Determination of Structures, Stabilities, and Electronic Properties for Bimetallic Cesium-Doped Gold Clusters: A Density Functional Theory Study

Making Sense of the Growth Behavior of Ultra-High Magnetic Gd2-Doped Silicon Clusters

The growth behavior, stability, electronic and magnetic properties of the Gd₂Si_n^- (n = 3-12) clusters are reported, which are investigated using density functional theory calculations combined with the Saunders 'Kick' and the Artificial Bee Colony algorithm. The lowest-lying structures of Gd₂Si_n^- (n = 3-12) are all exohedral structures with two Gd atoms face-capping the Si_n frameworks. Results show that the pentagonal bipyramid (PB) shape is the basic framework for the nascent growth process of the present clusters, and forming the PB structure begins with n = 5. The Gd₂Si₅^- is the potential magic cluster due to significantly higher average binding energies and second order difference energies, which can also be further verified by localized orbital locator and adaptive natural density partitioning methods. Moreover, the localized f-electron can be observed by natural atomic orbital analysis, implying that these electrons are not affected by the pure silicon atoms and scarcely participate in bonding. Hence, the implantation of these elements into a silicon substrate could present a potential alternative strategy for designing and synthesizing rare earth magnetic silicon-based materials.

Idarubicin-Gold Complex: From Crystal Growth to Gold Nanoparticles

Idarubicin (IDA) is the analog of daunorubicin (DNR). The absence of the methoxy group at position 4 of IDA remarkably improved lipophilicity, which is responsible for extra cellular uptake, higher DNA-binding ability, and considerable cytotoxicity in correlation with doxorubicin (DOX) and DNR. In this paper, we conceived two principal objectives: we realized the crystal structure of IDA by X-ray diffraction measurements on single crystals at room temperature (monoclinic, space group P2₁, a = 5.1302(2) Å, b = 9.9122(5) Å, c = 24.8868(11) Å; β = 91.425(4)°; V = 1265.14(10) ų) with refinements of the structure converged to the final R = 3.87%. The second objective has been to develop gold nanoparticles encapsulated with idarubicin through an original methodology in which gold salt (HAuCl₄) is chelated with IDA and diacid polymer (PEG) to form hybrid nanoparticles called IDA IN PEG-AuNPs in which drug solubility was enhanced. The computational studies were in agreement with the experimental observations. These hybrid nanoparticles and their precursors were analyzed by Raman, UV-Vis, ¹H NMR, and transmission electron microscopy (TEM). The main results are completed by a theoretical approach to understand the whole process.

Relativistic Effects Stabilize the Planar Wheel-like Structure of Actinide-Doped Gold Clusters: An@Au7 (An = Th to Cm)

Despite the chemistry of actinide-ligand bonding is continuing and of burgeoning interest, investigations of the chemical bonding of bimetallic complexes involving transuranics remain relatively less, and there are rarely studies on the bonding features between actinide and coinage metals (CM). We present a systematic research on the series of An@Au₇ (An = Th to Cm), UCM₇ (CM = Cu, Ag, Au), and WAu₇ clusters to investigate the unique geometries, electronic structures, and chemical bonding between An 5f6d orbitals and CM ns orbitals, and to find their periodicity across the actinides and within the group of transition metals. A unique planar wheel-like structure for An@Au₇ clusters with the help of actinide metals encapsulation via spin-orbit coupling, resulting in An(III). Instead, the transition-metal (TM) element W retains its usual six-gold-coordination structure in WAu₇, thus forcing the seventh Au out of plane. The An-CM interactions, depending on the ion radii, become stronger with the increase of the atomic number of the actinide metals, as well as the CM. These results show that the presence of actinides in clusters can lead to unique electronic and geometrical structures.

