Synthesis of S Acetyl Oligoarylenedithiols via Suzuki−Miyaura Cross-Coupling (original) (raw)
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The use of organic thin layers as active component in materials science and electronic devices is presently considered a potential alternative to conventional semiconductor based nano scale electronics since it directly provides precise well-defined nano-scale components for electronic devices which eventually allows for simple processing and device fabrication. In the area of interface and surface science covalently bound Self-Assembled Monolayers (SAMs) became of significant importance. In particular aromatic based materials became of paramount interest, since they exhibit strong intermolecular interactions, chemical stability and charge transport properties across metal-organic interface.
Journal of the American Chemical Society, 1994
Structures of self-assembled monolayers of 4'-alkoxybiphenyl-4-methanethiol, ~'-C H~(C H Z)~O C~H~C~H~-4-CHzSH (I), (6-alkoxynaphth-2-yl)methanethiol, ~C H~(C H~)~O C I~H~-~-C H~S H (11), and 4'-alkoxybiphenyl-4thiol, ~'-CH~(CHZ),OC~H~C~H~-~-SH (m) (m = IS, 16) on surfaces of evaporated Au and Ag were characterized and compared with the corresponding structures of n-alkanethiol, CH3(CH2),SH (N) (m = 15, 16). The results revealed that compounds I, 11, and J I I form well-ordered monolayers on Au and Ag, with nearly identical structure of the hydrocarbon tail, presumably because of the same herringbone packing of the aromatic chromophores on nearly identical lattices of Au and Ag substrates. The herringbone packing of the aromatic chromophores, supported by molecular mechanics calculations, in turn determines the lattice and the spacing of the hydrocarbon chains. That compounds I and 111 appear to have the same structure indicates that the binding geometry of sulfur can be either sp3 (surface4-C bond angle of-109") or sp hybridized (s u r f a d bond angle of-180°), depending on packing interactions in other parts of the molecules. The least sterically demanding n-alkanethiol (N) allows a greater density of packing on Ag but not on Au, causing the binding geometry of sulfur to the surface to differ on the two metals. The tighter packing of IV on Ag makes monolayers of thiols with short chains more ordered conformationally than those of Au.
Journal of the Brazilian Chemical Society, 2004
Tióis de cadeias carbônicas com tamanhos diferentes e contendo grupo terminal COOH foram usados para formar monocamadas auto-organizadas sobre a superfície de eletrodos de ouro. A transferência de elétrons do par Fe(CN) 6 3-/4para o eletrodo foi estudada em diferentes pH usandose as técnicas de voltametria cíclica (CV) e de espectroscopia de impedância eletroquímica (EIS). Mudanças no pH da solução resultaram em variações na carga do grupo terminal das monocamadas auto-organizadas e, conseqüentemente, em alterações na interação eletrostática da SAM com as espécies eletroativas em solução.
Self-assembled monolayers on gold substrates made from functionalized thiols and dithiols
2007
Selbst organisierte Monolagen (SAMs) bestehen aus dicht verpackten und langkettigen, organischen Molekülen die auf Metallsubstraten durch eine Schwefelkopfgruppe adsorbieren. Der Zweck diese Doktorarbeit, ist die Erforschung der Anordnung und Struktur der selbst organisierten Monolagen durch IR, XPS, NEXAFS, STM, Ellipsometry und Kontaktwinkel. Während die Struktur der ersten Gruppe der Triptycenethiole und der zweiten Gruppe der Moleküle Triarylaminethiole einen ungeordneten Film auf der Goldoberfläche bilden, zeigt die dritte Gruppe der Alkanthioacetate die Ausbildung hochgeordneter Strukturen mit flach orientierten Molekülen. Eine weitere Adsorption zu aufwärts orientierten Molekülen ist aufgrund kinetischer Effekte verhindert. Bei den Azobenzolen hat sich gezeigt, dass der Prozess der Photoisomerizierung reversible ist, aber die Moleküle wegen der kritischen Auswirkung von Azo-Teil keine geordnete Struktur auf die Oberfläche erlangen können
The Journal of Physical Chemistry C, 2009
Whereas thiols and thioethers are frequently used as binding units of oligodentate precursor molecules to fabricate self-assembled monolayers (SAMs) on coinage metal and semiconductor surfaces, their use for tridentate bonding configuration is still questionable. Against this background, novel tridentate thiol ligands, PhSi(CH 2 SH) 3 (PTT) and p-Ph-C 6 H 4 Si(CH 2 SH) 3 (BPTT), were synthesized and used as tripodal adsorbate molecules for the fabrication of SAMs on Au(111). These SAMs were characterized by X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The PTT and BPTT films were compared with the analogous systems comprised of same tripodal ligands with thioether instead of thiol binding units (anchors). XPS and NEXAFS data suggest that the binding uniformity, packing density, and molecular alignment of the thiol-based ligands in the respective SAMs is superior to their thioether counterparts. In addition, the thiol-based films showed significantly lower levels of contamination. Significantly, the quality of the PTT SAMs on Au(111) was found to be even higher than that of the films formed from the respective monodentate counterpart, benzenethiol. The results obtained allow for making some general conclusions on the specific character of molecular self-assembly in the case of tridentate ligands.
Low-Density Self-Assembled Monolayers on Gold Derived from Chelating 2-Monoalkylpropane-1,3-dithiols
Langmuir, 2000
Low-density self-assembled monolayers (SAMs) on gold were generated by the adsorption of a series of specifically designed 2-monoalkylpropane-1,3-dithiol derivatives, CH3(CH2)nCH[CH2SH]2, where n ) 11, 13, 14. The monolayers were characterized by optical ellipsometry, X-ray photoelectron spectroscopy, contact angle goniometry, polarization modulation infrared reflection absorption spectroscopy, and sumfrequency generation. Comparison of these data to those collected on SAMs generated from normal alkanethiols, CH3(CH2)n+2SH, and 2,2-dialkylpropane-1,3-dithiol derivatives, [CH3(CH2)n]2C[CH2SH]2, of similar chain length suggests that the new "monoalkanedithiol" SAMs are the least crystalline, exposing both methyl and methylene groups at the interface due to the low density of alkyl chains. Further comparison of these low-density SAMs to those obtained on branched and linear polyethylene films suggests that the exposure of interfacial methylene groups is greater for the polymer films.