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991.
[formula: see text] N-Confused meso-substituted porphyrin is a porphyrin isomer previously available from one-flask porphyrin syntheses as a low-yield byproduct (< 7.5%). We have found that methanesulfonic acid catalyzed condensation of pyrrole and benzaldehyde followed by DDQ oxidation provides N-confused tetraphenylporphyrin (NC-TPP) in up to 39% yield in analytical scale experiments. Preparative synthesis provided an isolated yield of 35% (800 mg). This represents a > 5-fold yield improvement and makes significant quantities of NC-TPP readily available. 相似文献
992.
The responsivity at a constant detection area of non-steady-state photoinduced electromotive force (photo-emf) detectors is improved by a factor equal to the number of contact pairs contained in asymmetric interdigitated surface contacts. The polar nature of photo-emf current generation requires contact asymmetry in which one increases the total signal by blocking the illumination between alternate contact pairs, in distinct contrast to the behavior of conventional interdigitated contacts fabricated upon isotropic photoconductors. 相似文献
993.
We report what is believed to be the first observation of lasing of an optically pumped thin CdS film formed by laser ablation on glass. Laser action is observed at room temperature, and the emission peak is at 501 nm. X-ray diffraction shows that the polycrystalline films are of wurtzite structure and have (002) preferred orientation. Fabry-Perot laser modes are spaced 16 nm apart, indicating a cavity length of 2.9mum . The cavity is formed by consistently self-formed microcavities within the hexagonal lattice. 相似文献
994.
995.
Radical thiol additions to 7-azanorbornadienes give 7-thio-substituted 2-azanorbornenes and Barton deoxygenations of 7-azabenzonorbornanols give 2-azabenzonorbornanes. The processes both involve novel nitrogen-directed radical rearrangements. The kinetics and mechanisms of the reactions are also discussed. 相似文献
996.
Braun M Atalick S Guldi DM Lanig H Brettreich M Burghardt S Hatzimarinaki M Ravanelli E Prato M van Eldik R Hirsch A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(16):3867-3875
Two dendritic fullerene (DF) monoadducts, 2 and 3, which can carry up to 9 and 18 negative charges, respectively, were examined with respect to electrostatic complexation with Cytochrome c (Cytc). To facilitate comprehensive photophysical investigations, the zinc analogue of Cytc (ZnCytc) was prepared according to a novel, modified procedure. The association of ZnCytc and DF, and consequential photoinduced electron transfer within ZnCytc-DF from the photoexcited protein to the fullerene, was proven by fluorescence spectroscopy and transient absorption spectroscopy. These findings were also supported by circular dichroism as well as by extensive molecular dynamics (MD) simulations. 相似文献
997.
998.
Varchi G Kofink C Lindsay DM Ricci A Knochel P 《Chemical communications (Cambridge, England)》2003,(3):396-397
The successive addition of PhMgCl and i-PrMgCl to functionalised iodoanilines allows their conversion to the corresponding amino-functionalised Grignard reagents, which react smoothly with a range of electrophiles in high yield. 相似文献
999.
Vandenabeele P Grimaldi DM Edwards HG Moens L 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2003,59(10):2221-2229
Dispersive Raman spectra of six copal resins, that were purchased in local markets in Mexico, are presented. The spectra were interpreted and compared with each other. For all these spectra, the relative intensity of the Raman band at approximately 1645 cm(-1), attributed to the exomethylene nu(C=C) stretching vibration, was rather low, especially as fresh samples are involved. In one resin, viz. Incienso, CaCO3 was detected. Probably this inorganic pigment was added as a whitener. In the spectrum of Lágrima a starch fraction was present. Raman spectra of a sample from an Aztec figurine were recorded. It was shown that its composition was inhomogeneous at the micrometer level. Here, too, CaCO3 was observed. It was not possible to identify the resin applied in the antique figurine due to material degradation by age and environmental exposure. 相似文献
1000.
Carlucci L Ciani G Proserpio DM Porta F 《Angewandte Chemie (International ed. in English)》2003,42(3):317-322