"; ?> http://www.cipsm.de/enn/feed/index.xml CIPSM Startseite en Ludwig-Maximilians-Universität Munich RSS Feed Generator 60 http://www.cipsm.de/enn/publications/researchAreaA/Increasing_the_efficiency/index.html For three indolylfulgides the quantum efficiency of the ring-opening reaction upon pre-excitation is investigated in a multipulse experiment. The quantum efficiency grows by factor of up to 3.4, when the pre-excitation pulse immediately precedes the excitation process. The change in quantum efficiency after pre-excitation is discussed as a function of ... http://www.cipsm.de/enn/publications/researchAreaB/Oxidation_State__Aggregation__and_Heterolytic_Dissociation_of_Allyl_Indium_Reagents/index.html Solutions of allyl indium reagents formed in the reactions of indium with allyl bromide and allyl iodide, respectively, in N,N-dimethylformamide, tetrahydrofuran, and water were analyzed by a combination of electrospray-ionization mass spectrometry, temperature-dependent 1H NMR spectroscopy, and electrical conductivity measurements. Additional mass ... http://www.cipsm.de/enn/publications/researchAreaB/A_Highly_Charged_Ag6_4__Core/index.html Small metal clusters fill the gap between the atomic scale and the metallic state with its distinctive bulk phenomena.[1] Besides being of high fundamental interest, this intermediate character of metal clusters also gives rise to unique and potentially useful electronic, magnetic, and optical properties.[ 2] To bring these properties to real-world ... http://www.cipsm.de/enn/publications/researchAreaB/Microsolvated_and_Chelated_Butylzinc_Cations__Formation__Relative_Stability__and_Unimolecular_Gas-Phase_Chemistry/index.html Solutions of butylzinc iodide in tetrahydrofuran, acetonitrile, and N,N-dimethylformamide were analyzed by electrospray ionization mass spectrometry. In all cases, microsolvated butylzinc cations [ZnBu(solvent)n]+, n=1-3, were detected. The parallel observation of the butylzincate anion [ZnBuI2]- suggests that these ions result from disproportionation of ... http://www.cipsm.de/enn/publications/researchAreaC/Radicals_in_enzymatic_catalysis/index.html The thermodynamic stability of radicals involved in enzymatic catalysis has been quantified using a series of theoretical methods. It is found that three of the most often encountered radicals located on the enzyme protein chain (tyrosyl, cysteinyl and glycyl radicals) are of similar stability. This is despite the fact that O–H, S–H and C–H bonds have ... http://www.cipsm.de/enn/publications/researchAreaB/Kinetics_of_Bromine-Magnesium_Exchange_Reactions_in_Heteroaryl_Bromides/index.html Bromine-magnesium exchange reactions of heteroaryl bromides provide an efficient entry to a wide variety of fiveand six-membered functionalized heteroaryl Grignard reagents, which can be used for the selective synthesis of polyfunctionalized heterocyclic compounds, such as thiazole, thiophene, furan, pyrrole, and pyridine derivatives.1,2 The resulting ... http://www.cipsm.de/enn/publications/researchAreaA/Nanostructured_Silica_Materials/index.html We apply mesoporous thin silica films with nanometer-sized pores as drug carriers and incorporate the widely used anticancer drug Doxorubicin. Through single-molecule based measurements, we gain mechanistic insights into the drug diffusion inside the mesoporous film, which governs the drug-delivery at the target-site. Drug dynamics inside the nanopores is ... http://www.cipsm.de/enn/publications/researchAreaB/The_Key_Role_of_Salvation_Dynamics_in_Intramolecular_Electron_Transfer__Time-Resolved_Photophysics_of_Crystal_Violet_Lactone/index.html The intramolecular electron-transfer reaction in crystal violet lactone in polar aprotic solvents is studied with femtosecond transient absorption spectroscopy. The initially excited charge transfer state 1CTA is rapidly converted into a highly polar charge transfer state 1CTB. This ultrafast electron transfer is seen as a solventdependent dual ... http://www.cipsm.de/enn/publications/researchAreaA/An_Unfolded_CH1_Domain_Controls/index.html A prerequisite for antibody secretion and function is their assembly into a defined