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971.
Fumaric acid was reacted with the binary superacidic systems HF/SbF5 and HF/AsF5. The O,O'-diprotonated [C4H6O4]2+([MF6]–)2 (M = As, Sb) and the O-monoprotonated [C4H5O4]+[MF6]– (M = As, Sb) species are formed depending on the stoichiometric ratio of the Lewis acid to fumaric acid. The colorless salts were characterized by low-temperature vibrational spectroscopy. In case of the hexafluoridoantimonates single-crystal X-ray structure analyses were carried out. The [C4H6O4]2+([SbF6]–)2 crystallizes in the monoclinic space group C2/c with four formula units per unit cell and [C4H5O4]+[SbF6]– crystallizes in the triclinic space group P1 with one formula unit per unit cell. The protonation of fumaric acid does not cause a notable change of the C=C bond length. The experimental data are discussed together with quantum chemical calculations of the cations [C4H6O4 · 4 HF]2+ and [C4H6O4 · 2 H2CO · 2 HF]2+. 相似文献
972.
973.
Dr. Sebastian Sobottka Maite Nößler Dr. Andrew L. Ostericher Dr. Gunter Hermann Noah Z. Subat Julia Beerhues Dr. Margarethe Behr-van der Meer Dr. Lisa Suntrup Dr. Uta Albold Dr. Stephan Hohloch Dr. Jean Christophe Tremblay Prof. Dr. Biprajit Sarkar 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(6):1314-1327
Asymmetric platinum donor–acceptor complexes [(pimp)Pt(Q2−)] are presented in this work, in which pimp=[(2,4,6-trimethylphenylimino)methyl]pyridine and Q2−=catecholate-type donor ligands. The properties of the complexes are evaluated as a function of the donor ligands, and correlations are drawn among electrochemical, optical, and theoretical data. Special focus has been put on the spectroelectrochemical investigation of the complexes featuring sulfonyl-substituted phenylendiamide ligands, which show redox-induced linkage isomerism upon oxidation. Time-dependent density functional theory (TD-DFT) as well as electron flux density analysis have been employed to rationalize the optical spectra of the complexes and their reactivity. Compound 1 ([(pimp)Pt(Q2−)] with Q2−=3,5-di-tert-butylcatecholate) was shown to be an efficient photosensitizer for molecular oxygen and was subsequently employed in photochemical cross-dehydrogenative coupling (CDC) reactions. The results thus display new avenues for donor–acceptor systems, including their role as photocatalysts for organic transformations, and the possibility to introduce redox-induced linkage isomerism in these compounds through the use of sulfonamide substituents on the donor ligands. 相似文献
974.
Dr. Christina Rest Dr. Divya Susan Philips Torsten Dünnebacke Dr. Papri Sutar Dr. Angel Sampedro Jörn Droste Dr. Vladimir Stepanenko Prof. Dr. Michael Ryan Hansen Dr. Rodrigo Q. Albuquerque Prof. Dr. Gustavo Fernández 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(44):10005-10013
Besides their widespread use in coordination chemistry, 2,2’-bipyridines are known for their ability to undergo cis–trans conformational changes in response to metal ions and acids, which has been primarily investigated at the molecular level. However, the exploitation of such conformational switching in self-assembly has remained unexplored. In this work, the use of 2,2’-bipyridines as acid-responsive conformational switches to tune supramolecular polymerization processes has been demonstrated. To achieve this goal, we have designed a bipyridine-based linear bolaamphiphile, 1 , that forms ordered supramolecular polymers in aqueous media through cooperative aromatic and hydrophobic interactions. Interestingly, addition of acid (TFA) induces the monoprotonation of the 2,2’-bipyridine moiety, leading to a switch in the molecular conformation from a linear (trans) to a V-shaped (cis) state. This increase in molecular distortion along with electrostatic repulsions of the positively charged bipyridine-H+ units attenuate the aggregation tendency and induce a transformation from long fibers to shorter thinner fibers. Our findings may contribute to opening up new directions in molecular switches and stimuli-responsive supramolecular materials. 相似文献
975.
Florian Ritter Dr. Lukas John Dr. Tobias Schindler Julian P. Schroers Simon Teeuwen Dr. Michael E. Tauchert 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(59):13436-13444
The dative Pd→B interaction in a series of RDPBR’ Pd0 and PdII complexes (RDPBR’=(o-PR2C6H4)2BR’, diphosphinoborane) was analyzed using XRD, 11B NMR spectroscopy and NBO/NLMO calculations. The borane acceptor discriminates between the oxidation state PdII and Pd0, stabilizing the latter. Reaction of lithium amides with [(RDPBR’)PdII(4-NO2C6H4)I] chemoselectively yields the C−N coupling product. DFT modelling indicates no significant impact of PdII→B coordination on the inner-sphere reductive elimination rate. 相似文献
976.
