Fe(III) chloride catalyzed conversion of epoxides to acetonides

A mild and efficient method for the preparation of acetonides from epoxides catalyzed by iron(III) chlorides has been developed.     

Dynamical analysis of a delayed ratio-dependent Holling-Tanner predator-prey model

In this paper, a delayed Holling-Tanner predator-prey model with ratio-dependent functional response is considered. It is proved that the model system is permanent under certain conditions. The local asymptotic stability and the Hopf-bifurcation results are discussed. Qualitative behaviour of the singularity (0,0) is explored by using a blow up transformation. Global asymptotic stability analysis of the positive equilibrium is carried out. Numerical simulations are presented for the support of our analytical findings.     

Characterization of the Hf-NTA complex

Hafnium ion forms a strong complex with nitrilotriacetic acid (NTA). But there is a controversy about the nature of the complex on whether it is a 1:1 or a 1:2 complex. We have carried out an electrophoresis experiment and supplemented data to establish the nature of the complex. Our data indicates that it is a 1:2 complex i.e. [Hf(NTA)₂]^2- in which the coordination number 8 has been satisfied for hafnium.     

Bandgap widening in highly conducting CdO thin film by Ti incorporation through radio frequency magnetron sputtering technique

Transparent and highly conducting thin films of cadmium oxide (CdO) with titanium doping were synthesized by using radio frequency magnetron sputtering technique. The thin films were deposited on glass and silicon substrates with different percentages of titanium at a fixed substrate temperature 473 K and a fixed pressure of 0.1 mbar in Ar atmosphere. The deposited films were characterized by studying their crystallographic structure, optical and electrical properties. X-ray diffractometer, atomic force microscope, UV–Vis–NIR spectrophotometer, and X-ray photoelectron spectrophotometer were used for different characterizations. All the films have a rock-salt structure. A systematic increase in the optical bandgap was found for the CdO thin films with Ti doping, so that it can be considered as a candidate material for different optoelectronic device applications. Electrical conductivity was also found to increase with Ti doping concentration.     

Zero-Sets of Quaternionic and Octonionic Analytic Functions with Central Coefficients

We prove that the zero set of any quaternionic (or octonionic)analytic function f with central (that is, real) coefficientsis the disjoint union of codimension two spheres in R⁴ or R⁸(respectively) and certain purely real points. In particular,for polynomials with real coefficients, the complete root-setis geometrically characterisable from the lay-out of the rootsin the complex plane. The root-set becomes the union of a finitenumber of codimension 2 Euclidean spheres together with a finitenumber of real points. We also find the preimages f^–1for any quaternion (or octonion) A. We demonstrate that this surprising phenomenon of complete spheresbeing part of the solution set is very markedly a special ‘real’phenomenon. For example, the quaternionic or octonionic Nthroots of any non-real quaternion (respectively octonion) turnout to be precisely N distinct points. All this allows us todo some interesting topology for self-maps of spheres.     

Copper-catalyzed Pummerer type reaction of α-thio aryl/heteroarylacetates: Synthesis of aryl/heteroaryl α-keto esters

A copper catalyzed Pummerer type reaction of α-thio aryl/heteroarylacetates is described for the first time. This transformation represents a new route to synthesize α-keto esters, which are important intermediates for pharmaceuticals and organic synthesis. The reaction proceeds via in situ generation of a thionium ion that undergoes hydrolysis to furnish α-keto esters in synthetically viable yields (up to 82%).     

Coumarin-based urea-amide scaffold in ratiometric fluorescence sensing of CN−

Coumarin-based urea and urea–amide scaffolds 1–3 have been designed and synthesized for the selective and naked eye detection of cyanide ion. Of the three, compound 3 exhibits ratiometric fluorescence change selectively in the presence of CN^? and validates the rationality in designing anion receptor. Upon interaction with CN^?, the color of the solution of 3 in CH₃CN under UV exposure becomes bright yellow, which is beneficial for its naked eye detection. Addition of CN^? of ～10^?4 M brings nice color change from colourless to yellow in ordinary light. The sensing event is supposed to be due to nucleophilic addition of CN^? to the coumarin unit enabling intramolecular charge transfer (ICT) mechanism.