Synthesis,crystal structure and vibrational spectra of uranium(IV) hypophosphite

The preparation, crystal structure, and infrared spectrum are reported for the new compound U(H₂PO₂)₄. The coordination geometry of uranium is approximately described as a square antiprism. The four independent hypophosphite groups which are bonded to each uranium atom also serve as bridging groups in linking the uranium centers into a three-dimensional network. The internal H₂PO ₂ ^– vibrational modes in the infrared spectrum of U(H₂PO₂)₄ show unit-cell group couplings, particularly for the P-H stretching vibrations, making the spectrum distinctly different from that of the simple bidentate non-bridging H₂PO ₂ ^– ion in KH₂PO₂ and VO(H₂PO₂)·H₂O.     

Luminescent Cyanoruthenate(II)?Diimine and Cyanoruthenium(II)?Diimine Complexes

To improve the emission and excited‐state properties of luminescent cyanometalates, new classes of highly solvatochromic luminescent cyanoruthenium(II) and cyanoruthenate(II) complexes of the general formulae [Ru(PR₃)₂(CN)₂($\widehat{NN}$ )] and K[Ru(PR₃)(CN)₃($\widehat{NN}$ )], respectively, were developed. These complexes could be readily synthesized through the ligand‐substitution reaction of K₂[Ru(CN)₄(PR₃)₂] with a diimine ligand. The geometrical isomerism of these complexes was characterized by using various spectroscopic techniques. Their photophysical properties, solvatochromism, and electrochemistry have also been investigated. Our detailed study showed that many of these complexes exhibited extremely environmentally sensitive emissions and significantly improved emission quantum efficiencies and lifetimes compared with the well‐studied tetracyanoruthenate systems.     

Variational methods in radiative transfer problems

An efficient variational-iterative method is applied to the problem of diffuse reflection by a plane-parallel inhomogeneous atmosphere with isotropic scattering. The emergent intensity I(τ = 0; μ, μ₀) with μ = μ₀ corresponds to the maximum of an associated functional. It is, however, shown that I(τ = 0; μ, μ₀) computed by the variational method alone has relatively large errors when μ ≠ μ₀. Such deficiencies are removed by a combined variational-iterative method. The interdependence of the iterative and variational methods is also investigated. They are shown to play a complementary role to each other. The proper choice of trial functions is emphasized in light of computational efficiency and flexibility. Two distinct classes of trial functions: the polynomials, and the step functions are investigated as possible choices of trial functions. The latter choice is shown to be far more efficient in computation. Numerical results for both approximate emergent intensities and source functions are presented and found to be in good agreement with the exact solutions. Simple analytic two-step function approximations of the source function and intensities are also presented for the case of a two-layer inhomogeneous model.     

Asymmetric Reduction of Acetophenones with NaBH4 in the Presence of Mono-6-(1-methyl-3-imidazolium)-6-deoxy-β-cyclodextrin Tosylate

The asymmetric reduction of acetophenone and its derivatives was achieved with sodium borohydride utilizing a novel chiral ionic liquid of β-cylclodextrin (CD), mono-6-(1-methyl-3-imidazolium)-6-deoxy-β-cyclodextrin tosylate (MIM-β-CDOTs). It was found that this chiral β-CD-based ionic liquid could provide higher enantioselectivity for the product alcohols. Moreover, the enantioselectivity of the product alcohols was highly dependent on the structure of prochiral ketones, structure of CD and reduction temperature. An erratum to this article can be found at     

Synthesis of azaheterocycles from aryl ketone O-acetyl oximes and internal alkynes by Cu-Rh bimetallic relay catalysts

A synthetic method for azaheterocycles from aryl ketone O-acetyl oximes and internal alkynes has been developed by using the Cu(OAc)(2)-[Cp*RhCl(2)](2) bimetallic catalytic system. The reactions proceeded with both of anti- and syn-isomers of oximes with a wide scope of substituents. The Cu-Rh bimetallic system could be applied for the synthesis of isoquinolines as well as β-carboline, furo[2.3-c]pyridine, pyrrolo[2,3-c]pyridine, and thieno[2,3-c]pyridine derivatives.     

AN ASSESSMENT OF THE MESHLESS WEIGHTED LEAST-SQUARE METHOD

I. INTRODUCTION The ?nite element method (FEM) has been the most frequently used and powerful numerical methodfor engineering analysis for the last thirty years. However, mesh generation required in FEM can bea very time-consuming and expensive task. Fu…     

Synthesis of a diazacrown ether containing polymers and formation of complexes with alkaline earth metals

We report the synthesis of a polymer that contains the diaza‐18‐crown‐6 moiety on the polymer main chain. Metal containing polymers were obtained when the respective barium or strontium complexes were used as monomers. These polymers emitted greenish blue light in solution, and the metal had little influence on absorption and emission energies. In the solid state, the position of the emission peaks was different probably due to a different degree of aggregation.