Variations in the structure and reactivity of thioester functionalized self-assembled monolayers and their use for controlled surface modification

• Inbal Aped,
• Yacov Mazuz and
• Chaim N. Sukenik

Beilstein J. Nanotechnol. 2012, 3, 213–220, doi:10.3762/bjnano.3.24

• also followed by XPS. SAMs of compounds 1 and 2 showed peaks corresponding to the expected divalent sulfur of the thioester at 163.8 ± 0.2 eV and 164.8 ± 0.2 eV in the expected 2:1 ratio (±10%), see for example Figure 4A. The additional (thiophene) sulfur in both compounds 3 and 4 leads to a broad

• for each sulfur and the expected 1:1 ratio for the two kinds of sulfurs in a single thiophene-bearing SAM show error bars of as much as 30%. Nevertheless, the XPS result confirms the presence of the thioester and thiophene sulfurs and attests to their complete disappearance (in all cases) upon

• oxidation to a sulfonic acid SAM (in which the one sulfur is at 168.2 ± 0.2 eV and 169.9 ± 0.2 eV). Finally, the photo-oxidations of the various types of thioesters were compared by using UV radiation of different wavelengths. A lamp whose output was around 254 nm was used for irradiation at shorter

When “small” terms matter: Coupled interference features in the transport properties of cross-conjugated molecules

• Gemma C. Solomon,
• Justin P. Bergfield,
• Charles A. Stafford and
• Mark A. Ratner

Beilstein J. Nanotechnol. 2011, 2, 862–871, doi:10.3762/bjnano.2.95

• to gold electrodes. The systems that we compare have the same underlying carbon skeleton but differ in the fact that the sulfur binding groups appear explicitly, rather than being effectively absorbed as part of the electrodes in the Hückel calculations. The gDFTB method [22][24][25] allows us to

Self-assembled monolayers and titanium dioxide: From surface patterning to potential applications

• Yaron Paz

Beilstein J. Nanotechnol. 2011, 2, 845–861, doi:10.3762/bjnano.2.94

• , demonstrating the usefulness of using SAM mediators. The same concept of using SAMs as mediators was demonstrated in a system comprising quantum dots and self-assembled-monolayer-coated titanium dioxide. Here, cadmium–sulfur–selenium (CdSSe) quantum dots were physically attached to hydrothermally synthesized

Direct monitoring of opto-mechanical switching of self-assembled monolayer films containing the azobenzene group

• Einat Tirosh,
• Enrico Benassi,
• Silvio Pipolo,
• Marcel Mayor,
• Michal Valášek,
• Veronica Frydman,
• Stefano Corni and
• Sidney R. Cohen

Beilstein J. Nanotechnol. 2011, 2, 834–844, doi:10.3762/bjnano.2.93

• . It uses an atomistic (although empirical) description of the molecules and of their interactions in the SAM, and allows simulation of the compression of the SAM by a nanoindenter. It includes an annealed SAM surface fixed at the base by sulfur atoms, with no explicit inclusion of the gold substrate

• ). Therefore: where A0 = A/N is the area of gold surface that one single molecule covers, and l0 is obtained in our model as the projection of the molecular length d0 (calculated as the largest interatomic distance between sulfur atom and an hydrogen atom) on the normal direction n with respect to the gold

• geometry. The structure of the SAM was built to reproduce the experimentally observed periodicity [10] (Figure 6) and the gold surface is described, in this first model, only implicitly by fixing the sulfur atom positions. Molecular dynamics (MD) simulations within the canonical ensemble at T = 300 K were

Terthiophene on Au(111): A scanning tunneling microscopy and spectroscopy study

• Berndt Koslowski,
• Anna Tschetschetkin,
• Norbert Maurer,
• Elena Mena-Osteritz,
• Peter Bäuerle and
• Paul Ziemann

Beilstein J. Nanotechnol. 2011, 2, 561–568, doi:10.3762/bjnano.2.60

• , and given in panels Figure 4(c) and Figure 4(g), respectively, suggests that the observed asymmetry can be attributed to the fact that the central sulfur atom does not contribute significantly to the HOMO of a free molecule, as opposed to its contribution to the LUMO. Thus, with respect to symmetry

Platinum nanoparticles from size adjusted functional colloidal particles generated by a seeded emulsion polymerization process

• Nicolas Vogel,
• Ulrich Ziener,
• Achim Manzke,
• Alfred Plettl,
• Paul Ziemann,
• Johannes Biskupek,
• Clemens K. Weiss and
• Katharina Landfester

