Boron implantation in Si: Channeling effects studied by SIMS and simulation

The axial channeling behaviour of boron implants in <100>, <110> and <111> silicon wafers is investigated by SIMS. Large differences of channeling characteristics such as channeled projected range (the projected range of channeled ions or channeling peak) and the fraction of channeled to implanted ions are observed among the three major crystal orientations. Within the critical angle, the channeling behaviour is very sensitive to the incidence beam angle with respect to crystal orientations. SIMS measurements are performed at different positions along several critical directions over a whole wafer. Well channeled profiles with an incidence beam angle to crystal orientations of 0 ° are obtained for each ion implantation energy and orientation. The results are used to test various models of ion implantation by simulation. A 3-parameter model for electronic stopping power of boron in silicon was proposed.     

4,10‐Dinitro‐2,6,8,12‐tetraoxa‐4,10‐diazaisowurtzitane (TEX): a nitramine with an exceptionally high density

The title compound (systematic name: 4,10‐di­nitro‐2,6,8,12‐tetraoxa‐4,10‐di­aza­tetra­cyclo­[5.5.0.0^3,11.0^5,9]­do­decane), C₆H₆N₄O₈, exhibits the highest density among known N‐nitramines, due to its close‐packed crystal structure. It may be regarded as consisting of a distorted hexagonal close‐packed lattice formed by the isowurtzitane cages, with the nitro groups occupying the free space between the cages.     

Isocamphananaloge mandelsäure

The synthesis of some new potentially, nitrogenefree spasmolytics is described. Formally the benzene nucleus in some mandelic acid esters, known by their mild spasmolytic activity, is substituted for the isocamphane bicyclus by a) SeO₂ oxidation of 1-(3,3-Dimethyl-2-exo-norbornyl)-ethanone (5) to the corresponding ketoaldehyde6, b) oxidation of6 to the isocamphane analogous mandelic acid4 and c) esterification of derivatives of4 with isoamylalcohol and benzylalcohol. Attemps to dehydrate the methylester7 to camphenylideneacetic acid methylester (12) by various methods failed, probably because of the ring strain.

Teil der Diplomarbeit vonB. Blach, Universität Wien 1981.     

Heteroallen-komplexe des molybdänocens

Reactions of the extremely labile molybdenocene olefin complexe Mo(η⁵-C₅H₅)₂[(Z)-C₆H₅CH=CHC₆H₅] with heteroallenes X=C=Y (X=C=Y = CS₂, (p-tolyl)NCN(p-tolyl), (C₆H₅)₂CCO) gives the corresponding heteroallene complexes of molybdenocene Mo(η⁵-C₅H₅)₂(X=C=Y) in high yields. Spectroscopic data clearly indicate a dihapto-coordination of the heteroallenes via the C=X bond (X = O, S, N).     

Unexpected open-chain molecular structure of a titanocenyl-substituted dimethyl ether

Reaction of (η-C₅H₄CH₃)₂TiCl₂ with CH₃OCH₂MgCl yielded (η-C₅H₄-CH₃)₂Ti(Cl)CH₂OCH₃ (2a). Complex 2a crystallizes in space group P2₁/n with cell constants a 8.162(1), b 11.004(2), c 15.297(2) Å, β 96.40(1)°. In contrast to the three-membered metallacyclic zirconium compound of analogous composition (η-C₅H₅)₂Zr(Cl)CH₂OCH₃ (1), the titanocenyl-substituted ether 2a has an open-chain (η¹-O“-outside”) type structure.     

Zur entmischung der Lösungsmittel bei der chromatographischen trennung—v: Sorption von fliessmitteldämpfen an cellulose

The sorption of solvent vapours onto dried cellulose has been investigated. The time-dependence and the effect of the solvent-water ratio is discussed. The studies concerned the properties of methanol, ethanol, propanol and butanol.     

Elektronenstruktur,Spektren und Magnetismus von Chinon-π-Komplexen des Nickels

Zusammenfassung Die Elektronenstrukturen von Bis-durochinon-nickel(0) und der Komplexe vom Typ Olefin-Ni(0)-Chinon werden im Rahmen der LCAO-MO-Näherung diskutiert und zur Deutung der Absorptionsspektren herangezogen. Den im freien Durochmon auftretenden Übergängen lassen sich in den Komplexspektren jeweils nur wenig verschobene Banden zuordnen. Darüber hinaus wird eine intensive Charge-Transfer-Bande beobachtet, die einem Übergang vom höchsten besetzten Nickelzustand zum tiefsten unbesetzten Chinon-Orbital entspricht. Aus der Intensität der Bande, die im freien Chinon dem b _3g 2b ₂ g-Übergang zugeordnet wird, ergibt sich für das gelöste Bis-durochinon-nickel(0)-Molekül die Symmetrie D _2h . Während die Komplexe mit Durochinon in Übereinstimmung mit der Theorie diamagnetisch sind, weisen die analogen Verbindungen der Dimethylchinone magnetische Momente von 1,52 bzw. 2,75 B. M. auf, woraus auf eine Mitbeteiligung polarer Strukturen am Grundzustand dieser Komplexe geschlossen wird.

