-by-side comparison into the structural, electronic, and optical properties of Au25(X…

2-(3,5-Dimethyl-1H-pyrazol-1-yl)-2-hydroxyimino-N0-[1-(pyridin-2-yl)ethylethylidene]

2012

Pyridinium bis(pyridine-jN)tetrakis(thiocyanato-cyanato-jN)ferrate(III)

2013

N2,N2.N6,N6-Tetrakis(perfluorobenzoyl)-2,6-diaminopyridine

2011

Multicriteria evaluation of alternatives for remote monitoring systems of municipal buildings

2014

Abstract Conservation of natural resources drives municipalities to monitor their heat, power and water consumption more accurately. The objective of this study was to evaluate different implementation possibilities for remote monitoring systems for the municipal buildings of two medium-sized municipalities, Hollola and Nastola in Southern Finland. Four different alternatives were considered: (1) a system by an external service provider, (2) a system provided by the local energy distribution company, (3) a system built by the municipalities themselves, and (4) using the current manual system but with more frequent data collection. The alternatives were evaluated in terms of multiple functio…