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11.
Marek Grzybowski Vincent Hugues Dr. Mireille Blanchard‐Desce Prof. Dr. Daniel T. Gryko 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(39):12493-12501
Structurally unique π‐expanded diketopyrrolopyrroles (EDPP) were designed and synthesized. Strategic placement of a fluorene scaffold at the periphery of a diketopyrrolopyrrole through tandem Friedel–Crafts‐dehydration reactions resulted in dyes with supreme solubility. The structure of the dyes was confirmed by X‐ray crystallography verifying a nearly flattened arrangement of the ten fused rings. Despite the extended ring system, the dye still preserved good solubility and was further functionalized by using Pd‐catalyzed coupling reactions, such as the Buchwald–Hartwig amination. Photophysical studies of these new functional dyes revealed that they possess enhanced properties when compared with expanded DPPs in terms of two‐photon absorption cross‐section. It is further demonstrated that in addition to the initial diacetals, the final electrophilic cyclization step can also be applied to diketones. By placing two amine groups at peripheral positions of the resulting dyes, values of two‐photon absorption cross‐section on the level of 2000 GM around 1000 nm were achieved, which in combination with high fluorescence quantum yield (Φfl), generated a two‐photon brightness of approximately 1600 GM. These characteristics in combination with strong red emission (665 nm) make these new π‐expanded diketopyrrolopyrroles of major promise as two‐photon dyes for bioimaging applications. Finally, the corresponding N‐alkylated DPPs displayed a solid‐state fluorescence. 相似文献
12.
13.
Flavio Antonio Franchina Delphine Zanella Eliane Lazzari Pierre‐Hugues Stefanuto Jean‐Franois Focant 《Journal of separation science》2020,43(9-10):1790-1799
Headspace gas chromatography is frequently used for aroma profiling thanks to its ability to naturally exploit the volatility of aroma compounds, and also to provide chemical information on sample composition. Its main advantages rely on simplicity, no use of solvent, amenability to automation, and the cleanliness of the extract. In the present contribution, the most effective sampling (dynamic extraction), separation (multidimensional gas chromatography), and detection (mass spectrometry) techniques for untargeted analysis are exploited in combination, showing their potential in unraveling aroma profiles in fruit beers. To complete the overall analytical process, a neat workflow for data analysis is discussed and used for the successful characterization and identification of five different beer flavors (berries, cherry, banana, apple, and peach). From the technical viewpoint, the coupling of purge‐and‐trap, comprehensive two‐dimensional gas chromatography, and mass spectrometry makes the global methodology unique, and it is for the first time discussed. A (low‐)flow modulation approach allowed for the full transfer into the second dimension with mass‐spectrometry compatible flow (< 7 mL/min), avoiding the need of splitting before detection and making the overall method sensitive (1.2–5.2‐fold higher signal to noise ratio compared to unmodulated gas chromatography conditions) and selective. 相似文献
14.
I. Charpentier J. Saint Jean Paulin 《Numerical Methods for Partial Differential Equations》1996,12(6):643-655
The homogenization process of the Poisson equations in a thin structure leads to partial differential equation systems on different subdomains. As a result, it produces artificial interfaces and particular transmission conditions. © 1996 John Wiley & Sons, Inc. 相似文献
15.
A novel multicomponent synthesis of 5-aminooxazole starting from simple and readily available inputs is described. Thus, simply heating a methanol solution of an aldehyde 3, an amine 4, and an alpha-isocyanoacetamide 5 provided the 5-aminooxazole (1) in good to excellent yield. The reaction of 1 with alpha,beta-unsaturated acyl chloride 13 lead to the formation of pyrrolo[3,4-b]pyridin-5-one (2) in a single operation. A triple domino sequence, acylation/IMDA/retro-Michael cycloreversion, is involved in this new scaffold-generating reaction. After the observation that ammonium chloride can significantly accelerate the oxazole formation in toluene, a one-pot four-component synthesis of 2 is developed. 相似文献
16.
Hugues dOrchymont Maurice P. Goeldner Jean-Fran?ois Biellmann 《Tetrahedron letters》1982,23(16):1727-1730
Beside the Wittig rearrangement and the migration of the cyclooctyl radical to the para position, the title carbanion gives rise to an elimination in a syn process. 相似文献
17.
Efficient and accurate integration of stochastic (partial) differential equations with multiplicative noise can be obtained through a split-step scheme, which separates the integration of the deterministic part from that of the stochastic part, the latter being performed by sampling exactly the solution of the associated Fokker-Planck equation. We demonstrate the computational power of this method by applying it to the most absorbing phase transitions for which Langevin equations have been proposed. This provides precise estimates of the associated scaling exponents, clarifying the classification of these nonequilibrium problems, and confirms or refutes some existing theories. 相似文献
18.
We apply the nonperturbative renormalization group method to a class of out-of-equilibrium phase transitions (usually called "parity-conserving" or, more properly, "generalized voter" class) which is out of the reach of perturbative approaches. We show the existence of a genuinely nonperturbative fixed point, i.e., a critical point that does not seem to be Gaussian in any dimension. 相似文献
19.
The phase transitions to absorbing states of the branching-annihilating reaction-diffusion processes mA-->(m+k)A, nA-->(n-l)A are studied systematically in one space dimension within a new family of models. Four universality classes of nontrivial critical behavior are found. This provides, in particular, the first evidence of universal scaling laws for pair and triplet processes. 相似文献
20.
We present here coadsorption data of ethylmercaptan with n-heptane or toluene on NaX at 298 K in the aim to use this adsorbent for removing mercaptans from natural gas. Results show that NaX has an adsorption affinity for sulphur compound strong enough to perform a deep desulphurization. NaX adsorbs preferentially ethylmercaptan over a large domain of pore filling. A displacement of n-heptane by ethylmercaptan is even observed. However, toluene becomes preferentially adsorbed at high filling. The dependence of filling and composition on selectivities and failed prediction of coadsorption equilibria by the IAS Theory indicate that the adsorbed mixture behaves as a non-ideal solution. Calorimetric measurements of coadsorption heats show that the coadsorption process is not governed by enthalpic effects but by entropic effects consecutive to steric hindrance of molecules in confined spaces. 相似文献