Beilstein J. Nanotechnol. 2011, 2, 459–472, doi:10.3762/bjnano.2.50

• spectroscopy (XPS), the lumps always contain PtO2. In this state also sodium and sulfur was detected when SDS was used as surfactant. Similar observations for Pt NPs produced from precursor-loaded colloids, prepared with emulsion or miniemulsion polymerization, have already been reported but were not

• with or without the precursor complex, and with SDS or Lutensol AT50 as surfactant. In contrast to SDS, which contains sodium and sulfur, Lutensol AT50 only consists of carbon, oxygen and hydrogen, which are likely to be transformed into volatile products during plasma treatment. The according etching

• proved by HRSEM (Figure 7, linear fit). In summary, the Pt precursor within the colloids as well as the surfactant SDS interferes with the etching process and, thus, leads to the saturated state. As they are not present in dispersion 4, non-volatile components such as metals (Pt, Na) and/or sulfur were

Towards a scalable and accurate quantum approach for describing vibrations of molecule–metal interfaces

• David M. Benoit,
• Bruno Madebene,
• Inga Ulusoy,
• Luis Mancera,
• Yohann Scribano and
• Sergey Chulkov

Beilstein J. Nanotechnol. 2011, 2, 427–447, doi:10.3762/bjnano.2.48

• vibrational structure, STM–IETS can be used to determine the adsorption geometry of a 4-mercaptopyridine molecule on the Au(111) surface [4]. This study confirmed that a coordination of the sulfur atoms by two gold atoms (bridge site or defect site) is likely to be the preferred binding mode for the adsorbate

• ) adsorbed on Au(111) (Figure 7) for different sizes of the partial Hessian matrix. The largest active system, mpy-ads-5, contains five gold atoms (the two gold atoms directly bonded to the sulfur atom, and the gold atoms which are bonded to both the first two gold atoms), thus yielding 48 normal modes. The

• next size down, mpy-ads-2, contains two gold atoms, both connected to the sulfur atom, giving 39 normal modes. Finally, mpy-ads-0 is a minimal model that does not include any gold atoms in the partial Hessian matrix (33 modes). The calculations were carried out using the Vasp [48] program and projector

Influence of water on the properties of an Au/Mpy/Pd metal/molecule/metal junction

• Jan Kučera and
• Axel Groß

Beilstein J. Nanotechnol. 2011, 2, 384–393, doi:10.3762/bjnano.2.44

• significant reduction of the DOS at the Fermi level results. Only upon the consideration of additional adsorbents, such as sulfur, nitrogen, thiolates, amines, or H on the Pd layer, can a downshift of the DOS in agreement with the experiment be obtained in the calculations [12]. However, there is no clear

• as Mpy since the sulfur head group of Mpy hardly affects the N–Pd contact. Upon the attachment of an up-right standing pyridine molecule to the Pd monolayer, with the water molecule adsorbed at the other side, the water adsorption energy was lowered to Eads = −1.10 eV, i.e., the water binding became

Studies towards synthesis, evolution and alignment characteristics of dense, millimeter long multiwalled carbon nanotube arrays

• Pitamber Mahanandia,
• Jörg J. Schneider,
• Martin Engel,
• Bernd Stühn,
• Somanahalli V. Subramanyam and
• Karuna Kar Nanda

Beilstein J. Nanotechnol. 2011, 2, 293–301, doi:10.3762/bjnano.2.34

• CNT synthesis, growth promoters such as thiophene, pure sulfur or hydrogen, and chemical oxidants such as oxygen, organic molecules (e.g., ethanol, ethers, aldehydes, ketones) or water have been employed for preparing ultra-long, aligned CNTs [8][23][24][25]. The ratio of the carbonaceous CxHy

Twofold role of calcined hydrotalcites in the degradation of methyl parathion pesticide

• Alvaro Sampieri,
• Geolar Fetter,
• María Elena Villafuerte-Castrejon,
• Adriana Tejeda-Cruz and
• Pedro Bosch

Beilstein J. Nanotechnol. 2011, 2, 99–103, doi:10.3762/bjnano.2.11

• . Conclusion In this work, the basic character of hydrotalcite oxides (M2+/Al3+) is reported for the first time to be essential for MP degradation. The resulting compounds are (p-NP) and other inorganic (sulfur and phosphorus containing compounds etc.) substances. The degradation of MP with hydrotalcite oxides