Ring selectivity and migratory aptitude of Cp*Ru+ complexation to acecorannulene

Synthesis and spectral characterization of acecorannulene CpRu+ complexes, in combination with ab initio quantum chemical computations, leads to the hypothesis that eta6-metal binding prefers the exo face in the region of least curvature.     

A novel method for the generation of nitrile oxides on solid phase: application to the synthesis of substituted benzopyranoisoxazoles

A solid-phase synthesis of substituted benzopyranoisoxazoles is described. The six-step synthesis features a novel method of generating nitrile oxides on a polymer support followed by an intramolecular 1,3-dipolar cycloaddition with a tethered alkyne for assembly of the benzopyranoisoxazole scaffold. Furthermore, the utilization of single-bead attenuated total reflectance Fourier transform infrared (ATR-IR) microspectroscopy as an essential analytical tool for reaction optimization is highlighted.     

In Appreciation¶A Lifetime of Connections: Otto Herbert Schmitt, 1913 - 1998

Otto H. Schmitt was born in St. Louis, Missouri, in 1913. As a youth, he displayed an affinity for electrical engineering but also pursued a wide range of other interests. He applied his multi-disciplinary talents as an undergraduate and graduate student at Washington University, where he worked in three departments: physics, zoology, and mathematics. For his doctoral research, Schmitt designed and built an electronic device to mimic the propagation of action potentials along nerve fibers. His most famous invention, now called the Schmitt trigger, arose from this early research. Schmitt spent most of his career at the University of Minnesota, where he did pioneering work in biophysics and bioengineering. He also worked at national and international levels to place biophysics and bioengineering on sound institutional footings. His years at Minnesota were interrupted by World War II. During that conflict - and the initial months of the Cold War to follow - Schmitt carried out defense-related research at the Airborne Instruments Laboratory in New York. Toward the end of his career at Minnesota, Schmitt coined the term biomimetics. He died in 1998. RID="*" ID="*"Jon M. Harkness received his Ph.D. degree in the history of science from the University of Wisconsin in 1996. During the spring of 2002, he is an adjunct assistant professor of the history of medicine at the University of Minnesota.     

Lemnalol,a new sesquiterpenoid from the soft coral Lemnaliatenuis Verseveldt

The structure and absolute stereochemistry of lemnalol (1), a new ylangene-type sesquiterpenoid isolated from the soft coral $\text{Lemnalia}$$\text{tenuis}$ Verseveldt, has been established by spectroscopic, chemical, and x-ray crystallographic analyses.     

The assignment of molecular infrared spectra from a laser magnetic resonance spectrometer

Mathematical techniques are presented which have proved useful in assigning the laser magnetic resonance pure-rotation spectrum of HO₂, i.e., useful in assigning an absorption spectrum obtained when molecular energy levels are Zeeman shifted by an external magnetic field until transition frequencies coincide with a fixed-frequency radiation source. The techniques described should have general applicability to the laser magnetic resonance vibration-rotation spectrum of any molecule in an orbitally nondegenerate electronic state and a doublet electronic spin state ($\text{S =}\text{1}\text{2}$). Equations involving both Zeeman line positions and Zeeman line intensities are presented. These allow the assignment of M_J quantum numbers, the determination of the spin-rotation interaction constant γ and rotational quantum number N for both the upper and the lower state, and the determination of the zero-field transition frequency. The equations can be used without prior knowledge of the molecular structure or energy levels.     

The torsional-wagging tunneling problem and the torsional-wagging-rotational problem in hydrazine

Results derived previously for the rotational levels of the eight-framework and three-large-amplitude vibrational problem in N₂H₄, using a tunneling formalism based on a treatment of the vibration-rotation problem as a whole, are rederived here in a much simpler fashion, using a tunneling formalism based on separate treatment of the vibrational and rotational problems. The present formalism is thus much more akin to the usual vibration-rotation formalism, and the origins of the various contributions to the vibration-rotation energy levels can be understood relatively easily. It is convenient here, as earlier, to make extensive use of permutation-inversion and extended-group (double-group) ideas, but it is necessary in the present treatment to consider tunneling between 16 minima in molecular coordinate space, i.e., between a number of minima which is twice the number of nonsuperimposable molecular frameworks that can actually be constructed for N₂H₄.     

Comparison of closed-loop and open-loop feedback schemes of message decoding using chaotic laser diodes

An experimental study of a chaotic optical communication scheme using an external cavity laser diode to encode a message is reported. The message is decoded in closed- and open-loop receiver schemes. Both schemes show effective decoding of a 1-GHz message. The synchronization and effectiveness of encoding are compared in both schemes.