Copper-doped silica cuprous sulfate (CDSCS) as a highly efficient and new heterogeneous nano catalyst for [3+2] Huisgen cycloaddition

The synthesis and characterization of copper-doped silica cuprous sulfate (CDSCS) as a new and efficient heterogeneous nano catalyst are described. CDSCS has been fully characterized by different microscopic, spectroscopic and physical techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic forced microscopy (AFM), X-ray diffraction (XRD), inductively coupled plasma (ICP) analysis, thermogravimetric analysis (TGA) and FT-IR. CDSCS is proved to be a useful heterogeneous nano catalyst in Cu(I)-catalyzed ‘Click’ cycloaddition of organic azides with terminal alkynes. CDSCS catalyzes the 1,3-dipolar cycloaddition reactions of β-azido alcohols and alkynes at room temperature, in THF/H₂O (1:1, v/v) solution. Using CDSCS, 1,4-disubstituted 1,2,3-triazole adducts are mainly obtained, in good to excellent yields and in short reaction times. These compounds have featural resemblance to β-adrenoceptor blocking agents. CDSCS was approved as a chemically and thermally stable nano catalyst that can be reused for many consecutive trials without a significant decline in its reactivity.     

Engineering the nonlinear phase shift

We treat the nonlinear phase shift response in the weak perturbation limit as a linear digital filter that can be synthesized into the values of its poles and zeros and mapped onto an optical architecture. This procedure results in a significant enhancement in the nonlinear sensitivity with a response that is robust to frequency changes within the filter passband. A precompensation technique can be used to reduce distortions under strongly driven nonlinear operation to achieve a larger phase shift. We also show that nonlinear sensitivity improves with increasing filter group delay and can be increased within constant linear bandwidth by use of higher-order filters.     

Efficient access to novel tetra- and pentacyclic dihydroquinolin-2-ones by catalyst-free domino Knöevenagel hetero-Diels–Alder reactions from <Emphasis Type="Italic">N</Emphasis>-(2-formylphenyl)-<Emphasis Type="Italic">N</Emphasis>-methylcinnamamides and cyclic 1,3-dicarbonyls in water

An efficient catalyst-free synthesis of novel annulated hybrid derivatives of two known scaffolds, dihydroquinolinone and pyranopyranone, pyranopyrimidinedione, pyranocoumarin or chromenone is described. N-(2-Formylphenyl)-N-methylcinnamamides underwent a one-pot domino Knöevenagel hetero-Diels–Alder reaction with dimedone, N,N-dimethylbarbituric acid, 1,3-indanedione, 4-hydroxycoumarins and 4-hydroxy-6-methyl-2H-pyran-2-one in water, affording the desired tetra and pentacyclic pyranoquinolinones in excellent yields.     

One-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones,thiones and 2-selenoxo DHPMs using 1-butyl-3-methylimidazolium hydrogen sulfate as non-halogenated ionic liquid

Abstract

1-Butyl-3-methylimidazolium hydrogen sulfate ([BMIM][HSO₄]) as a non-halogenated ionic liquid (IL) was used for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones and thiones or 2-selenoxo DHPMs in a Biginelli type multi-component reaction. By using this ionic liquid, the reaction time was significantly reduced and the products were obtained in good to high yields. Also, in this method, the synthesis of novel 2-selenoxo DHPMs is introduced in the presence of this ionic liquid and their structures were determined by ¹H and ¹³C NMR, FT-IR, and Elemental analysis.     

‘Click Synthesis’ of Some Novel Benzimidazol Oxime Ethers Containing Heterocycle Residues as Potential ß‐Adrenergic Blocking Agents

The ‘click synthesis’ of some novel O‐substituted oximes, 5a – 5j , which contain heterocycle residues, as new analogs of ß‐adrenoceptor antagonists is described (Scheme 1). The synthesis of these compounds was achieved in four steps. The formation of (E)‐2‐(1H‐benzo[d]imidazol‐1‐yl)‐1‐phenylethanone oxime, followed by their reaction with 2‐(chloromethyl)oxirane, afforded mixture of oil compounds 3 and 4 , which by a subsequent tetra‐n‐butylammonium bromide (TBAB)‐catalyzed reaction with N H heterocycle compounds (Scheme 1), led to the target compounds 5a – 5j in good yields.     

