The fundamental understanding of adsorption and self-organization of biological molecules at surfaces is of greatest importance for a huge variety of possible applications, ranging from molecular electronics to the study of biocompatible materials, hygiene, and biofouling. In spite of that, the characterization of the interactions of organic molecules of biological ...

In this work, an amine-terminated poly (amidoamine) dendrimer containing Pt nanoparticles (PAMAM/Pt) nanocomposite was synthesized and a novel amperometric H(2)O(2) biosensor based on PAMAM/Pt and MWCNTs was developed. The resulting film of MWCNTs/PAMAM/Pt was characterized by transmission electron microscopy (TEM), linear sweep voltammetry (LSV) and amperometric i-t curve. It demonstrates ...

The structural, electronic, bonding, magnetic, and optical properties of bimetallic [Ru(n)Au(m)](0/+) (n + m ≤ 3; n, m = 0-3) clusters were computed in the framework of the density functional theory (DFT) and time-dependent DFT (TD-DFT) using the full-range PBE0 non local hybrid GGA functional combined with the Def2-QZVPP basis ...

Electrospray ionization (ESI) of tryptophan gives rise to multiply charged, non-covalent tryptophan cluster anions, [Trp(n)-xH](x-), in a linear ion trap mass spectrometer, as confirmed by high-resolution experiments performed on a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The smallest multiply charged clusters that can be formed in the linear ...

The interaction of O(2) with the doped icosahedral X@Al(12) (X = Al(-), P(+), C, Si) clusters with 40 valence electrons were investigated using density functional theory methods. A different behavior exhibited between Al(13)(-) and X@Al(12) (X = P(+), C, Si) when they interact with O(2). The dissociation of O(2) on ...

The electronic structure and the optical response of free catechol, [Ti(cat)(3)](2-) complex, and catechol bound to TiO(2) nanoclusters have been analysed using time dependent density functional theory (TD-DFT) performing calculations both in real time and frequency domains. Both approaches lead to similar results providing the basis sets and functionals are ...

We report an extensive first-principles study of the structure and electronic properties of Ag(n) (n = 1-8) clusters isolated in gas phase and deposited on the α-Al(2)O(3) surface. We have used the plane wave based pseudopotential method within the framework of density functional theory. The electron ion interaction has been ...

Transition states and reaction paths for a hydrogen molecule dissociating on small aluminum clusters have been calculated using density functional theory. The two lowest spin states have been taken into account for all the Al(n) clusters considered, with n=2-6. The aluminum dimer, which shows a (3)Π(u) electronic ground state, has ...

The photodissociation dynamics of pyrrole-ammonia clusters (PyH·(NH(3))(n), n = 2-6) has been studied using a combination of velocity map imaging and non-resonant detection of the NH(4)(NH(3))(n-1) products. The excited state hydrogen-atom transfer mechanism (ESHT) is evidenced through delayed ionization and presents a threshold around 236.6 nm, in agreement with previous ...

Metal atom clusters constitute very promising candidates as luminophores for applications in biotechnology because they are nanosized entities offering robust luminescence in the near-infrared field (NIR). However, they cannot be used as prepared for biological applications because of potential toxic effects and quenching of the clusters' luminescence in aqueous media, ...

The roles of hydrogen bonds in the solvation of an excess electron and a lithium atom in water hexamer cluster at 150 K have been studied by means of ab initio molecular dynamics simulations. It is found that the hydrogen bonded structures of (H(2)O)(6)(-) and Li(H(2)O)(6) clusters are very different ...

DFT/TDDFT calculations have been carried out for a series of silver and gold nanorod clusters (Ag(n), Au(n), n = 12-120) whose structures are of cigar-type. Pentagonal Ag(n) clusters with n = 49-121 and hexagonal Au(n) clusters with n = 14-74 were also calculated for comparison. Metal-metal distances, binding energies per ...

Quantitative techniques are essential to analyze the structure of soft multicomponent nanobioclusters. Here, we combine electrospray differential mobility analysis (ES-DMA), which rapidly measures the size of the entire cluster, with transmission electron microscopy (TEM), which detects the hard components, to determine the presence and composition of the softer components. Coupling ...