---

The electronic structures of bis-duroquinone-nickel(0) and complexes of the type olefine-Ni(0)-quinone are discussed in the MO-LCAO approximation and used for an interpretation of the absorption spectra. The transitions of the free duroquinone can be correlated with transitions of the complexes at nearly the same wavelengths. In addition, an intense charge transfer band is observed which corresponds to a transition from the highest occupied nickel orbital to the lowest unoccupied quinone orbital. From the intensity of the band which corresponds to b _3g 2b_2g in the free quinone, the symmetry D _2h for the dissolved bis-duroquinone-nickel(0) molecule is deduced. Whereas the duroquinone complexes are diamagnetic in agreement with theory, analogous compounds of the diméthylquinones exhibit magnetic momenta of 1.52 and 2.75 B. M. suggesting the participation of polar structures in the ground state of these complexes.

---

Résumé Les structures électroniques du bis-duroquinone-nickel(0) et des complexes du type oléfine-Ni(0)-quinone sont discutées dans le cadre del'approximationMO-LCAO et utilisées pour l'interprétation des spectres d'absorption. Aux transitions de la duroquinone libre peuvent être attribuées des bandes peu déplacées dans les spectres des complexes. En outre on observe une bande intense correspondant à une transition de la plus haute orbitale occupée du nickel à la plus basse orbitale libre de la quinone. L'intensité de la bande nommée b _3g 2b _2g dans la quinone libre indique la symétrie D _2h pour la molécule dissoute du bis-duroquinone-nickel(0). Tandis que les complexes de la duroquinone sont diamagnétiques en accord avec la théorie, des composés analogues des diméthylquinones présentent des moments magnétiques de 1,52 et de 2,75 B. M. d'où l'on infère la participation de structures polaires à l'état fondamental de ces complexes.

---

---

6. Mitteilung über Komplexe vom Typ des Bis-durochinon-nickel(0). 5. Mitt. vgl. [11].     

TreeDock: a tool for protein docking based on minimizing van der Waals energies

Predicting protein-protein and protein-ligand docking remains one of the challenging topics of structural biology. The main problems are (i) to reliably estimate the binding free energies of docked states, (ii) to enumerate possible docking orientations at a high resolution, and (iii) to consider mobility of the docking surfaces and structural rearrangements upon interaction. Here we present a novel algorithm, TreeDock, that addresses the enumeration problem in a rigid-body docking search. By representing molecules as multidimensional binary search trees and by exploring a sufficient number of docking orientations such that two chosen atoms, one from each molecule, are always in contact, TreeDock is able to explore all clash-free orientations at very fine resolution in a reasonable amount of time. Due to the speed of the program, many contact pairs can be examined to search partial or complete surface areas. The deterministic systematic search of TreeDock is in contrast to most other docking programs that use stochastic searches such as Monte Carlo or simulated annealing methods. At this point, we have used the Lennard-Jones potential as the only scoring function and show that this can predict the correct docked conformation for a number of protein-protein and protein-ligand complexes. The program is most powerful if some information is known about the location of binding faces from NMR chemical-shift perturbation studies, orientation information from residual dipolar coupling, or mutational screening. The approach has the potential to include docking-site mobility by performing molecular dynamics or other randomization methods of the docking site and docking families to families of structures. The performance of the algorithm is demonstrated by docking three complexes of immunoglobulin superfamily domains, CD2 to CD58, the V(alpha) domain of a T-cell receptor to its V(beta) domain, and a T-cell receptor to a pMHC complex as well as a small molecule inhibitor to a phosphatase.     

Synthese und Reaktionen von Bicyclo[6.4.0]dodecan-3-carbonsäure-Derivaten

Synthesis and Reactions of the Bicyclo[6.4.0]dodecane-3-carboxylic Acid Derivatives The synthesis and some consecutive reactions of the compounds 5-8 , derivatives of bicyclo[6.4.0]dodecane-3-carboxylic acid ( 1 ), are described. The esters 7 and 8 can be obtained by Baeyer-Villiger oxidation of 2-hydroxy-8-methyltricyclo[7.3.1.0^2,7]tridecan-13-one ( 4 ) and subsequent hydrolysis of the lactone 5 . The structure and configuration of these compounds has been evaluated by spectroscopic techniques (mainly 2D-NMR methods). The formation of 7 via 1,2-H shift and subsequent isomerization to 8 has been studied. The esters 11 and 13 are formed stereospecifically from 7 and 8 .