Search results for "Optical"
showing 10 items of 7671 documents
The inherent structural instability: concentration-dependent transformation of pyrogallarene to pyrogallarene lactones.
2011
Pyrogallarene shows concentration-dependent instability in dilute solutions resulting in elimination of two ketene molecules and formation of pyrogallarene lactones. This unexpected phenomenon, which is not observed with resorcinarenes, highlights the significance of the four hydroxyl groups at 2-position for the molecular characteristics of pyrogallarenes.
Adhesion and adhesion hysteresis of mica surfaces covered with bola-amphipiles in dry and humid air
1998
Abstract Bola-amphiphiles with spherical hydrophilic chinuclidinium head groups form laterally ordered monolayers on mica by adsorption from solution. To measure the surface adhesion, JKR-type compression/decompression cycles have been performed with the surface forces apparatus (SFA). In an inert atmosphere, the adhesion energy on increasing the contact area is much lower than predicted by wetting experiments. Furthermore, the pronounced adhesion hysteresis varies from sample to sample in a wide range, indicating a defect-rich surface. On increase of the relative humidity (rh), the reproducibility improves and the values for the adhesion energy measured on compression and decompression con…
Rational linkage of magnetic molecules using click chemistry
2015
Established CuAAC click reactions are used for the first time to assemble magnetic molecules to an extended molecular arrangement. This novel synthetic approach is expected to be a general approach to link SMMs as an important precondition to realize quantum computing.
Tetrathiafulvalene-based molecular nanowires.
2008
A new molecular wire suitably functionalized with sulfur atoms at terminal positions and endowed with a central redox active TTF unit has been synthesized and inserted within two atomic-sized Au electrodes; electrical transport measurements have been performed in STM and MCBJ set-ups in a liquid environment and reveal conductance values around 10(-2) G0 for a single molecule.
Atomic structure solution of the complex quasicrystal approximant Al77Rh15Ru8 from electron diffraction data
2014
The crystal structure of the novel Al77Rh15Ru8phase (which is an approximant of decagonal quasicrystals) was determined using modern direct methods (MDM) applied to automated electron diffraction tomography (ADT) data. The Al77Rh15Ru8E-phase is orthorhombic [Pbma,a= 23.40 (5),b= 16.20 (4) andc= 20.00 (5) Å] and has one of the most complicated intermetallic structures solved solely by electron diffraction methods. Its structural model consists of 78 unique atomic positions in the unit cell (19 Rh/Ru and 59 Al). Precession electron diffraction (PED) patterns and high-resolution electron microscopy (HRTEM) images were used for the validation of the proposed atomic model. The structure of the E…
Steering molecular island morphology on an insulator surface by exploiting sequential deposition
2011
Depending on the deposition order in coadsorption of C(60) and SubPc molecules on CaF(2) (111), distinctly different island morphologies can be obtained. We demonstrate that non-equilibrium processes can play a significant role in molecular structure formation and constitute a new route for complex molecular patterning of an insulating surface.
Rotational spectrum and equilibrium structure of silanethione, H2SiS
2008
Unsubstituted silanethione, H(2)Si=S, has been characterized experimentally for the first time by means of rotational spectroscopy; the equilibrium structure of this fundamental molecule has been evaluated through a combination of experimental data from a total of ten isotopologues and results of high-level coupled-cluster calculations.
Structure and stability of hexadentate complexes of ligands based on AAZTA for efficient PET labelling with gallium-68
2012
Pre-organised tricarboxylate ligands based on 6-amino-perhydro-1,4-diazepine bind (68)Ga rapidly and selectively in acetate buffer at pH 4 to 7, forming kinetically stable complexes suitable for use in PET imaging.
Relatively strong intramolecular antiferromagnetic coupling in a neutral Cr(III)2Nb(V)2 heterobimetallic molecular square.
2015
A relatively large antiferromagnetic interaction between the two chromium(III) ions from the molecular square [{Cr(dmso)4}2{Nb(μ-O)2(C2O4)2}2] () (J = -12.0 cm(-1)) is mediated by the diamagnetic oxo-Nb(V)-oxo pathway, its nature and magnitude being substantiated by DFT type theoretical calculations.
Studien zum Vorgang der Wasserstoffübertragung, 57 Einige Beispiele zur diastereoselektiven Hydrierung von Verbindungen mit prochiralen CC-Bindungen
1979
(1R,2S)-N,N-Dimethylephedriniumchlorid, (1S,2S)-N,N-Dimethylpseudoephedriniumchlorid, (1R,2S)-N-Methylephedrin, (1S,2S)-N-Methylpseudoephedrin und [(2S)-2-Hydroxy-2-phenyl-ethyl]trimethylammoniumchlorid werden mit α- und β-Methylzimtsaure zu 1–4 und 7 verestert und an Raney-Nickel, Palladium, Platin und einer Reihe von Edelmetalltragerkatalysatoren hydriert. Die hydrierten Ester werden verseift und die optische Ausbeute der α- bzw. β-Methyldihydrozimtsaure bestimmt. Die optischen Ausbeuten bewegen sich in Abhangigkeit von der optisch aktiven Hilfskomponente zwischen 68 und 4%. Bei optischen Ausbeuten uber 10% wird die absolute Konfiguration der α- oder β-Methyldihydrozimtsaure von der Konfi…