Trapping of defects at 111In impurities In e−-irradiated Al

The trapping and detrapping of interstitials and vacancies at ¹¹¹In impurities in aluminium after low-temperature electron irradiation was observed. Using perturbed angular correlation of ¹¹¹Cd the electric field gradients caused by nearby lattice defects were determined and used to monitor the formation and dissociation of impurity-defect complexes.     

Electric quadrupole interaction of recoil-implanted zinc in cadmium

The electric quadrupole interaction of the 605 keV 9/2⁺ state of ⁶⁷Zn in Cd metal was measured by the recoil implantation technique combined with the DPAD method (DIMPAD). The result, ν_Q = eQV_ZZ/h = 39.0(4) MHz (T = 373 K), is compared with the known quadrupole coupling constants in the Zn-Cd system.     

Spontaneous chiral resolution of a coordination polymer with distorted helical structure consisting of achiral building blocks

Reaction of achiral 2,5-diphenyl-3,4-di(3-pyridyl)cyclopenta-2,4-dien-1-one (2) with ZnCl2 and HgBr2, respectively, afforded the helically chiral coordination polymers [(2)ZnCl2]infinity and [(2)HgBr2]infinity, which show spontaneous chiral resolution, forming colonies of homochiral crystals.     

Collision detection for complicated polyhedra using the fast multipole method or ray crossing

The purpose of this paper is a comparison of two different methods that can be used for collision detection. One method is called the ray-crossing method, a commonly used geometrical approach. The other method is the fast multipole method, usually used for boundary element methods, which is also applied for collision detection purposes here. Both methods are especially of interest when the collision for arbitrarily shaped polyhedra has to be detected. Here, both methods are described and compared for different examples of complex shaped polyhedra with up to 5 × 10⁵ faces and more than 5 × 10⁵ test points regarding efficiency and required calculation time.     

Metalloradical Cations and Dications Based on Divinyldiphosphene and Divinyldiarsene Ligands

Metalloradicals are key species in synthesis, catalysis, and bioinorganic chemistry. Herein, two iron radical cation complexes ( 3-E )GaCl₄ [( 3-E )^.+ = [{(IPr)C(Ph)E}₂Fe(CO)₃]^.+, E = P or As; IPr = C{(NDipp)CH}₂, Dipp = 2,6-iPr₂C₆H₃] are reported as crystalline solids. Treatment of the divinyldipnictenes {(IPr)C(Ph)E}₂ ( 1-E ) with Fe₂(CO)₉ affords [{(IPr)C(Ph)E}₂Fe(CO)₃] ( 2-E ), in which 1-E binds to the Fe atom in an allylic (η³-EEC_vinyl) fashion and functions as a 4e donor ligand. Complexes 2-E undergo 1e oxidation with GaCl₃ to yield ( 3-E )GaCl₄. Spin density analysis revealed that the unpaired electron in ( 3-E )^.+ is mainly located on the Fe (52–64 %) and vinylic C (30–36 %) atoms. Further 1e oxidation of ( 3-E )GaCl₄ leads to unprecedented η³-EEC_vinyl to η³-EC_vinylC_Ph coordination shuttling to form the dications ( 4-E )(GaCl₄)₂.     

Enantiomerically Pure Tribenzotriquinacenes through Stereoselective Synthesis

Inherently chiral acetophenones and benzaldehydes bearing the large, bowl‐shaped framework of tribenzotriquinacene (TBTQ) were synthesized in enantiomerically pure form employing enzyme catalysis. Five‐step sequences involving lipase CAL‐B lead to the (M)‐enantiomers, (+)‐2‐acetyl‐TBTQ (M)‐ 5 and (+)‐2‐formyl‐TBTQ (M)‐ 6 , whereas use of lipase PS leads to the (P)‐enantiomers, (?)‐2‐acetyl‐TBTQ (P)‐ 5 and (?)‐2‐formyl‐TBTQ (P)‐ 6 , with at least 99 % ee in each case. The absolute configuration of these rigid 3D building blocks was determined by X‐ray diffraction analysis of the ketones 5 and by comparison of their chiroptical properties with those of the aldehydes 6 .     

Shape-persistent macrocycles: building blocks for complex organic and polymeric architectures

Alkyl- and Oligostyrene substituents were attached to shape-persistent macrocycles based on a phenyl-ethynyl backbone. In good solvents for both the rigid core and the flexible corona no aggregation occurred. Whereas, addition of a solvent that selectively solubilizes the corona induced a solvophobic aggregation. For alkyl substituted rings the experimental data were described by a monomer-dimer equilibrium. In contrast, the oligostyrene substituted rings formed more expanded aggregates which were investigated by scattering and by imaging methods. The superstructures are consequently described as hollow supramolecular cylindrical brushes.