Olefin metathesis polymerization: Some recent developments in the precise polymerizations for synthesis of advanced materials (by ROMP,ADMET)

Recent results for synthesis of end-functionalized polymers (EFP) by using olefin metathesis polymerization have been introduced including basic characteristics in ring-opening metathesis polymerization (ROMP) of cyclic olefins and acyclic diene metathesis (ADMET) polymerization for synthesis of conjugated polymers. Several approaches were demonstrated for synthesis of EFP by living ROMP using molybdenum (exclusive coupling with aldehyde) and ruthenium catalysts (sacrificial ROMP, chain transfer). Cis specific (Z selective) ROMPs were achieved by molybdenum, ruthenium, and vanadium catalysts by the ligand modification. The catalytic synthesis of EFP with high cis selectivity has been achieved by combined ROMP with chain transfer by V(CHSiMe₃)(N-2,6-Cl₂C₆H₃)[OC(CF₃)₃](PMe₃)₂. The ADMET polymerization using molybdenum and ruthenium catalysts afforded defect-free, high molecular weight poly(arylene vinylene)s containing all trans olefinic double bonds. The methods for precise synthesis of EFPs, exhibiting unique optical properties combined with the end groups, were developed. The catalytic one-pot syntheses for EFPs have also been developed.     

N-Bromosuccinimide assisted oxidation of 5-aminopyrazoles: formation of bis diazenylderivatives

Treatment of 5-amino-4-cyanopyrazoles with N-bromosuccinimide, in DMF at rt gave azo dyes resulting from dimerization through the amino groups and further oxidation.With bromine water the dimer was also formed but, bromination occurred on the aryl ring, either at reflux or rt. Reduction of the azo group with zinc in acetic acid originated the corresponding pyrazoles.     

“Universal” CNDO/2 method (CNDO/2-U)

The Pople-Santry-Segal CNDO/2 method and the modified CNDO/2 version worked out recently by Clack for transition-metal complexes have been extended to the full periodic table.     

Studies with enaminonitriles: Synthesis and chemical reactivity of 2‐phenyl‐3‐piperidin‐1‐yl acrylonitrile under microwave heating

Benzyl cyanide reacts with triethylorthoformate and piperidine in DMF solution to yield the title compound 2 . This reacted with aromatic amines to yield either aminoacrylonitriles or quinoline depending on reaction conditions and substitution pattern on the aromatic amine. The reaction of compound 2 with hydrazine hydrate could only be effected in the microwave oven and resulted in the formation of aminopyrazole 7 . Diazotization of 7 and coupling with an active methylene reagent afforded pyrazolo[5,1‐c]‐[1,2,4]triazine derivatives.     

Synthesis,Characterization and Photocatalytic Behavior of SiO2@nitrized-TiO2 Nanocomposites Obtained by a Straightforward Novel Approach

We report on the facile synthesis of SiO₂@nitrized-TiO₂ nanocomposite (NST) by calcination of TiO₂ xerogel with OctaAmmonium POSS® (N-POSS; POSS=polyhedral oligomeric silsesquioxanes). The as-obtained nanoporous mixed oxide is constituted by uniformly distributed SiO₂ and nitrized-TiO₂, where the silica component is present in an amorphous state and TiO₂ in an anatase/rutile mixed phase (92.1 % vs. 7.9 %, respectively) with very small anatase crystallites (3.7 nm). The TiO₂ lattice is nitrized both at interstitial and substitutional positions. NST features a negatively charged surface with a remarkable surface area (406 m² g⁻¹), endowed with special adsorption capabilities towards cationic dyes. Its photocatalytic behavior was tested by following the degradation of standard aqueous methylene blue and methyl orange solutions under UV and visible light irradiation, according to ISO 10678:2010. For comparison, analogous investigations were carried out on a silica-free N−TiO₂, obtained by using NH₄Cl as nitrogen source.     

Solid body motion prediction using a unit quaternion-based solver with actuator disk

A six-Dof motion solver based on unit quaternions and an actuator disk model are implemented for ship hydrodynamics predictions. The six-Dof module is tested using the water entry phenomenon of a free falling sphere. The displacement history and impacting forces are analyzed. A KCS (KRISO container ship) model with the allowances of sinkage and trim is then simulated and validated. The actuator disk model is used to replace a real propeller. The open-water test of a KP458 propeller is first carried out to obtain the thrust and torque coefficients, using both the multi-run and single-run approaches. Oblique Towing Tank (OTT) tests using the actuator disk are conducted at last and the results agree well with the experiments. These models can be used for simulating six-Dof motions and captive model tests of ships.     

Some reactions with ω-bromoacetophenone: Synthesis of Δαβ-butenolide and its transformation into pyrrole derivatives

ω-Bromoacetophenone reacts with the sodium salt of ethyl cyanoacetate to afford α-cyano-β-phenyl-Δ^αβ-butenolide. This butenolide undergoes azo coupling with diazotized aromatic amines (ArNH₂) to afford the hydrazo derivatives. These hydrazo derivatives (ArPh, 4-ClC₆H₄, 4-MeC₆H₄, 4-MeOC₆H₄) were transformed into the corresponding 3(2H)-pyridazinone derivatives on stirring in methanol in the presence of potassium hydroxide. These latter compounds were converted into the corresponding 3-cyano-2,5-dihydroxy-4-phenyl-N-arylpyrrole derivatives on reduction with zinc dust in refluxing acetic acid, presumably via reductive cleavage of the N N bond of the pyridazine followed by recyclization via loss of ammonia.     

Reactivity of 4,5-Dichlorophthalic Anhydride towards Thiosemicarbazide and Amines: Synthesis,Spectroscopic Analysis,and DFT Study

The cyclic anhydrides are broadly employed in several fields, such as the chemical, plastic, agrochemical, and pharmaceutical industries. This study describes the chemical reactivity of 4,5-dichlorophthalic anhydride towards several nucleophiles, including thiosemicarbazide and different amines, to produce the carboxylic acid derivatives resulting from anhydride’s opening, namely, phthalimide and dicarboxylic acid (1–12) products. Their chemical structures are confirmed by NMR, IR and MS spectra analyses. Density–functional theory (DFT) studies are performed using (DFT/B3LYP) with the 6-311G(d, p) basis sets to recognize different chemical and physical features of the target compounds.     

Investigating Route to Chaos in Nonlinear Plasmonic Dimer

The route to chaos of a plasmonic dimer formed of two identical nanoparticles with Kerr-type nonlinear response and illuminated by an external electric field is reported. It is shown that this system has a complex dynamical behavior with chaotic nature. This complexity is analyzed using Lyapunov exponents, the Kaplan–Yorke dimension, and correlation dimensions. The existence of familiar period-doubling sequences route to chaos is pointed out, and domains corresponding to the onset of period doubling and chaos in the plane of parameters are evidenced.     

Dynamic light scattering by weakly ionized gels: Effects of inhomogeneities and non-ergodicity

Small angle neutron scattering and light scattering experiments have been performed on partially neutralized poly(acrylic acid) solutions and gels. The structure factor obtained from small angle scattering and static light scattering reveals the absence of significant contribution from large scale inhomogeneities in the gels as soon as the ionization degree exceeds 9·10⁻³. The comparison of the time and ensemble averages of the autocorrelation function of scattered light intensity shows that the gels behave with respect to that experiment as ergodic media.