quaternary structure, composed of two heavy and two light chains for IgG. Unassembled heavy chains are actively retained in the endoplasmic reticulum (ER). Here, we show that the CH1 domain of the heavy chain is intrinsically disordered invitro, which sets it apart from other ... http://www.cipsm.de/enn/publications/researchAreaB/Nucleophilicities_of_the_Anions_of_Arylacetonitriles_and_Arylpropionitriles_in_Dimethyl_Sulfoxide/index.html The rates of the reactions of the colored para-substituted phenylacetonitrile anions 1a-c and the phenylpropionitrile anions 2a-c with Michael acceptors (3a-u) were determined by UV-vis spectroscopy in DMSO at 20 °C. The reactions follow second-order kinetics, and the corresponding rate constants k2 obey the linear-free-energy relationship log k2(20 °C) ) ... http://www.cipsm.de/enn/publications/researchAreaB/Kinetics_of_Bromine_Magnesium_Exchange_Reactions_in_Substituted_Bromobenzenes/index.html Competition experiments have been performed to determine the relative reactivities of substituted bromobenzenes, bromonaphthalenes, and 9-bromoanthracene toward i-PrMgCl · LiCl in THF at 0 °C. The rates of the bromine-magnesium exchange reactions are accelerated by electron-acceptor substituents, the activating efficiency of which increases in the order ... http://www.cipsm.de/enn/publications/researchAreaA/beta-Lactam_Probes_As_Selective_Chemical-Proteomic_Tools/index.html With the development of antibiotic resistant bacterial strains, infectious diseases have become again a life threatening problem. One of the reasons for this dilemma is the limited number and breadth of current therapeutic targets for which several resistance strategies have evolved over time. To identify resistance associated targets and to understand their ... http://www.cipsm.de/enn/publications/researchAreaC/Ab_Initio_Studies_on_the_Photophysics_of_Guanine_Tautomers__Out_of_Plane_Deformation_and_NH_Dissociation_Pathways_to_Conical_Intersections/index.html The radiationless decay mechanisms of the S1 excited states of the 7H-keto-amino, 7H-enol-amino, and 7Hketo- imino tautomers of guanine have been investigated with the CASPT2//CASSCF method. Out-of-plane deformation of the six-membered ring or the imino group as well as dissociation of NH bonds have been considered as photochemical pathways leading to ... http://www.cipsm.de/enn/publications/researchAreaC/Nonradiative_Decay_Mechanisms_of_the_Biologically_Relevant_Tautomer_of_Guanine/index.html We present the excited-state potential energy profiles of the biologically relevant 9H-keto-amino tautomer of guanine with respect to the radiationless decay via the out-of-plane deformation of the six-membered ring as well as the dissociation of NH bonds. The CASPT2//CASSCF method is employed for the reaction-path calculations. The reaction path for the ... http://www.cipsm.de/enn/publications/researchAreaA/Thymine_Dimerization_in_DNA_Model_Systems/index.html Photoreactions induced by ultraviolet radiation are among the most important external hazards for the integrity of DNA.1 The photolesion with the highest abundance is the [2 + 2] photoaddition of thymine bases adjacent on a DNA strand.2 This photoaddition yields a cyclobutane pyrimidine dimer (CPD). The formation of the CPD lesion has first been ... http://www.cipsm.de/enn/publications/researchAreaA/Accelerated_and_Efficient_Photochemistry_From_Higher_Excited_Electronic_States_in__Fulgide_Molecules/index.html The photoinduced electrocyclic ring-opening of a fluorinated indolylfulgide is investigated by stationary and ultrafast spectroscopy in the UV/vis spectral range. Photoreactions, initiated by optical excitation into the S1 (570 nm) and SN (340 nm) absorption band of the closed isomer, lead to considerable differences in reaction dynamics and quantum ... http://www.cipsm.de/enn/publications/researchAreaA/Structurally_Refined_b-Lactones/index.html With decreasing efficiency of antibiotic therapies against hospital- and community-acquired bacterial pathogens, the treatment of infectious diseases again represents a tremendous challenge for medicinal research. This challenge seems to be particularly