First-principle density functional theory is used for studying the anion gold clusters doped with magnesium atom. By performing geometry optimizations, the equilibrium geometries, relative stabilities, and electronic and magnetic properties of [Au(n)Mg]⁻ (n = 1-8) clusters have been investigated systematically in comparison with pure gold clusters. The results show that ...

The great promise of ceria-supported gold clusters as catalysts of the future for important industrial processes, such as the water gas shift reaction, has prompted a flurry of activity aimed at understanding the molecular-level details of their operation. Much of this activity has focused on experimental and theoretical studies of ...

NifEN plays a key role in the biosynthesis of the iron-molybdenum cofactor (FeMoco) of nitrogenase. A scaffold protein that hosts the conversion of a FeMoco precursor to a mature cofactor, NifEN can assume three conformations during the process of FeMoco maturation. One, designated ΔnifB NifEN, contains only two permanent [Fe(4)S(4)]-like ...

Density functional theory calculations were carried out to characterize a series of transition-metal-doped aluminum hydrides, forming TMAl(n)H(2n) and TMAl(n)H(2n+1) (TM = Sc, Ti, V; n = 3,4), in either charged or neutral form. A new electron-counting rule for these clusters was formulated as PSEN (paired skeleton electron number) = 4n, ...

Possible structures of the carbon-nitrogen clusters of the form C(m)N(n) (m = 1-4, n = 1-4, m + n = 2-5) were predicted for the neutral, anion, and cation species in the singlet, doublet, and triplet states, whenever appropriate. The calculations were performed at the G3, MP2(fc)/6-311+G*, and B3LYP/6-311+G* levels ...

Anion photoelectron spectra of Ga(x)N(y)(-) cluster anions, in which x = 4-12, y = 1 and x = 7-12, y = 2, were measured. Ab initio studies were conducted on Ga(x)N(y)(-) cluster anions in which x = 4-7, y = 1 and Ga(7)N(2)(-), providing their structures and electronic properties. The ...

The vibrationally resolved anion photoelectron (PE) spectra of MoVO(y)(-) (y = 2 - 5) metal suboxide clusters are presented and analyzed in the context of density functional theory (DFT) calculations. The electronically congested spectra reflect an increase in cluster electron affinity with increasing oxidation state. Ion beam hole-burning results reveal ...

The interaction of Au(n) and Pt(n) (n=2,3) clusters with the stoichiometric and partially reduced rutile TiO(2) (110) surfaces has been investigated using periodic slab and periodic electrostatic embedded cluster models. Compared to Au clusters, Pt clusters interact strongly with both stoichiometric and reduced TiO(2) (110) surfaces and are able to ...

Assembling ionic solids where clusters are arranged in different architectures is a promising strategy for developing band gap-engineered nanomaterials. We synthesized a series of cluster-assembled ionic solids composed of [As(7)-Au(2)-As(7)](4-) in zero-, one-, and two-dimensional architectures. Higher connectivity is expected to decrease the band gap energy through band broadening. However, ...

NADH:ubiquinone oxidoreductase (complex I) plays a central role in the respiratory electron transport chain by coupling the transfer of electrons from NADH to ubiquinone to the creation of the proton gradient across the membrane necessary for ATP synthesis. Here the atomistic details of electronic wiring of all Fe/S clusters in ...

Anionic tetrahydrofuran clusters (THF)(n) (-) (1≤n≤100) are studied with photoelectron imaging as gas-phase precursors for electrons solvated in THF. Photoelectron spectra of clusters up to n=5 show two peaks, one of which is attributed to a solvated open chain radical anion and the other to the closed THF ring. At ...

In this work we present the analysis by aberration corrected electron microscopy of the formation of gold clusters based on the proton irradiation of larger nanoparticles (NP). Pentagonal arrays have been observed and energetic calculations have been performed in order to prove the stability of these materials.

