Materials and characterization techniques for high-temperature polymer electrolyte membrane fuel cells

• Roswitha Zeis

Beilstein J. Nanotechnol. 2015, 6, 68–83, doi:10.3762/bjnano.6.8

• occurs through the Grotthus mechanism. Phosphoric acid has an amphoteric nature and could act as either a proton donor (acidic) or a proton acceptor (base). It forms a dynamic hydrogen bond network; in which protons can readily transfer though the formation and cleavage of covalent bonds. Figure 5

• illustrates this dynamic hydrogen bond network between PBI and phosphoric acid. As shown in Figure 6 the conductivity of highly doped PBI is nearly as high as that of Nafion. Since the transfer of protons occurs by “hopping” though the hydrogen bond network, the conductivity of the acid-doped PBI is governed

• the channel wall enable hydronium conduction. Illustration of the proton conducting mechanisms in phosphoric acid (Grotthuss mechanism). 'Excess' proton or protonic defect diffuses through the hydrogen bond network of phosphoric acid. Chemical structures of m-PBI (poly[2,2-(m-phenylene)-5,5

Formation of stable Si–O–C submonolayers on hydrogen-terminated silicon(111) under low-temperature conditions

• Yit Lung Khung,
• Siti Hawa Ngalim,
• Andrea Scaccabarozzi and
• Dario Narducci

Beilstein J. Nanotechnol. 2015, 6, 19–26, doi:10.3762/bjnano.6.3

• cleave the silicon–hydrogen bond at the surface to form surface radicals. However previous studies had shown that hydrosilylation could also proceed at a lower temperature (110 °C). Wood et al. further suggested a reaction mechanism in which trace oxygen is involved in the extraction of hydrogen off from

Anticancer efficacy of a supramolecular complex of a 2-diethylaminoethyl–dextran–MMA graft copolymer and paclitaxel used as an artificial enzyme

• Yasuhiko Onishi,
• Yuki Eshita,
• Rui-Cheng Ji,
• Masayasu Onishi,
• Takashi Kobayashi,
• Masaaki Mizuno,
• Jun Yoshida and
• Naoji Kubota

Beilstein J. Nanotechnol. 2014, 5, 2293–2307, doi:10.3762/bjnano.5.238

• that of DDMC, the starting material. This means that the association with the hydrogen bond itself is weakened, which then reassembles the supramolecular complexes by a hydrophobic reaction between them. The escape of the crystallization water and the binding of DDMC to PTX decrease the entropy

• association, and the ζ-potential was approximately +24 mV. Considering that the average primary particle diameter of DDMC is approximately 25 nm, it seems that the DDMC/PTX complex forms small clusters of self-assembled supramolecular assemblies by its hydrophobic force following cleavage of the hydrogen bond

• . The DDMC/PTX complex, with a diameter of 200–300 nm, may make stable polymeric micelles by both the hydrophobic force and hydrogen bond. The ζ-potential of the particles, outside of the electric double layer, was +36 mV, which helps to stabilize the dispersion of the DDMC/PTX complex. Considering the

Influence of the supramolecular architecture on the magnetic properties of a Dy^III single-molecule magnet: an ab initio investigation

• Julie Jung,
• Olivier Cador,
• Kevin Bernot,
• Fabrice Pointillart,
• Javier Luzon and
• Boris Le Guennic

Beilstein J. Nanotechnol. 2014, 5, 2267–2274, doi:10.3762/bjnano.5.236

• ]imidazole. The magnetic susceptibility and magnetization at low temperature are found to be strongly influenced by supramolecular interactions. Moreover, taking into account the hydrogen-bond networks in the calculations allows to explain the orientation of the magnetic axes. This strongly suggests that

• , the latter behaves as a SMM in CH2Cl2 solution. This drastic difference of behavior between solid state and solution was attributed, with no clear experimental evidence, to the breaking of the hydrogen-bond network in solution. This is what we would like to clarify in the present work. Following this

• intramolecular interactions is not able to explain the solid-state magnetism of this complex. As already mentioned in the introduction, subtle geometric effects may change both magnetic susceptibility and orientation of the easy axis [39][40]. Contrary to Dy2, intermolecular hydrogen bond networks organize the

