Synthesis of novel thiazolo[3,2-a]chromeno[4,3-d]pyrimidine-6(7H)-ones by bioactive Fe3O4@gly@thiophen@Cu(NO3)2 as reusable magnetic nanocatalyst

In this study, new Fe₃O₄@gly@thiophen@Cu(NO₃)₂ magnetic nanoparticles were synthesized. The final product was used as an efficient and novel magnetic nanocatalyst for synthesizing new derivatives of thiazolo[3,2-a] chromeno[4,3-d]pyrimidine-6(7H) in a short time and with higher efficiency. In the synthesis of Fe₃O₄@gly@thiophen@Cu(NO₃)₂ magnetic nanoparticles, the use of glycine proved an inexpensive and readily available coating for Fe₃O₄ than previously reported materials, and the structure was confirmed using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy-dispersive x-ray (EDX) spectroscopy, EDX mapping, Fourier-transform infrared spectroscopy, thermogravimetric analysis/derivative thermogravimetry, and vibrating sample magnetometry. The biological properties of magnetic nanoparticles were evaluated, and they exhibited acceptable antifungal and antibacterial properties in terms of minimum inhibitory concentration, minimum fungicidal concentration, and minimum bactericidal concentration.     

Preparation and characterization of MNPs–PhSO3H as a heterogeneous catalyst for the synthesis of benzo[b]pyran and pyrano[3,2-c]chromenes

Research on Chemical Intermediates - In this study, an efficient and novel procedure has been reported for loading sulfanilic acid on the surface of magnetite Fe3O4 nanoparticles using...     

Some explicit formulas for the polynomial decomposition of the matrix exponential and applications

This paper is devoted to the study of some formulas for polynomial decomposition of the exponential of a square matrix A. More precisely, we suppose that the minimal polynomial M_A(X) of A is known and has degree m. Therefore, e^tA is given in terms of P₀(A),…,P_m−1(A), where the P_j(A) are polynomials in A of degree less than m, and some explicit analytic functions. Examples and applications are given. In particular, the two cases m=5 and m=6 are considered.     

Application of a new ion-imprinted polymer for solid-phase extraction of bismuth from various samples and its determination by ETAAS

A batch process was developed to extract bismuth ions by a novel and selective sorbent. In this study, a new Bi(III)-ion imprinted polymer was prepared by formation of 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol complex for selective preconcentration of ultra trace amounts of bismuth. Polymerization was performed with ethylene glycol dimethacrylate, as crosslinking monomer and methacrylic acid as functional monomer; in the presence of 2,2-azobisisobutyronitrile, as initiator, via bulk polymerization. Optimum pH for maximum sorption was 2.5–3.5. Maximum sorbent capacity and enrichment factor for bismuth were 35.9?mg?g^?1 and 300, respectively. The relative standard deviation and limit of detection the method were evaluated as ±4.1% and 8.6?ng?L^?1. This method is simple, selective and sensitive and can be applied to the determination of bismuth in water, biological and plant samples.     

An Efficient Synthesis of Stable Phosphorus Ylides Derived from Hydantoin and 5,5-dialkylhydantoins

Stable crystalline phosphorus ylides are obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and dialkyl acetylenedicarboxylates in the presence of strong NH-acids, such as hydantoin and 5,5-dialkylhydantoins. These stable ylides exist in solution as a mixture of two geometrical isomers as a result of restricted rotation around the carbon-carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group.     

Equilibrium geometry and gas‐phase proton affinity of 2‐thiouracil derivatives

The ground‐state geometries of uracil, 6‐hydroxy‐uracil, and 6‐hydroxy‐, 6‐amino‐, 6‐methyl‐, 6‐trifluoro‐, and 6‐phenyl‐2‐thiouracil were optimized at the Hartree–Fock level. The molecular structures were fully optimized using the 6‐31G and 6‐31G* basis sets. The effect of substituents on the geometry and electronic structural features of 2‐thiouracils were examined. The perturbation effects of the OH and NH₂ groups are by far more pronounced on the geometric features and the dipole moment magnitude and direction of 2‐thiouracil. The potential energy per atom criteria was used to compare the relative tightness of binding in the studied series. Proton affinity and deprotonation enthalpy on each of the possible sites in 2‐thiouracil and its derivatives have been calculated at the 6‐31G/MP2 level of theory. The obtained results show that thiouracils behave as bases where they possess a high tendency to abstract protons. Substituents in the 6‐position have the general effect of enhancing the basicity strength of the thiocabonyl site in the order Ph < CH3 ≈ NH2 < OH. The CF3 group has the effect of reducing considerably the basicity strength and enhances the acidity strength at both N1 and N3. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002     

Rotating polarizer analyzer ellipsometer with a fixed compensator

Recently, a rotating polarizer analyzer ellipsometer (RPAE) in which the two optical elements rotate in opposite directions with the same angular speed has been proposed. Calculated optical constants of some materials obtained from this ellipsometric configuration were in good agreement with published values except in the low photon energy regime. We here improve the structure by adding a fixed compensator after the rotating polarizer. The optical constants of c-Si calculated from the noisy signal in the low energy regime show a high reduction in the percent error when compared to that obtained from the previous structure that does not contain the fixed compensator.     

Influence of Microwave Synthesis Parameters on the Size and Morphology of the Resulting MgAl2O4 Nanoparticles

In the present study, Nano-sized magnesium aluminate powders were successfully synthesized via microwave process based on the reaction between Mg (NO₃)₂·6H₂O and Al (NO₃)₃·9H₂O in distilled water, at various conditions. The products were characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy, photoluminescence (PL) spectroscopy, and EDAX analysis. The effects of different parameters such as reaction time and microwave power on the morphology, particle size, and PL properties of the product were studied by SEM images and the PL.