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Synthesis, Monolayer Formation, Characterization, and Nanometer-Scale Photolithographic Patterning of Conjugated Oligomers Bearing Terminal Thioacetates

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journal contribution
posted on 16.03.2010, 00:00 by Iain Barlow, Shuqing Sun, Graham J. Leggett, Michael Turner
The synthesis of α-thioacetate terminated quaterthiophene and phenylene−thiophene materials, possessing thioacetate, oxetane, and alkyl groups at their ω-termini, is described. After deprotection these molecules were adsorbed onto Au films and the resulting self-assembled monolayers were characterized by X-ray photoelectron spectroscopy (XPS) and friction force microscopy (FFM). FFM indicated that monolayers formed by the dithioacetates had the highest coefficients of friction, followed by the oxetane-terminated adsorbates, with the alkyl-functionalized materials showing the lowest friction coefficients. These data may be understood in terms of differences in molecular packing. The quaterthiophene adsorbates also yielded higher friction coefficients than their phenylene−thiophene counterparts. Micrometer-scale patterns were fabricated by mask-based exposure to 244 nm light, and characterized by FFM. Nanometer-scale patterns were fabricated using near-field exposure and characterized by FFM. The images obtained demonstrated that features of conjugated oligomers with high spatial resolution (59 nm, ca. λ/4) were achievable.