Supramolecular Assemblies of Phosphorylated Cavitands

The recent results in the chemistry of cavitands have proved that they are very efficient molecular receptors and potential precursors of molecular devices. In this context, we have investigated the synthesis and binding properties of phosphorylated cavitands. The stereoselective synthesis and the structural studies of the new compounds showed that these bowl-shaped molecules possess a well defined aromatic cavity surrounded by four phosphoryl groups (P=O or P=S). They are very efficient ligands for metal and organic cations. They are able to encapsulate cationic species by cooperative effect of the preorganized aromatic cavity and the four phosphorylated groups. Moreover, the upper and lower rim functionalitics can lead to the formation of molecular capsules and supramolecular assemblies whose properties and structures have been investigated by X-ray diffraction and NMR studies in solution.     

Mechanisms of Ceftazidime and Ciprofloxacin Transport through Porins in Multidrug-Resistance Developed by Extended-Spectrum Beta-Lactamase <Emphasis Type="Italic">E.coli</Emphasis> Strains

Resistance towards antibiotics stands out today as a major issue in the clinical act of treatment of bacterial-generated infections. This process was characterized in proteoliposomes reconstituted from an E.coli strain isolated from invasive infections (blood culture) occurred in patients with a cardio-vascular device admitted for surgery. Fluorescence spectroscopy and patch-clamp technique have been used. Two types of antibiotics have been targeted: ceftazidime and ciprofloxacin. Antibiotics addition in proteoliposomes suspension undergoes a quenching in tryptophan residues from outer membrane porins structure, probably due to the formation of a transient non-fluorescent porin-antibiotic complex. Patch-clamp recordings revealed strong ion current blockages for both antibiotics, reflecting antibiotic–channel interactions but with varying strength of interaction. The present study puts forward the mechanism of multidrug-resistance in extended-spectrum beta-lactamase E.coli strains, as being caused by alterations of the antibiotics transport across the porins of the outer bacterial membrane.     

SF and SC Activation of SF6 and SF5 Derivatives at Rhodium: Conversion of SF6 into H2S

The degradation of SF₆ and SF₅ organyls by S? F and S? C bond‐activation reactions at [{Rh(μ‐H)(dippp)}₂] under mild conditions is reported. Fluorido and thiolato species were identified as products or intermediates, and were characterized by X‐ray diffraction analysis and multinuclear NMR spectroscopy. An unprecedented cyclic process for the conversion of the potent greenhouse gas SF₆ into H₂S was developed.     

Tightening up the structure,lighting up the pathway: application of molecular constraints and light to manipulate protein folding,self-assembly and function

Chemical cross-linking provides an effective avenue to reduce the conformational entropy of polypeptide chains and hence has become a popular method to induce or force structural formation in peptides and proteins.Recently,other types of molecular constraints,especially photoresponsive linkers and functional groups,have also found increased use in a wide variety of applications.Herein,we provide a concise review of using various forms of molecular strategies to constrain proteins,thereby stabilizing their native states,gaining insight into their folding mechanisms,and/or providing a handle to trigger a conformational process of interest with light.The applications discussed here cover a wide range of topics,ranging from delineating the details of the protein folding energy landscape to controlling protein assembly and function.     

Electron impact mass spectrometry of some benzodioxole derivatives of pharmacological interest,their synthons and synthetic intermediates

The mass spectrometric behaviour of two newly synthesized β-blocking benzodioxole derivatives, their synthons and synthetic intermediates has been studied in detail with the aid of exact mass measurements, linked scans, collisionally activated decomposition mass analysed ion kinetic energy spectra and deuterium labelling experiments. A retrosynthetic process, leading to the original synthons, is described.     

Density functional studies of the dipole polarizabilities of the linear polyacenes benzene through nonacene

We report Ab Initio studies of the electric dipole polarizability of the linear polyacene series benzene through nonacene. A number of Ab Initio studies were done at different levels of theory for benzene, with all remaining Ab Initio calculations being at the B3LYP/6-311G(2d, 1p)//B3LYP/6-311+G(2d, 1p) level of theory. We find that the NN tensor component shows a constant increment of 20 atomic units per ring. AM1 and QSAR-quality empirical calculations show poor absolute agreement with the Ab Initio results but given excellent statistical correlation coefficients with the Ab Initio values. This implies that the results of such cheaper calculations can be suitably scaled for predictive purposes.     

A new particle solution in aesthetic field theory

In present theories a particle is commonly associated with a singularity of the field. A more realistic picture would describe the particle by an intense but singularity-free field. We have found a new solution to the aesthetic field equations for which the field associated with the particle has a very large magnitude. The particle appears to be bounded despite the large numbers appearing in the solution. We prove that this present solution is not equivalent to theO(3)-invariant solution discussed in Muraskin (1973b). Since our present solution appears well-behaved, the suggestion is that we do not confine ourselves toO(3)-invariant data in future work. Owing to the large magnitude fields, we were unable to study trajectories of the particle in any detail. There is nothing wrong, in itself, with large numbers. The present solution, which we have now studied, is the first instance in our work on aesthetic field theory in which large numbers appear without the suggestion of unboundedness.