difficult if one considers the sophisticated resistance strategies, which are effective against almost ... http://www.cipsm.de/enn/publications/researchAreaB/Nucleophilic_Reactivities_of_Azulene_and_Fulvenes/index.html The kinetics of the reactions of azulene (1), 6,6-dimethylfulvene (2), 6-[4-(dimethylamino)phenyl]fulvene (3) and 6-(julolidin-9-yl)fulvene (4) with a set of benzhydrylium ions (reference electrophiles) have been investigated in MeCN. The second-order rate constants for these reactions correlate linearly with the electrophilicity parameters (E) of the ... http://www.cipsm.de/enn/publications/researchAreaA/Local_conformational_dynamics/index.html Coupling fast triplet–triplet energy transfer (TTET) between xanthone and naphthylalanine to the helix–coil equilibrium in alanine-based peptides allowed the observation of local equilibrium fluctuations in α-helices on the nanoseconds to microseconds time scale. The experiments revealed faster helix unfolding in the terminal regions compared with the ... http://www.cipsm.de/enn/publications/researchAreaB/Formation_of_Organozincate_Anions/index.html Tetrahydrofuran solutions of the products formed in LiCl-mediated zinc insertion reactions into various organic halides RHal were analyzed by anion-mode electrospray ionization (ESI) mass spectrometry. In all cases, organozincate anions were observed. The reactions with RHal, Hal ) Br and I, yielded predominantly mononuclear complexes, such as ZnRHal2 - ... http://www.cipsm.de/enn/publications/researchAreaB/Negishi_Cross-Couplings_Compatible/index.html The Pd-catalyzed cross-coupling of unsaturated halides with organometallic reagents is one of the best methods for making Csp2-Csp2 bonds. Among many organometallic reagents used in these cross-couplings, organozinc reagents (Negishi reaction) have proven to react under very mild conditions. Furthermore, organozinc compounds are compatible with many ... http://www.cipsm.de/enn/publications/researchAreaB/Nucleophilicity_Parameters_for_Phosphoryl-Stabilized/index.html The kinetics of the reactions of four phosphoryl-stabilized carbanions 1a−d and four phosphorus ylides 1e−h with benzhydrylium ions 2a−h and structurally related quinone methides 2i−m have been determined by UV−vis spectroscopy. The second-order rate constants (k) correlated linearly with the electrophilicity parameters E of 2a−m, as required by the ... http://www.cipsm.de/enn/publications/researchAreaB/Aggregation_and_Reactivity_of_Organozincate/index.html Electrospray ionization (ESI) of mixtures of organolithium compounds and zinc chloride in tetrahydrofuran produced manifold mono- and polynuclear organozincate anions. Formation of the latter is strongly favored by the incorporation of chloride ligands, which apparently adopt bridging binding modes. Analysis of LinBu/ZnCl2 solutions at different ... http://www.cipsm.de/enn/publications/researchAreaA/beta-Lactones_as_Specific_Inhibitors_of_ClpP_Attenuate_the_Production_of_Extracellular_Virulence_Factors_of_Staphylococcus_aureus1/index.html With the evolution of multidrug resistant bacterial pathogens, infectious diseases pose once again a serious threat to public health. Especially the opportunistic pathogen Staphylococcus aureus has gained importance through the dramatically increasing appearance of methicillin-resistant (MRSA) strains in hospitals and the recent emergence of epidemic ... http://www.cipsm.de/enn/publications/researchAreaA/Beta-Lactams_as_Selective_Chemical_Probes_for_the_in_Vivo_Labeling_of_Bacterial_Enzymes_Involved_in_Cell_Wall_Biosynthesis__Antibiotic_Resistance__and_Virulence/index.html With the development of antibiotic-resistant bacterial strains, infectious diseases have become again a life-threatening problem. One of the reasons for this dilemma is the limited number and breadth of current therapeutic targets for which several resistance strategies have evolved over time. To expand the number of addressable enzyme targets and to ... http://www.cipsm.de/enn/publications/researchAreaA/The_structure_of_a_folding_intermediate/index.html Folding intermediates play a key role in defining protein folding and assembly