Emergence of a Low-Energy Peak in the Smoothed Absolute Value Circular Dichroism Spectra of Small Helical Gold Nanorods.

We calculate, using time-dependent density functional theory, absorption and circular dichroism (CD) spectra for a series of small helical gold nanorod structures with a width of 0.6 nm and length increasing from 0.7 nm for Au to 1.

Engineering magic number Au and Au cage structures using electron withdrawing atoms.

Gold cages are a subset of gold nanoparticles and these structures are of major interest due to their favourable physiochemical properties. In order for these structures to be useful in applications, they must be chemically stable. The objective of this research is to transform non-magic number cage structures into magic number cage structures by the addition of electron-withdrawing groups on the cages.

Triskelion Structured Colloidal Quantum Dots.

We show, using density functional theory and ab initio molecular dynamics, that certain small colloidal quantum dots with a mixed nanocrystal core capped with achiral surface ligands spontaneously form a triskelion (from the Greek, three-legged) structure with (approximate) symmetry that can be dynamically stable at room temperature when additionally capped with small amine ligands. Furthermore, the nanocrystal core also forms a triskelion structure. The focus of our study is a colloidal quantum dot with a CdSeTe core (and a charge of +12) capped with negatively charged surface ligands to achieve charge neutrality-in the simplest instance, 12 Cl-to form the colloidal quantum dot CdSeTeCl.

Bonding and metastability for Group 12 dications.

Electronic structure and bonding properties of the Group 12 dications M (M = Zn, Cd, Hg) are investigated and electron density-derived quantities are used to characterize the metastability of these species. Of particular interest are the complementary descriptions afforded by the Laplacian of the electron density ∇ ρ(r) and the one-electron Bohm quantum potential (Q =  ) along the bond path. Further, properties derived from the pair density including the localization-delocalization matrices (LDMs) and the interacting quantum atoms (IQA) energies are analyzed within the framework of the quantum theory of atoms in molecules (QTAIM).

Stabilization of Columnar Liquid Crystal Phases via Arene-Perfluoroarene Interactions.

We report the synthesis of novel polycatenar dibenzopentacenequinones and that are designed to form columnar liquid crystalline phases. The mesomorphic properties of these compounds were investigated by polarized optical microscopy, differential scanning calorimetry, and powder X-ray diffraction. While compound exhibits two distinct columnar mesophases between 148 and 177 °C, fluorinated exhibits a columnar mesophase from 121 to 336 °C.

Iron doped gold cluster nanomagnets: determination of barriers for demagnetization.

Magnetic properties of small- and nano-sized iron doped gold clusters are calculated at the level of second order multireference perturbation theory. We first assess the methodology for small AuFe and AuFe clusters, which are representative of even and odd electron count systems. We find that larger active spaces are needed for the odd electron count system, AuFe, which exhibits isotropic magnetization behaviour.

(Meta-)stability and Core-Shell Dynamics of Gold Nanoclusters at Finite Temperature.

Gold nanoclusters have been the focus of numerous computational studies, but an atomistic understanding of their structural and dynamical properties at finite temperature is far from satisfactory. To address this deficiency, we investigate gold nanoclusters via ab initio molecular dynamics, in a range of sizes where a core-shell morphology is observed. We analyze their structure and dynamics using state-of-the-art techniques, including unsupervised machine-learning nonlinear dimensionality reduction (sketch-map) for describing the similarities and differences among the range of sampled configurations.

Helical gold nanorods as chiral recognition nanostructures: a relativistic density functional theory study.

We establish helical gold nanorods as the first examples of chiral recognition nanostructures by examining the simple chiral molecule CClHDT adsorbed on the helical Au40 nanorod. We calculate the vibrational circular dichroism (VCD) spectra of the R and S enantiomers of CClHDT adsorbed on the R (or S) enantiomer of Au40 using relativistic density functional theory. The highest adsorption energy is found when the Cl atom of CClHDT binds to a low-coordinated Au atom at the edge of Au40.

Density functional theory calculations on the complexation of p-arsanilic acid with hydrated iron oxide clusters: structures, reaction energies, and transition states.

Aromatic organoarsenicals, such as p-arsanilic acid (pAsA), are still used today as feed additives in the poultry and swine industries in developing countries. Through the application of contaminated litter as a fertilizer, these compounds enter the environment and interact with reactive soil components such as iron and aluminum oxides. Little is known about these surface interactions at the molecular level.

Formation of chlorinated species through reaction of SO₂ with NaClO₂ powder and their role in the oxidation of NO and Hg⁰.

This study examines gaseous chlorinated species generated from the reaction of sulfur dioxide (SO₂) with sodium chlorite powder (NaClO₂(s)) to obtain insight into the propensity of this process to enhance NO and Hg⁰ oxidation. A packed bed reactor containing NaClO₂(s) was used and the reaction temperature was set to 130 °C. Initially, we determined that the presence of SO₂ enhances the oxidation of NO and Hg⁰ by reaction with NaClO₂(s).

Investigations of strong hydrogen bonding in (ROH)n...FHF- (n = 1, 2 and R = H, CH3, C2H5) clusters via high-pressure mass spectrometry and quantum calculations.

An examination of strong hydrogen bonds found in (ROH)(n)...