Dandan Shi Xiaobo Yu Liangliang Chen Daoliang Chen Zitong Liu Xisha Zhang Guanxin Zhang Deqing Zhang 《中国化学》2020,38(10):1075-1080
The development of selenophene‐flanked DPP (SeDPP) based copolymers, especially for the ambipolar ones, lags behind other aromatic group flanked DPP‐based polymers. Herein, we report two new ambipolar SeDPP‐based conjugated polymers. One is the alternating polymer PSeDPPFT with normal SeDPP and 3,4‐difluorothiophene units. The other is PSeFDFT , in which the electron acceptor unit is replaced by a new SeDPP derivative, referred as to half‐fused SeDPP. The more planar structure of half‐fused SeDPP endows the backbone of PSeFDFT with good rigidity and planarity. Both polymers exhibit ambipolar transporting properties in air. The PSeFDFT based field‐effect transistors (FETs) display higher and more balanced ambipolar properties with μhave of 0.27 cm2·V–1·s–1, μeave of 0.18 cm2·V–1·s–1, and μhave/μeave of 1.5 than those of PSeDPPFT (μhave = 0.11 cm2·V–1·s–1, μeave = 0.042 cm2·V–1·s–1, and μh/μe = 2.6). This is attributed to the more planar structure, lower LUMO level, higher HOMO level, and better interchain packing orientations of PSeFDFT by comparing with PSeDPPFT . Therefore, a new molecular design strategy to modulate the hole and electron transporting properties is proposed for conjugated D‐A polymers. 相似文献
977.
978.
Bioelectrochemical systems (BESs) have been intensively studied in the past decade, but precise understanding of BESs performance is hindered by unclear definition of several key parameters. Herein, we analyze and discuss three sets of terms about conversion efficiency, energy performance, and pilot scale. It is suggested that ‘Coulombic recovery’ can avoid the misleading results because of different organic removals, compared with ‘Coulombic efficiency.’ Power density is not a suitable term to describe energy performance of BESs, and energy production/consumption should be reported in the energy unit such as kWh. Pilot-scale BESs should meet several criteria, including hydraulic capacity, use of actual wastewater, non-laboratory condition, and long-term operation. Proper use of those terms is strongly encouraged and will be critically important to BESs research and development. 相似文献
979.
M.A. Mujawar H. Gohel S.K. Bhardwaj S. Srinivasan N. Hickman A. Kaushik 《Materials Today Chemistry》2020
Biosensors are emerging as efficient (sensitive and selective) and affordable analytical diagnostic tools for early-stage disease detection, as required for personalized health wellness management. Low-level detection of a targeted disease biomarker (pM level) has emerged extremely useful to evaluate the progression of disease under therapy. Such collected bioinformatics and its multi-aspects-oriented analytics is in demand to explore the effectiveness of a prescribed treatment, optimize therapy, and correlate biomarker level with disease pathogenesis. Owing to nanotechnology-enabled advancements in sensing unit fabrication, device integration, interfacing, packaging, and sensing performance at point-of-care (POC) has rendered diagnostics according to the requirements of disease management and patient disease profile i.e. in a personalized manner. Efforts are continuously being made to promote the state of art biosensing technology as a next-generation non-invasive disease diagnostics methodology. Keeping this in view, this progressive opinion article describes personalized health care management related analytical tools which can provide access to better health for everyone, with overreaching aim to manage healthy tomorrow timely. Considering accomplishments and predictions, such affordable intelligent diagnostics tools are urgently required to manage COVID-19 pandemic, a life-threatening respiratory infectious disease, where a rapid, selective and sensitive detection of human beta severe acute respiratory system coronavirus (SARS-COoV-2) protein is the key factor. 相似文献
980.
Since 1996, a growing number of strained macrocycles, comprising only sp2‐ or sp‐hybridized carbon atoms within the ring, have become synthetically accessible, with the [n]cycloparaphenyleneacetylenes ( CPPAs ) and the [n]cycloparaphenylenes ( CPPs ) being the most prominent examples. Now that robust and relatively general synthetic routes toward a diverse range of nanohoop structures have become available, the research focus is beginning to shift towards the exploration of their properties and applications. From a supramolecular chemistry perspective, these macrocycles offer unique opportunities as a result of their near‐perfect circular shape, the unusually high degree of shape‐persistence, and the presence of both convex and concave π‐faces. In this Minireview, we give an overview on the use of strained carbon‐rich nanohoops in host–guest chemistry, the preparation of mechanically interlocked architectures, and crystal engineering. 相似文献