The role of intermolecular polarization for the stability of lithium intercalation compounds of alpha- and beta-perylene

Lithium intercalation compounds of alpha- and beta-perylene are investigated by photoelectron spectroscopy. Spectroscopic data together with a Born-Haber cycle provide information on the formation enthalpy of those materials. This approach allows understanding the amount of charge transferred from the alkali metal atoms to the pi system, and illuminates the role of molecular versus solid-state properties in the formation of the intercalation compounds. In the bulk of alpha-perylene material, molecular dimerization survives upon intercalation which reduces the Madelung energy of the intercalation compound but increases the electron-accepting capability of the organic system and facilitates the ionization of lithium atoms in the molecular solid environment. The lower ionization potential results in a larger charge transfer (about two electrons per molecule) in alpha-perylene compared to the monomeric system, beta-perylene.     

Analysis of tamoxifen and its metabolites in synthetic gastric fluid digests and urine samples using high-performance liquid chromatography with electrospray mass spectrometry

We report on the transformation of tamoxifen at 37 degrees C in synthetic gastric fluid as studied by high-performance liquid chromatography with triple quadrupole mass spectrometry. The major transformation products detected were (E)-isomer of tamoxifen, metabolite D, and several unidentified components having m/z 404. Addition of pepsin to the gastric fluid inhibited formation of all of these products. We analyzed several urine samples from breast cancer patients undergoing tamoxifen treatment. Metabolite D was identified in the urine samples and in the gastric fluid digest at a retention time of 22.0 min eluting from a reversed-phase HPLC column. Although several metabolites were found in all the urine samples of patients, some metabolites were detected in one sample but not others, suggesting tamoxifen metabolism varies in patients.     

Intramolecular Alkyne Coupling in the Reaction of 1,8-bis(phenylethynyl)naphthalene with Pt2Ru4(CO)18

The reaction of Pt₂Ru₄(CO)₁₈, 1 with 1,8-bis(phenylethynyl)naphthalene, 2 has yielded two metal carbonyl cluster complexes: Ru₂(CO)₆[- ²-C₁₀H₆C₄Ph₂], 3 (60% yield) and Ru₂Pt(CO)₆[- ²-C₁₀H₆C₄Ph₂]₂, 4 (8% yield). Both compounds were characterized by a single crystal X-ray diffraction analysis. Both products were formed as a result of fragmentation of the Pt₂Ru₄ cluster of 1. Compound 3 contains two ruthenium atoms. They are bridged by a tricyclic C₁₀H₆C₄Ph₂ ligand formed by the coupling of the two -carbon atoms of the alkyne groups. The -carbon atoms of the alkynes are -bonded to one of the ruthenium atoms to form a metallacycle and this entire group is -bonded to the second ruthenium atom. Compound 4 contains two ruthenium atoms with a platinum atom between them. This molecule contains two tricyclic C₁₀H₆C₄Ph₂ ligands similar to that in 3, and two metallacycles formed by coordination of the -carbon atoms of both ligands to the platinum atom. One ligand is -bonded to each of the ruthenium atoms.     

The infrared spectra and theoretical calculations of frequencies of fac-tricarbonyl octahedral complexes of manganese(I)

The carbonyl stretching frequencies in the infrared spectra of 38 fac-tricarbonyl octahedral complexes of manganese(I) prepared in this laboratory were determined. These complexes may be grouped into three types: (a) neutral complexes of the structure (CO)(3)Mn(P-P)Z where P-P represents depe, dppe, or dppp, and Z represents various anionic functional groups bonded to the manganese; (b) ionic complexes of the structure [(CO)(3)Mn(P-P)Z](+)BF(4)(-) where Z represents various neutral molecules possessing one phosphorous, nitrogen, or oxygen atom coordinated to the manganese; (c) complexes of the structure (CO)(3)Mn(pn)Z where the chelating pn represents 1,1-diphenylphosphino-2,2-dimethylaminoethane, Ph(2)PCH(2)CH(2)NMe(2). All of these complexes show three carbonyl stretching modes (2A' + A"). The effects on the frequencies of these modes induced by both the various Z groups and the various ligands are discussed. Theoretical calculations (B3LYP/6-31G) with optimization of the full molecule make it possible to distinguish between the three stretching modes and to make unambiguous assignments of appropriate symmetry species to each.     

Therapeutic potential of phosphoinositide 3-kinase inhibitors

At least one Holy Grail for many academic researchers and pharmaceutical research divisions alike has been to identify therapeutically useful selective PI3K inhibitors. There are several different but closely related PI3Ks which are thought to have distinct biological roles. Until now, however, researchers have been frustrated by poor selectivity of the available pharmacological inhibitors, which are unable to distinguish the different isoforms of PI3K adequately. Fortunately, recently published work gives cause for optimism; there are now several patent specifications published that describe new PI3K inhibitors, including some that are more selective for the delta isoform of PI3K. Given the involvement of PI3Ks in a plethora of biological settings, such isoform-selective inhibitors may have immense potential use for the treatment of patients with inflammatory and autoimmune disorders as well as cancer and cardiovascular diseases.     

Theoretical studies on the substitution effect of fluorine on ethylene

The substitution effect of fluorine on ethylene is investigated by means of studyingthe properties of the charge distribution at the bond critical points with the theory of atomsin molecules.It is found that fluorine atom acts not only as a σ electron acceptor,but also asa π electron donor,and these double effects are reflected in the quantity of ellipticity,Lap-lacian and the charge density of charge distribution at the bond critical points.For C—C,C—Fbonds,the major axis of elliptical contours is perpendicular to the molecular plane,but forC—H bond,it is parallel to the molecular plane.Other effects originating from the substi-tution have also been discussed.     

Theorems for carbon cages

New theorems are established for cages (or polyhedra) with trivalent vertices. One theorem says that all such cages have at least three Kekulé structures (or perfect matchings). Thence, resonance generally appears as a possibility. Another theorem says that for every even vertex count >70 there is at least one cage of a preferable subclass, while for vertex count <70 the sole preferable cage is that of the truncated icosahedron. Thence, the unique role of the buckminsterfullerene structure for C₆₀ is mathematically indicated.[/p]Work supported by the Welch Foundation of Houston, Texas.     

Fullerenes-extracted soot: a new adsorbent for collecting volatile organic compounds in ambient air

Fullerenes-extracted soot (FES) is the by-product of fullerenes production. Retention characteristics at different temperatures for 17 volatile organic compounds (VOCs) on FES are measured. The adsorption and desorption efficiencies for VOCs on FES adsorbent tubes range from 40.8 to 117%, most of them being 100+/-20%. The values are compared with Tenax GR, an adsorbent commonly used in environmental analysis. FES can be used as an adsorbent of low cost to collect VOCs in environmental samples.     

Oxidation of Oxazolines and Thiazolines to Oxazoles and Thiazoles. Application of the Kharasch-Sosnovsky Reaction

Using a modification of the Kharasch-Sosnovsky reaction, the oxidation of oxazolines and thiazolines bearing a variety of 2-alkyl substituents (chiral and achiral) were smoothly oxidized to their corresponding oxazoles and thiazoles, respectively. The key feature involved in the successful implementation of this important oxidation was the use of a mixture of Cu(I) and Cu(II) salts to enhance the oxidation of the intermediate captodative radical, 24. The main limitation of this method was shown when the oxidation failed with oxazolines/thiazolines lacking the carboalkoxy group at C-4.