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231.
Benedikt Niepötter Dr. Regine Herbst‐Irmer Dr. Daniel Kratzert Dr. Prinson P. Samuel Dr. Kartik Chandra Mondal Prof. Dr. Herbert W. Roesky Paul Jerabek Prof. Dr. Gernot Frenking Prof. Dr. Dietmar Stalke 《Angewandte Chemie (International ed. in English)》2014,53(10):2766-2770
An experimental and theoretical charge density study confirms the interpretation of (cAAC)2Si as a silylone to be valid. Two separated VSCCs present in the non‐bonding region of the central silicon are indicative for two lone pairs. In the experiment, both the two crystallographically independent Si? C bond lengths and ellipticities vary notably. It is only the cyclohexyl derivative that shows significant differences in these values, both in the silylones and the germylones. Only by calculating increasing spheres of surrounding point charges we were able to recover the changes in the properties of the charge density distribution caused by weak intermolecular interactions. The nitrogen–carbene‐carbon bond seems to have a significant double‐bond character, indicating a singlet state for the carbene carbon, which is needed for donor acceptor bonding. Thus the sum of bond angles at the nitrogen atoms seems to be a reasonable estimate for singlet versus triplet state of cAACs. 相似文献
232.
Dr. Anne‐Laure Fameau Adrian Carl Dr. Arnaud Saint‐Jalmes Dr. Regine von Klitzing 《Chemphyschem》2015,16(1):66-75
Remarkable properties have emerged recently for aqueous foams, including ultrastability and responsiveness. Responsive aqueous foams refer to foams for which the stability can be switched between stable and unstable states with a change in environment or with external stimuli. Responsive foams have been obtained from various foam stabilizers, such as surfactants, proteins, polymers, and particles, and with various stimuli. Different strategies have been developed to design this type of soft material. We briefly review the two main approaches used to obtain responsive foams. The first approach is based on the responsiveness of the interfacial layer surrounding the gas bubbles, which leads to responsive foams. The second approach is based on modifications that occur in the aqueous phase inside the foam liquid channels to tune the foam stability. We will highlight the most sophisticated approaches, which use light, temperature, and magnetic fields and lead to switchable foam stability. 相似文献
233.
Synthesis,Characterization, and Theoretical Investigation of Two‐Coordinate Palladium(0) and Platinum(0) Complexes Utilizing π‐Accepting Carbenes
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Dr. Sudipta Roy Dr. Kartik Chandra Mondal Dipl.‐Chem. Jann Meyer Dipl.‐Chem. Benedikt Niepötter Christian Köhler Dr. Regine Herbst‐Irmer Prof. Dr. Dietmar Stalke Dr. Birger Dittrich Dr. Diego M. Andrada Prof. Dr. Gernot Frenking Prof. Dr. Herbert W. Roesky 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(26):9312-9318
An elegant general synthesis route for the preparation of two coordinate palladium(0) and platinum(0) complexes was developed by reacting commercially available tetrakis(triphenylphosphine)palladium/platinum with π‐accepting cyclic alkyl(amino) carbenes (cAACs). The complexes are characterized by NMR spectroscopy, mass spectrometry, and single‐crystal X‐ray diffraction. The palladium complexes exhibit sharp color changes (crystallochromism) from dark maroon to bright green if the C‐Pd‐C bond angle is sharpened by approximately 6°, which is chemically feasible by elimination of one lattice THF solvent molecule. The analogous dark orange‐colored platinum complexes are more rigid and thus do not show this phenomenon. Additionally, [(cAAC)2Pd/Pt] complexes can be quasi‐reversibly oxidized to their corresponding [(cAAC)2Pd/Pt]+ cations, as evidenced by cyclic voltammetry measurements. The bonding and stability are studied by theoretical calculations. 相似文献
234.
