Efficient Approach for the Synthesis of Novel Functionalized Isoxazolines from Limonene

New functionalized isoxazolines were effeciently and easily prepared from limonene. The procedure involves a peri‐ and regioselective 1,3‐dipolar cycloaddition of nitrile oxides on the monoterpene external double bond, followed by a highly chemoselective RuCl₃‐NaIO₄ oxidative cleavage of the internal one. All the newly prepared isoxazolyl‐ketoacids were fully characterized from their spectroscopic data.     

Free vibration characteristics of a functionally graded beam by finite element method

This paper presents the dynamic characteristics of functionally graded beam with material graduation in axially or transversally through the thickness based on the power law. The present model is more effective for replacing the non-uniform geometrical beam with axially or transversally uniform geometrical graded beam. The system of equations of motion is derived by using the principle of virtual work under the assumptions of the Euler–Bernoulli beam theory. The finite element method is employed to discretize the model and obtain a numerical approximation of the motion equation. The model has been verified with the previously published works and found a good agreement with them. Numerical results are presented in both tabular and graphical forms to figure out the effects of different material distribution, slenderness ratios, and boundary conditions on the dynamic characteristics of the beam. The above mention effects play very important role on the dynamic behavior of the beam.     

Copper catalyzed oxidative cross-coupling of aromatic amines with 2-pyrrolidinone: a facile synthesis of N-aryl-γ-amino-γ-lactams

Synthesis of N-aryl-γ-amino-γ-lactams by oxidative coupling of aromatic amines with 2-pyrrolidinone using catalytic amount of CuO nanoparticles is described. The procedure has broad substrate scope, good yields, complete regioselectivity and catalyst recyclability.     

Synthesis,characterization and X-ray crystallographic investigation of 2-D hybrid hydrogen bonded and rectangular grid networks in Cu(II) and Co(II) metal complexes

Two copper/cobalt metal complexes, [Cu(l-cys)(2,2′-bpy)(H₂O)] (1) and {[Co(l-cys)(4,4′-bpy)(H₂O)]·H₂O}_n (2), with the N-donor ligands 2,2′-bipyridyl/4,4′-bipyridyl and the l-cysteate dianion (l-cys) have been synthesized by different reaction methods and structurally characterized. Compound 1 exists as a discrete monomeric unit in which the metal ions possess a distorted square-pyramidal coordination environment provided by nitrogen atoms from the 2,2′-bpy ligand and the amino-carboxylate group of l-cys in a chelated coordination, constituting the square base, and with a water molecule occupying the axial coordination site to complete the penta coordination. Packing and hydrogen bonding interactions of 1 reveal that the screw related monomeric units are involved in intermolecular hydrogen bonding with the formation of helical bilayers via O–H?O and N–H?O interactions. These hydrogen bonded bilayered helical nets are involved in stacking and C–H?O interactions which generate a two dimensional hydrogen bonded network in the bc-plane. Complex 2 is a two dimensional coordination polymer which is insoluble in common polar and non-polar solvents. The coordination around the metal center possesses a distorted octahedral geometry. The adjacent metal centers are bridged via the carboxylate group of the l-cys moiety in a syn–anti fashion, generating a one dimensional helical network along the b-axis. Adjacent helical chains are further pillared by the 4,4′-bpy ligand through the terminal nitrogen atoms, generating a two dimensional square grid type coordination network. Both the complexes are characterized well by various physico-chemical techniques such as CHN analysis, IR spectroscopy, PXRD and CD analysis.     

