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711.
This paper presents the photophysical and photochemical characteristics of four new poly(amidoamine) dendrimers of zero and second generation whose periphery has been modified with 1,8-naphthalimide units. Nitro- and allylamino groups have been used as substitutents at the C-4 position of the 1,8-naphthalimide fluorophores. The discussion is focused on the photodegradation of the dendrimers in N,N-dimethylformamide and dioxan solutions. Investigations have shown that the photodegradation of the dendrimers with 4-nitro substituted 1,8-naphthalimide proceed with yellow colour development in the solvent while no colour changes followed the same process in dendrimers with allylamino group substituent. The results also show that the photostability of the dendrimers depends on their generation. 相似文献
712.
Christine Robaut Christian Rivalle Marylis Rautureau Jean-Marc Lhoste Emile Bisagni Jean-Claude Chermann 《Tetrahedron》1985,41(10):1945-1951
1-Chloro-5-methyl-5H-pyrido[4,3-b]benzo[f]indole-6,11-quinones, variously substituted on ring D, have been synthesised from 4-chloro-3-formyl-1-methylpyrrolo[3,2-c]pyridine and lithiated N,N-diethylbenzamides. These, with amines, formed the corresponding 1-alkylamino derivatives. In some cases the substitution was accompanied by the formation of polysubstituted by-products. It was found that the méthoxy groups of 7- and 10-methoxy-5-methyl-5H-pyrido[4,3-b]benz[f]indole-6,11-quinones are themselves substituted by amines; this accounts for the complexity of the reaction products formed on substitution of some chloro-intermediates mono- or poly-methoxylated on ring D. 相似文献
713.
Jean Guillaumel Pierre Demerseman Jean-Marc Clavel Ren Royer 《Journal of heterocyclic chemistry》1980,17(7):1531-1536
When treated with acetyl chloride and ferric chloride in methylene chloride, at 0°, monosubstituted β-nitrostyrene derivatives such as 2,3 or 4-methyl, -chloro or -fluoro and 3-nitro-β-nitrostyrenes cyclize into the new corresponding 3-chloro-1,3-dihydro-2H-indol-2-one. Reaction with other metal chlorides such as aluminum chloride and titanium tetrachloride does not lead to these heterocyclic derivatives but only produces N-acetyl-N-hydroxy-α-chlorobenzeneacetamides and/or N-(acetyloxy)-α-chlorobenzeneethanimidoyl chlorides. 相似文献
714.
Two new families of orthogonally protected cyclic homooligomers with two to four sugar units were synthesized from pyranoid sugar amino acids. Cyclic oligomers composed of amide-linked sugar amino acids (1-3) were prepared by cyclization of linear oligomers of the novel orthogonally protected pyranoid sugar amino acid 12 using a solution-phase coupling method. These orthogonally protected cyclic molecules can be selectively or fully deprotected, affording the macrocycles ready to further functionalization. The straightforward reduction of the amide bonds in the cyclic oligomers 1-3 gave the corresponding amine-linked macrocycles 4-6. This kind of amine-linked carbohydrate-based cyclic oligomer has never been reported before. These flexible molecular receptors could be studied as molecular hosts for molecular, cationic, and anionic recognition. Conformational analysis by molecular modeling (AM1) showed that all of the deprotected cyclic trimers and tetramers preferred a (4)C(1) chair conformation with oxygen atoms of the sugar ring located on the interior of the cavity and the secondary hydroxyl groups outward. In the amide-linked macrocycles, all of the amide bonds are in s-trans conformation. The estimated size of the internal cavity is about 4.5 A for the cyclic trimer and 6.9 A for the cyclic tetramer. The amine-linked macrocycles displayed similar conformational behavior with a slight decrease in internal cavity. 相似文献
715.
