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101.
Julia Beerhues Maren Neubrand Dr. Sebastian Sobottka Dr. Nicolás I. Neuman Hannes Aberhan Shubhadeep Chandra Prof. Dr. Biprajit Sarkar 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(21):6557-6568
Carbene-based radicals are important for both fundamental and applied chemical research. Herein, extensive electrochemical investigations of nine different 1,2,3-triazolylidene selenium adducts are reported. It is found that the half-wave potentials of the first reduction of the selones correlate with their calculated LUMO levels and the LUMO levels of the corresponding triazolylidene-based mesoionic carbenes (MICs). Furthermore, unexpected quasi-reversibility of the reduction of two triazoline selones, exhibiting comparable reduction potentials, was discovered. Through UV/Vis/NIR and EPR spectroelectrochemical investigations supported by DFT calculations, the radical anion was unambiguously assigned to be triazoline centered. This electrochemical behavior was transferred to a triazolylidene-type MIC-gold phenyl complex resulting in a MIC-radical coordinated AuI species. Apart from UV-Vis-NIR and EPR spectroelectrochemical investigations of the reduction, the reduced gold-coordinated MIC radical complex was also formed in situ in the bulk through chemical reduction. This is the first report of a monodentate triazolylidene-based MIC ligand that can be reduced to its anion radical in a metal complex. The results presented here provide design principles for stabilizing radicals based on MICs. 相似文献
102.
Lucas Ueberricke Dr. Bahiru Punja Benke Tobias Kirschbaum Dr. Sebastian Hahn Dr. Frank Rominger Prof. Dr. Uwe H. F. Bunz Prof. Dr. Michael Mastalerz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(6):2043-2049
A six-step synthesis towards a tribenzotriquinacene (TBTQ) bearing three quinoxalinophenanthrophenazine (QPP) units is presented. The optoelectronic properties are investigated and the effect of the three-dimensional arrangement of the individual QPP planes is examined using optical spectroscopy, electrochemical analysis and quantum-chemical calculations. 相似文献
103.
Dr. Ali Abdulkarim Marvin Nathusius Rainer Bäuerle Dr. Karl-Philipp Strunk Dr. Sebastian Beck Dr. Hans Joachim Räder Prof. Annemarie Pucci Dr. Christian Melzer Daniel Jänsch Dr. Jan Freudenberg Prof. Uwe H. F. Bunz Prof. Klaus Müllen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(1):281-288
The synthesis of unsubstituted oligo-para-phenylenes ( OPP ) exceeding para-hexaphenylene—in the literature often referred to as p-sexiphenyl—has long remained elusive due to their insolubility. We report the first preparation of unsubstituted para-nonaphenylenes ( 9PP s) by extending our precursor route to poly-para-phenylenes ( PPP ) to a discrete oligomer. Two geometric isomers of methoxylated syn- and anti-cyclohexadienylenes were synthesized, from which 9PP was obtained via thermal aromatization in thin films. 9PP was characterized via optical, infrared and solid-state 13C NMR spectroscopy as well as atomic force microscopy and mass spectrometry, and compared to polymeric analogues. Due to the lack of substitution, para-nonaphenylene, irrespective of the precursor isomer employed, displays pronounced aggregation in the solid state. Intermolecular excitonic coupling leads to formation of H-type aggregates, red-shifting emission of the films to greenish. 9PP allows to study the structure–property relationship of para-phenylene oligomers and polymers, especially since the optical properties of PPP depend on the molecular shape of the precursor. 相似文献
104.
Gene Senges Dr. Lin Li Dr. Artur Wodyński Dr. Helmut Beckers Dr. Robert Müller Prof. Dr. Martin Kaupp Prof. Dr. Sebastian Riedel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(54):13642-13650
Molecular platinum fluorides PtFn, n=1–6, are prepared by two different routes, photo-initiated fluorine elimination from PtF6 embedded in solid noble-gas matrices, and the reaction of elemental fluorine with laser-ablated platinum atoms. IR spectra of the reaction products isolated in rare-gas matrices under cryogenic conditions provide, for the first time, experimental vibrational frequencies of molecular PtF3, PtF4 and PtF5. Photolysis of PtF6 enabled a highly efficient and almost quantitative formation of molecular PtF4, whereas both PtF5 and PtF3 were formed simultaneously by subsequent UV irradiation of PtF4. The vibrational spectra of these molecular platinum fluorides were assigned with the help of one- and two-component quasirelativistic DFT computation to account for scalar relativistic and spin–orbit coupling effects. Competing Jahn-Teller and spin–orbit coupling effects result in a magnetic bistability of PtF4, for which a spin-triplet (3B2g, D2h) coexists with an electronic singlet state (1A1g, D4h) in solid neon matrices. 相似文献
105.
