The on-the-fly surface-hopping program system Newton-X: Application to ab initio simulation of the nonadiabatic photodynamics of benchmark systems

The great importance of ultrafast phenomena in photochemistry and photobiology has made dynamics simulations an essential methodology in these areas. In this work, we present the Newton-X program package containing a new implementation of a direct dynamics approach to perform adiabatic (Born–Oppenheimer) and nonadiabatic simulations. The nonadiabatic dynamics is based on Tully's surface hopping approach. The program has been developed with the aim of (1) to create a flexible tool to be used in connection with a multitude of third-party electronic-structure program packages and (2) to provide the most common options for excited-state dynamics simulations. Benchmark calculations on the nonadiabatic dynamics are presented for the methaniminium, butatriene and pentadieniminium cations. The simulation of UV absorption spectra is presented for the methaniminium cation and pyrazine.     

Coordination chemistry of 1,3,5-triaza-7-phosphaadamantane (PTA) and derivatives. Part II. The quest for tailored ligands,complexes and related applications

This review paper covers the recent developments (2004–2009) on the tailored synthetic modifications and related coordination chemistry of the water-soluble cage-like aminophosphine ligand 1,3,5-triaza-7-phosphatricyclo-[3.3.1.1]decane (PTA), together with the new applications in the fields of catalysis, material science and medicinal chemistry.     

On the effect of a point mutation on the reactivity of CuZn superoxide dismutase: a theoretical study

In this paper, we investigate the effects of a point mutation on the enzymatic activity of copper-zinc superoxide dismutase, which we recently studied in detail by means of a theoretical-computational procedure. Comparison of the reactivity of the initial catalytic steps in this mutant (G93A mutation far from the active site) with our previous data, reveals the beautiful mechanical-dynamical architecture of the enzyme, altered by such an apparently irrelevant mutation. Finally, our results suggest a possible atomic-molecular-based explanation for the mutant-pathology correlation, in line with the most recent experimental data.     

Synthesis and crystal structure of bis(dimethylthioacetonedicarboxylate)nickel(II)

Summary The title compound has been synthesized and characterized. The crystal structure has been determined by single-crystal x-ray analysis from diffractometer data, and refined to R= 0.063 for 1889 observed reflections. Crystals are monoclinic, space group P2₁/n, witha=21.97(2),b=8.21(1),c=10.44(1) A, and =101.87(3), and Z=4. Both ligands are coordinated to nickel through sulphur and one oxygen atom to realize thecis form of the complex in the square planar coordination geometry. Bond distances are: Ni-S, 2.14(1), Ni-O, 1.87(1) and 1.90(1) Å. Each nickel atom also forms two close contacts with oxygen atoms from adjacent molecules.     

Transfer Hydrogenation of Ketones Catalyzed by Surface‐Active Ruthenium and Rhodium Complexes in Water

An improved, high‐yield, one‐pot synthetic procedure for water‐soluble ligands functionalized with trialkyl ammonium side groups H₂N(CH₂)₂NHSO₂‐p‐C₆H₄CH₂[NMe₂(C_nH_2n+1)]⁺ ( [HL ⁿ ]⁺ ; n=8, 16) was developed. The corresponding new surface‐active complexes [(p‐cymene)RuCl( L ⁿ )] and [Cp*RhCl( L ⁿ )] (Cp*=η⁵‐C₅Me₅) were prepared and characterized. For n=16 micelles are formed in water at concentrations as low as 0.6 mM , as demonstrated by surface‐tension measurements. The complexes were used for catalytic transfer hydrogenation of ketones with formate in water. Highly active catalyst systems were obtained in the case of complexes bearing C₁₆ tails due to their ability to be adsorbed at the water/substrate interface. The scope of these catalyst systems in aqueous solutions was extended from partially water soluble aryl alkyl ketones (acetophenone, butyrophenone) to hydrophobic dialkyl ketones (2‐dodecanone).     