Modification of a single-molecule AFM probe with highly defined surface functionality

• Fei Long,
• Bin Cao,
• Ashok Khanal,
• Shiyue Fang and
• Reza Shahbazian-Yassar

Beilstein J. Nanotechnol. 2014, 5, 2122–2128, doi:10.3762/bjnano.5.221

• and the Au-coated probe, respectively. The other force curves showed either no obvious adhesion or only forces at zero separation (due to non-specific interaction). The forces that appear at non-zero tip–surface separations are believed to result from the rupture of a hydrogen bond between the

• 1.1–1.5, respectively, for the silicon probe, and 95 ± 64 pN, 111 ± 33 pN, and 3.5–4.4, respectively, for the Au-coated probe. Both probes had similar values of Fi, showing the same nature of the specific hydrogen bond interaction between the carboxylic acid groups on the probe and amino groups on the

• substrate. These values agreed with single hydrogen bond rupture forces of 50–250 pN reported in the literature [23][25]. The F0 value of the Au-coated probe was larger than that of the Si probe. This can be attributed to the larger radius of Au-coated probe due to coating layer of about 35 nm, and the

Sequence-dependent electrical response of ssDNA-decorated carbon nanotube, field-effect transistors to dopamine

• Hari Krishna Salila Vijayalal Mohan,
• Jianing An and
• Lianxi Zheng

Beilstein J. Nanotechnol. 2014, 5, 2113–2121, doi:10.3762/bjnano.5.220

• of the ssDNA–DA complex containing bases G and A, which have better affinity to SWCNT [35], causes the charge traps formed by ssDNA–DA adducts to be in greater proximity to the nanotube surface, thus, increasing the hysteresis gap (+∆H). Anions such as UA are predominantly involved in hydrogen bond

Non-covalent and reversible functionalization of carbon nanotubes

• Antonello Di Crescenzo,
• Valeria Ettorre and
• Antonella Fontana

Beilstein J. Nanotechnol. 2014, 5, 1675–1690, doi:10.3762/bjnano.5.178

• with N,N-dimethylformamide (DMF) [40], highlighting that a high value of β (the hydrogen bond acceptance basicity), a negligible value of R (the hydrogen bond donation parameter of Taft and Kamlet) and a high value for π* (solvochromic parameter) [41] are necessary, although not sufficient conditions

A sonochemical approach to the direct surface functionalization of superparamagnetic iron oxide nanoparticles with (3-aminopropyl)triethoxysilane

• Bashiru Kayode Sodipo and
• Azlan Abdul Aziz

Beilstein J. Nanotechnol. 2014, 5, 1472–1476, doi:10.3762/bjnano.5.160

• surface of SPION via hydrogen bond can be observed by the appearance of the bands at 1627 and 3419 cm−1 in Figure 1a. Similar to the report of Ma et al., [14], the peaks of the N–H bending and stretching of terminal primary amine group cannot be seen in Figure 1b, as they overlap with the 1627 and 3419 cm

DFT study of binding and electron transfer from colorless aromatic pollutants to a TiO₂ nanocluster: Application to photocatalytic degradation under visible light irradiation

• Corneliu I. Oprea,
• Petre Panait and
• Mihai A. Gîrţu

Beilstein J. Nanotechnol. 2014, 5, 1016–1030, doi:10.3762/bjnano.5.115

• hydrogen bond involving the same carboxy group. We clearly demonstrate that the ‘common knowledge’ that the binding configuration is in a six ring chelate, suggested by infrared spectroscopy measurements [19][20] or simply assumed by other authors [14][18], is wrong. There are two direct bonds to two

Adsorption and oxidation of formaldehyde on a polycrystalline Pt film electrode: An in situ IR spectroscopy search for adsorbed reaction intermediates

• Zenonas Jusys and
• R. Jürgen Behm

Beilstein J. Nanotechnol. 2014, 5, 747–759, doi:10.3762/bjnano.5.87

• intermediates in density functional theory based studies of the interaction of methanol with a Pt(111) surface [50]. The importance of water in the initial steps of dehydrogenation of methanol over Pt(111) via polarization of the hydroxyl due to hydrogen bond formation with a neighboring water molecule was