Nicolas Papageorgiou Eric Salomon Thierry Angot Jean-Marc Layet Luca Giovanelli Guy Le Lay 《Progress in Surface Science》2004,77(5-8):139-170
This paper focuses on the structural arrangements, as seen in scanning tunneling microscopy, chemical and electric properties, as studied especially by high resolution synchrotron radiation photoelectron spectroscopy and energy loss spectroscopy of sub-monolayer up to few monolayer thin films of phthalocyanines adsorbed on narrow band gap III–V semiconductors where they form ordered superstructures, as well as on silicon surfaces. Special emphasis will be put on non-planar metal phthalocyanines where the central atom is either lead or tin. These molecules have been studied in detail from the experimental point of view as well as theoretically by ab initio quantum calculations. Comparison with metal free and metal substituted planar phthalocyanines (H2Pc, CuPc, CoPc, …) adsorbed on semiconductors or noble metal surfaces is included. Perspectives and novel potential applications are finally outlined. 相似文献
716.
A new chiral benzoimidazole-pyrrolidine ligand (BIP) was shown to catalyze an aldol process in the presence of an equimolar amount of a Brönsted acid, leading to the aldol adduct in high yield and enantioselectivity. Remarkably, the aldol reaction was still effectively catalyzed when starting from equimolar amounts of aldehyde and ketone in THF. 相似文献
717.
Hsieh Y Wang G Wang Y Chackalamannil S Brisson JM Ng K Korfmacher WA 《Rapid communications in mass spectrometry : RCM》2002,16(10):944-950
An ultrafast bioanalytical method using monolithic column high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) was evaluated for the simultaneous determination of a drug discovery compound and its metabolite in plasma. Baseline separation of the two compounds was achieved with run times of 24 or 30 s under isocratic or gradient conditions, respectively. The monolithic column HPLC/MS/MS system offers shorter chromatographic run times by increasing flow rate without sacrificing separation power for the drug candidate and its biotransformation product (metabolite). In this work, the necessity for adequate chromatographic resolution was demonstrated because the quantitative determination of the drug-related metabolism product was otherwise hampered by interference from the dosed drug compound. The chromatographic performance of a monolithic silica rod column as a function of HPLC flow rates was investigated with a mixture of the drug component and its synthetic metabolite. The assay reliability of the monolithic column HPLC/MS/MS system was checked for matrix ionization suppression using the post-column infusion technique. The proposed methods were successfully applied to the analysis of study rat plasma samples for the simultaneous quantitation of both the dosed drug and its metabolite. The analytical results obtained by the proposed monolithic column methods and the 'standard' silica particle-packed HPLC column method were in good agreement, within 10% error. 相似文献
718.
Dubois L Xiang DF Tan XS Pécaut J Jones P Baudron S Le Pape L Latour JM Baffert C Chardon-Noblat S Collomb MN Deronzier A 《Inorganic chemistry》2003,42(3):750-760
Reactions of the unsymmetrical phenol ligand 2-(bis(2-pyridylmethyl)aminomethyl)-6-((2-pyridylmethyl)(benzyl)aminomethyl)-4-methylphenol with Mn(OAc)(2).4H(2)O or Mn(H(2)O)(6)(ClO(4))(2) in the presence of NaOBz affords the dimanganese(II) complexes 1(CH(3)OH), [Mn(2)(L)(OAc)(2)(CH(3)OH)](ClO(4)), and 2(H(2)O), [Mn(2)(L)(OBz)(2)(H(2)O)](ClO(4)), respectively. On the other hand, reaction of the ligand with hydrated manganese(III) acetate furnishes the mixed-valent derivative 3(H(2)O), [Mn(2)(L)(OAc)(2)(H(2)O)](ClO(4))( 2). The three complexes have been characterized by X-ray crystallography. 1(CH(3)OH) crystallizes in the monoclinic system, space group P2(1)/c, with a = 10.9215(6) A, b = 20.2318(12) A, c = 19.1354(12) A, alpha = 90 degrees, beta = 97.5310(10) degrees, gamma = 90 degrees, V = 4191.7 A(3), and Z = 4. 