On the goethite to hematite phase transformation

This study deals with some microstructural and crystallographic aspects of the thermally induced transformation of goethite (α-FeOOH) into hematite (α-Fe₂O₃), occurring at about 300 °C. Powder specimens of goethite have been annealed in air at different temperatures, ranging from 200 °C up to 1,000 °C. The resulting products have been analyzed for a complete characterization of the changes brought about by the thermal treatments, using a multianalytical approach, based on: thermogravimetry, differential thermal analysis, transmission electron microscopy, Raman spectroscopy, and X-ray diffraction. At lower temperatures, the transition to hematite produces no important changes in size and shape of the original goethite grains. Recrystallization, and partial sintering, occurs only at temperatures in excess of 800 °C. The relevant evolution of pores present in both phases has been also considered, as it may provide important indications on the actual formation mechanism of hematite.     

On perfect hashing of numbers with sparse digit representation via multiplication by a constant

Consider the set of vectors over a field having non-zero coefficients only in a fixed sparse set and multiplication defined by convolution, or the set of integers having non-zero digits (in some base b) in a fixed sparse set. We show the existence of an optimal (or almost-optimal, in the latter case) ‘magic’ multiplier constant that provides a perfect hash function which transfers the information from the given sparse coefficients into consecutive digits. Studying the convolution case we also obtain a result of non-degeneracy for Schur functions as polynomials in the elementary symmetric functions in positive characteristic.     

Preparation and crystal structure of a copper(II) uranyl(VI) binuclear chelate

Summary The structure of the heterobinuclear complex of Cu²⁺ and [UO₂]²⁺ with the tetraanionic ligand derived from the condensation of 1,2-diaminoethane witho-acetoacetylphenol has been determined from diffractometer data and refined to R = 5.2%. The crystals are monoclinic,P2₁/a, witha = 26.22(2),b = 14.79(2),c = 8.10(1) Å and = 104.65(5)°; Z = 4. The ligand employed has two different coordination sets of atoms, N₂O₂ and O₂O₂, two oxygen atoms being common to both donor sets. In the complex the copper atom, which is retained in the inner N₂O₂ chamber, is five coordinate being axially bonded to a solvent molecule, whilst the uranyl ion is incorporated in the outer O₂O₂ chamber. Another molecule of solvent is retained to preserve the preferred seven coordination of uranium.     

Mixing efficiency and instrumental delay effect on recorded kinetic curves

The effect of reactant addition time and instrumental response time on recorded kinetic curves was considered. The mixing-time. effect was considered for first- and second-order reactions in the case that a simple function of the concentration is measured, and for first-order reactions in the more complex case of non-adiabatic enthal-pimetric measurements. For any ratio of addition time to half-transformation time the proposed equations allow calculation of the correct rate constant and the error in the calculated initial concentration extrapolated from the experimental curve and show which portion of the experimental curve must be disregarded owing to the misleading effect of the addition time. The distortion due to the response-time of a thermistor used as concentration transducer has been calculated from a simplified model. The experimental kinetic measurements performed by quasi- and non-adiabatic enthalpimetry agree very satisfactorily with the theoretical data.     

One-pot triple functionalization of carbon nanotubes

Carbon nanotubes (CNTs) are very promising as carriers for the delivery of bioactive molecules. The multifunctionalization of CNTs is necessary to impart multimodalities for the development of future CNT-based multipotent therapeutic constructs. In this context, we report the first example of covalent trifunctionalization of different types of CNTs. Our strategy is a simple and efficient methodology based on the simultaneous functionalization of the nanotube surface with three different active groups. The reaction is performed in one step by arylation with diazonium salts generated in situ. The CNTs are functionalized with benzylamine moieties blocked with three different protecting groups that can be selectively removed under specific conditions. The trifunctionalized CNTs were characterized by TEM, thermogravimetric analysis, and Raman and UV/Vis/NIR spectroscopy, while the amine loading was determined by using the Kaiser test. The sequential removal of the protecting groups of the amine functions allows the grafting of the molecules of interest on the nanotube surface to be controlled.