A5023710002- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Synthesis and Properties of Aromatic Compounds
- Crystallography and molecular interactions
- Fullerene Chemistry and Applications
- Chemical Synthesis and Analysis
- Porphyrin and Phthalocyanine Chemistry
- Advanced Chemical Physics Studies
- Photochromic and Fluorescence Chemistry
- Fluorine in Organic Chemistry
- Molecular Junctions and Nanostructures
- Synthesis and Catalytic Reactions
- Inorganic Fluorides and Related Compounds
- Organometallic Complex Synthesis and Catalysis
- Molecular spectroscopy and chirality
- Molecular Sensors and Ion Detection
- Luminescence and Fluorescent Materials
- Asymmetric Synthesis and Catalysis
- Photochemistry and Electron Transfer Studies
- Cyclization and Aryne Chemistry
- Supramolecular Chemistry and Complexes
- Graphene research and applications
- Molecular Spectroscopy and Structure
- Magnetism in coordination complexes
- Synthesis and characterization of novel inorganic/organometallic compounds
BASF (United States)
2019
ETH Zurich
2002-2011
MS-Schramberg (Germany)
2010
TRUMPF (Germany)
2010
Board of the Swiss Federal Institutes of Technology
1980-2005
Laboratoire de Chimie Physique
1994
École Polytechnique Fédérale de Lausanne
1981-1989
Analytisches Laboratorium
1980
University of Basel
1971-1972
Roche (Switzerland)
1972
X-ray analyses of ferrocene [Fe(CsHs) 2, CmH~0Fe] at room temperature and 173 K yield vibrationalellipsoid patterns that are incompatible with pure rotational disorder the cyclopentadienyl rings. Below 164 becomes triclinic. Relationships between diffraction monoclinic hightemperature (HT) triclinic low-temperature (LT) structures suggest formally centrosymmetric molecule disordered HT phase can be described in good approximation as an averaged superposition four molecules present primitive...
Abstract A wide variety of monomeric and oligomeric, donor‐substituted 1,1,4,4‐tetracyanobutadienes (TCBDs) have been synthesized by [2+2] cycloaddition between tetracyanoethylene (TNCE) alkynes, followed electrocyclic ring opening the initially formed cyclobutenes. Reaction yields are often nearly quantitative but can be affected electron‐donating power steric demands alkyne substituents. The intramolecular charge‐transfer (CT) interactions donor TCBD acceptor moieties were comprehensively...
Donor-acceptor molecules with 4-(dimethylamino)phenyl donor and 1,1,4,4-tetracyanobuta-1,3-diene acceptor moieties are readily prepared by short, high-yielding routes. The quite small chromophores characterised X-ray crystallography feature intense intramolecular charge-transfer bands, substantial quinoid character in the rings, reversible electrochemical reductions oxidations powerful third-order optical nonlinearities.
A highly fluorophilic environment comprising the HCαCO unit of Asn 98 in active site thrombin was identified by X-ray crystallography a complex formed between enzyme and synthetic inhibitor (see partial structure, distances are Angstroms). Short CF⋅⋅⋅HCα CF⋅⋅⋅CO contacts involving fragments were also frequently observed small-molecule crystal structures.
Plenty of room on top: Unprecedented one- and two-dimensional fullerene patterns were obtained upon evaporation pristine C60 onto pre-organized porphyrin monolayers silver surfaces following a bottom-up approach. The arrangement the molecules patterned layer can be controlled by structure (see scanning tunneling microscopy images). Supporting information for this article is available WWW under http://www.wiley-vch.de/contents/jc_2002/2004/z460562_s.html or from author. Please note: publisher...
Rivaling the best one: Thermal [2+2] cycloadditions of TCNE, TCNQ, and F(4)-TCNQ to N,N-dimethylanilino-substituted cyanoalkynes afforded a new class organic super-acceptors featuring efficient intramolecular charge-transfer interactions. These acceptors rival acceptor in propensity for reversible electron uptake as well affinity (see figure), which makes them interesting p-type dopants potential application optoelectronic devices.Thermal tetracyanoethene (TCNE),...
Programmed with an unusual number of functions, the tetraethynylethene derivative 1 exhibits three addressable switching subunits, which can undergo individual reversible cycles that are controllable by pH and light. Three “write/erase” processes one “AND” logic gate process be separately addressed, in each case efficient nondestructive readout is possible.
Abstract In a systematic fluorine scan of rigid inhibitor to map the fluorophilicity/fluorophobicity active site in thrombin, one or more F substituents were introduced into benzyl ring reaching D pocket. The 4‐fluorobenzyl showed five tenfold higher affinity than ligands with other fluorination patterns. X‐ray crystal‐structure analysis protein–ligand complex revealed favorable CF⋅⋅⋅HC α CO and CF⋅⋅⋅CO interactions 4‐F substituent backbone HC unit Asn98. importance these was further...