Adsorbate-enhanced field-emission from single-walled carbon nanotubes: a comparative first-principles study

We report a comparative ab initio study of different types of adsorbates and their adsorption mechanism on the field-emission performance of single-walled carbon nanotubes by analyzing electrical properties and transport characteristics and considering the thermal stability of the adsorbed structure. Adsorbates were found to reduce the work function by up to 1.3 eV, enhance tunneling near the carbon nanotube tip, and increase the field-emission current by as much as two orders of magnitude. A significant localization of the electron cloud was also observed near the adsorbates under a high applied electric field.

Theoretical investigation on the low-energy isomer identification, structural evolution, stability, and electronic properties of Al10-xBex (x = 1-9) nanoalloys

Numerous isomeric equilibrium structures have been identified for the Al_10-xBe_x (x = 1-9) nanoalloy clusters by using the stochastic search procedure in combination with density functional theory calculations. The relative stability and various electronic properties of the lowest-energy Al_10-xBe_x (x = 0-10) clusters have been systematically studied by using the B3LYP and CCSD(T) methods with the aug-cc-pVDZ basis set. The evolution of the binding energies, the second difference in energy, HOMO-LUMO gaps, vertical detachment energies, vertical ionization potentials, vertical electron affinities, and hardness with the increasing number of Be atoms in the most stable Al_10-xBe_x (x = 0-10) clusters demonstrates that the global minimum of Al₈Be₂ cluster possesses a special stability. Thus, the electronic structure of the lowest-energy Al₈Be₂ cluster has been also detected in detail. In addition, it is found that the polarizabilities gradually decrease with increasing number of Be atoms, and the charges always transfer from Al to Be atoms in these nanoalloy clusters. We hope this work could provide helpful insight into the composition-dependent electronic properties of BeAl alloy at the nanoscale, serving as powerful guidelines for future experimental research.

Probing the structural, electronic and magnetic properties of AgnSc (n = 1–16) clusters

The structural, electronic and magnetic properties of Ag_nSc (n = 1–16) clusters have been studied on the basis of density functional theory and the CALYPSO structure prediction method.

Exploration of the Structural, Electronic and Tunable Magnetic Properties of Cu₄M (M = Sc-Ni) Clusters

The structural, electronic and magnetic properties of Cu₄M (M = Sc-Ni) clusters have been studied by using density functional theory, together with an unbiased CALYPSO structure searching method. Geometry optimizations indicate that M atoms in the ground state Cu₄M clusters favor the most highly coordinated position. The geometry of Cu₄M clusters is similar to that of the Cu₅ cluster. The infrared spectra, Raman spectra and photoelectron spectra are predicted and can be used to identify the ground state in the future. The relative stability and chemical activity are investigated by means of the averaged binding energy, dissociation energy and energy level gap. It is found that the dopant atoms except for Cr and Mn can enhance the stability of the host cluster. The chemical activity of all Cu₄M clusters is lower than that of Cu₅ cluster whose energy level gap is in agreement with available experimental finding. The magnetism calculations show that the total magnetic moment of Cu₄M cluster mainly come from M atom and vary from 1 to 5 μ_B by substituting a Cu atom in Cu₅ cluster with different transition-metal atoms.

Design and structural characterization of the all-metal aromatic sandwich species [Bi3Au3Bi3]3−: insight from density functional theory

The [Bi₃Au₃Bi₃]³⁻ species, with hollow features, has a unique all-metal sandwich aromatic structure.

Selective hydrogenation of cinnamaldehyde catalyzed by Co-doped Pt clusters: a density functional theoretical study

The reaction mechanism of the selective hydrogenation of cinnamaldehyde catalyzed by pure Pt clusters and Co-doped Pt clusters was studied by the density functional theory.

Reactivity of the free and (5,5)-carbon nanotube-supported AuPt bimetallic clusters towards O2 activation: a theoretical study

Density functional theory (DFT)-based calculations were carried out to predict the geometry, energy and electronic structures of the small bimetallic Au_mPt_n (2 ≤ m + n ≤ 4) clusters deposited on a single-wall (5,5)-carbon nanotube (CNT).