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991.
The aim of this work is the investigation of the flow and electrokinetic transport in a micro‐analysis‐system. A mathematical model for electroosmotic and electrophoretic phenomena is introduced in order to perform two‐dimensional, time‐dependent Finite Element simulations for an existing device. The model includes the feature of the flow field, the mass transfer, the external applied electric field and the involved chemistry. The results of the simulation are validated against experimental data and show good agreement. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
992.
Miroslav Zabadal Dominik Heger Marek Ne
as Petr Kln 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(2):o77-o79
The structures of the bichromophoric compounds N‐(1‐naphthylacetyl)glycine phenacyl ester, C22H19NO4, (I), and its oxygen analogue, phenacyl (1‐naphthylacetoxy)acetate, C22H18O5, (II), have been determined. The molecules of (I) are held together by intermolecular N—H⋯O hydrogen bonds between the carbonyl and N—H groups, while compound (II) does not show any hydrogen bonding in the crystal. 相似文献
993.
Bartomiej Sadowski Marzena Kaliszewska Yevgen M. Poronik Magorzata Czichy Patryk Janasik Marzena Banasiewicz Dominik Mierzwa Wojciech Gadomski Trevor D. Lohrey John A. Clark Mieczysaw apkowski Bolesaw Kozankiewicz Valentine I. Vullev Andrzej L. Sobolewski Piotr Piatkowski Daniel T. Gryko 《Chemical science》2021,12(42):14039
Nitroaromatics seldom fluoresce. The importance of electron-deficient (n-type) conjugates, however, has inspired a number of strategies for suppressing the emission-quenching effects of the strongly electron-withdrawing nitro group. Here, we demonstrate how such strategies yield fluorescent nitroaryl derivatives of dipyrrolonaphthyridinedione (DPND). Nitro groups near the DPND core quench its fluorescence. Conversely, nitro groups placed farther from the core allow some of the highest fluorescence quantum yields ever recorded for nitroaromatics. This strategy of preventing the known processes that compete with photoemission, however, leads to the emergence of unprecedented alternative mechanisms for fluorescence quenching, involving transitions to dark nπ* singlet states and aborted photochemistry. Forming nπ* triplet states from ππ* singlets is a classical pathway for fluorescence quenching. In nitro-DPNDs, however, these ππ* and nπ* excited states are both singlets, and they are common for nitroaryl conjugates. Understanding the excited-state dynamics of such nitroaromatics is crucial for designing strongly fluorescent electron-deficient conjugates.Dipyrrolonaphthyridinedione appended with para- or meta-nitrophenyl substituents exhibits strong fluorescence from a 1ππ* S1 state. 相似文献
994.
995.
Paulina Summa Katarzyna
wirk Dominik Wierzbicki Monika Motak Ivo Alxneit Magnus Rnning Patrick Da Costa 《Molecules (Basel, Switzerland)》2021,26(21)
Co-precipitated Ni-Mg-Al hydrotalcite-derived catalyst promoted with vanadium were synthesized with different V loadings (0–4 wt%) and studied in CO2 methanation. The promotion with V significantly changes textural properties (specific surface area and mesoporosity) and improves the dispersion of nickel. Moreover, the vanadium promotion strongly influences the surface basicity by increasing the total number of basic sites. An optimal loading of 2 wt% leads to the highest activity in CO2 methanation, which is directly correlated with specific surface area, as well as the basic properties of the studied catalysts. 相似文献
996.
997.
Chantalle J. Krajewska Sen R. Kavanagh Lina Zhang Dominik J. Kubicki Krishanu Dey Krzysztof Gakowski Clare P. Grey Samuel D. Stranks Aron Walsh David O. Scanlon Robert G. Palgrave 《Chemical science》2021,12(44):14686
Lead-free halides with perovskite-related structures, such as the vacancy-ordered perovskite Cs3Bi2Br9, are of interest for photovoltaic and optoelectronic applications. We find that addition of SnBr2 to the solution-phase synthesis of Cs3Bi2Br9 leads to substitution of up to 7% of the Bi(iii) ions by equal quantities of Sn(ii) and Sn(iv). The nature of the substitutional defects was studied by X-ray diffraction, 133Cs and 119Sn solid state NMR, X-ray photoelectron spectroscopy and density functional theory calculations. The resulting mixed-valence compounds show intense visible and near infrared absorption due to intervalence charge transfer, as well as electronic transitions to and from localised Sn-based states within the band gap. Sn(ii) and Sn(iv) defects preferentially occupy neighbouring B-cation sites, forming a double-substitution complex. Unusually for a Sn(ii) compound, the material shows minimal changes in optical and structural properties after 12 months storage in air. Our calculations suggest the stabilisation of Sn(ii) within the double substitution complex contributes to this unusual stability. These results expand upon research on inorganic mixed-valent halides to a new, layered structure, and offer insights into the tuning, doping mechanisms, and structure–property relationships of lead-free vacancy-ordered perovskite structures.Mixed valence Sn doping of Cs3Bi2Br9 leads to broad visible light absorption. 相似文献
998.
999.
1000.
Dr. Jacopo Perego Dr. Andrea Daolio Dr. Charl X. Bezuidenhout Dr. Sergio Piva Dr. Giacomo Prando Benjamin Costarella Prof. Pietro Carretta Prof. Luciano Marchiò Dr. Dominik Kubicki Prof. Piero Sozzani Prof. Silvia Bracco Prof. Angiolina Comotti 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(10):e202317094
Engineering coordinated rotational motion in porous architectures enables the fabrication of molecular machines in solids. A flexible two-fold interpenetrated pillared Metal-Organic Framework precisely organizes fast mobile elements such as bicyclopentane (BCP) (107 Hz regime at 85 K), two distinct pyridyl rotors and E-azo group involved in pedal-like motion. Reciprocal sliding of the two sub-networks, switched by chemical stimuli, modulated the sizes of the channels and finally the overall dynamical machinery. Actually, iodine-vapor adsorption drives a dramatic structural rearrangement, displacing the two distinct subnets in a concerted piston-like motion. Unconventionally, BCP mobility increases, exploring ultra-fast dynamics (107 Hz) at temperatures as low as 44 K, while the pyridyl rotors diverge into a faster and slower dynamical regime by symmetry lowering. Indeed, one pillar ring gained greater rotary freedom as carried by the azo-group in a crank-like motion. A peculiar behavior was stimulated by pressurized CO2, which regulates BCP dynamics upon incremental site occupation. The rotary dynamics is intrinsically coupled to the framework flexibility as demonstrated by complementary experimental evidence (multinuclear solid-state NMR down to very low temperatures, synchrotron radiation XRD, gas sorption) and computational modelling, which helps elucidate the highly sophisticated rotor-structure interplay. 相似文献