A facile one‐pot reactive solution blending approach for main‐chain donor–acceptor polymeric materials

A high‐temperature solution blending process has been used to synthesize a series of copolymers incorporating varying mole ratios of perylenebisimide (PBI) into the backbone of an engineering thermoplastic polyester [poly(1,4‐cyclohexylenedimethylene‐1,4‐cyclohexanedicarboxylate)] (PCCD). A random donor–acceptor copolymer incorporating oligo(p‐phenylene vinylene) (OPV) and PBI was also synthesized. The chemical incorporation of these chromophores into PCCD was confirmed by carrying out the melt condensation using 1,4‐cyclohexanedimethanol and 1,4‐dimethylcyclohexane dicarboxylate with hydroxyl‐functionalized PBI and OPV derivatives. Higher extent of incorporation of PBI (35 mol %) could be achieved using the blending approach retaining solubility, film‐forming ability, and higher molecular weights. The PBI polymers produced using the two different approaches exhibited structural variations. The polymers formed from the solution blending approach had a semicrystalline nature with blocks of PCCD separating the PBI units, whereas those produced using the melt condensation route were amorphous polymers. This structural variation was reflected in their photophysical properties also with the reactive solution‐blended polymers exhibiting higher fluorescence quantum yields. These results demonstrate the easy incorporation of suitably functionalized donor and acceptor moieties into a completely aliphatic polyester backbone to produce free‐standing films of hitherto nonprocessable polymers. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Fluorescence Quenching of Tris(2,2′-bipyridine)Ruthenium(II) Dichloride by Certain Organic Dyes

Fluorescence quenching of [Ru(bpy)₃]²⁺ by a series of organic dyes has been investigated by using the steady state fluorescence technique in aqueous medium. The dyes used are anthraquinone dyes: uniblue, acid blue 129, alizarin, alizarin red S and the azo dyes: congo red, sunset yellow, methyl orange, tartrazine, acid orange 63, methyl red and erichrome black T. The quenching of [Ru(bpy)₃]²⁺ was found to obey the Stern-Volmer equation and the corresponding Stern-Volmer plots were linear indicating dynamic quenching. The quenching rate constants (k _q) were calculated from the fluorescence data. The mechanism of quenching was discussed on the basis of the quenching rate constants as well as the reduction potential of dyes. The electron transfer mechanism has been proved by the calculation of Gibbs energy changes (ΔG _et) by applying the Rehm-Weller equation.     

Convertible Fluorous Sulfonate Linker for the Synthesis of Diverse Library Scaffolds

Aryl perfluorooctanesulfonates (fluorous sulfonate) have been developed as triflates and nonaflates alternatives for Pd‐catalyzed coupling reactions to form C‐C, C‐N, C‐S, C‐H, and C‐CN bonds. They also serve as phase‐tags for fluorous solid‐phase extraction (F‐SPE) to facilitate product purifications. Other synthetic techniques such as microwave reactions and multicomponent reactions are combined with the fluorous linker strategy to further increase synthetic efficiency. The utility of fluorous sulfonate linkers in the synthesis of biologically interested library scaffolds is summarized in this short review article.     

Synthesis of a 1,3,5-benzotriazepine-2,4-dione based library

A library of benzotriazepines have been synthesised employing microwave-mediated synthesis, supported resins and parallel synthesis methodology.     

Randers change of <Emphasis Type="Italic">m</Emphasis><Superscript>th</Superscript> root metric

The present paper deals with a Randers metric that has been derived after a particular β-change in the mth root metric. Various geometers such as [7], [9], [10] etc. have studied the mth root metric and its transformations. We have obtained some tensors and theorems holding the relation between the Finsler space equipped with the mth root metric and the one obtained after its Randers change.     

Mixed ligand complexes of manganese(III) with dithiocarbamate and glycine/acetylacetone ligands: magnetic,spectral and thermal studies

Summary Mixed ligand complexes of Mn^III with morpholyl and piperidyldithiocarbamates (A) and glycine/acetylacetone (A) have been prepared with the general formule MnAA₂, MnA₂A and Mn(A)₃, and have been characterised by elemental analysis, magnetic susceptibility measurements, i.r. electronic and e.s.r. spectral techniques and by thermal analysis. The complexes exhibit magnetic moment in the 4.5–5.3 B.M. range. The ligands are bidentate. E.s.r. studies suggest that all the complexes have six-coordinate actahedral geometry. T.g.a. studies reveal one step decomposition of complexes and formation of manganese dioxide.     

