Green and Rapid Strategy for Synthesis of Novel and Known Pyrroles by the Use of Molybdate Sulfuric Acid

Molybdate sulfuric acid as a highly efficient catalyst has been employed for the modified Paal–Knorr synthesis of some novel and known pyrroles under solvent‐free conditions. Catalyst loads as low as 1 mol% could be used leading to high yields of pure pyrrole derivatives at an oil bath temperature of 60 °C. This method has advantages such as the use of very low amounts of a recyclable catalyst, avoidance of organic solvents, and high product yields.     

Nature of closed‐ and open‐shell interactions between noble metals and rare gas atoms

Interactions between noble metals and rare gases have become an interesting topic over the last few years. In this work, a computational study of the open‐shell (d¹⁰s¹) and closed‐shell (d¹⁰s and d¹⁰s²) noble metals (M = Cu, Ag, and Au) with three heaviest rare gas atoms (Rg = Kr, Xe, and Rn) has been performed. Potential energy curves based on ab initio [MP2, MP4, QCISD, and CCSD(T)] and DFT functionals (M06‐2X and CAM‐B3LYP) were obtained for ionic and neutral AuXe complexes. Dissociation energies indicate that neutral metals have the lowest and cationic metals have the highest affinities for interaction with rare gas atoms. For the same metals, there is a continuous increase in dissociation energies (D_e) from Kr to Rn. The nature of bonding and the trend of D_e and equilibrium bond lengths (R_e) have been interpreted by means of quantum theory of atoms in molecules, natural bond orbital, and energy decomposition analysis. © 2013 Wiley Periodicals, Inc.     

Synthesis and characterization of novel biodegradable epoxy‐modified polyurethane elastomers

Biodegradable polyurethane elastomers with the potential for applications in medical implants were synthesized from the reaction of epoxy‐terminated polyurethane prepolymers (EUPs) with 1,6‐hexamethylenediamine as a curing agent. EUPs were themselves prepared from the reaction of glycidol and isocyanate‐terminated polyurethanes made from different molecular weights of poly(ε‐caprolactone) (CAPA) and 1,6‐hexamethylene diisocyanate. All materials were characterized by spectroscopic methods. The curing conditions were optimized by gel content measurements. The curing kinetic and kinetic parameters were determined from differential scanning calorimetry measurements. The effects of changing the crosslink density and crystallinity of elastomers via the alteration of the CAPA polyol molecular weight on the physical, mechanical, and degradation properties of the final elastomeric polymers were examined fully. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2985‐2996, 2005     

Nonlinear Diameter Preserving Maps Between Certain Function Spaces

Let X, Y be compact Hausdorff spaces and A, B be subspaces of C(X) and C(Y), respectively, containing the constant functions such that B is point separating and the evaluation functionals are linearly independent on B. In this paper, we give the general form of a surjective, not assumed to be linear, diameter preserving map \({T:A \longrightarrow B}\) for the case where A is dense in C(X). Fixing a point \({x_1\in X}\), we show that there exist a subset \({Y_0}\) of Y, a scalar \({\beta\in \mathbb{T}}\), a bijective continuous map \({\Psi: Y_0 \longrightarrow X}\) and a constant function \({\alpha: Y_0 \longrightarrow \{-1,1\}}\) such that

$$\begin{aligned}T_{1} f(y) - T_{1} f(y_{1}) = & \beta ({\rm Re} (f(\Psi(y)) - f(\Psi(y_{1}))) \\ & + \alpha(y) i {\rm Im} (f(\Psi(y)) - f(\Psi(y_{1}))))\end{aligned}$$

for all \({f\in A}\) and \({y\in Y_0}\), where \({T_1=T-T0}\) and \({\Psi(y_1)=x_1}\). In particular, either

$$T_1(f)(y)=\beta f(\Psi(y))+L(f) \qquad (f\in A,y\in Y_0),$$

or

$$T_1(f)(y)=\beta \overline{f(\Psi(y))}+L(f) \qquad (f\in A, y\in Y_0),$$

holds for some functional L on A, which is linear (resp. real-linear) whenever T is so.

