Solid‐State NMR Correlation Experiments and Distance Measurements in Paramagnetic Metalorganics Exemplified by Cu‐Cyclam

We show how to record and analyze solid‐state NMR spectra of organic paramagnetic complexes with moderate hyperfine interactions using the Cu‐cyclam complex as an example. Assignment of the ¹³C signals was performed with the help of density functional theory (DFT) calculations. An initial assignment of the ¹H signals was done by means of ¹H–¹³C correlation spectra. The possibility of recording a dipolar HSQC spectrum with the advantage of direct ¹H acquisition is discussed. Owing to the paramagnetic shifting the resolution of such paramagnetic ¹H spectra is generally better than for diamagnetic solid samples, and we exploit this advantage by recording ¹H–¹H correlation spectra with a simple and short pulse sequence. This experiment, along with a Karplus relation, allowed for the completion of the ¹H signal assignment. On the basis of these data, we measured the distances of the carbon atoms to the copper center in Cu‐cyclam by means of ¹³C R₂ relaxation experiments combined with the electronic relaxation determined by EPR.     

Viox,a COX‐II inhibitor

Viox {2,5‐di­hydro‐4‐[4‐(methyl­sulfonyl)­phenyl]‐3‐phenyl‐2‐furan­one, C₁₇H₁₄O₄S, (I)} is one of the selective COX‐II inhibitors with anti‐arthritic activity. The absolute structure of viox has been determined on the basis of anomalous scattering effects. Molecules are held together in the crystal structure only by normal van der Waals interactions.     

On q-variant of Dai–Yuan conjugate gradient algorithm for unconstrained optimization problems

Nonlinear Dynamics - In this paper, we propose a modified q-Dai–Yuan (q-DY) conjugate gradient algorithm based on q-gradient for solving unconstrained optimization problems. The q-gradient is...     

Controlled copolymerization of 1‐octene and butyl methacrylate via RAFT and their nonisothermal model‐free thermokinetic decomposition study

Reversible addition fragmentation chain transfer (RAFT) copolymerization of 1‐octene and butyl methacrylate (BMA) was carried out for the first time using 4‐cyano‐4‐(phenylcarbonothioylthio)pentanoic acid as RAFT agent in N,N′‐dimethyl formamide. Poly(1‐octene‐co‐BMA) copolymers with well‐controlled molecular weights and narrow molecular weight distribution were obtained throughout the polymerization. The copolymers have been well characterized by different analytical techniques such as SEC, FT‐IR, NMR, SEM, AFM, XRD, and TG analyses. FT‐IR and NMR analyses confirmed the synthesis of poly(1‐octene‐co‐BMA) copolymers. SEM and AFM analyses demonstrated the wavy‐lamellar morphological structure of the copolymers. Thermogravimetric analysis revealed good thermal stability of poly(1‐octene‐co‐BMA) copolymers synthesized via RAFT mediated polymerization. The thermokinetic parameters were evaluated by adopting model‐free methods of Friedman and Flynn–Wall–Ozawa using the nonisothermal thermogravimetric data. The multivariate nonlinear regression analysis established the most appropriate kinetic model and the corresponding kinetic parameters of thermal decomposition of poly(1‐octene‐co‐BMA) copolymers were also calculated. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2093–2103     

Non-isothermal decomposition kinetics of in-chain functionalized poly(MMA-co-ethylene)

Journal of Thermal Analysis and Calorimetry - Efficient incorporation of polar monomers in polyolefin can lead to many desirable properties in the parent chain. Herein, we report the synthesis of...     

Brownian dynamic simulation for the prediction of effective thermal conductivity of nanofluid

Nanofluid is a colloidal solution of nanosized solid particles in liquids. Nanofluids show anomalously high thermal conductivity in comparison to the base fluid, a fact that has drawn the interest of lots of research groups. Thermal conductivity of nanofluids depends on factors such as the nature of base fluid and nanoparticle, particle concentration, temperature of the fluid and size of the particles. Also, the nanofluids show significant change in properties such as viscosity and specific heat in comparison to the base fluid. Hence, a theoretical model becomes important in order to optimize the nanofluid dispersion (with respect to particle size, volume fraction, temperature, etc.) for its performance. As molecular dynamic simulation is computationally expensive, here the technique of Brownian dynamic simulation coupled with the Green Kubo model has been used in order to compute the thermal conductivity of nanofluids. The simulations were performed for different concentration ranging from 0.5 to 3 vol%, particle size ranging from 15 to 150 nm and temperature ranging from 290 to 320 K. The results were compared with the available experimental data, and they were found to be in close agreement. The model also brings to light important physical aspect like the role of Brownian motion in the thermal conductivity enhancement of nanofluids.     

NC palladacycles in the Heck arylation of ethylene: Synthesis, structure and their reactivity

Monomeric cyclopalladated complexes with NC coordination using ligands 2-phenylpyridine, 2-phenylquinoline, 8-methylquinoline have been synthesized and the structures have been determined by single crystal X-ray structure analysis. The crystal structures of monomeric palladacycles prepared using benzophenone oxime, and 2-phenylpyridine have also been determined. The use of these complexes in the Heck arylation of ethylene with 2-bromo-6-methoxynaphthalne (BMN) to give 2-vinyl-6-methoxynapthalene which is an intermediate for the synthesis of anti-inflammatory drug Naproxen has been examined and also arylation of ethylene with 3-bromo-benzophenone and 4-bromo-isobutylbenzene was investigated. These palladacycles with NC coordination show excellent catalytic activity with a TOF > 4000 h⁻¹.