With the goal of achieving high-performance electrically stable organic field-effect transistors (OFETs), we chemically graft a fluorinated polymer nanolayer onto the polar oxide dielectric surfaces via a simple and easy fabrication process in ambient air. The para-fluorine-thiol click reaction between poly(pentafluorostyrene) (PFS) and mercaptopropyltrimethoxysilane is used to synthesize a graftable fluorinated polymer (gPFS). The surface characteristics of the gPFStreated SiO 2 dielectrics and the crystal structure and grain growth of the overlying organic semiconductors are investigated. Various semiconductor materials are employed for the OFETs prepared with gPFS-treated SiO 2 dielectrics, including vacuum-processed pentacene, N,N-ditridecyl-3,4,9,10-perylenetetracarboxylic diimide, solution-processed 5,11-bis-(triethylsilylethynyl)anthradithiophene, and poly[2,5-bis(2-octyldodecyl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione-(E)-1,2-di-(2,2′-bithiophen-5-yl)ethane. Three OFETs are prepared with different dielectrics: (i) bare SiO 2 , (ii) gPFS-treated SiO 2 , and (iii) perfluorooctyltriethoxysilane-treated SiO 2 . The OFETs prepared with the gPFS-treated SiO 2 dielectrics display the highest mobilities and smallest hysteresis. Furthermore, the gPFS-treated SiO 2 provides the best device stability under a sustained gate bias, suggesting that the gPFS surface minimize the number of traps present in the OFET.
Because of frequent co-occurrence of metals with chlorinated organic pollutants, Fe(II), Co(II), Ni(II), and Hg(II) were evaluated for their impact on the dechlorination pathways of PCE and TCE and the subsequent transformation of the initial dechlorination products by FeS. PCE transforms to acetylene via beta-elimination, TCE via hydrogenolysis, and 1,1-DCE via alpha-elimination, while TCE transforms to acetylene via beta-elimination and cis-DCE and 1,1-DCE via hydrogenolysis. Acetylene subsequently transforms in FeS batches, but little transformation of cis-DCE and 1,1-DCE was observed. Branching ratio calculations indicate that the added metals decrease the reductive transformation of PCE and TCE via beta-elimination relative to hydrogenolysis, resulting in a higher production of the toxic DCE byproducts. Nonetheless, acetylene is generally the dominant product. Production of highly water-soluble compound(s) is suspected as a significant source for incomplete mass recoveries. In the transformation of PCE and TCE, the formation of unidentified product(s) is most significant in Co(II)-added FeS batches. Although nearly complete mass recoveries were observed in the other FeS batches, the subsequent transformation of acetylene would lead to the formation of unidentified product(s) over long time periods.
A new strapped calix[4]pyrrole containing a fluorophore as part of the strap has been synthesized and characterized. Association constants with various anions have been determined using both fluorescence titration and isothermal titrations calorimetry (ITC). The two sets of association constants were found to be in good agreement with one another. The fluorescence emission properties of this new receptor could be controlled by addition of Na+ (or H2O) and anions. However, the fluorescence quenching by anions is only observed in the presence of Na+ (or H2O). All the experimental evidence is consistent with the notion that independent PET processes are modulated by separate cation and anion recognition events. As such, this system operates as an elementary logic gate wherein anion and cation concentrations serve as the input and fluorescence intensity changes provide the output.
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