Spin relaxation in antiferromagnetic Fe–Fe dimers slowed down by anisotropic Dy^III ions

• Valeriu Mereacre,
• Frederik Klöwer,
• Yanhua Lan,
• Rodolphe Clérac,
• Juliusz A. Wolny,
• Volker Schünemann,
• Christopher E. Anson and
• Annie K. Powell

Beilstein J. Nanotechnol. 2013, 4, 807–814, doi:10.3762/bjnano.4.92

• hydrogen bond from a (μ3-OH) ligand. The coordination is completed by two azido anions coordinated to the outer iron atoms (Fe(2) and Fe(4)). All four Fe ions are six-coordinate with distorted octahedral geometries, while the DyIII ions are eight-coordinate with coordination polyhedra that may best be

Large-scale atomistic and quantum-mechanical simulations of a Nafion membrane: Morphology, proton solvation and charge transport

• Pavel V. Komarov,
• Pavel G. Khalatur and
• Alexei R. Khokhlov

Beilstein J. Nanotechnol. 2013, 4, 567–587, doi:10.3762/bjnano.4.65

• will not contribute significantly to the actual diffusion of protons in water phase. This picture is in agreement with both experimental observation [101] and theoretical work [102] which predicts that proton transfer along the hydrogen bond network should be essentially barrierless. Also, the proton

• aqueous medium occur very fast, typically within 0.1–0.2 ps. Due to the further solvation, the ion pairs transform into shared proton complexes SO3−·H3O+·(H2O). The Zundel cations are then formed via the proton transfer reaction H3O+ + H2O → H5O2+. At the next step, the topological defects in the hydrogen

• bond network occur in the form of Zundel–Zundel transformations. Also, the solvated hydronium complexes in the form of the Eigen cations exist as an intermediate state in Zundel–Eigen–Zundel proton exchange. The hydronium and the nearest water molecules constantly interchange the proton within a very

Molecular dynamics simulations of mechanical failure in polymorphic arrangements of amyloid fibrils containing structural defects

• Hlengisizwe Ndlovu,
• Alison E. Ashcroft,
• Sheena E. Radford and
• Sarah A. Harris

Beilstein J. Nanotechnol. 2013, 4, 429–440, doi:10.3762/bjnano.4.50

• properties [23]. The SMD pulling geometries are designed to disrupt the stabilising hydrophobic core and backbone hydrogen bond networks from a variety of directions. We then assess how the mechanical response in the simulations is affected by doubling the length of the model fibrils, and how the mechanical

•  5. All three fibril polymorphs demonstrate an anisotropic response to mechanical probing. Similar mean peak forces are required to break the fibrils when the hydrogen-bond networks are probed (“shear” and “stretch”). There are however, very distinct responses in the SMD simulations that probe the

• demonstrates how the details imposed by polymorphic arrangements of the peptides in the fibril can determine the mechanical characteristics when a force is applied in a particular direction. Hydrogen-bond-network response: In the two pulling geometries (“shear” and “stretch”) that primarily interrogate the

Nanoscopic surfactant behavior of the porin MspA in aqueous media

• Ayomi S. Perera,
• Hongwang Wang,
• Tej B. Shrestha,
• Deryl L. Troyer and
• Stefan H. Bossmann

Beilstein J. Nanotechnol. 2013, 4, 278–284, doi:10.3762/bjnano.4.30

• surfaces has a disruptive effect on the water structure. Whereas the hydrogen bond network of water around an alkane of modest length (e.g., C6H14) is not distorted significantly, the solvation of extended hydrophobic structures has a disruptive effect on the water structure because it prohibits the

Dimer/tetramer motifs determine amphiphilic hydrazine fibril structures on graphite

• Loji K. Thomas,
• Nadine Diek,
• Uwe Beginn and
• Michael Reichling

Beilstein J. Nanotechnol. 2012, 3, 658–666, doi:10.3762/bjnano.3.75

• in Figure 4c). As evident from Figure 4c and Figure 5a, such a flipped molecule can form only one hydrogen bond with the neighbouring dimer and is tilted in the opposite direction yielding a step in the molecular contour of the hydrogen-bonded units. The loss of one hydrogen bond at defect sites is

