Search results for "Mole"
showing 10 items of 35882 documents
A novel MALDI-MS approach for the analysis of neutral metallosupramolecular architectures
2011
Matrix assisted laser desorption/ionisation mass spectrometry (MALDI-MS) methods have been developed for the characterisation of neutral [2×2] metallogrids derived fromdiimine, dihydrazone and diacylhydrazone ligands. Such grids may be protonated in solution to give cationic species but in most cases these are labile, so that rather delicate conditions are required for observation of the intact metallogrids as monoprotonated derivatives in the gas phase. As a MALDI matrix, 2,4,6-trihydroxyacetophenone (THAP) is sufficiently acidic to enable monoprotonation of the grids unaccompanied by dissociation, and if the grid sample is initially deposited by a layering technique to avoid any prelimina…
An aryl-fused redox-active tetrathiafulvalene with enhanced mixed-valence and radical-cation dimer stabilities.
2018
Molecular recognition of stable organic radicals is a relatively novel, but important structural binding motif in supramolecular chemistry. Here, we report on a redox-switchable veratrole-fused tetrathiafulvalene derivative VTTF which is ideally suited for this purpose and for the incorporation into stimuli-responsive systems. As revealed by electrochemistry, UV/Vis measurements, X-ray analysis, and electrocrystallisation, VTTF can be reversibly oxidised to the corresponding radical-cation or dication which shows optoelectronic and structural propterties similar to tetrathiafulvalene and tetrakis(methylthio)tetrathiafulvalene. However, theoretical calculations, variable temperature EPR, and…
Modellmembranen auf Oberflächen. Verankert und doch mobil
2008
Membranmodelle, die auf Festkorperoberflachen verankert sind, ermoglichen es, elektrische Verfahren sowie oberflachenanalytische und abbildende Methoden einzusetzen. So kann mit Membranen auf Oberflachen die laterale Organisation von Lipiden und Proteinen bis in den Nanometerbereich hinein visualisiert werden. Gleichzeitig sind diese Membranen sehr stabil und damit attraktiv fur verschiedene Bereiche der Biosensorik. Durch eine individuelle Adressierung kleinster mikrometergroser Membranareale mit verschiedenen Lipidkompositionen ist es moglich geworden, die Bindung von Proteinen an funktionale Membranen auf kleinstem Raum zu quantifizieren und zu parallelisieren. Fur die Untersuchung von T…
A study on stabilization of HHeF molecule upon complexation with Xe atoms
2004
In the present work, we computationally study energetic stabilization of HHeF by its complexation with Xe atoms. For the studied HHeF ��� Xen systems ðn ¼ 1–4; 6Þ, we found a large complexation-induced decrease of energy of HHeF with respect to its dissociation into atoms. As a working hypothesis, we assume that this stabilization effect continues for the larger systems (n > 6) as well. This suggests that dissociation of HHeF via the H–He stretching coordinate might be suppressed and its lifetime might be increased by inserting it into large Xe clusters or matrices. 2004 Elsevier B.V. All rights reserved.
Structural studies of homoisoflavonoids: NMR spectroscopy, X-ray diffraction, and theoretical calculations
2010
Abstract In this article we present a detailed structural investigation for five homoisoflavonoids, molecules important from the pharmacological point of view. For studying the electron distribution as well as its influence on the physicochemical properties, NMR spectroscopy, X-ray diffraction, and theoretical calculations have been used. Nuclear magnetic shieldings obtained by using DFT calculations for optimized molecular geometries are correlated with the experimentally determined chemical shifts. The theoretical data are well in agreement with the experimental values. The single crystal X-ray structures of homoisoflavonoid derivatives 1, 3, and 4 have been solved. The molecular geometri…
Kinetic control in the temperature-dependent sequential growth of surface-confined supramolecular copolymers
2017
We report the sequential growth of supramolecular copolymers on gold surfaces, using oppositely charged dendritic peptide amphiphiles. By including water-solubilising thermoresponsive chains in the monomer design, we observed non-linear effects in the temperature-dependent sequential growth. The step-wise copolymerisation process is characterised using temperature dependent SPR and QCM-D measurements. At higher temperatures, dehydration of peripheral oligoethylene glycol chains supports copolymer growth due to more favourable comonomer interactions. Both monomers incorporate methionine amino acids but remarkably, desorption of the copolymers via competing sulphur gold interactions with the …
Two bimetallic layered materials with “Cu4Fe3” defective cubane units: syntheses, structures and magnetic properties of {[CuII(tn)]2[FeII(CN)6]}3·[Na…
2005
Abstract Reactions of the [Fe III (CN) 6 ] 3− anion with the [Cu II (tn)] 2+ ion (tn = 1,3-diaminopropane) afford the compounds {[Cu II (tn)] 2 [Fe II (CN) 6 ]}3·[Na 3 Fe III (CN) 6 ]·12H 2 O (1) and {[Cu n (tn)] 2 [Fe II (CN) 6 ]}·KCl·5H 2 O (2). Despite the differences concerning their asymmetric units, both structures present strong similar features: in both structures, the Cu(II) ion presents a square-base pyramidal CuN 5 environment and each [Fe II (CN) 6 ] 4− anion is linked to six Cu(II) ions through its six N atoms leading to infinite [Cu II (tn)] 2 [Fe II (CN) 6 ] layers which can be viewed as 2-D layered arrangement generated by the defective cubane units Cu 4 Fe 3 involving Fe-CN…
A green and efficient method for the synthesis of homodimeric (β-dicarbonyl) arylmethanes and dihydropyridine from dimedone in water
2018
A direct method has been developed for the synthesis of the dihydropyridine ring system by means of Michael reaction. The reaction of dimedone with 1 .0 equiv. of amines in water provides intermediate product, which allowed dihydropyridine derivatives by intramolecular cyclization in various yields. Of particular interest is the use of the water as solvent of reaction and in absence of catalyst. Also these operating conditions protect the environment and economic points of view.Keywords: aqueous synthesis; bioactivity; dihydropyridine; dimedone; green method; selective conditions
Exploring the Chemoselectivity towards Cysteine Arylation by Cyclometallated Au III Compounds: New Mechanistic Insights
2020
To gain more insight into the factors controlling the efficient cysteine arylation by cyclometalated Au(III) complexes, the reaction between selected gold compounds and different peptides was investigated by high‐resolution liquid chromatography electrospray ionization mass spectrometry (HR‐LC‐ESI‐MS). The deducted mechanisms of C–S cross‐coupling, also supported by density functional theory (DFT) and quantum mechanics/molecular mechanics (QM/MM) calculations, evidenced the key role of secondary peptidic gold binding sites in favouring the process of reductive elimination.
Assembling Halogen-Bonded Capsules via Cation Exchange
2017
Dr. Lotta Turunen is currently a postdoctoral researcher within Acad. Prof. Kari Rissanen's research group at the University of Jyvaskyla in Finland. Under his supervision, she obtained her MSc in organic chemistry and completed her PhD in chemistry in late September 2017. Her research focused on designing, synthesizing, and characterizing halogen-bonded supramolecular assemblies, capsules, and cages.