On the stereochemistry of photoaddition between α,β-unsaturated ketones and olefins—II

Some years ago an empirical rule, which allows the prediction of product stereochemistry in cis-photocycloaddition reactions of α,β-unsaturated ketones and olefins was tentatively proposed. Several additional examples, both selected from the literature and synthesized in our laboratory, seem to strengthen the validity of the rule.     

GC-MS and GC-FTIR identification of volatile radiolytic products in water-nitrobenzene-carbon tetrachloride two phase systems

Various volatile products formed in the -radiolysis of water-nitrobenzene-carbon tetrachloride two phase systems have been identified using GC-MS and GC-FTIR systems. The conditions for the separation of the products are described in detail. It was found that product formation is dependent on the composition of the systems. In case when the volume ratio of carbon tetrachloride is higher, chlorobenzene appears to be one of the major radiolytic products. This means that substitution of the nitro group by chlorine atom occurs in the presence of water. Substitution of the nitro group and hydrogen atom by chlorine atom and/or HO free radical is also observed, depending on the composition of the mixture. Formation of phenyl isocyanate is proposed to be the result of interaction of dichlorocarbene and nitrobenzene. The mechanism of some main product formation is described briefly.This paper constitutes part of the Ph.D. thesis of M. K. SAHOO and was presented at the 9th Czecho-Slovak Spectroscopic Conference with International Participation, eské Budjovice, C.S.F.R., June 22–24, 1992.     

A first principle study of hydrogen storage in titanium-doped small carbon clusters (C2nTin,n = 2–6)

Structural Chemistry - Hydrogen storage in Ti-doped small carbon clusters, C2nTin (n = 2–6), has been studied using density functional theory. Using the principle of maximum hardness (η)...     

Chemoselective Alkylation of Thiols: A Detailed Investigation of Reactions of Thiols with Halides

Arylthiols, aralkylthiols and alkane thiols can be readily alkylated by alkyl/aralkyl halides in presence of K₂CO₃DMF to yield unsymmetrical sulphides in nearly quantitative yields. 2-Mercaptoethanol gave the thioether chemoselectively.     

Exceptionally Plastic/Elastic Organic Crystals of a Naphthalidenimine-Boron Complex Show Flexible Optical Waveguide Properties

The design of molecular compounds that exhibit flexibility is an emerging area of research. Although a fair amount of success has been achieved in the design of plastic or elastic crystals, realizing multidimensional plastic and elastic bending remains challenging. We report herein a naphthalidenimine–boron complex that showed size-dependent dual mechanical bending behavior whereas its parent Schiff base was brittle. Detailed crystallographic and spectroscopic analysis revealed the importance of boron in imparting the interesting mechanical properties. Furthermore, the luminescence of the molecule was turned-on subsequent to boron complexation, thereby allowing it to be explored for multimode optical waveguide applications. Our in-depth study of the size-dependent plastic and elastic bending of the crystals thus provides important insights in molecular engineering and could act as a platform for the development of future smart flexible materials for optoelectronic applications.     

A sharp‐interface immersed boundary framework for simulations of high‐speed inviscid compressible flows

A new finite‐volume flow solver based on the hybrid Cartesian immersed boundary (IB) framework is developed for the solution of high‐speed inviscid compressible flows. The IB method adopts a sharp‐interface approach, wherein the boundary conditions are enforced on the body geometry itself. A key component of the present solver is a novel reconstruction approach, in conjunction with inverse distance weighting, to compute the solutions in the vicinity of the solid‐fluid interface. We show that proposed reconstruction leads to second‐order spatial accuracy while also ensuring that the discrete conservation errors diminish linearly with grid refinement. Investigations of supersonic and hypersonic inviscid flows over different geometries are carried out for an extensive validation of the proposed flow solver. Studies on cylinder lift‐off and shape optimisation in supersonic flows further demonstrate the efficacy of the flow solver for computations with moving and shape‐changing geometries. These studies conclusively highlight the capability of the proposed IB methodology as a promising alternative for robust and accurate computations of compressible fluid flows on nonconformal Cartesian meshes.