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51.
Desmond Cunningham Mark Little Kevin McLoughlin 《Journal of organometallic chemistry》1979,165(3):287-294
New adducts Et4N(RSnCl4 · L) (R butyl and phenyl; L pyridine, trimethylamine, tri-n-butylphosphine, triphenylphosphine oxide, triphenylarsine oxide, dimethylsulphoxide, dimethylformamide) have been isolated and their Mössbauer spectra studied. Definite structural assignments are made for the phosphine and phosphine oxide adducts from Mössbauer quadrupole splitting data. Comments are made on the choice of partial splitting values for phenyl and butyl groups. 相似文献
52.
The doublet electronic states of ketene, and ketene-d2, radical cations produced by photoionisation with Helα (58.4 nm) and Hellα (30.4 nm) radiation, were studied by photoelectron spectroscopy. Seven such states were found below 28 eV ionisation energy and were assigned by comparison with the ionisation energies calculated by the correlated PNO-CEPA approach. The agreement is within ≈ 0.3 eV of the experimental data. An analysis of the contributions of reorganisation and correlation effects to the calculated ionisation energies is presented. The vibrational frequencies exciteα in four of the states of ketene-d2 and ketene are presented and discussed in view of the assignments. 相似文献
53.
Abstract Although additions of α-pyrones to dienophiles have received extensive study,1 there have been few reports of additions of α-pyrones to quinones.2 In attempts to add benzoquinone (1) to coumalic acid (2), we have found that keeping these compounds in methanol and acetic acid in the presence of sodium acetate for 4 hours at 0°C followed by removal of the solvents under reduced pressure and purification by flash chromatography gave compound 3 3 (22%4) mp 158–161°C raised to mp 160–162°C (benzene) UV (MeOH) λ;306 nm (ε 4700), 215 (12,500); IR (CHCl3) vmax 3340, 1770 cm?1; 1H NMR ((CD3)2CO) δ 3.5 (s, 3H), 5.52 (s, 1H), 6.35 (d, J=5 Hz, 1H), 6.55 (m, 1H), 6.85 (m, 2H), 7.55 (d, J=5 Hz, 1H); 13C 171.5, 153.8, 153.4, 150.9, 122.3, 121.8, 119.6, 111.8, 110.8, 94.7, 56.9; mass specteum m/e (relative intensity) 234.0530 (54), 202.0267 (100), 174.0320 (34), 146.0367 (88), 98.0371 (47); m/e calcd for C12H10O5. 相似文献
54.
Zhuqing Liu C.Scott Shultz Candice A. SherwoodShane Krska Peter G. DormerRichard Desmond Claire LeeEdward C. Sherer Joseph ShpunginJames Cuff Feng Xu 《Tetrahedron letters》2011,52(14):1685-1688
An efficient preparation of highly enantiomerically enriched aryl β-hydroxy α-amino esters via dynamic kinetic resolution (DKR), asymmetric transfer hydrogenation of α-amino β-keto esters is described. The anti β-hydroxyl α-amino esters were obtained both in high yields and high diasteroselectivity. The observed high anti selectivity is inconsistent with the previous results in literature. The absolute stereochemistry of the aryl β-hydroxy α-amino esters was unambiguously confirmed via chemical derivatization as well as Vibrational Circular Dichroism (VCD) techniques. 相似文献
55.
Desmond C. Cook 《Hyperfine Interactions》2004,153(1-4):61-82
Corrosion research, and the need to fully understand the effects that environmental conditions have on the performance of structural steels, is one area in which Mössbauer spectroscopy has become a required analytical technique. This is in part due to the need to identify and quantify the nanophase iron oxides that form on and protect certain structural steels, and that are nearly transparent to most other spectroscopic techniques. A review is given of the most recent Mössbauer characterization of rusts that have formed on structural steels exposed to different environments. Mössbauer spectroscopy is playing an important role in a new corrosion program in the United States in which steel bridges, old and new, are being evaluated for corrosion problems that may reduce their serviceable lifetimes. Mössbauer spectroscopy has been used to characterize the corrosion products that form the protective patina on weathering steel, as well those that form in adverse environments in which the oxide coating is not adherent or protective to the steel. Mössbauer spectroscopy has also become an important analytical technique for investigating the corrosion products that have formed on archeological artifacts, and it is providing guidance to aid in the removal of the oxides necessary for their preservation. 相似文献
56.