Synthesis and curing studies of PPG based telechelic urethane methacrylic macromonomers

A New class of telechelic urethane methacrylic (TUMA) macromonomers were synthesized by a two-step condensation of 1, 6-hexamethylenediisocyanate (HMDI) with polypropylene glycol (PPG) of various molecular weights and capped with hydroxyl ethyl methacrylate (HEMA). A model compound based on diethylene glycol (DEG)—M-1 was synthesized as a low molecular weight analogue. Another model compound—M-2 was also synthesized by direct coupling of two equivalents of HEMA with HMDI. The structure of the telechelic urethanes were confirmed by ¹H, ¹³C NMR and FTIR spectroscopy. Photopolymerization of these telechelic systems was investigated using 2,2-diethoxy acetophenone as the photoinitiator at 5 wt.%. Trihydroxymethylpropane trimethacrylate (30 parts), PPG diacrylates (25 parts), ethylhexyl acrylate (20 parts) were mixed with the various telechelic urethane methacrylates (25 parts) for curing studies. The kinetics of the curing was monitored by following the disappearance of the methacrylic double bonds at 1628 cm⁻¹ using IR spectroscopy. TUMAPPG-425 had the fastest cure rate among the telechelic urethane methacrylates. This could be accounted for by hydrogen bonding pre-association in these systems. The thermal properties of the cured films were studied using TGA measurements. The cured films of the neat resin had a lower 50 wt.% loss temperature compared with that of the same resin in the formulation.     

Synthesis, characterization and optical properties of silver and gold nanowires embedded in mesoporous MCM-41

Uniform nanowires of silver and gold inside the channels of MCM-41 were prepared by controlled reduction of their respective metal salts with sodium borohydride (NaBH₄). Presence of nanowires of silver and gold in MCM-41 were confirmed by high angle X-ray diffraction (XRD) data (peaks between 2ϑ = 30 − 60°) and transmission electron microscopy (TEM) confirmed the diameter of the nanowires. Diameter of nanowires is found to be ∼ 2.8 nm which is coincident with channel diameter of MCM-41. Optical properties of these heterostructured materials Ag-MCM-41 and Au-MCM-41 reveals the presence of surface plasmon absorption peaks of silver and gold respectively, and the shift in the absorption bands are associated to agglomeration of clusters inside the channels. Room temperature photoluminescence spectra exhibits interesting optical properties as observed for direct band gap semiconductors. Non-linear optical properties (NLO) corresponding to second harmonic generation (SHG) values were also recorded for self supported films of these heterostructured materials. Enhanced optical non-linearity was found to be arising from a corresponding increase of local field near the surface plasmon resonance. Further enhancement in SHG was found with poling due to an induction of orientation order.     

Sorption and diffusion of methyl substituted benzenes through cross-linked nitrile rubber/poly(ethylene co-vinyl acetate) blend membranes

The diffusion and sorption of methyl substituted benzenes through cross-linked nitrile rubber/poly(ethylene co-vinyl acetate) (NBR/EVA) blend membranes has been studied. The influence of blend composition, cross-linking systems, temperature and size of penetrants on the transport behaviour has been analysed. It was observed that as the EVA content increases in the blends, the solvent uptake decreases. An increase in the penetrant size also decreases the solvent uptake. The diffusion experiments were carried out in the temperature range 23–75 °C. As temperature increases the equilibrium uptake also increases. The transport coefficients namely diffusion coefficient, sorption coefficient and permeation coefficient have been calculated. The sorption data has been used to estimate the activation energies for permeation and diffusion. The van’t Hoff relationship was used to determine the thermodynamic parameters. The affine and phantom models for chemical cross-links were used to predict the nature of cross-links. Models for permeability were used and the theoretical values compared with the experimental results.     

Anion exchange studies of lead in chloride and malonate solutions separation from mixtures

Summary Lead forms anionic chloride complexes in 4 M hydrochloric acid and a malonate complex at pH 4.8 with malonic acid. The behaviour of these complexes has been studied on Dowex 21-K resin with various eluants and methods have been developed for the separation of lead from several elements. The technique has been extended to the analysis of lead-based alloys. Satisfactory results are obtained.

---

Zusammenfassung Die anionischen Chlorid- und Malonatkomplexe des Bleis wurden in ihrem Verhalten am Ionenaustauscher Dowex 21-K untersucht und Methoden zur Abtrennung des Bleis von mehreren anderen Elementen ausgearbeitet. An einem Beispiel wird die Analyse einer Bleilegierung beschrieben. Es werden zufriedenstellende Ergebnisse erhalten.