No abstract

Two neutral salicylaldiminato methyl pyridine nickel(II) complexes were synthesized and evaluated for ethylene polymerization. Each catalyst bears a methoxy group in the 3position and a halogen atom in the 5-position of the salicyl ligand, chlorine in case of catalyst 3a and bromine in 3b. Molecular structures of the catalysts were obtained by X-ray crystallography. The resulting polymerization activities, for example, indicated by a maximum turnover frequency of 4,870 mol ethylene/(mol Ni  h) for 1-h runs obtained with 3a, were higher than those of similar catalysts at comparable conditions reported in the literature. Catalyst 3a was slightly more active than catalyst 3b. The polymers are branched as measured by 1 H NMR and 13 C NMR. This was also reflected in the melting temperatures between 76 and 113 C obtained by differential scanning calorimetry. By using gel permeation chromatography measurements, it was determined that the M w of the polymers ranges between about 5,400 and 21,600 g/mol. In particular, the effect of the polymerization temperature on the catalyst activity, degree of branching, and molecular weight properties has been described. V C 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: [986][987][988][989][990][991][992][993][994][995] 2012

Dye molecules were modified through exchange of a central nucleofugal functional group. Profound changes in the bandgap spacing and HOMO-LUMO levels were observed. Concentration quenching was observed for all the dyes and increases in external quantum efficiency of devices were observed after dyes were diluted through distribution within a polymer host. The addition of the phenoxy functional group in one derivatized dye appeared to reduce the effect of fluorescence concentration quenching. All characterization herein allows for prediction of the effects of other nucleofugal syntheses on these dyes for more successful application in NIR bulk heterojunction photovoltaics.