Synthesis of S Acetyl Oligoarylenedithiols via Suzuki−Miyaura Cross-Coupling (original) (raw)
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.
Self-Assembly of Mono- And Bidentate Oligoarylene Thiols onto Polycrystalline Au
Langmuir, 2013
Four thiolated oligoarylene molecules (i) 4-methoxy-terphenyl-4″-methanethiol (MTM), (ii) 4-methoxy-terphenyl-3″,5″-dimethanethiol (MTD), (iii) 4-nitro-terphenyl-4″-methanethiol (NTM), and (iv) 4-nitro-terphenyl-3″,5″-dimethanethiol (NTD) were synthesized and self-assembled as monolayers (SAMs) on polycrystalline Au electrodes of organic field-effect transistors (OFETs). SAMs were characterized by contact angle and AC/DC electrochemical measurements, whereas atomic force microscopy was used for imaging the pentacene films grown on the coated electrodes. The electrical properties of functionalized OFETs, the electrochemical SAMs features and the morphology of pentacene films were correlated to the molecular organization of the thiolated oligoarylenes on Au, as calculated by means of the density functional theory. This multi-methodological approach allows us to associate the systematic replacement of the SAM anchoring head group (viz. methanethiol and dimethanethiol) and/or terminal tail group (viz. nitro-, -NO2, and methoxy, -OCH3) with the change of the electrical features. The dimethanethiol head group endows SAMs with higher resistive features along with higher surface tensions compared with methanethiol. Furthermore, the different number of thiolated heads affects the kinetics of Au passivation as well as the pentacene morphology. On the other hand, the nitro group confers further distinctive properties, such as the positive shift of both threshold and critical voltages of OFETs with respect to the methoxy one. The latter experimental evidence arise from its electron-withdrawing capability, which has been verified by both DFT calculations and DC electrochemical measurements.
Langmuir, 2001
Self-assembled monolayers of a series of ω- (4′-methyl-biphenyl-4-yl)-alkanethiols (CH3-C6H4-C6H4-(CH2)m-SH, m ) 1-6) formed on polycrystalline gold and silver surfaces were characterized in detail by contact angle measurements, optical ellipsometry, X-ray photoelectron spectroscopy (XPS), reflection absorption infrared spectroscopy (IRRAS), and near-edge X-ray absorption fine structure spectroscopy (NEXAFS). The orientation of the biphenyl moiety, determined by combining the results from IRRAS and NEXAFS, exhibits a pronounced dependence on the number of methylene groups. Similar to n-alkanethiols an odd-even effect is observed which on silver is opposite to that on gold. For m ) odd on gold and m ) even on silver the arrangement of the aromatic moieties agrees well with the bulk structure of biphenyl, and the bonding of the thiols to the substrate is in agreement with an sp 3 hybridization of the sulfur on gold and sp on silver, respectively. In the opposite case of m ) even on gold and m ) odd on silver, the biphenyl moieties adopt a significantly more canted orientation which, as a consequence, results in a lower coverage. The odd-even behavior of the coverage is in sharp contrast to that seen for n-alkanethiols. The experiments provide evidence that a significant driving force exists to pertain the sp 3 and sp hybridization of sulfur on gold and silver, respectively. In the case of gold substrates the experimental results are in conflict with available bending potentials derived from ab initio calculations.
ChemPhysChem, 2013
The wire-like properties of four S,-[4-[2-[4-(2-phenylethynyl)phenyl]ethynyl]phenyl]thioacetate derivatives, PhCCC6H4CCC6H4SAc 1, H2NC6H4CCC6H4CCC6H4SAc 2, PhCCC6H2(OMe)2CCC6H4SAc 3 and AcSC6H4CCC6H4CCC6H4SAc 4 (Figure 1), all of which possess a high degree of conjugation along the oligo(phenyleneethynylene) (OPE) backbone, were investigated as self-assembled monolayers (SAMs) on gold and platinum electrodes by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The redox probe [Fe(CN)6] 4was used in both the CV and impedance experiments. The results indicate that the thiolates derived from thioacetate-protected precursor molecules 1 and 2 form well-ordered monolayers on a gold electrode, whereas SAMs derived from 3 and 4 exhibit randomly distributed pinholes. The electron tunnelling resistance and fractional coverage of self-assembled monolayers (SAMs) of all four compounds were examined using electron tunnelling theory. The analysis of the results revealed that the well-ordered SAMs of 1 and 2 exhibit higher charge transfer resistance in comparison to the defect-ridden SAMs of 3 and 4. The addition steric bulk offered by the methoxy groups in 3 likely prevent efficient packing within the SAM, leading to microelectrode behaviour, when assembled on a gold electrode surface. The protected dithiol derivative 4 probably binds to the surface through both terminal groups which prevents dense packing and leads to the formation of a monolayer with randomly distributed pinholes. Atomic force microscopy (AFM) was used to examine the morphology of the monolayers and height images gave root-mean-square (RMS) roughness's which are in agreement with the proposed SAM structures.
