Silver(I) promoted rearrangement of bishomocubane derivatives

Silver(I) ion catalyzes the conversion of bishomocubane derivatives into dicyclopentadiene derivatives in quantitative yield.     

Bidirectional iterative synthesis of alternating benzene-furan oligomers towards molecular wires

Reaction of propargylic dithioacetal 2a with BuLi gives the sulfur-substituted allenyllithium 3a which is allowed to react with a dialdehyde to yield the corresponding alternating benzene-furan oligoaryls 6. Functional group transformation converts the ester groups in 6 to dialdehyde 8 which can be used for the synthesis of higher homologues towards molecular wires. A combination of this furan annulation, Heck reaction and Sonogashira coupling leads to a variety of benzene-furan-alkene/alkyne conjugated oligomers of precise length.     

Universal matrix-overconvergence of noncontinuable holomorphic functions

Summary Assume that there are given a simply connected domain Gin the complex plane containing the open unit disk, but not the closed unit disk and an infinite triangular matrix A. Under suitable conditions on A, which are even weaker than its P-regularity, in this paper we construct a noncontinuable holomorphic function Φ on Gsuch that the A-transforms of its Taylor expansion around any point of Gtend to a scalar multiple of Φ compactly in Gand exhibit universal properties in the complement of Gwith respect to uniform approximation on compact sets and to almost everywhere approximation on measurable sets.     

The D 1Sigma+ state of 7LiH: comparison of observations with vibronic theory

The excited D (1)Sigma(+) electronic state of (7)LiH has been observed up to near its dissociation limit by a pulsed optical-optical double resonance fluorescence depletion spectroscopic technique. An extensive vibronic calculation has been performed with a diabatic approach with purely potential couplings involving a set of eight diabatic states of (1)Sigma(+) symmetry, corresponding to seven neutral states and one ionic state. Twenty-six new vibrational levels have been observed. Both the derived vibrational energy spacings and the vibronic ones are similarly irregular. The observed spectral linewidths and vibronic resonance widths are found to vary similarly with increasing energy. Observed asymmetric spectral lineshapes may be attributed to the strong radial couplings between the discrete levels of the D (1)Sigma(+) electronic state and the continuum states of the C (1)Sigma(+) electronic state. The mutual agreement between the spectral results and the vibronic results demonstrates that the D (1)Sigma(+) electronic state of (7)LiH is better characterized by the vibronic approach.     

Sequential electrochemical oxidation of alternating benzene-furan oligomers

Electrochemical oxidation of pentaaryl 2 containing two furan moieties occurs sequentially to give diketone 8 after two-electron transfer. Further oxidation with another two-electron transfer gives the corresponding tetraketone 9. Radical cation intermediate is detected by absorption spectroscopy. The radical intermediates of different regiochemistry have been shown to exhibit different oxidation potentials as revealed by the differential pulse voltammetry.     

Dextrous Workspaces of Manipulators,Part III: Calculation of Continuation Curves at Bifurcation Points

ABSTRACT

An efficient numerical method is presented to obtain all tangent vectors at bifurcation points of continuation curves that define the boundary of manipulator workspaces. The method developed is based on analytical criteria presented in Part I of this paper [1] and computational methods presented in Part II [2]. As observed in the latter paper, difficulties in mapping boundaries of accessible output sets include (1) systematically finding an initial point on the boundary and (2) efficiently calculating tangent vectors at multiple bifurcation points. The first difficulty has been solved by Haug, Luh, Adkins, and Wang [3]. The second difficulty is resolved in this paper.