2(H(2)O) crystallizes in the monoclinic system, space group P2(1)/n, with a = 10.9215(6) A, b = 20.2318(12) A, c = 19.1354(12) A, alpha = 90 degrees, beta = 97.5310(10) degrees, gamma = 90 degrees, V = 4191.7 A(3), and Z = 4. 3(H(2)O) crystallizes in the monoclinic system, space group P2(1)/c, with a = 11.144(6) A, b = 18.737(10) A, c = 23.949(13) A, alpha = 90 degrees, beta = 95.910(10) degrees, gamma = 90 degrees, V = 4974(5) A(3), and Z = 4. Magnetic measurements revealed that the three compounds exhibit very similar magnetic exchange interactions -J = 4.3(3) cm(-)(1). They were used to establish tentative magneto-structural correlations which show that for the dimanganese(II) complexes -J decreases when the Mn-O(phenoxo) distance increases as expected from orbital overlap considerations. For the dimanganese(II,III) complexes, crystallographic results show that the Mn(II)-O(phenoxo) and Mn(III)-O(phenoxo) bond lengths are inversely correlated. An interesting magneto-structural correlation is found between -J and the difference between these bond lengths, delta(Mn)(-)(O) = d(Mn)()II(-)(O) - d(Mn)()III(-)(O): the smaller this difference, the larger -J. Electrochemical studies show that the mixed-valence state is favored in 1-3 by ca. 100 mV with respect to analogous complexes of symmetrical ligands, owing to the asymmetry of the electron density as found in the analogous diiron complexes. 相似文献
719.
Gaumont AC Pellerin B Cabioch JL Morise X Lesvier M Savignac P Guenot P Denis JM 《Inorganic chemistry》1996,35(23):6667-6675
Primary and secondary alpha-chlorophosphines 2a-g are prepared in ca. 70% yield by chemoselective reduction of the corresponding phosphonic and phosphinic esters with AlHCl(2) and are characterized by (31)P, (13)C, and (1)H NMR and by HMRS. They can be kept several weeks in the refrigerator after purification. They lead then to the corresponding phosphaalkenes 3a-g by HCl elimination. For the volatile alpha-chlorophosphines 2a-e HCl elimination occurs in the gas phase on solid potassium carbonate under VGSR conditions (vacuum gas-solid reactions); the corresponding phosphaalkenes 3a-e are characterized by real time HRMS analysis of the gaseous flow (VGSR/HRMS coupling) and by solid-phase IR spectroscopy after condensation of the gaseous flow on a KBr window cooled to 77 K. The decomposition of phosphaalkenes at this temperature is monitored by IR spectroscopy. The alpha-chlorophosphines 2a-g undergo a HCl elimination in the liquid phase in the presence of a Lewis base; the formation of the transient phosphaalkenes is monitored by (31)P FT-NMR. The temperature of HCl elimination is dependent both upon the P-H acidity of the phosphine precursors and the nature of the base. The (31)P NMR data of the simple phosphaalkenes 3a-g are for the first time reported. They are consistent with the proposed structure. The stereochemistry of the (Z)- and (E)-isomers is established according to the "cis-rule". Phosphaalkenes 3a-g are also characterized by chemical trapping in solution with various dienes, dipoles, or thiols. All of these experiments confirm the transient character of these species. The synthetic potential of this route is evaluated. 相似文献
720.
Jean-Marc Rasoamanana 《Journal of Differential Equations》2008,244(5):1011-1048
In this article, we investigate the resurgent properties of divergent WKB solutions of a class of Airy type perturbed differential equations. In particular, we extend and propose a new proof of a reduction theorem, due to Aoki et al. [T. Aoki, T. Kawai, Y. Takei, The Bender-Wu analysis and the Voros theory, in: Special Functions, ICM-90 Satell. Conf. Proc., Okayama, 1990, Springer, Tokyo, 1991, pp. 1-29], near a simple turning point, in the framework of exact WKB analysis. Our scheme of proof is based on a Laplace-integral representation derived from an existence theorem of holomorphic solutions for a singular linear partial differential equation. 相似文献