(E)-4-Hydroxy-3-methylbut-2-enyl diphosphate synthase (GcpE/IspG) converts 2-C-methyl-D-erythritol-2,4-cyclodiphosphate (MEcPP) into (E)-4-hydroxy-3-methyl-but-2-enyl diphosphate (HMBPP) in the penultimate step of the methyl-erythritol phosphate (MEP) pathway for isoprene biosynthesis. MEcPP is a cyclic compound and the reaction involves the opening of the ring and removal of the C3 hydroxyl group consuming a total of two ...

The electron kinetic energy dependence of the photoelectron spectra and angular distributions of I(-)⋅CH(3)X (X=Cl,Br,I) cluster anions are measured via velocity mapped imaging at wavelengths between 350 and 270 nm. Processes analogous to those encountered in free CH(3)X-electron interactions are revealed. In particular, the presence and energies of resonances associated ...

By use of density functional theory, a systemic theoretical study was conducted on the structural and electronic properties of ground-state silicon monoxide clusters ((SiO)(n), where n = 1-26). In our calculations, the most energetically favorable geometry for each cluster size was found to undergo a structural change from one dimension ...

We have used a recently developed electron-methanol molecule pseudopotential in approximate quantum mechanical calculations to evaluate and statistically analyze the physical properties of an excess electron in the field of equilibrated neutral methanol clusters ((CH(3)OH)(n), n=50-500). The methanol clusters were generated in classical molecular dynamics simulations at nominal 100 and ...

We have developed the uncoupled version of multireference Mukherjee's coupled cluster method with connected triexcitations. The method has been implemented in ACES II program package. The agreement between the uncoupled and the standard version of Mukherjee's multireference coupled cluster method has been reported previously at the singles and doubles level ...

In surface science, much effort has gone into obtaining a deeper understanding of the size-selectivity of nanocatalysts. In this article, electronic and chemical properties of various model catalysts consisting of Au are reported. Au supported by oxide surfaces becomes inert towards chemisorption and oxidation as the particle size became smaller ...

In this paper we report the geometries, properties, and reactivity descriptors of 12 structural isomers located on the MP2/SDDALL potential energy surface of the (1)Au(6)Pt binary clusters. A nonplanar, D(3d) symmetry, cyclohexane chairlike structure is predicted to be the global minimum. Binding energies per atom in the range ≈44-51 kcal/mol ...

Bimetallic palladium-gold Pd(n)Au(m) clusters of low nuclearity (n + m ≤ 14) are studied using the density functional theory at B3LYP level with a Lanl2DZ pseudopotential to understand the evolution of various structural, electronic, and energetic properties as a function of size (n + m) and composition (n/m) of the ...

We report the synthesis of highly luminescent, water soluble quantum clusters (QCs) of gold, which are stabilized by an iron binding transferrin family protein, lactoferrin (Lf). The synthesized AuQC@Lf clusters were characterized using UV-Visible spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), photoluminescence (PL), matrix assisted laser desorption ionization ...

The equilibrium structure, stability, and electronic properties of the Al(13)X (X=H,Au,Li,Na,K,Rb,Cs) clusters have been studied using a combination of photoelectron spectroscopy experiment and density functional theory. All these clusters constitute 40 electron systems with 39 electrons contributed by the 13 Al atoms and 1 electron contributed by each of the ...

Unbiased search on the potential energy surface of medium-sized boron clusters, with B(80), B(74), and B(68) as representatives, was carried out using simulated annealing incorporated with first-principles molecular dynamics. These boron clusters thermodynamically prefer the B(12)-centered core-shell structures, which resemble the fragment of bulk boron solids. Though these core-shell clusters ...

The performance of various density functional theory methods on the geometries and energetics of Au(2), Au(3), Au(4), and Au(5) has been systematically evaluated. The results were compared with those from experiments or high-level wave function theory methods. In the present study, spin-orbit (SO) coupling was considered. It was found that ...

In the past a variety of electron binding motifs has been identified for sodium chloride cluster anions. As for all of these clusters the excess electron is predicted to be bound in self-consistent-field calculations, the different binding mechanisms can be understood in terms of a one-electron potential largely due to ...

