Organometallic quinonoid linkers: a versatile tether for the design of panchromatic ruthenium(II) heteroleptic complexes

The synthesis, X-ray structure determination, and photophysical investigation of a novel series of heteroleptic ruthenium(II) polypyridine complexes with organometallic linkers are reported. The displayed panchromatic absorption features are assigned by means of time-dependent density functional theory studies.     

Development of Hybrid BiOClxBr1−x‐Embedded Alumina Films and Their Application as Highly Efficient Visible‐Light‐Driven Photocatalytic Reactors

A highly stable 75 wt % BiOCl_xBr_1?x‐loaded alumina composite film has been developed for the fabrication of glass‐based photoreactors. A very simple approach has been adopted that does not involve the use of a special instrument and can be applied to all types of substrates irrespective to their size and shape. The structure and morphology of the films were well characterized by XRD, SEM, TEM, N₂‐sorption, IR, Raman, and UV/Vis diffuse reflectance spectroscopy. BiOCl_xBr_1?x microspheres (1–3 μm) with closely packed thin nanoplates (width ≈10 nm) were integrated within alumina to develop a hybrid film. The photocatalytic capacity of the films was evaluated for the decomposition of Rhodamine B (RhB) and naphthalene under visible‐light irradiation. The composite films showed a remarkable photocatalytic activity and stability and have been reused for several cycles without any deterioration of their original activity.     

Numerical solution of nonlinear equations by an optimal eighth-order class of iterative methods

Solving nonlinear equations by using iterative methods is discussed in this paper. An optimally convergent class of efficient three-point three-step methods without memory is suggested. Analytical proof for the class of methods is given to show the eighth-order convergence and also reveal its consistency with the conjecture of Kung and Traub. The beauty in the proposed methods from the class can be seen because of the optimization in important effecting factors, i.e. optimality order, lesser number of functional evaluations; as well as in viewpoint of efficiency index. The accuracy of some iterative methods from the proposed derivative-involved scheme is illustrated by solving numerical test problems and comparing with the available methods in the literatures.     

Induced Circular Dichroism in Phosphine Gold(I) Aryl Acetylide Urea Complexes through Hydrogen‐Bonded Chiral Co‐Assemblies

Phosphine gold(I) aryl acetylide complexes equipped with a central bis(urea) moiety form 1D hydrogen‐bonded polymeric assemblies in solution that do not display any optical activity. Chiral co‐assemblies are formed by simple addition of an enantiopure (metal‐free) complementary monomer. Although exhibiting an intrinsically achiral linear geometry, the gold(I) aryl acetylide fragment is located in the chiral environment displayed by the hydrogen‐bonded co‐assemblies, as demonstrated by induced circular dichroism (ICD).     

Wing box transonic-flutter suppression using piezoelectric self-sensing diagonal-link actuators

The main objective of this research is to study the capability of Piezoelectric (PE) self-sensing actuators to suppress the transonic wing-box flutter, which is a flow-structure interaction phenomenon. The unsteady general frequency modified Transonic Small Disturbance (TSD) equation is used to model the transonic flow about the wing. The wing-box structure and the piezoelectric actuators are modeled using the equivalent plate method, which is based on the first-order shear deformation plate theory (FSDPT). The piezoelectric actuators are used as diagonal-links. The optimal electromechanical-coupling conditions between the piezoelectric actuators and the wing are collected from previous work. Three main different control strategies; Linear Quadratic Gaussian (LQG) which combines the Linear Quadratic Regulator (LQR) with the Kalman Filter Estimator (KFE), Optimal Static Output Feedback (SOF), and Classic Feedback Controller (CFC); are studied and compared. The optimum actuators and sensors locations are determined using the Norm of Feedback Control Gains (NFCG) and Norm of Kalman Filter Estimator Gains (NKFEG), respectively. A genetic algorithm (GA) optimization technique is used to calculate the controller and estimator parameters to achieve a target response.     