Sebastian Hamer Jan-Simon von Glasenapp Fynn Röhricht Dr. Chao Li Prof. Dr. Richard Berndt Prof. Dr. Rainer Herges 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(69):17452-17458
A set of dipolar molecular rotor compounds was designed, synthesized and adsorbed as self-assembled 2D arrays on Ag(111) surfaces. The title molecules are constructed from three building blocks: (a) 4,8,12-trioxatriangulene (TOTA) platforms that are known to physisorb on metal surfaces such as Au(111) and Ag(111), (b) phenyl groups attached to the central carbon atom that function as pivot joints to reduce the barrier to rotation, (c) pyridine and pyridazine units as small dipolar units on top. Theoretical calculations and scanning tunneling microscopy (STM) investigations hint at the fact that the dipoles of neighboring rotors interact through space through pairs of energetically favorable head-to-tail arrangements. 相似文献
106.
Scalable bottom‐up assembly of suspended carbon nanotube and graphene devices by dielectrophoresis
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Antonios Oikonomou Nick Clark Sebastian Heeg Andrey Kretinin Sarah Varey Geliang Yu Aravind Vijayaraghavan 《固体物理学:研究快报》2015,9(9):539-543
Bottom‐up assembly by dielectrophoresis (DEP) has emerged in recent years as a viable alternative to conventional top–down fabrication of electronic devices from nanomaterials, particularly carbon nanotubes and graphene. Here, we demonstrate how this technique can be extended to fabricate devices containing carbon nanotubes and graphene suspended between two electrodes over a back‐gate electrode. The suspended device geometry is critical for the development of nano‐electromechanical devices and to extract maximum performance out of electronic and optoelectronic devices. This technique allows for parallel assembly of devices over large scale. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
107.
108.
Bahamonde Sebastian Jamil Mubasher 《The European Physical Journal C - Particles and Fields》2015,75(10):1-11
The European Physical Journal C - LArGe is a Gerda low-background test facility to study novel background suppression methods in a low-background environment, for future application in the Gerda... 相似文献
109.
Ştefan Ţălu Sebastian Stach Joana Zaharieva Maria Milanova Dimitar Todorovsky Stefano Giovanzana 《International Journal of Polymer Analysis and Characterization》2014,19(5):404-421
The structural complexity of the 3-D surface of poly(methylmethacrylate) films with immobilized europium β-diketonates was studied by atomic force microscopy and fractal analysis. Fractal analysis of surface roughness revealed that the 3-D surface has fractal geometry at the nanometer scale. Poly(methylmethacrylate) (PMMA) as immobilization matrix is dense and uniform, and a tendency for formation of chain structures was observed. Fractal analysis can quantify key elements of 3-D surface roughness such as the fractal dimensions D f determined by the morphological envelopes method of the Eu(DBM)3 and Eu(DBM)3 · dpp nanostructures, which are not taken into account by traditional surface statistical parameters. 相似文献
110.
Substitution pattern elucidation of hydroxypropyl Pinus pinaster (Ait.) bark polyflavonoid derivatives by ESI(−)‐MS/MS
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Danny E. García Marrero Wolfgang G. Glasser Antonio Pizzi Sebastian Paczkowski Marie‐Pierre G. Laborie 《Journal of mass spectrometry : JMS》2014,49(10):1050-1058
The structure of condensed tannins (CTs) from Pinus pinaster bark extract and their hydroxypropylated derivatives with four degrees of substitution (DS 1, 2, 3 and 4) has been characterized for the first time using negative‐ion mode electrospray ionization tandem mass spectrometry (ESI(?)‐MS/MS). The results showed that P. pinaster bark CTs possess structural homogeneity in terms of monomeric units (C15, catechin). The oligomer sizes were detected to be dimers to heptamers. The derivatives showed typical phenyl‐propyl ether mass fragmentation by substituent elimination (58 amu) and inherent C15 flavonoid fissions. The relative abundance of the product ions revealed a preferential triple, tetra‐/penta‐ and octa‐ hydroxypropylation substitution pattern in the monomer, dimer and trimer derivatives, respectively. A defined order of –OH reactivity towards propylene oxide was established by means of multistage experiments (A‐ring ≥ B‐ring > C‐ring). A high structural heterogeneity of the modified oligomers was detected. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献