Gelatin-based protonic electrolyte for electrochromic windows

Proton-conducting gel polymer electrolytes based on gelatin plasticized with glycerol and containing acetic acid were investigated, characterized, and applied to electrochromic window. For glycerol contents varying from 7% to 48%, the conductivity of the uniform and predominantly amorphous gel electrolyte was found to follow a Vogel–Tamman–Fulcher behavior with the temperature. Typically, for the electrolyte chosen to make 7 × 2 cm² electrochromic smart window with the configuration: glass/fluor-doped tin oxide (FTO)/WO₃/gelatin electrolyte/CeO₂–TiO₂/FTO/glass and containing 28% of glycerol, the conductivities were found to be of the order of 5 × 10⁻⁵ S/cm at room temperature and 3.6 × 10⁻⁴ S/cm at 80 °C. The device was characterized by spectroelectrochemical techniques and was tested up to 10,000 cycles showing a fast coloring/bleaching behavior, where the coloring process was achieved in 10 s and the bleaching in 2 s. The transmission variation at the wavelength of 550 nm was about 15%. The cyclic voltammograms showed a very good reversibility of the cathodic/anodic processes, and the charge density was about 3.5 mC/cm². The memory tests showed that the transmittance in the colored state increased by 8% in 90 min after removing the potential.     

UV–Vis and NMR spectroscopic investigations on effective and selective non-covalent interactions between fullerenes and calix[6]arene

Ground state non-covalent interactions between a macro cyclic calixarene receptor, namely, 4-tert-butylcalix[6]arene (1), and fullerenes (C₆₀ and C₇₀) were studied in toluene medium by absorption spectrophotometric method. Absorption band due to the charge transfer (CT) transition have been observed in the visible region between fullerenes and 1. Utilizing the CT absorption bands, various important physicochemical parameters like oscillator strength, resonance energy, transition dipole strength of the fullerene-1 complexes and ionization potential of 1 is determined in present investigations. From Jobs method of continuous variation, it is observed that both C₆₀ and C₇₀ form stable 1:1 complexes with 1. The most fascinating feature of the present study is that 1 binds selectively C₇₀ compared to C₆₀ as obtained from binding constant (K) data of C₆₀–1 (K_C60–1) and C₇₀–1 (K_C70–1) complexes, i.e., K_C60–1 = 32,400 dm³·mol^? 1 and K_C70–1 = 110,000 dm³.mol^? 1 and selectivity (K_C70–1/K_C60–1) = 3.4. ¹H NMR analysis provides very good support in favor of strong binding between C₇₀ and 1.     

The 20-Tungsto-4-Tellurate(IV) [H2Te4W20O80]22− and the 15-Tungstotellurate(IV) [NaTeW15O54]13−

The 20-tungsto-4-tellurate(IV) polyanion [H₂Te₄W₂₀O₈₀]^22? (1) has been synthesized and isolated in the form of its hydrated sodium salt Na₂₂[H₂Te₄W₂₀O₈₀]·64H₂O (Na-1). Na-1 has been characterized in the solid state by FTIR and TGA. Single-crystal X-ray diffraction analysis revealed that Na-1 crystallizes in the triclinic space group P ${\bar 1}The 20-tungsto-4-tellurate(IV) polyanion [H₂Te₄W₂₀O₈₀]²²⁻ (1) has been synthesized and isolated in the form of its hydrated sodium salt Na₂₂[H₂Te₄W₂₀O₈₀]·64H₂O (Na-1). Na-1 has been characterized in the solid state by FTIR and TGA. Single-crystal X-ray diffraction analysis revealed that Na-1 crystallizes in the triclinic space group P , with a = 12.741(2) ?, b = 16.842(3) ?, c = 17.197(4) ?, α = 93.961(10)°, β = 107.466(8)°, γ = 108.548(8)°, V = 3281.5(11) ?³ and Z = 1. The polyanion 1 comprises two [HTe₂W₁₀O₄₀]¹¹⁻ fragments, connected through Te−O–W μ₂-oxo bridges, and each containing a pair of face-shared WO₆ octahedra. Furthermore, the 15-tungstotellurate(IV) polyanion [NaTeW₁₅O₅₄]¹³⁻ (2) was synthesized and crystallized as a sodium salt in the orthorhombic space group Pccn, with a = 11.8841(5) ?, b = 20.8934(11) ?, c = 31.801(2) ?, V = 7896.3(7) ?³ and Z = 4. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Dedicated to Professor C. N. R. Rao on the occasion of his 75th birthday     

