Spectral effects in cyclobutane derivatives : The bathochromic-hypochromic shifts in compounds related to verbenone

The bathochromic-hypochromic spectral shifts, observed in bicyclic enones that contain a 4- or a 3-membered ring, are discussed in molecular-mechanical and molecular-orbital terms. It is proposed that the effect, not only by the cyclopropane but also by the cyclobutane ring, is due to extension of the CCCO chromophore, and not to its mere distortion from “normal” geometry. The high-energy absorption of umbellulone (3), 220 nm in ethanol, is characterized as a second π-π^*. 2-Methylbicyclo[3.2.1]oct-2-en-4-one (7) has been synthesized, and its preparation and spectrum are described.     

A combinatorial approach toward the discovery of non-peptide, subtype-selective somatostatin receptor ligands

The tetradecapeptide somatostatin is widely distributed throughout the body and is thought to be involved with a variety of regulatory functions. Recently, five human somatostatin receptors (hSSTR1-5) have been cloned and characterized. Several selective peptidal agonists of the hSSTR receptors are known, and we sought to apply this information to the design of novel non-peptide small molecule ligands for each receptor. Initial computational methods identified a 200 nM murine SSTR2 active compound via a database search of our sample collection. A combinatorial library was designed around the structural class of the compound with the goal of rapidly developing this initial lead into the desired subtype-selective small molecules in order to characterize the pharmacology of each of the receptor subtypes. The library was synthesized using the resin-archive, iterative deconvolution format. The total number of unique compounds in the library was expected to be 131,670, present in 79 mixtures of 1330 or 2660 compounds per mixture. Through sequences of screening and mixture deconvolution, the components of selective and highly active (Ki = 50 pM to 200 nM) non-peptide small molecule ligands for somatostatin subtypes 1, 2, 4, and 5 were identified. In addition to discovering compounds with the desired activity and selectivity, useful structure/activity information was generated which can be used in the design of new compounds and second-generation combinatorial libraries.     

Separation of hydration isomers of51CrCl3·6H2O by thin-layer chromatography and its application to the investigation of isomeric transitions occurring in the titration of these isomers with a base

A thin-layer chromatographic method was elaborated for the separation of hydration isomers of⁵¹CrCl₃·6H₂O. The layer consists of Dowex 50WX4 and microcrystalline cellulose. As developing solvent the aqueous solution of NaClO₄ and NaCl is used. The precision of the method for the determination of the amounts of the dark-and light-green isomers is ±2 abs %., and for that of the violet isomer ±0.5 abs %. The method was used in the study of changes occurring in the aqueous solutions of pure isomers in the course of titration with NaOH or in back titration with HCl. From the results obtained it follows that the transitions of hydration isomers of CrCl₃·6H₂O from dark- and light-green to the violet form or the basic forms of chromium(III) chloride or chromium(III) hydroxide is irreversible in aqueous solutions.     

Linear combination of hybrid orbitals: Acyclic alkanes

A LCHO SCF-CI semiempirical scheme is formulated for compounds of carbon and hydrogen, and far-UV transition energies computed for a number of acyclic alkanes. The type of spectral bands (CH CH*, etc.) and symmetries of subbands are assigned, and their dependence on conformation and branching discussed. It is argued that, for pentanes and higher alkanes, spectral quantities can be estimated from data on the lower alkanes.Multi-Conformational Compounds, part X. For part IX, see Ref. [1].     

Synthesis and some heterocyclisation reactions of CF2H- and CF2Cl-substituted 1,1-dicyanoethylenes

New CF₂X-analogues of 1,1-dicyano-2,2-bis(trifluoromethyl)ethylene (1) (X=H, Cl) were synthesised by the condensation of polyfluoroketones with malononitrile followed by dehydration using thionyl chloride (or phosphorus pentoxide). The heterocyclisation reactions of new CF₂X-analogues of 1,1-dicyano-2,2-bis(trifluoromethyl)ethylene with amidines, 5-aminopyrazoles and 3-methyl-2-pyrazolin-5-ones were systematically investigated.     

Arene-Ruthenium(II) Complexes with Carbothiamidopyrazoles as a Potential Alternative for Antibiotic Resistance in Human

To meet the demand for alternatives to commonly used antibiotics, this paper evaluates the antimicrobial potential of arene-ruthenium(II) complexes and their salts, which may be of value in antibacterial treatment. Their antimicrobial activity (MIC, MBC/MFC) was examined in vitro against Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Pseudomonas aeruginosa, Proteus vulgaris and Candida albicans and compared with classic antibiotics used as therapeutics. Selected arene-ruthenium(II) complexes were found to have synergistic effects with oxacillin and vancomycin against staphylococci. Their bactericidal effect was found to be associated with cell lysis and the ability to cut microbial DNA. To confirm the safety of the tested arene-ruthenium(II) complexes in vivo, their cytotoxicity was also investigated against normal human foreskin fibroblasts (HFF-1). In addition, the antioxidant and thus pro-health potential of the compounds, i.e., their nonenzymatic antioxidant capacity (NEAC), was determined by two different methods: ferric-TPTZ complex and DPPH assay.     

Stress Distribution at the Contact of Absolutely Rigid Stamp and Elastic Orthotropic Strip

A plane elastic problem for an orthotropic infinite strip with mixed boundary conditions is investigated. A model of the strip has been built by using the method of integral Fourier transforms. We obtain relationships which allow us to formulate singular integral equations for the various types of boundary conditions on one of its edges. The problems in the case of both smooth stamp-strip contact and rigid stamp-strip adhesion have been considered. It is shown that the effect of anisotropy on the contact stress distribution is minor. The stress intensity factors at the stamp corners, which are the main parameters of fracture, are evaluated. The quasi-invariance of a certain combination of the stress intensity factors is confirmed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Energy dependence of the n-γ angular correlation in the <Superscript>9</Superscript>Be(α, nγ)<Superscript>12</Superscript>C reaction

A technique for selecting the parameters required for describing the angular correlation function and finding their energy dependence has been developed. Joint analysis of a Doppler-broadened 4.44 MeV γ lineshape from the ⁹Be(α, nγ)¹²C reaction in the range 1.9–4.5 MeV of E _α energies and with n- and γ-angular distributions was performed. The Doppler-broadened lineshapes were modeled and compared using data measured in the JET plasma experiment. Relativistic effects were analyzed.