Inside Cover: Synthesis,Characterization, and Theoretical Investigation of Two‐Coordinate Palladium(0) and Platinum(0) Complexes Utilizing π‐Accepting Carbenes (Chem. Eur. J. 26/2015)
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Dr. Sudipta Roy Dr. Kartik Chandra Mondal Dipl.‐Chem. Jann Meyer Dipl.‐Chem. Benedikt Niepötter Christian Köhler Dr. Regine Herbst‐Irmer Prof. Dr. Dietmar Stalke Dr. Birger Dittrich Dr. Diego M. Andrada Prof. Dr. Gernot Frenking Prof. Dr. Herbert W. Roesky 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(26):9266-9266
235.
Peter G. Jones Fabiola Vancea Regine Herbst‐Irmer 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(11):o665-o668
In the isomeric title compounds, viz. 2‐, 3‐ and 4‐(chloromethyl)pyridinium chloride, C6H7ClN+·Cl?, the secondary interactions have been established as follows. Classical N—H?Cl? hydrogen bonds are observed in the 2‐ and 3‐isomers, whereas the 4‐isomer forms inversion‐symmetric N—H(?Cl??)2H—N dimers involving three‐centre hydrogen bonds. Short Cl?Cl contacts are formed in both the 2‐isomer (C—Cl?Cl?, approximately linear at the central Cl) and the 4‐isomer (C—Cl?Cl—C, angles at Cl of ca 75°). Additionally, each compound displays contacts of the form C—H?Cl, mainly to the Cl? anion. The net effect is to create either a layer structure (3‐isomer) or a three‐dimensional packing with easily identifiable layer substructures (2‐ and 4‐isomers). 相似文献
236.
237.
V. M. Garamus G. E. Milkereit Regine Willumeit V. Vill 《Journal of Thermal Analysis and Calorimetry》2005,82(2):477-481
In this work, we investigated the lyotropic aggregation behaviour in dilute solutions of two synthetic glycolipids with same
alkyl chain. The chemical structure of the carbohydrate headgroups is similar, nevertheless as reported the thermotropic phase
behaviour is different. We found that the slightly tilted compound showing a complex thermotropic phase behaviour forms large
aggregates with substructure already in dilute solutions and the significantly tilted compound with its simple thermotropic
phase behaviour forms small spherical micelles near the CMC. 相似文献
238.
Luís A. S. de A. Prado G. Goerigk M. L. Ponce V. M. Garamus H. Wittich R. Willumeit K. Schulte S. P. Nunes 《Journal of Polymer Science.Polymer Physics》2005,43(21):2981-2992
The distribution of ZrO2 and phosphotungstic acid (PTA) in a matrix of sulfonated polyether ketone was investigated by anomalous small‐angle X‐ray scattering (ASAXS). Scattering curves were obtained using X‐ray energies near the Zr and W absorption edges, allowing the independent analysis of the distribution of ZrO2 and PTA in the sample. The interaction between both inorganic components improved their dispersion considerably when compared with films containing just one of the additives. The synergism was correlated to previous investigations concerning proton conductivity and permeability of the membranes developed for direct methanol fuel cell. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2981–2992, 2005 相似文献
239.
Regine Müller Peter Fuhrberg Heinrich-Otto Teichmann Wolfgang Vil 《Optics & Laser Technology》2005,37(7):570-576
A Cr,Tm:YAG laser, under simultaneous flashlamp and diode laser excitation, was demonstrated. With respect to diode pumping a cw-output power of 35 W with a slope efficiency of 20% was achieved. With flashlamp excitation pulse energies up to 465 mJ were realised. This operation was supported by simultaneous diode pumping to bring the laser close to threshold. Repetition rates up to 10 Hz were demonstrated with this simultaneous pumping mode of the Cr,Tm:YAG laser crystal. 相似文献
240.
Cover Picture: Maculatic Acids—Sex Attractant Pheromone Components of Bald‐Faced Hornets (Angew. Chem. Int. Ed. 36/2018)
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