A dual function blue fluorescent protein from Vibrio vulnificus is also an NADPH-dependent oxidoreductase, rendering it a useful tool for biophysical studies. 相似文献
57.
Lucian-Cristian Pop Desmond Mac-Leod CareyAlvaro Muñoz-Castro Luminita Silaghi-DumitrescuAnnie Castel Ramiro Arratia-Pérez 《Polyhedron》2011,30(5):841-845
The relativistic electronic structure calculations of N,N′-chelated pnictogenium cations containing aminotroponiminate units, (E = P(1), As(2), Sb(3), Bi(4)), have been investigated employing density functional (DF) methods, including spin-orbit relativistic corrections, via the two-component zeroth order regular approximation (ZORA) Hamiltonian. The role of replacement of the pnictogen atom when going down into the 15 group was discussed on the basis of geometrical parameters, Hirshfield charge analyses, DF reactivity indexes. The degree of electronic delocalization into the five- and seven membered rings was estimated via the electron localization function (ELF) and the nuclear independent chemical shifts (NICS) indexes.Our results show an existence of a lack of systems 2-4 to act as donor ligands for the metal complexation, compared with 1, due to the positive charge over the pnictogen atoms besides the lone-pair orbital of the pnictogen atom which lies at low energies from their corresponding reacting HOMO’s. It is also interesting to note some effects over the aromaticity when going down into the 15 group, i.e., the C5 ring is affected by the change of the pnictogen atom, while the aromaticity on the C7 ring is not affected, as suggested by the analysis of the ELF, NICS and geometrical parameters. 相似文献
58.
Fazila ZulfiqarSamir A. Ross Desmond Slade Safwat A. Ahmed Mohamed M. RadwanZulfiqar Ali Ikhlas A. Khan Mahmoud A. ElSohly 《Tetrahedron letters》2012,53(28):3560-3562
Cannabisol (1), a unique dimer of Δ9-tetrahydrocannabinol (Δ9-THC) with a methylene bridge, was isolated from Cannabis sativa. This is the first example of a C-bridged dimeric cannabinoid. The structure of 1 was unambiguously deduced by HRESIMS, GCMS, and NMR spectroscopy. A plausible biogenesis of 1 is described. 相似文献
59.
Lee J Chubb AJ Moman E McLoughlin BM Sharkey CT Kelly JG Nolan KB Devocelle M Fitzgerald DJ 《Organic & biomolecular chemistry》2005,3(20):3678-3685
Currently available non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin are directed at the cyclooxygenase (COX) site, but not the peroxidase (POX) activity of prostaglandin H2 synthase (PGHS). They are thus unable to inhibit the free-radical induced tissue injury associated with PGHS peroxidase activity, which can occur independently of the COX site. A lead compound, anthranilic hydroxamic acid (AHA) was found to have significant PGHS-POX inhibitory activity (IC50= 72 microM). To define the critical parameters for PGHS-POX inhibition, we investigated 29 AHA derivatives, synthesised from their acid precursors, using solid phase synthesis. In vitro analysis demonstrated a ten-fold improvement in inhibition with 3,5-diiodoanthranilic hydroxamic acid (IC50= 7 microM). 相似文献
60.
Nelson Nuñez-Dallos Natalia Lopez-Barbosa Alvaro Muñoz-Castro Desmond Mac-Leod Carey Assunta De Nisi Magda Monari 《Journal of Coordination Chemistry》2017,70(19):3363-3378
The use of a new copper(I) coordination polymer (CP) as additive in transparent composite films of 190 nm of thickness for ultraviolet (UV) shielding is presented. The luminescent 1-D Cu(I) CP was easily synthesized through a self-assembly process between Cu(I) iodide and 2,6-bis(1H-benzotriazol-1-ylmethyl)pyridine (L). The CP, [Cu2(μ ? I)2(μ ? L)2]n, was structurally characterized by infrared, UV–visible diffuse reflectance and photoluminescence spectroscopy, elemental and thermogravimetric analyses, single-crystal and powder X-ray diffraction, and relativistic density functional theory calculations. The CP was dispersed and immobilized into a polymeric matrix in the presence of Sudan I, yielding a composite material that exhibits a reduction of 49% of the UV transmittance at 350 nm. Thus, the use of a new Cu(I) CP in polymeric composite films appears as a novel approach toward ultrathin and transparent UV shielding films, which have potential applications as protection layers of paints and coatings that tend to degrade when exposed to UV radiation. 相似文献