A general, efficient, and regioselective synthesis of a series of hydroxylated 1-methylphenanthrenes 9 by a combined directed ortho metalation (DoM)-Suzuki-Miyaura cross-coupling-directed remote metalation (DreM) sequence is reported. Diversity to this methodology was achieved by a regioselective DoM rather than DreM reaction, affording more highly substituted phenanthrols ( Table 2 ). Application of the turbo-Grignard reagent (i-PrMgCl·LiCl) in the Ni-catalyzed Corriu-Kumada reaction gave efficient decarbamoylation ( Tables 3 and 4 ). Additional features are the TMS protecting group and halo-induced ipso-desilylation tactics applied to the regioselective synthesis of phenanthrenes ( Scheme 2 ).
The high‐pressure behavior of group II element nitrides M3N2 (M=Be, Mg, Sr, and Ba) was studied up to 100 GPa and beyond. Evaluating a manifold of hypothetical polymorphs of composition A3X2 leads to proposing a new high‐pressure polymorph of Be3N2 with an anti‐A‐sesquioxide structure appearing at 82 GPa. Two high‐pressure phases were found for Mg3N2: first an anti‐B‐sesquioxide‐type structure should appear at 21 GPa followed by an anti‐A‐sesquioxide‐type structure at 65 GPa. While structure and true nature of Sr3N2 and Ba3N2 are not yet experimentally determined, we identified an anti‐bixbyite structure to be the ground state structure of Sr3N2 and a distortion variant of the anti‐A‐sesquioxide‐type structure as lowest energy modification for Ba3N2. For Sr3N2 the sequence of high‐pressure phases are (1) an anti‐Rh2O3‐II structure appearing at 3 GPa, (2) an anti‐B‐sesquioxide structure becoming most stable at 12 GPa and (3) a hexagonal P 63/mmc structure favored at 26 GPa. The development of the c /a ‐ratio of anti‐A‐sesquioxide Ba3N2 under pressure was examined, revealing a gradual reduction under pressure. Three high‐pressure polymorphs are then further proposed for Ba3N2: (1) an anti‐Rh2O3‐II structure at 2 GPa, (2) an anti‐CaIrO3 structure at 32 GPa and (3) a hexagonal P 63/mmc structure at 52 GPa. The results for all group II element nitrides M3N2 were compared. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cubic and circular hexagonal mesoporous carbon phases in the confined environment of the pores of anodic alumina membranes (AAM) were obtained by organic-organic self-assembly of a preformed oligomeric resol precursor and the triblock copolymer templates Pluronic F127 or P123, respectively. Casting and solvent evaporation were followed by self-assembly and the formation of a condensed wall material by thermopolymerization of the precursor oligomers, thus resulting in mesostructured phenolic resin phases. Subsequent thermal decomposition of the surfactant and carbonization were achieved through thermal treatment at temperatures up to 1000 °C under an inert atmosphere. The resulting hierarchical mesoporous composite materials were characterized by small-angle X-ray scattering and nitrogen-sorption measurements. The structural features were directly imaged in TEM cross-sections of the composite membranes. For both structures, the AAM pores were completely filled and no shrinkage was observed due to strong adhesion of the carbon-wall material to the AAM pore walls. As a consequence, the pore size of the mesophase system stays almost constant even after thermal treatment at 1000 °C.
The attachment of two different functionalities in a site-selective fashion represents a great challenge in protein chemistry. We report site specific dual functionalizations of peptides and proteins capitalizing on reactivity differences of cysteines in their free (thiol) and protected, oxidized (disulfide) forms. The dual functionalization of interleukin 2 and EYFP proceeded with no loss of bioactivity in a stepwise fashion applying maleimide and disulfide rebridging allyl-sulfone groups. In order to ensure broader applicability of the functionalization strategy, a novel, short peptide sequence that introduces a disulfide bridge was designed and site-selective dual labeling in the presence of biogenic groups was successfully demonstrated.
Single-molecule Förster Resonance Energy Transfer (smFRET) can be used to obtain structural information on biomolecular complexes in real-time. Thereby, multiple smFRET measurements are used to localize an unknown dye position inside a protein complex by means of trilateration. In order to obtain quantitative information, the Nano-Positioning System (NPS) uses probabilistic data analysis to combine structural information from X-ray crystallography with single-molecule fluorescence data to calculate not only the most probable position but the complete three-dimensional probability distribution, termed posterior, which indicates the experimental uncertainty. The concept was generalized for the analysis of smFRET networks containing numerous dye molecules. The latest version of NPS, Fast-NPS, features a new algorithm using Bayesian parameter estimation based on Markov Chain Monte Carlo sampling and parallel tempering that allows for the analysis of large smFRET networks in a comparably short time. Moreover, Fast-NPS allows the calculation of the posterior by choosing one of five different models for each dye, that account for the different spatial and orientational behavior exhibited by the dye molecules due to their local environment.Here we present a detailed protocol for obtaining smFRET data and applying the Fast-NPS. We provide detailed instructions for the acquisition of the three input parameters of Fast-NPS: the smFRET values, as well as the quantum yield and anisotropy of the dye molecules. Recently, the NPS has been used to elucidate the architecture of an archaeal open promotor complex. This data is used to demonstrate the influence of the five different dye models on the posterior distribution.
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