pathways as well as those of misfolding and aggregation. Yet, due to their transient nature, they are poorly accessible to high-resolution techniques. Here, we made use of the intrinsically slow folding reaction of an antibody domain to characterize its major folding intermediate ... http://www.cipsm.de/enn/publications/researchAreaB/Negishi_Cross-Couplings/index.html A wide range of polyfunctional aryl, heteroaryl, alkyl, and benzylic zinc reagents were coupled with unsaturated halides bearing an acidic NH or OH function, using Pd(OAc)2 (1 mol %) and S-Phos (2 mol %) as catalyst without the need of protecting groups. http://www.cipsm.de/enn/publications/researchAreaB/Reactions_of_Nitroheteroarenes_with_Carbanions/index.html The relative rate constants for the vicarious nucleophilic substitution (VNS) of the anion of chloromethyl phenyl sulfone with a variety of nitroheteroarenes, for example, nitropyridines, nitropyrroles, nitroimidazoles, 2-nitrothiophene, and -nitropyrazole, have been determined by competition experiments. It was shown that nitropyridines are approximately ... http://www.cipsm.de/enn/newsEvents/news/New_Members_of_the_SFB_749/index.html The SFB is happy to present its two new members: Prof. Thomas Kiefhaber from the Technische Universität München und Dr. Konrad Koszinowski from the Ludwig-Maximilians-Universität München. http://www.cipsm.de/enn/newsEvents/news/2008_Kopernikus-Preis_an_SFB749-Forscher_Wolfgang_Domcke/index.html For his merits in the German-Polish collaboration in science SFB749-researcher Prof. Domcke will be honored with the 2008 Kopernikus-Preis of the DFG and FNP. http://www.cipsm.de/enn/publications/researchAreaA/beta-Lactones_as_Privileged_Structures/index.html Evolution of multiresistant bacterial strains has meant that infectious diseases once again pose a major threat to public health. Since many antibiotics still target only a limited set of cellular functions, it is a desirable goal to expand the number and breadth of therapeutic targets as well as to gain a deeper understanding of the molecular mechanisms ... http://www.cipsm.de/enn/publications/researchAreaA/Ultrafast_Ring-Closure_Reaction_of_Photochromic_Indolylfulgimides_Studied_with/index.html The ring-opening and ring-closure reactions of a photochromic indolylfulgimide are investigated with femtosecond vibrational spectroscopy. Spectral signatures due to excited-state decay and vibrational cooling are seen in the mid-IR region. For the ring-opening reaction triggered with visible pulses, a lifetime of the excited electronic state of 4 ps was ... http://www.cipsm.de/enn/publications/researchAreaB/Ambident_Reactivity_of_the_Cyanate_Anion/index.html The cyanate anion is an ambident nucleophile, which may react with electrophiles either at the oxygen terminus to yield alkyl cyanates or at the nitrogen terminus to yield isocyanates. Because the charge density is higher at the more electronegativeoxygen center while the larger HOMO coefficient is at nitrogen, the concept of charge and orbital control ... http://www.cipsm.de/enn/publications/researchAreaA/Ultrafast_dynamics_and_temperature_effects/index.html The ultrafast ring-opening reaction of the molecular switch 1,2-Dimethyl-3-indolylfulgide dissolved in acetonitrile is investigated by temperature dependent quantum efficiency measurements and time-resolved transient absorption spectroscopy in the ultraviolet and visible spectral range. The photoreaction is found to be thermally activated with an activation ... http://www.cipsm.de/enn/publications/researchAreaA/Chemical_control_of_Hemithioindigo-photoisomerization/index.html Hemithioindigo-molecules show a photochromic behavior due to a photo-induced Z/E-isomerization on a picosecond timescale. Changes in the reaction kinetics, caused by polar substituents attached to the thioindigo-moiety, are studied using time-resolved absorption spectroscopy. The experiments reveal that substituents in the thioindigo-part influence the ... http://www.cipsm.de/enn/publications/researchAreaC/Ultrafast_dissociation_pathways_of_diphenylmethyl_chloride_to/index.html The primary processes in the formation of electrophilic