It all clicks into place: The cycloaddition of tetracyanoethylene (TCNE) to electron-rich alkynes ("click" reaction) followed by retro-electrocyclization affords multivalent charge-transfer chromophores that accept up 24 electrons. cascade additions TCNE and tetrathiafulvalene (TTF) polyynes provides access conjugated donor–acceptor-substituted [AB] oligomers with promising optoelectronic properties (see scheme). Supporting information for this article is available on the WWW under...
A series of donor-acceptor molecules, featuring intense low-energy intramolecular charge-transfer bands, was prepared by regioselective [2 + 2] cycloaddition between 7,7,8,8-tetracyanoquinodimethane (TCNQ) and N,N-dialkylanilino-substituted (DAA-substituted) alkynes, followed ring opening the initially formed cyclobutenes.
A series of ionic stilbazolium salts with benzenesulfonates different substituents in the para position have been synthesized. Single crystals 4-N,N-dimethylamino-4′-N′-methylstilbazolium p-methoxybenzenesulfonate (DSMOS) were successfully grown methanol solution by slow cooling. X-ray studies revealed that DSMOS crystallized triclinic space group P1 its molecular dipoles perfectly aligned one direction—favorable for large nonlinear optical and electro-optical effects. Kurtz powder tests a...
In just four steps from ferrocene, macrocyclic ferrocenyl bispalladacyles have been synthesized by using a diastereoselective biscyclopalladation reaction as the key step. The complexes not only possess fascinating structure but are also first highly active catalysts for title (see scheme), requiring little 0.1 mol % of catalyst most substrates. Ts=toluene-4-sulfonyl. Supporting information this article is available on WWW under http://www.wiley-vch.de/contents/jc_2002/2007/z603568_s.pdf or...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe absence of bonding electron density in certain covalent bonds as revealed by x-ray analysisJack D. Dunitz and Paul SeilerCite this: J. Am. Chem. Soc. 1983, 105, 24, 7056–7058Publication Date (Print):November 1, 1983Publication History Published online1 May 2002Published inissue 1 November 1983https://pubs.acs.org/doi/10.1021/ja00362a007https://doi.org/10.1021/ja00362a007research-articleACS PublicationsRequest reuse permissionsArticle...
Abstract The X‐ray structures of fifteen 1, 3‐imidazolidine, 3‐oxazolidine, 3‐dioxan‐4‐one, and hydropyrimidine‐4(1 H )‐one derivatives are described ( Table 2 ) compared with known similar compounds Figs. 1–20 ). differences between containing exocyclic N ‐acyl groups those lacking this structural element arise from the A 1,3 effect amide moieties. Even t ‐Bu forced into axial positions six‐ring half‐chair or flag‐pole twist‐boat conformers by 16–20 In ‐acylated five‐membered heterocycles,...
Abstract The preparation of tetraethynylethene (3,4‐diethynylhex‐3‐ene‐1,5‐diyne) 1 as well a great diversity differentially mono‐, di‐, and triprotected derivatives by newly developed synthetic routes is described. These fully cross‐conjugated molecules are versatile building blocks precursors to two‐dimensional all‐C networks novel C‐rich nanoarchitecture with unusual structural electronic properties, such perethynylated expanded radialenes, or molecular wires polymers the polytriacetylene...
Abstract By the tether‐directed remote functionalization method, a series of bis‐ to hexakis‐adducts C 60 , i.e. 1 – 7 ( Fig. ), had previously been prepared with high regioselectivity. An efficient method for removal tether‐reactive‐group conjugate was now developed and its utility demonstrated in regioselective synthesis tetrakis(methano)fullerenes = di‐ tetracyclopropafullerenes‐C ‐ I h ) 9 11 starting from 4 5 respectively Schemes 2, ). This versatile protocol consists O 2 ene reaction...
We report on the synthesis of new and previously described β-peptides (1 – 6), consisting up to twelve β2,2- or β3,3-geminally disubstituted β-amino acids which do not fit into any secondary structural patterns β-peptides, hitherto disclosed. The required 2,2- 3,3-dimethyl derivatives 3-aminopropanoic acid are readily obtained from 3-methylbut-2-enoic ammonia (Scheme 1) Boc-protected methyl 3-aminopropanoate by enolate methylation 2). Protected (Boc for solution-, Fmoc solid-phase syntheses)...
The H-atoms of the phenylamidinium needle tricyclic thrombin inhibitors, which interacts with Asp189 at bottom selectivity pocket S1 enzyme, were systematically exchanged F-atoms in an attempt to improve pharmacokinetic properties by lowering pKa value. Both values and inhibitory constants Ki against trypsin decreased upon F-substitution. Interestingly, linear free energy relationships (LFERs) revealed that binding affinity is much more affected a decrease than trypsin. Surprising effects...