A series of hexagonal mesoporous germanium semiconductors with tunable wall thickness is reported. These nanostructures possess uniform pores of 3.1-3.2 nm, wall thicknesses from 1.3 to 2.2 nm, and large internal BET surface area in the range of 404-451 m(2)/g. The porous Ge framework of these materials is assembled from ...

The structure of 55-atom Li-Na and Na-K nanoalloys is determined through combined empirical potential (EP) and density functional theory (DFT) calculations. The potential energy surface generated by the EP model is extensively sampled by using the basin hopping technique, and a wide diversity of structural motifs is reoptimized at the ...

A one-pot hemimicellar synthesis of oriented, amphiphilic, and fluorescent Janus gold clusters, establishing the Janus character in terms of ligand asymmetry and distribution, has been demonstrated. The method was based on the efficient Langmuir strategy, where the in situ two-dimensional (2D) reduction of Au(3+) in the sprayed micellar electrostatic complex, ...

An in-depth spectroscopic EPR investigation of a key intermediate, formally notated as [PV(IV)V(V)Mo(10)O(40)](6-) and formed in known electron-transfer and electron-transfer/oxygen-transfer reactions catalyzed by H(5)PV(2)Mo(10)O(40), has been carried out. Pulsed EPR spectroscopy have been utilized: specifically, W-band electron-electron double resonance (ELDOR)-detected NMR and two-dimensional (2D) hyperfine sub-level correlation (HYSCORE) measurements, which ...

We have systematically investigated mixed inorganic/organic ligand sandwich clusters comprised of 3d transition metal (TM) atoms with C(60) and benzene (Bz) molecules, BzTMC(60), by using all electron density functional theory. We found the bonding type between TM and C(60) in the ground state evolves from eta(6) (TM = Sc-Cr) to ...

The electronic and geometrical structures of oxygen-rich neutral and negatively charged FeO(5), FeO(6), FeO(7), FeO(8), FeO(9), FeO(10), FeO(11), and FeO(12) clusters were obtained using density functional theory with generalized gradient approximation. With the exception of FeO(11) and FeO(12), all clusters are found to possess a large number of isomers composed ...

The improved variant of the local correlation coupled-cluster (CC) framework termed "cluster-in-molecule" (CIM), defining the single-environment (SE) CIM-CC approach, is presented and tested at the CC singles and doubles (CCSD) level. In the proposed SECIM-CC method, the previous design of the CIM orbital subsystems [Li, W.; Gour, J. R.; Piecuch, ...

The quantum theorem of corresponding states is applied to N=13 and N=26 cold quantum fluid clusters to establish where para-hydrogen clusters lie in relation to more and less quantum delocalized systems. Path integral Monte Carlo calculations of the energies, densities, radial and pair distributions, and superfluid fractions are reported at ...

The vertical excitation energies of small helium clusters, He(7) and He(25), have been calculated using configuration interaction singles, and the character of the excited states was determined using attachment/detachment density analysis. It was found that in the n = 2 manifold the excitations could be interpreted as superpositions of atomic ...

Ba(Ar)(approximately 750) clusters were generated by associating the supersonic expansion and the pick-up techniques. A femtosecond pump (266.3 nm)-probe (792 or 399.2 nm) experiment was performed to document the dynamics of electronically excited barium within the very multidimensional environment of the argon cluster. Barium was excited in the vicinity of ...

The chemistry of boron clusters has been dominated by icosahedral carboranes for over half a century. Only in recent years has significant progress been made in the chemistry of supercarboranes (carboranes with more than 12 vertices). A number of CAd (carbon-atoms-adjacent) 13- and 14-vertex carboranes, and CAp (carbon-atoms-apart) 13-vertex carboranes ...

We study the contribution of electron-atom interaction to the equation of state for partially ionized hydrogen plasma using the cluster-virial expansion. We use the Beth-Uhlenbeck approach to calculate the second virial coefficient for the electron-atom (bound cluster) pair from the corresponding scattering phase shifts and binding energies. Experimental scattering cross-sections ...