We present the synthesis and characterization of a fused-ring compound, dithieno[2,3-d:2',3'-d']thieno[3,2-b:4,5-b']dithiophene (pentathienoacene, PTA). In contrast to pentacene, PTA has a larger band gap than most semiconductors used in organic field-effect transistors (OFETs) and therefore is expected to be stable in air. The large pi-conjugated and planar molecular structure of PTA would also form higher molecular orders that are conductive for carrier transport. X-ray diffraction and atomic force microscopy experiments on its films show that the molecules stack in layers with their long axis upright from the surface. X-ray photoelectron spectroscopy suggests that there are no chemical bonds at the PTA/Au interface. OFETs based on the PTA have been constructed, and their performances as p-type semiconductors are also presented. A high mobility of 0.045 cm(2)/V s and an on/off ratio of 10(3) for a PTA OFET have been achieved, demonstrating the potential of PTA for application in future organic electronics.

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A new form of graphene-coated silica (GCS) has been prepared by mixing exfoliated graphene oxide with acid-treated silica and reducing it with hydrazine hydrate so that it coats the silica particles. This method is simple, convenient, and robust. The GCS composite particles have been characterized using optical photographs, Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) analysis, and elemental analysis.These analyses show that the reaction effectively coats silica particles with graphene. The composite particles achieve higher levels of adsorption and are more widely applicable than five other sorbents (graphite carbons, activated carbon, pure graphene, C18 silica, and silica) for the eleven pesticides assayed. We discuss the adsorption mechanism and consider it to be dependent on the electrondonating abilities of the S, P, and N atoms and the strong p-bonding network of the benzene rings. This research demonstrates that graphene-based composite materials could be used to remove pesticide residues in aqueous environments.