Chromium(III), manganese(II) and iron(III) complexes based on hydrazone Schiff-base and azide ligands: synthesis,crystal structure and antimicrobial activity

A tridentate NNO donor hydrazine Schiff base, HL, was obtained from condensation of pyridine 2-carbaldehyde and 4-hydroxy benzohydrazide. HL and azide ligands with Cr(III), Mn(II) and Fe(III) have been used to synthesize [Cr(L)(N₃)(OCH₃)]₂ (1), [Mn(HL)₂(N₃)₂] (2), and [Fe(L)(N₃)(OCH₃)]₂·H₂O (3). HL is quite diverse in its chelating ability and can be a neutral or monoanionic ligand as a tridentate unit. In this paper, we report structures showing different denticities of the ligand having different charges. The ligand 1–3 was characterized by elemental analysis, FT-IR, and UV–vis spectral studies and solid-state structures were determined by single-crystal X-ray diffraction analysis, revealing that 1 and 3 are binuclear, while 2 is mononuclear. The efficiencies of the ligand and the three complexes were evaluated for antimicrobial activity; MIC data revealed that HL 1–3 are not strongly active in comparison to standard drugs.     

Capping-Barrier Layer Effect on Quantum Dot Optoelectronic Characteristics

We present a study of capping-barrier layer （CBL） effect on electro-optical properties of box- and spherical-shaped quantum dots as well as of the electronic transport of a QDs-array It is shown that increasing the CBL-width leads to a considerable enhancement in third-order optical nonlinear susceptibilities （14 times in the quadratic electro-optic effect, 31 times for ω = ω0/3 and 14 times for ω = ω0 in the third harmonic generation）. The capping-barrier layer thus can be employed as a degree of freedom in engineering the electro-optical specifications of quantum-dot-based devices.     

Calculation of on-state I–V characteristics of LDMOSFETs based on an accurate LDD resistance modeling

In this paper, we present an I–V model for LDMOSFETs. It is based on modeling the Lightly-Doped Drain (LDD) region of the device as voltage-controlled resistors where velocity saturation effect is also taken into account. Using the LDD region model along with a model for the channel region of the device, the on-state I–V characteristic of the transistor is accurately calculated. The models for the LDD region resistors can be incorporated into a circuit simulator such as HSPICE which has an accurate model for the channel region of the transistor. The accuracy of the models is verified by comparing its results with those of a device simulator. The results show a maximum error of 1% for a wide range of voltages and overlapped LDD region lengths.     

Primal-dual interior-point algorithm for semidefinite optimization based on a new kernel function with trigonometric barrier term

In this paper we propose primal-dual interior-point algorithms for semidefinite optimization problems based on a new kernel function with a trigonometric barrier term. We show that the iteration bounds are $O(\sqrt{n}\log(\frac{n}{\epsilon}))$ for small-update methods and $O(n^{\frac{3}{4}}\log(\frac{n}{\epsilon}))$ for large-update, respectively. The resulting bound is better than the classical kernel function. For small-update, the iteration complexity is the best known bound for such methods.     

Condensation of an ideal gas with intermediate statistics on the horizon

We consider a boson gas on the stretched horizon of the Schwartzschild and Kerr black holes. It is shown that the gas is in a Bose?CEinstein condensed state with the Hawking temperature T _c =T _H if the particle number of the system be equal to the number of quantum bits of space-time $N \simeq{A}/{l_{p}^{2}}$ . Entropy of the gas is proportional to the area of the horizon (A) by construction. For a more realistic model of quantum degrees of freedom on the horizon, we should presumably consider interacting bosons (gravitons). An ideal gas with intermediate statistics could be considered as an effective theory for interacting bosons. This analysis shows that we may obtain a correct entropy just by a suitable choice of parameter in the intermediate statistics.