Nickel-catalyzed synthesis of nanoporous organic frameworks and their potential use in gas storage applications

The synthesis of highly nanoporous organic frameworks (NPOFs) has been established using nickel(0)-catalyzed Yamamoto coupling reactions, which has afforded highly porous polymers featuring remarkable chemical and thermal stability. Treatment of 1,3,5-tris(4-bromophenyl)benzene, 1,2,4,5-tetrakis(4-bromophenyl)benzene, or 1,3,5,7-tetrakis(4-iodophenyl)adamantane with Ni(cod)₂ in DMF at 80°C for 48 h afforded the nanoporous organic frameworks, NPOF-1, NPOF-2, and NPOF-3, respectively, as white powders in quantitative yields. All NPOFs are insoluble in common organic solvents such as dimethylformamide, tetrahydrofuran, toluene, dichloromethane, and methanol. The chemical composition and structural aspects of NPOFs were investigated by spectral and analytical methods while porosity was examined by nitrogen porosity measurements. In spite of their amorphous nature, NPOFs exhibit permanent porosity and high Langmuir surface areas (NPOF-1: 2,635 m² g^?1; NPOF-2: 4,227 m² g^?1; NPOF-3: 2,423 m² g^?1), which make them attractive for subsequent use in gas storage and separation applications, among others. The performance of NPOFs in hydrogen storage was evaluated at 1 bar and 77 K and revealed that these highly porous architectures can store up to 1.45 wt% of hydrogen.     

Lanthanide polyoxocationic complexes: experimental and theoretical stability studies and Lewis acid catalysis

The [ε-PMo(V)(8)Mo(VI)(4)O(36)(OH)(4){Ln(III)(H(2)O)}(4)](5+) (Ln=La, Ce, Nd, Sm) polyoxocations, called εLn(4), have been synthesized at room temperature as chloride salts soluble in water, MeOH, EtOH, and DMF. Rare-earth metals can be exchanged, and (31)P NMR spectroscopic studies have allowed a comparison of the affinity of the reduced {ε-PMo(12)} core, thus showing that the La(III) ions have the highest affinity and that rare earths heavier than Eu(III) do not react with the ε-Keggin polyoxometalate. DFT calculations provide a deeper insight into the geometries of the systems studied, thereby giving more accurate information on those compounds that suffer from disorder in crystalline form. It has also been confirmed by the hypothetical La→Gd substitution reaction energy that Ln ions beyond Eu cannot compete with La in coordinating the surface of the ε-Keggin molybdate. Two of these clusters (Ln=La, Ce) have been tested to evidence that such systems are representative of a new efficient Lewis acid catalyst family. This is the first time that the catalytic activity of polyoxocations has been evaluated.     

Silylated Phosphines and Phosphoranimines

Abstract

The N-silyl phosphoranimines [e.g., Me₃SiN=P(OCH₂CF₃)Me₂] undergo a variety of reactions including deprotonation/substitution of the P-Me groups, transilylation, and condensation with reactive phosphines. Some new 1,2-addition and oxidation reactions of the P=C systems, R₂NP=CHR, R₂NP(=NR)=CHR, and R₂NP=CR-CH=CHR (R = SiMe₃) are also reported.     

New Bacteriocin from Bacillus clausii StrainGM17: Purification, Characterization, and Biological Activity

A bacteriocin-producing strain (9,000 AU/ml) was isolated from the rhizosphere of Algerian healthy plants Ononis angustissima Lam. and identified as Bacillus clausii strain GM17. The bacteriocin, called Bac-GM17, was purified from the culture supernatant after heat treatment, ammonium sulfate precipitation, Sephadex G-50 chromatography and Mono Q fast-performance liquid chromatography (FPLC). Based on matrix-assisted laser desorption ionization-time of flight mass spectrometry analysis, the purified Bac-GM17 is a monomer protein with a molecular mass of 5,158.11 Da. The N-terminal sequencing allowed for the straightforward identification of its first 20 residues, which were of pure bacteriocin. It also revealed that this bacteriocin contained a unique sequence, namely DWTCSKWSCLVCDDCSVELT, which suggests the identification of a novel compound. Bac-GM17 was extremely heat stable (20 min at 120 °C) and was stable within the pH range (3–9). It was found to be resistant to the proteolytic action of trypsin, pepsin, papain, pronase E, and proteinase K. It was also noted to display a bactericidal mode of action against Agrobacterium tumefaciens C58 and a fungistatic mode of action against Candida tropicalis R2 CIP203.