Unsaturated polyoxalates: Synthesis and mass spectral study of their thermal behavior

The thermal decomposition of a series of four saturated and unsaturated C₄ polyoxalates shows competing modes of depolymerization, fragmentation to polyenes and CO₂, and crosslinking. These decompositions, which were studied by DSC and TGA, and intensively by EI- and CI-MS, could be rationalized in terms of the structure of the alcohol portions of the polyesters. The polymers were synthesized by ester interchange, which gave materials with DP values of 5–32.     

Synthesis and biological evaluation of -n[4-(2-trans-[([2,6-diamino-4(3H)-oxopyrimidin-5-yl]methyl)thio]cyclobutyl)benzoyl] -l-glutamic acid a novel 5-thiapyrimidinone inhibitor of dihydrofolate reductase

The synthesis and biological evaluation of N-[4-(2-trans-[([2,6-diamino-4(3H)-oxopyrimidin-5-yl]methyl)thio]cyclobutyl)benzoyl]-L-glutamic acid (1) is reported. Compound 1 is a potent dihydrofolate reductase (DHFR) inhibitor (K_j = 12 nM) with excellent in vitro cell culture growth inhibition (L1210, IC₅₀ = 29 nM). Protection experiments showed that the cell growth inhibitory activity was due to DHFR inhibition. The key step in the synthesis was the coupling of a cyclobutylmethylthiol with the 5-bromo-2,6-diamino-4-oxopyrimidine ⁸.     

Adsorption and photodegradation of dimethyl methylphosphonate vapor at TiO(2) surfaces

The adsorption and degradation of the nerve agent simulant dimethyl methylphosphonate (DMMP) over UV-irradiated TiO(2) powders and thin films has been investigated. Adsorption of vapor-phase DMMP on TiO(2) powder is characterized by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Photochemically assisted oxidation of adsorbed DMMP is carried out in situ by irradiation of samples in the DRIFTS accessory, giving kinetic data and information on specific site binding of DMMP and catalyst poisoning. Gas-phase intermediates from a static vapor phase reaction are identified by gas chromatography-mass spectrometry analysis, and surface-bound intermediates and products are analyzed by high-performance liquid chromatography-mass spectrometry, and ion chromatography of both aqueous and organic extractions from the TiO(2). Adsorbed DMMP is photodegraded in a stepwise fashion to give methylphosphonic acid, PO(4)(3-), H(2)O, and CO(2) as products. A proposed reaction pathway is consistent with a rapid degradation of DMMP but with extensive poisoning of the catalyst by surface-bound phosphonate products.     

INACTIVATION OF Trypanosoma cruzi TRYPOMASTIGOTE FORMS IN BLOOD COMPONENTS BY PHOTODYNAMIC TREATMENT WITH PHTHALOCYANINES

Abstract— -Three phthalocyanine dyes HOSiPcOSi(CH₃)₂(CH₂)₃N(CH₃)₂ (Pc 4), HOSiPc-OSi(CH₃)₂(CH₂)₃N+(CH₃)3I- (Pc 5) and aluminum tetrasulfophthalocyanine hydroxide (AlOHPcS₄) were evaluated for their ability to inactivate the trypomastigote form of Trypanosoma cruzi in fresh frozen plasma (FFP) and red blood cell concentrates (RBCC). The compound Pc 4 was found to be highly effective in killing T. cruzi, Pc 5 less effective and AlOHPcS₄ ineffective. With FFP as the medium, a complete loss of parasite infectivity in vitro (≥5 log₁₀) was found to occur with 2 μ M Pc 4 after irradiation with red light (>600 nm) at a fiuence of 7.5 J/cm², while with RBCC as the medium, a complete loss was found to occur at a fiuence of 15 J/cm². Even without illumination, Pc 4 at 2 μ M also killed about 3.7-4.1 log₁₀ of T. cruzi in FFP during 30 min. Observed differences in T. cruzi killing by the various phthalocyanines may relate to differences in binding; Pc 4 binds to the parasites about twice as much as Pc 5. Ultrastructural analysis of treated parasites suggests that mitochondria are a primary target of this photodynamic treatment. The data indicate that Pc 4 combined with exposure to red light could be used to eliminate bloodborne T. cruzi parasites from blood components intended for transfusion. The inactivation of T. cruzi by Pc 4 in the dark suggests a possible therapeutic application.     

Synthesis of the first difunctional N-fluoro perfluoroalkylsulfonylimides, CF3SO2NFSO2(CF2)nSO2NFSO2CF3

Synthesis of difunctional N,N′-difluoro perfluoroalkylsulfonamides, CF₃SO₂NFSO₂(CF₂)_nSO₂NFSO₂CF₃, where n=4, 6 is reported. A related compound with an oxygen linkage CF₃SO₂NFSO₂(CF₂)₂O(CF₂)₂SO₂NFSO₂CF₃ has also been prepared. These reagents showed good activity for electrophilic fluorination.     

Organothiol Monolayer Formation Directly on Muscovite Mica

Organothiol monolayers on metal substrates (Au, Ag, Cu) and their use in a wide variety of applications have been extensively studied. Here, the growth of layers of organothiols directly onto muscovite mica is demonstrated using a simple procedure. Atomic force microscopy, surface X‐ray diffraction, and vibrational sum‐frequency generation IR spectroscopy studies revealed that organothiols with various functional endgroups could be self‐assembled into (water) stable and adaptable ultra‐flat organothiol monolayers over homogenous areas as large as 1 cm². The strength of the mica–organothiol interactions could be tuned by exchanging the potassium surface ions for copper ions. Several of these organothiol monolayers were subsequently used as a template for calcite growth.