Photophysical Investigations on Determination of Ionicity and Electronic Structures for the Non-covalent Complexes of Calix[4]resorcinarene with Fullerenes C<Subscript>60</Subscript> and C<Subscript>70</Subscript> in the Solution State

Ground state non-covalent interactions between a macrocyclic receptor, C-methylcalix[4]resorcinarene (1) and fullerenes (C₆₀ and C₇₀) have been studied in benzonitrile by an absorption spectrophotometric method. Absorption bands are located in the visible region due to the charge transfer (CT) transition between 1 and various electron acceptors (including fullerenes), namely, 2,3-dichloro-5,6-dicyano-p-benzoquinone, tetracyanoquinodimethane and p-chloranil. Utilizing the CT absorption bands, various important physicochemical parameters, including oscillator strength, resonance energy, transition dipole strength of all the acceptor-1 complexes and vertical ionization potential of 1 are determined. Job’s method of continuous variation reveals 1:1 stoichiometry between fullerenes and 1. The most fascinating feature of the present study is that 1 binds selectively to C₇₀ compared to C₆₀ as obtained from binding constant (K) data of C₆₀-1 (K_C60-1K_{\mathrm{C}60\mbox{-}\mathbf{1}}) and C₇₀-1 (K_C70-1K_{\mathrm{C}70\mbox{-}\mathbf{1}}) complexes, i.e., K_C60-1=190K_{\mathrm{C}60\mbox{-}\mathbf{1}}=190 dm³⋅mol⁻¹ and K_C70-1=5,800K_{\mathrm{C}70\mbox{-}\mathbf{1}}=5{,}800 dm³⋅mol⁻¹ and selectivity (K_C70-1 /K_C60-1 ) ∼30. Quantum chemical calculations based on hybrid density functional theory estimate the enthalpies of formation of the fullerene-1 complexes in vacuo and provide very good support for selectivity in the K values of the C₇₀ and C₆₀ complexes of 1. The exchange and correlation energies have been calculated using a hybrid DFT functional method. We have opted to use the hybrid DFT functional over the Hartree-Fock method, as it can account for correlation effects also. Molecular electrostatic potential map calculations give a clear picture on the electronic structures of the fullerene-1 complexes.     

Arithmetic approach for complex PSA cycle scheduling

An algebraic model was derived for obtaining complex pressure swing adsorption (PSA) cycle schedules. This new approach involves a priori specifying the cycle steps, their sequence and any constraints, and then solving a set of analytical equations. The solution identifies all the cycle schedules for a given number of beds, the minimum number of beds required to operate the specified cycle step sequence, the minimum number and location of idle steps to ensure alignment of coupled cycle steps, and a simple screening technique to aid in identifying the best performing cycles that deserve further examination. The methodology was tested successfully against 10, 12 and 16 bed PSA systems in the literature that all utilized the same 13 step cycle sequence that has four pressure equalization steps. It completely resolved all the corresponding cycle schedules for these 13 step multi-bed PSA systems with ease, and showed that the number of cycle schedules was hundreds to thousands of times greater than the few ever reported in the literature for each one. Overall, this new methodology for complex PSA cycle scheduling can be applied to any number of cycle steps, any corresponding cycle step sequence, and any number of constraints, with the outcome being the complete set of cycle schedules for any number of beds greater than or equal to the minimum number it determines.     

Light-induced isotopic exchange between O2 and semiconductor oxides, a characterization method that deserves not to be overlooked

This article first indicates the various types of temperature-induced oxygen isotopic exchange (OIE) that can occur between labeled gaseous O₂ and solid oxides. Earlier main results of light-induced OIE with semiconductor oxides are then briefly reviewed. The core of the article reports new results about the use of light-induced OIE to assess (i) the lability of TiO₂ surface O atoms, as altered by calcination or Se deposits, via the comparison of OIE with the photocatalytic removal of methanol in air and (ii) the accessibility of TiO₂ affixed on a fiberglass material by means of a silica binder. Both this overview and these novel results illustrate the interest of OIE in heterogeneous photocatalysis.