Al3Li4(BH4)13: A Complex Double‐Cation Borohydride with a New Structure

The new double‐cation Al–Li–borohydride is an attractive candidate material for hydrogen storage due to a very low hydrogen desorption temperature (～70 °C) combined with a high hydrogen density (17.2 wt %). It was synthesised by high‐energy ball milling of AlCl₃ and LiBH₄. The structure of the compound was determined from image‐plate synchrotron powder diffraction supported by DFT calculations. The material shows a unique 3D framework structure within the borohydrides (space group=P‐43n, a=11.3640(3) Å). The unexpected composition Al₃Li₄(BH₄)₁₃ can be rationalized on the basis of a complex cation [(BH₄)Li₄]³⁺ and a complex anion [Al(BH₄)₄]^?. The refinements from synchrotron powder diffraction of different samples revealed the presence of limited amounts of chloride ions replacing the borohydride on one site. In situ Raman spectroscopy, differential scanning calorimetry (DSC), thermogravimetry (TG) and thermal desorption measurements were used to study the decomposition pathway of the compound. Al–Li–borohydride decomposes at ～70 °C, forming LiBH₄. The high mass loss of about 20 % during the decomposition indicates the release of not only hydrogen but also diborane.     

Radford's Formula for Bifrobenius Algebras and Applications

In a biFrobenius algebra H, in particular in the case that H is a finite dimensional Hopf algebra, the antipode 𝒮:H → H can be decomposed as 𝒮 = _tc ○ c_φ where c_φ:H → H* and _tc:H* → H are the Frobenius and coFrobenius isomorphisms. We use this decomposition to present an easy proof of Radford's formula for 𝒮⁴. Then, in the case that the map 𝒮 satisfies the additional condition that 𝒮  id = id  𝒮 = u ?, we prove the trace formula tr(𝒮²) = ?(t)φ(1). We finish by applying the above results to study the semisimplicity and cosemisimplicity of H.     

Local differentiable pole assignment

Given a general local differentiable family of pairs of matrices, we obtain a local differentiable family of feedbacks solving the pole assignment problem, that is to say, shifting the spectrum into a prefixed one. We point out that no additional hypothesis is needed. In fact, simple approaches work in particular cases (controllable pairs, constancy of the dimension of the controllable subspace, and so on). Here the general case is proved by means of Arnold's techniques: the key point is to reduce the construction to a versal deformation of the central pair; in fact to a quite singular miniversal one for which the family of feedbacks can be explicitly constructed. As a direct application, a differentiable family of stabilizing feedbacks is obtained, provided that the central pair is stabilizable.     

A combination of molecular dynamics and docking calculations to explore the binding mode of ADS-J1, a polyanionic compound endowed with anti-HIV-1 activity

The HIV-1 entry process is an important target for the design of new pharmaceuticals for the multidrug therapy of AIDS. A lot of polyanionic compounds, such as polysulfonated and polysulfated, are reported in the literature for their ability to block early stages of HIV-1 replication. Several studies have been performed to elucidate the mechanism of the anti-HIV-1 activity of sulfated polysaccharides and polyanions in general, including binding to cell surface CD4 and interfering with the gp120-coreceptor interaction. Here, we show molecular modeling investigations on ADS-J1, a polyanionic compound with anti-HIV activity that is able to interfere with gp120-coreceptor interactions. Agreeing with experimental data, computer simulations suggested that the V3 loop of gp120 was the preferential binding site for ADS-J1 onto HIV-1. Moreover, mutations induced by the inhibitor significantly changed the stereoelectronic properties of the gp120 surface, justifying a marked drop in the affinity of ADS-J1 toward an ADS-J1-resistant HIV-1 strain.     

Correlation between photophysical parameters and gold-gold distances in gold(I) (4-pyridyl)ethynyl complexes

The systematic analysis of the luminescence of a series of alkynyl gold derivatives with general formulas [(diphos)(AuC≡Cpy)(2)] (diphosphane =2,2'-bis(diphenylphosphanyl)propane or dppip (1), bis(diphenylphosphanyl)acetylene or dppa (2), 1,2-bis(diphenylphosphanyl)ethane or dppe (3) and 1,4-bis(diphenylphosphanyl)butane or dppb, (4), has shown a straightforward correlation between the Au(I)···Au(I) distance and the emission quantum yields and decaytimes. The analysis of the decaytimes, quantum yields and thus, the corresponding calculated rate constants demonstrated the existence of a correlation between Au(I)···Au(I) distance and the radiative rate constant for the deactivation of the emissive triplet states. It was concluded that the increased emission of these compounds results from the increase in spin-orbit coupling that favors the spin forbidden transition to the singlet ground state.