precursor ions are studied on a microscopic scale by quantum chemical and quantum dynamical methods. For the competing reaction channels of heterolysis and homolysis in the photochemically induced dissociation of diphenylmethyl chloride, ab initio data for the ground and excited electronic states are ... http://www.cipsm.de/enn/publications/researchAreaA/Ultrafast_reaction_dynamics_of_the_complete_photo_cycle/index.html The reaction dynamics of the complete photo cycle, ring-opening (C→E) and ring-closure (E→C), of N-methyl-(6-bromo-1,2-dimethyl-3-indolyl) fulgimide dissolved in acetonitrile are analysed via steady-state and ultrafast spectroscopy using transient absorption in the UV/VIS and mid-IR complemented by ultrafast fluorescence broad-band spectroscopy with a ... http://www.cipsm.de/enn/publications/researchAreaA/Diffusion_of_Oriented_Single_Molecules/index.html Single dye molecules incorporated into a mesoporous matrix can act as highly sensitive reporters of their environment. Here, we use single TDI molecules incorporated as guests into hexagonal mesoporous films containing highly structured domains. The dye molecules allow us to map the size of these domains which can extend to over 100 m. Investigation of the ... http://www.cipsm.de/enn/publications/researchAreaA/Dissecting_the_Differences/index.html The oxidative DNA lesion, FaPydG rapidly anomerizes to form a mixture of the a and b anomer. To investigate the mutagenic potential of both forms, we prepared stabilized bioisosteric analogues of both configurational isomers and incorporated them into oligonucleotides. These were subsequently used for thermodynamic melting-point studies and for ... http://www.cipsm.de/enn/publications/researchAreaB/Regio-_and_Stereoselective_Ring-Opening_Reactions/index.html Aliphatic and aromatic epoxides react regio- and stereoselectively with indoles and pyrroles in 2,2,2-trifluoroethanol without the use of a catalyst or any other additive. While aromatic epoxides are selectively attacked at the benzylic position, aliphatic epoxides react at the less-substituted position. Chiral epoxides react with >99% ee (ee=enantiomeric ... http://www.cipsm.de/enn/publications/researchAreaA/Selective_Detection_of_5-Methylcytosine_Sites_in_DNA/index.html After the complete sequencing of the human genome, one of the next important steps is to decipher the genetic mechanisms which allow cells to switch genes on and off. These processes are fundamental for cellular development. At the chemical level, gene silencing requires the selective methylation of of the C5-position of cytidines in DNA, and this ... http://www.cipsm.de/enn/publications/researchAreaB/Mayr_Knochel_relative/index.html The accessibility of functionalized Grignard reagents has opened new dimensions in organic synthesis. One of us has previously demonstrated that treatment of substituted bromoarenes with iPrMgCl·LiCl provides a straightforward access to functionalized aryl Grignard reagents by bromine–magnesium exchange. In accord with the suggested mechanism for these ... http://www.cipsm.de/enn/publications/researchAreaB/Mayr_Knochel_relative1/index.html Die Entwicklung funktionalisierter Grignard-Reagentien hat der organischen Synthese neue Möglichkeiten eröffnet. Einer der Autoren hat früher bereits demonstriert, dass die Umsetzung substituierter Bromarene mit iPrMgCl·LiCl über einen Brom-Magnesium-Austausch einen einfachen Zugang zu funktionalisierten Aryl-Grignard-Reagentien ermöglicht. In Einklang mit ... http://www.cipsm.de/enn/publications/researchAreaB/Mayr_Knochel_Cu/index.html Polyfunctional alkynes are important intermediates for the preparation of natural products, pharmaceuticals, and organic materials such as molecular wires. The Sonogashira reaction and the Negishi cross-coupling are very powerful methods for preparing polyfunctional alkynes through the formation of a C(sp2)-C(sp) bond. However, the Sonogashira coupling ... http://www.cipsm.de/enn/newsEvents/events/International_Conference_of_the_SFB_749_at_Kloster_Irsee__Allg__u/index.html Kloster Irsee
Klosterring 4
87660 Irsee
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