     

Study on the interaction of three structurally related cationic Pt(II) complexes with human serum albumin: importance of binding affinity and denaturing properties

Human serum albumin (HSA) primarily functions as a transport carrier for a vast variety of natural ligands and pharmaceutical drugs. In the present study, three structurally related cationic Pt(II) complexes ([Pt(ppy)(dppe)]CF₃CO₂: 1, Pt(bhq)(dppe)]CF₃CO₂: 2, and [Pt(bhq)(dppf)]CF₃CO₂: 3) were used to evaluate their interaction with HSA under different experimental setups, using UV–Vis absorption spectroscopy, fluorescence and circular dichroism techniques. The spectroscopic results suggest that upon binding to HSA, the Pt(II) complexes could effectively induce structural alteration of the protein. The complexes can bind to HSA with the binding affinities of the following order: 3 > 2 > 1. Also, thermodynamic parameters of binding between these complexes and HSA indicated the existence of entropy-driven spontaneous interaction which primarily dominated with the hydrophobic forces. Also, docking simulation study revealed the binding details of these complexes on HSA. Complex 3 with highest binding affinity for HSA indicates lowest denaturing effect on this protein. The low denaturation properties of 3 appear important in the terms of lower susceptibility of this platinum complex for possible development of deleterious side effects.     

Fast, high-throughput creation of size-tunable micro/nanoparticle clusters via evaporative self-assembly in picoliter-scale droplets of particle suspension

We report a fast, high-throughput method to create size-tunable micro/nanoparticle clusters via evaporative assembly in picoliter-scale droplets of particle suspension. Mediated by gravity force and surface tension force of a contacting surface, picoliter-scale droplets of the suspension are generated from a nanofabricated printing head. Rapid evaporative self-assembly of the particles on a hydrophobic surface leads to fast clustering of micro/nanoparticles and forms particle clusters of tunable sizes and controlled spacing. The evaporating behavior of the droplet is observed in real-time, and the clustering characteristics of the particles are understood based on the physics of evaporative-assembly. With this method, multiplex printing of various particle clusters with accurate positioning and alignment are demonstrated. Also, size-unifomity of the cluster arrays is thoroughly analyzed by examining the metallic nanoparticle cluster-arrays based on surface-enhanced Raman spectroscopy (SERS).     

A highly selective magnetic solid-phase extraction method for preconcentration of Cd(II) using N,N′-bis(salicylidene)ethylenediamine in water and food samples

Research on Chemical Intermediates - In this work, a highly selective method is presented for the preconcentration of cadmium. The developed magnetic solid-phase extraction is based on the...     

New Correlative Models to Improve Prediction of Fracture Permeability and Inertial Resistance Coefficient

Presence of fracture roughness and occurrence of nonlinear flow complicate fluid flow through rock fractures. This paper presents a qualitative and quantitative study on the effects of fracture wall surface roughness on flow behavior using direct flow simulation on artificial fractures. Previous studies have highlighted the importance of roughness on linear and nonlinear flow through rock fractures. Therefore, considering fracture roughness to propose models for the linear and nonlinear flow parameters seems to be necessary. In the current report, lattice Boltzmann method is used to numerically simulate fluid flow through different fracture realizations. Flow simulations are conducted over a wide range of pressure gradients through each fracture. It is observed that creeping flow at lower pressure gradients can be described using Darcy’s law, while transition to inertial flow occurs at higher pressure gradients. By detecting the onset of inertial flow and regression analysis on the simulation results with Forchheimer equation, inertial resistance coefficients are determined for each fracture. Fracture permeability values are also determined from Darcy flow as well. According to simulation results through different fractures, two parametric expressions are proposed for permeability and inertial resistance coefficient. The proposed models are validated using 3D numerical simulations and experimental results. The results obtained from these two proposed models are further compared with those obtained from the conventional models. The calculated average absolute relative errors and correlation coefficients indicate that the proposed models, despite their simplicity, present acceptable outcomes; the models are also more accurate compared to the available methods in the literature.     

Conjugated 1,10-Phenanthrolines as Tunable Fluorophores

Multiple emission colors can be generated with the same compound from a novel family of highly emissive and visibly fluorescent 1,10-phenanthrolines 1 . The emission wavelength of any derivative is dictated by the nature of its substituent and can be further modulated by exogenous additives such as protons or metal ions. R=H, Me, OMe, NMe₂.