Poly(ethylene glycol) enhances the surface activity of a pulmonary surfactant

The primary role of lung surfactant is to reduce surface tension at the air–liquid interface of alveoli during respiration. Axisymmetric drop shape analysis (ADSA) was used to study the effect of poly(ethylene glycol) (PEG) on the rate of surface film formation of a bovine lipid extract surfactant (BLES), a therapeutic lung surfactant preparation. PEG of molecular weights 3350; 8000; 10,000; 35,000; and 300,000 in combination with a BLES mixture of 0.5 mg/mL was studied. The adsorption rate of BLES alone at 0.5 mg/mL was much slower than that of a natural lung surfactant at the same concentration; more than 200 s are required to reach the equilibrium surface tension of 25 mJ/m². PEG, while not surface active itself, enhances the adsorption of BLES to an extent depending on its concentration and molecular weight. These findings suggest that depletion attraction induced by higher molecular weight PEG (in the range of 8000 to 35,000) may be responsible for increasing the adsorption rate of BLES at low concentration. The results provide a basis for using PEG as an additive to BLES to reduce its required concentration in clinical treatment, thus reducing the cost for surfactant replacement therapy.     

Der Einfluß der hydroxylgruppen auf die Ultraviolett-spektren von substituerten aromatischen Molekülen,die an kieselsäureoberflächen adsorbiert sind

Ohne Zusammenfassung     

A study of the bonding between platinum(II) and the group VI donor ligand in the isostructural complexes chloropentafluorophenolato-o-vinyl-n, ndimethylanilineplatinum(II) and chloropentafluorothiophenolato-o-vinyl-N, Ndimethylanilineplatinum(II)

The molecular structures of Pt(VMN)Cl(OC₆F₅), and Pt(VMN)Cl(SC₆F₅), (VMN = o-Me₂NC₆H₄CHCH₂) have been determined from single crystal X-ray diffraction data. Both complexes crystallize in the P$\text{1}$ space group with lattice constants a 8.661(4), b 10.458(8), c 10.102(8) Å, and a 8.724(3), b 10.385(5), c 10.414(8) Å, respectively. Least squares refinements gave conventional R values of 0.033, and 0.045. The molecules are essentially isostructural and the coordination geometries have been used in conjunction with platinum—olefinic hydrogen coupling constants to reveal a small but significant degree of π-bonding between platinum(II) and the thiol sulphur.     

The stereochemistry of intermediates involved in the synthesis of tricyclovetivane sesquiterpenes

The stereospecificity of addition to the double bond of 2-substituted bicyclo[6.2.1.0^1·6]undec - 5 - enes has been studied and shown to be influenced mainly by the bicycloheptyl moiety in the case of epoxidation and hydroboration. These reactions proceed to give predominantly products of endo attack on the double bond. However for osmylation the important effect is the stereochemistry of the C₂-substituent due to steric interactions involved in the cyclic osmate ester intermediate. This results in attack by OsO₄ on the double bond trans to the C₂-substituent.     

Synthesis and characterization of 8-(dimethylamino)-1-naphthyl derivatives of aluminum, gallium, and indium

The group 13 dichlorides of formula Ar'MCl2 [Ar' = 8-(dimethylamino)-1-naphthyl (8-(Me2N)C10H6)], M = Al (1), Ga (2), and In (3), have been prepared via the salt elimination reaction of 1 equiv of Ar'Li with MCl3 in toluene solution at -78 degrees C. The reaction of 1 with LiAlH4 in diethyl ether solution at -78 degrees C produced the dihydride [Ar'AlH2]2 (4). The X-ray crystal structures of 1-4 have been determined and show that 1 and 2 are monomeric while 3 and 4 are dimeric in the solid state. The reaction of 1 with RLi in toluene solution at -78 degrees C results in ligand redistribution and formation of Ar'2AlR (R = Me (5), t-Bu (6)). The chloride analogue of 5 and 6, Ar'2AlCl (7), can be prepared directly from the reaction of 2 equiv of Ar'Li with AlCl3 in toluene solution at -78 degrees C. The homoleptic derivative Ar'3Al (8) was obtained when 3 equiv of Ar'Li was employed. Crystal data for 1: monoclinic, space group P2(1), a = 6.534(1) A, b = 10.801(1) A, c = 9.631(2) A, beta = 105.57(2) degrees, V = 654.8(2) A3, Z = 2, R = 0.0453. Crystal data for 2: monoclinic, space group P2(1), a = 6.552(2) A, b = 10.833(2) A, c = 9.601(2) A, beta = 106.05(2) degrees, V = 654.9(3) A3, Z = 2, R = 0.0609. Crystal data for 3: monoclinic, space group P2(1)/c, a = 7.401(2) A, b = 15.746 A, c = 10.801(4) A, beta = 92.37(3) degrees, V = 1257.6(7) A3, Z = 2, R = 0.0712. Crystal data for 4: monoclinic, space group P2(1)/c, a = 13.343(2) A, b = 11.228(2) A, c = 7.505(1) A, beta = 100.64(1) degrees, V = 1105.0(4) A3, Z = 4, R = 0.0560.     

UV Photodissociation Action Spectroscopy of Haloanilinium Ions in a Linear Quadrupole Ion Trap Mass Spectrometer

UV–vis photodissociation action spectroscopy is becoming increasingly prevalent because of advances in, and commercial availability of, ion trapping technologies and tunable laser sources. This study outlines in detail an instrumental arrangement, combining a commercial ion-trap mass spectrometer and tunable nanosecond pulsed laser source, for performing fully automated photodissociation action spectroscopy on gas-phase ions. The components of the instrumentation are outlined, including the optical and electronic interfacing, in addition to the control software for automating the experiment and performing online analysis of the spectra. To demonstrate the utility of this ensemble, the photodissociation action spectra of 4-chloroanilinium, 4-bromoanilinium, and 4-iodoanilinium cations are presented and discussed. Multiple photoproducts are detected in each case and the photoproduct yields are followed as a function of laser wavelength. It is shown that the wavelength-dependent partitioning of the halide loss, H loss, and NH₃ loss channels can be broadly rationalized in terms of the relative carbon-halide bond dissociation energies and processes of energy redistribution. The photodissociation action spectrum of (phenyl)Ag₂ ⁺ is compared with a literature spectrum as a further benchmark.