The biological targets of acivicin inspired 3-chloro- and 3-bromodihydroisoxazole scaffolds

Target analysis of acivicin derived 3-halodihydroisoxazoles scaffolds in living non-pathogenic and pathogenic bacteria.     

High resolution electron attachment to CO₂ clusters

Electron attachment to CO? clusters performed at high energy resolution (0.1 eV) is studied for the first time in the extended electron energy range from threshold (0 eV) to about 10 eV. Dissociative electron attachment (DEA) to single molecules yields O(-) as the only fragment ion arising from the well known (2)Π(u) shape resonance (ion yield centered at 4.4 eV) and a core excited resonance (at 8.2 eV). On proceeding to CO? clusters, non-dissociated complexes of the form (CO?)(n)(-) including the monomer CO?(-) are generated as well as solvated fragment ions of the form (CO?)(n)O(-). The non-decomposed complexes appear already within a resonant feature near threshold (0 eV) and also within a broad contribution between 1 and 4 eV which is composed of two resonances observed for example for (CO?)(4)(-) at 2.2 eV and 3.1 eV (peak maxima). While the complexes observed around 3.1 eV are generated via the (2)Π(u) resonance as precursor with subsequent intracluster relaxation, the contribution around 2.2 eV can be associated with a resonant scattering feature, recently discovered in single CO? in the selective excitation of the higher energy member of the well known Fermi dyad [M. Allan, Phys. Rev. Lett., 2001, 87, 0332012]. Formation of (CO?)(n)(-) in the threshold region involves vibrational Feshbach resonances (VFRs) as previously discovered via an ultrahigh resolution (1 meV) laser photoelectron attachment method [E. Leber, S. Barsotti, I. I. Fabrikant, J. M. Weber, M.-W. Ruf and H. Hotop, Eur. Phys. J. D, 2000, 12, 125]. The complexes (CO?)(n)O(-) clearly arise from DEA at an individual molecule within the cluster involving both the (2)Π(u) and the core excited resonance.     

Optimizing the accuracy and precision of the single‐pulse Laue technique for synchrotron photo‐crystallography

The accuracy that can be achieved in single‐pulse pump‐probe Laue experiments is discussed. It is shown that with careful tuning of the experimental conditions a reproducibility of the intensity ratios of equivalent intensities obtained in different measurements of 3–4% can be achieved. The single‐pulse experiments maximize the time resolution that can be achieved and, unlike stroboscopic techniques in which the pump‐probe cycle is rapidly repeated, minimize the temperature increase due to the laser exposure of the sample.     

Characterization of amorphous organic thin films, determination of precise model for spectroscopic ellipsometry measurements

The optical properties of tris(8-hydroxyquinoline) aluminum (Alq₃), N,N′-diphenyl-N,N′-bis(1-naphthyl)-1-1′biphenyl-4,4″diamine (α-NPD) and other amorphous organic materials for OLEDs application, e.g. 4,4-bis(2,2-diphenyl vinyl)-1,1-biphenyl (DPVBI) and Spiro-DPVBI have been studied by multi-angle spectroscopic ellipsometry (SE). The thin films of these materials have been deposited by organic vapor phase deposition (OVPD). The structural characterization has been performed using atomic force microscopy (AFM) and X-ray reflectometry (XRR). Comparison of the measurements using these different independent techniques enables the precise determination of the optical model for dielectric function of these thin films. The detail analyses on Alq₃ and α-NPD show that the Kim model with Gaussian broadening provides a significantly better fit to the ellipsometry data than the frequently used harmonic oscillator model. This conclusion is further proved by performing similar measurements on other amorphous organic samples for OLEDs application, e.g. DPVBI and Spiro-DPVBI. This result can be explained by the characteristic features of electronic states in organic molecules.     

Two Coordination Modes of Bidentate Aminopyrazine Ligands in Cubane-type Cluster Complex Re4Te4Cl8(C4N3H4)4 · 2DMF

Abstract  A new cubane-type cluster complex Re₄Te₄Cl₄(C₄H₄N₃)₄ · 2DMF has been synthesized by reaction of Re₄Te₄Cl₈(TeCl₂)₄ with 2-aminopyrazine C₄H₅N₃ in DMF. The crystal structure of compound has been solved by X-ray single crystal diffraction method. Crystal data for Re₄Te₄Cl₄(C₄N₃H₄)₄ · 2DMF: a = 22.8718(16) ?, b = 8.5936(7) ?, c = 20.5720(17) ?, β ^o = 106.493(2), V = 3877.1(5) ?³, R ₁ = 0.0466, R _w(F ²) = 0.1191. In the complex bidentate aminopyrazine ligands are coordinated in two different types, namely, two of four aminopyrazine ligands bind to a single rhenium atom, and each of two other ligands is coordinated as bridge between two rhenium atoms. Graphical Abstract  A new cubane-type cluster complex Re₄Te₄Cl₄(C₄H₄N₃)₄  · 2DMF with two coordination modes of bidentate aminopyrazine ligands has been synthesized and structurally characterized.      

An experimental and theoretical investigation into the hydrolysis of dichloro(ethylenediamine)platinum(II) via electrospray mass spectrometry and density functional theory

Dichloro(ethylenediamine)platinum(II), Pt(en)Cl₂, was dissolved in H₂O and D₂O, and the resulting aqueous solutions were electrosprayed into a quadrupole ion-trap mass spectrometer. A series of major and minor ionic hydrolysis products were detected. These ions were then subjected to collision-induced dissociation. As an aid in interpreting the experimental results, density functional theory calculations were carried out. These computations permitted the structures and energetics associated with the hydrolysis products to be determined. An understanding of the hydrolysis of PtenCl₂ and related coordination complexes is essential in the rational design of metal-based drugs.     

On the relation between the non-adiabatic vibrational reduced mass and the electric dipole moment gradient of a diatomic molecule

The relation between the non-adiabatic vibrational correction to the reduced mass, i.e. the vibrational g-factor, and the electric dipole moment gradient of a diatomic molecule is investigated. An explicit expression for the “irreducible” non-adiabatic contribution in terms of excited electronic states is derived. The importance of this expression for the analysis of vibration-rotational spectra of diatomic molecules is discussed and explicit expressions are presented for the first two fitting parameters in an expansion of the non-adiabatic vibrational term in an effective vibration-rotational Hamiltonian. Results of ab initio multiconfigurational self consistent field calculations of the non-adiabatic contribution to vibrational g-factor of hydrides and fluorides of Li, B, Al, Ga and monoxides of C, Si and Ge are presented and compared with the corresponding non-adiabatic contributions to the rotational g-factor.     

Evidence for C?Cl/C?Br⋅⋅⋅π Interactions as an Important Contribution to Protein–Ligand Binding Affinity

Attractive chlorine : Noncovalent interactions between chlorine or bromine atoms and aromatic rings in proteins open up a new method for the manipulation of molecular recognition. Substitution at distinct positions of two factor Xa inhibitors improves the free energy of binding by interaction with a tyrosine unit. The generality of this motif was underscored by multiple crystal structures as well as high‐level quantum chemical calculations (see picture).