Search results for "Metals"

Design of a real-time spectroscopic rotating compensator ellipsometer without systematic errors

2014

6th International Conference on Spectroscopic Ellipsometry (ICSE), Kyoto, JAPAN, MAY 26-31, 2013; International audience; We describe a spectroscopic ellipsometer in the visible domain (400-800 nm) based on a rotating compensator technology using two detectors. The classical analyzer is replaced by a fixed Rochon birefringent beamsplitter which splits the incidence light wave into two perpendicularly polarized waves, one oriented at +45 degrees and the other one at-45 degrees according to the plane of incidence. Both emergent optical signals are analyzed by two identical CCD detectors which are synchronized by an optical encoder fixed on the shaft of the step-by-step motor of the compensato…

Thermal and light induced polymorphism in iron(II) spin crossover compounds.

2004

The spin crossover complexes {Fe[H2B(pz)2]2L} ([H2B(pz)2]2 = dihydrobis(pyrazolyl)borate, L = 2,2'-bipyridine (1), bipy and 1,10-phenanthroline, phen (2)) undergo both thermal and light induced spin crossover, but the structure of the low spin and light induced high spin states for 2 are different from that of the thermally induced high spin state and from those of 1. Real Cabezos, Jose Antonio, Jose.A.Real@uv.es

Intermolecular interaction energies and magnetic properties of spin-isolated multinuclear CuII complexes

2020

Dinuclear CuII complexes with 3,5-dinitrobenzoates and 2,2′-bipyridine (2) or 1,10-phenanthroline (3) were synthesized and characterized. A complete energy framework analysis using the HF/3-21G energy model was performed which found that dispersion forces and C—H...O interactions are responsible for the crystal structure features. The magnetic properties of the complexes show a weak magnetic exchange between spins, resulting in low exchange constants of −2.72 (1) cm−1 and −1.10 (1) cm−1 for complexes (2) and (3), respectively. This results from the low overlap between magnetic orbitals induced by 3,5-dinitrobenzoate bridges and the arrangement of the magnetic orbitals. Consequently, the din…

2019

Energy-level alignment at organic-metal interfaces plays a crucial role for the performance of organic electronic devices. However, reliable models to predict energetics at strongly coupled interfaces are still lacking. We elucidate contact formation of 1,2,5,6,9,10-coronenehexone (COHON) to the (1 1 1)-surfaces of coinage metals by means of ultraviolet photoelectron spectroscopy, x-ray photoelectron spectroscopy, the x-ray standing wave technique, and density functional theory calculations. While for low COHON thicknesses, the work-functions of the systems vary considerably, for thicker organic films Fermi-level pinning leads to identical work functions of 5.2 eV for all COHON-covered meta…

Competitive Profiling of Ligandable Cysteines in Staphylococcus aureus with an Organogold Compound

2022

With the idea of exploiting metal-templated reactions to achieve selective modification of cysteines in proteins for antibacterial applications, an organometallic cyclometalated Au(III) compound was explored in a competitive chemoproteomic approach based on the isoDTB-ABPP (isotopically labelled desthiobiotin azide-activity-based protein profiling) technology in S. aureus cell extracts. In this way, more than 100 ligandable cysteines where identified, of which 10 were close to functional sites of proteins encoded by essential genes indicating potential for antibiotic development. Interestingly, more than 50% of the identified ligandable sites were not engaged by organic α-chloroacetamides i…

Comparative optical reflection and mass spectrometry analysis of thermodesorption of Langmuir-Blodgett films

1992

Abstract Thermodesorption of cadmium arachidate multilayers is studied by optical surface analysis and by mass spectrometry measurements. The optical reflection technique has been improved to discriminate signal contributions from desorption and light scattering. The scattering arises from film heterogeneities that are also observed by Nomarsky microscopy. The assessment of these heterogeneities is important to understand mass spectrometry data. Both the optical technique and mass spectrometry are sensitive to observing the multilayer phase transition at 110 °C and the desorption near 200 °C (at the heating rate applied). The mass spectrometry analysis yields detailed information on the des…

Fluorescence quenching by trapped charge carriers in N,N-dimethylaminobenzylidene 1,3-indandione films

2010

Effects caused by the applied voltage on the steady state and time-resolved fluorescence of vacuum evaporated N,N-dimethylaminobenzylidene 1,3-indandione films sandwiched between gold and aluminium electrodes were investigated and discussed. Fluorescence enhancement and quenching as well as the fluorescence band narrowing depending on the applied voltage have been observed. Fluorescence decay and recovery take place on a time scale of tens of seconds after voltage is switched on and off. Similar fluorescence decay also takes place after switching on the excitation light. These fluorescence changes are attributed to the exciton quenching by trapped charge carriers.

Topologically Novel Multiple Rotaxanes and Catenanes Based on Tetraurea Calix[4]arenes

2006

Calix[4]arenes bearing at their wide rim four urea residues easily form hydrogen bonded dimeric capsules. This has been used to preorganise alkenyl functions attached to these urea groups for their controlled connection via metathesis reaction. Multimacrocyclic tetraurea derivatives are thus obtained in excellent yields via heterodimers which are formed exclusively with tetratosylurea derivatives. Heterodimerisation of such bis- and tetraloop tetraureas leads analogously to multicatenanes, or to rotaxanes by stoppering. Huge macrocycles are detached from tetraloop derivatives by cleavage of the urea function.

A heteropentanuclear oxalato-bridged [ReIV 4GdIII] complex: synthesis, crystal structure and magnetic properties

2012

The compound (NBu 4) 5[Gd III{Re IVBr 4(μ-ox)} 4(H 2O)]·H 2O (1), with intramolecular antiferromagnetic coupling, is the first Re(iv) system incorporating a 4f ion. © 2012 The Royal Society of Chemistry.

Chemically driven phase separation in black lipid membranes and its coupling to membrane functions

1992

Abstract We analysed the single-channel current fluctuations of gramicidin in bimolecular lipid membranes in order to demonstrate (i) the influence of protein binding to the lateral organisation of a mixed membrane, and (ii) how this couples to the function of the ionophore. Examples of phase separations induced by synthetic polyelectrolytes, as models for peripheral membrane proteins, and specific ligand-receptor interactions are presented and discussed in view of the important lateral order-function relationship in biomembranes.