Inorganica Chimica Acta, 1996
The preparation of self-assembled monolayers (SAMs) of the double-ended dithiols 4,4'-biphenyldithiol, and a,a'-p-xylyldithiol, the double-ended diisocyanides 1,4-phenylenediisocyanide, 4,4'-biphenyldiisocyanide, 4,4'-p-terphenyldiisocyanide, 1,6-hexanediisocyanide, 1,12_dodecanediisocyanide, and 1,4-di(4-isocyano-phenylethynyl)-2-ethylbenzene, and the 4-sulfido phenyl isocyanide capped trinuclear nickel cluster 4-013-iodo-tris(bis(diphenylphosphino)me~ane)-t~~ckel-(isocy~o)phenylenesul~de by direct adsorption or by displacement of a pre-existing SAM of I-octadecanethiol on gold is reported. The SAMs were characterized using reflection-absorption infrared spectroscopy (RAIR), optical ellipsometry, and advancing contact-angle (0,) measurements. The substitution chemistry of SAMs was found to be irreversible. The dithiols and aryl diisocyanides were found to form SAMs with only one functional group attached to the surface. The SAMs of dithiols were used to covalently attach nanometer scale gold clusters to the exposed thiol surface of the SAM. Scanning tunneling microscopy (STM) was used to image these immobilized gold clusters. The diisocyanides have been used to covalently anchor trinuclear nickel clusters. The SAM of the 4-sulfido phenyl isocyanide capped trinuclear nickel cluster 4-0r3-iodo-tris(bis(diphenylphosphino)me~~e)-~nickel-(isocy~o)-phenylenesul~de, was studied by cyclic voltammetry. The electron acceptors methylviologen (MV2+) and the methyl ester of cobaltocenium [MeCOOCpCp]+[PF& were used to demonstrate rectification in the interfacial electron transfer from nickel cluster SAM modified gold electrodes to the electron acceptors.
Self-assembly of terminally aryl-substituted long-chain alkanethiols on silver
Vibrational Spectroscopy, 2007
Self-assembled monolayers (SAM) from para-substituted benzyl-16-mercaptohexadecanoates (R =-Cl;-OCH 3 ;-NO 2 ;-CN) were prepared using standard deposition procedures on silver substrates. The substituents were attached to the terminal benzyl group of the SAM precursor molecules in order to modify the properties of the outer film surface and to probe their influence on the organizational order of the monolayers. The SAMs were characterized by infrared spectroscopic ellipsometry and contact angle measurements. The carbonyl stretching as well as the methylene symmetric and antisymmetric stretching vibrations were employed to determine the tilt angle of the methylene chains. The water advancing contact angles implied that the wetting of the film's outermost surface is substantially different from that expected for more polar groups like NO 2 , CN and OCH 3 and is much closer to that reported for aryl terminated SAMs. The flexible methylene linkage can facilitate the free rotation around C-Ph bond that leads to a specific orientation of the terminal phenyl rings in which they are closely exposed to the interface. An attempt was made to qualitatively characterize the phenyl ring orientations of the different SAMs using the IR spectroscopic ellipsometry data and IR absorption spectra of the same molecules.
Nanotechnology
Self-Assembled Monolayers (SAM) on Au(111) are able to control the functionality of a gold surface. We use scanning tunnelling microscopy (STM) in air and contact angle measurements to compare the morphology and the chemistry of three alkylthiol SAMs differing by their tail groups: 1,9-nonanedithiol (NDT) and 1,4-butanedithiol (BDT) and 11mercaptoundecanol (MUOH). STM reveals very different morphologies: hexagonal lattice for MUOH and parallel rows for NDT and BDT. In the case of NDT, we find that the thiol tail groups may form disulfide bridges for long immersion times. The availability of-SH group for chemical reactions is checked by attaching gold nanoparticles (AuNPs). When the thiol tail group is available, AuNPs readily attach as shown with atomic force microscopy (AFM). When disulfide bridges are formed the gold surface is not able to bind nanoparticles.