Nucleophile‐Directed Selective Transformation of cis‐1‐Tosyl‐2‐tosyloxymethyl‐3‐(trifluoromethyl)aziridine into Aziridines,Azetidines, and Benzo‐Fused Dithianes,Oxathianes, Dioxanes,and (Thio)morpholines

A five‐step procedure for the synthesis of cis‐1‐tosyl‐2‐tosyloxymethyl‐3‐(trifluoromethyl)aziridine was developed, starting from 1‐ethoxy‐2,2,2‐trifluoroethanol, involving imination, aziridination, ester reduction, hydrogenation, and N‐,O‐ditosylation steps. Further synthetic elaborations revealed a remarkable difference in the reactivity of cis‐1‐tosyl‐2‐tosyloxymethyl‐3‐(trifluoromethyl)aziridine with respect to aromatic sulfur and oxygen nucleophiles, thus enabling the selective deployment of this versatile substrate as a building block for the synthesis of functionalized aziridines, azetidines, and benzo‐fused dithianes, oxathianes, dioxanes, and (thio)morpholines.     

Sensitivity analysis in lightning protection risk management

The total risk R can be expressed by the following equation: R = NPL, where N is the number of dangerous events, P is the probability of damage and L measures the amount of loss. These parameters can be regarded as macroparameters in the sense that they can be given as a function of additional parameters (microparameters).Methods of calculation, check and refinement of parameter values have always been general themes of the standardization. The comparison of standards IEC 62305-2:2006 Ed. 1 and IEC 62305-2:2010 Ed. 2 is a good example of these efforts, as changes underwent in the determination of the collection area of service and the value of some parameters, moreover new parameters were introduced in order to break existent parameters into more components.Though the international standard contains the value of parameters, it does not give any information about the procedure how these values were determined, nor about the theoretical considerations behind. Therefore it is proper to ask whether the changes of a given parameter value or introduction of a new parameter make radical changes in resulting risk value or not.In this study sensitivity analysis was used to investigate how the individual macro- and micro parameters influence the risk. Moreover it was determined whether or not new parameters and calculations have an effect on the importance of the respective components of the resulting risk.The sensitivity analysis was done for two case studies in the standard, a country house and an office building respectively, with both editions of the standard.     

The Picard group of a coarse moduli space of vector bundles in positive characteristic

Let C be a smooth projective curve over an algebraically closed field of arbitrary characteristic. Let M _r,L ^ss denote the projective coarse moduli scheme of semistable rank r vector bundles over C with fixed determinant L. We prove Pic(M _r,L ^ss) = ℤ, identify the ample generator, and deduce that M _r,L ^ss is locally factorial. In characteristic zero, this has already been proved by Drézet and Narasimhan. The main point of the present note is to circumvent the usual problems with Geometric Invariant Theory in positive characteristic.     

Progress on Olga Taussky-Todd’s circulant problem

Determining the possible values of integer circulant determinants is an open problem proposed by Taussky-Todd. Recent interest in this question comes from studying the Lehmer constant of finite cyclic groups. By refining the approach by Laquer and Newman we contribute to the circulant determinant problem in the case that the order is a power of two.     

Organoruthenium Antagonists of Human A3 Adenosine Receptors

Human A₃ adenosine receptor (hA₃AR) is a membrane‐bound G protein‐coupled receptor implicated in a number of severe pathological conditions, including cancer, in which it acts as a potential therapeutic target. To derive structure–activity relationships on pyrazolo–triazolo–pyrimidine (PTP)‐based A₃AR antagonists, we developed a new class of organometallic inhibitors through replacement of the triazolo moiety with an organoruthenium fragment. The objective was to introduce by design structural diversity into the PTP scaffold in order to tune their binding efficacy toward the target receptor. These novel organoruthenium antagonists displayed good aquatic stability and moderate binding affinity toward the hA₃ receptor in the low micromolar range. The assembly of these complexes through a template‐driven approach with selective ligand replacement at the metal center to control their steric and receptor‐binding properties is discussed.     

2H‐Tetrakis(3,5‐di‐tert‐butyl)phenylporphyrin on a Cu(110) Surface: Room‐Temperature Self‐Metalation and Surface‐Reconstruction‐Facilitated Self‐Assembly

The adsorption behavior of 2H‐tetrakis(3,5‐di‐tert‐butyl)phenylporphyrin (2HTTBPP) on Cu(110) and Cu(110)–(2×1)O surfaces have been investigated by using variable‐temperature scanning tunneling microscopy (STM) under ultrahigh vacuum conditions. On the bare Cu(110) surface, individual 2HTTBPP molecules are observed. These molecules are immobilized on the surface with a particular orientation with respect to the crystallographic directions of the Cu(110) surface and do not form supramolecular aggregates up to full monolayer coverage. In contrast, a chiral supramolecular structure is formed on the Cu(110)–(2×1)O surface, which is stabilized by van der Waals interactions between the tert‐butyl groups of neighboring molecules. These findings are explained by weakened molecule–substrate interactions on the Cu(110)–(2×1)O surface relative to the bare Cu(110) surface. By comparison with the corresponding results of Cu–tetrakis(3,5‐di‐tert‐butyl)phenylporphyrin (CuTTBPP) on Cu(110) and Cu(110)–(2×1)O surfaces, we find that the 2HTTBPP molecules can self‐metalate on both surfaces with copper atoms from the substrate at room temperature (RT). The possible origins of the self‐metalation reaction at RT are discussed. Finally, peculiar irreversible temperature‐dependent switching of the intramolecular conformations of the investigated molecules on the Cu(110) surface was observed and interpreted.     

A new sample environment for cryogenic nuclear resonance scattering experiments on single crystals and microsamples at P01, PETRA III

In order to carry out orientation dependent nuclear resonance scattering (NRS) experiments on small single crystals of e.g. iron proteins and/or chemical complexes but also on surfaces and other micrometer-sized samples a 2-circle goniometer including sample positioning optics has been installed at beamline P01, PETRA III, DESY, Hamburg. This sample environment is now available for all users of this beamline. Sample cooling is performed with a cryogenic gas stream which allows NRS measurements in the temperature range from 80 up to 400 K. In a first test this new sample environment has been used in order to investigate the orientation dependence of the nuclear inelastic scattering (NIS) signature of (i) a dinuclear iron(II) spin crossover (SCO) system and (ii) a hydrogen peroxide treated metmyoglobin single crystal.