• fragment may result if the specific zigzag structure facilitates a hydrogen-bond closure from open hydrogen bonds, as indicated (unbonded H atoms at the top of the net and O atoms at the bottom) in Figure 5a. Fibril fragments can grow with different diameters depending on the number of molecules in the

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

• ,ω-dicyano substituted β,β'-dibutylquaterthiophene (DCNDBQT) molecules by forming a hydrogen bond between the cyano group of CNBTPA and a hydrogen on the thiophene ring of DCNDBQT, and by forming a hydrogen bond between the cyano group of DCNDBQT and a hydrogen on the thiophene ring of CNBTPA [90]. A

STM study on the self-assembly of oligothiophene-based organic semiconductors

• Elena Mena-Osteritz,
• Marta Urdanpilleta,
• Erwaa El-Hosseiny,
• Berndt Koslowski,
• Paul Ziemann and
• Peter Bäuerle

Beilstein J. Nanotechnol. 2011, 2, 802–808, doi:10.3762/bjnano.2.88

• moments of the molecules, which are oriented along the molecular axis (Figure 2, right; plain arrows). The carboxylic acid groups of two head-to-head arranged molecules are able to undergo hydrogen-bond formation, additionally stabilizing the monolayer (Figure 2, right). In the current image (Figure 2

Approaches to nanostructure control and functionalizations of polymer@silica hybrid nanograss generated by biomimetic silica mineralization on a self-assembled polyamine layer

• Jian-Jun Yuan and
• Ren-Hua Jin

Beilstein J. Nanotechnol. 2011, 2, 760–773, doi:10.3762/bjnano.2.84

• associate with acidic molecules to form complexes by hydrogen-bond interaction. This simple acid–base complex chemistry has been exploited to control silica nanostructures in solution and further to achieve porphyrin functionalization of LPEI@silica powder materials with 5,10,15,20-tetrakis-(4

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

• as it contains 78 modes and the weak π–hydrogen bond requires correlated electronic structure methods. The computed harmonic frequency for the stretching mode of HF adsorbed on pyrene is 3661 cm−1 which is −112 cm−1 away from that of the free HF molecule, ω(HF) = 3773 cm−1 at this level of theory. At

Intermolecular vs molecule–substrate interactions: A combined STM and theoretical study of supramolecular phases on graphene/Ru(0001)

• Michael Roos,
• Benedikt Uhl,
• Daniela Künzel,
• Harry E. Hoster,
• Axel Groß and
• R. Jürgen Behm

Beilstein J. Nanotechnol. 2011, 2, 365–373, doi:10.3762/bjnano.2.42

• limitation to specific adsorption sites in combination with the distinct positions of the hydrogen bond donors and acceptors within the molecule results in the formation of 1D chain structures (Figure 3b), similar to findings recently reported for the adsorption of PTCDI molecules on graphene/Rh(111) [18

Novel acridone-modified MCM-41 type silica: Synthesis, characterization and fluorescence tuning

• Maximilian Hemgesberg,
• Gunder Dörr,
• Yvonne Schmitt,
• Andreas Seifert,
• Zhou Zhou,
• Robin Klupp Taylor,
• Sarah Bay,
• Stefan Ernst,
• Markus Gerhards,
• Thomas J. J. Müller and
• Werner R. Thiel

Beilstein J. Nanotechnol. 2011, 2, 284–292, doi:10.3762/bjnano.2.33

• cm−1, 1609 cm−1) indicating an interaction of the carbonyl group with Lewis or Brønsted acidic or with hydrogen-bond-donating surface sites, which has previously been described for fluorescent probes such as Michler’s ketone [19]. This again changes after the reaction with Sc(OTf)3: A single C=O

Review and outlook: from single nanoparticles to self-assembled monolayers and granular GMR sensors

• Alexander Weddemann,
• Inga Ennen,
• Anna Regtmeier,
• Camelia Albon,
• Annalena Wolff,
• Katrin Eckstädt,
• Nadine Mill,
• Michael K.-H. Peter,
• Jochen Mattay,
• Carolin Plattner,
• Norbert Sewald and
• Andreas Hütten

Beilstein J. Nanotechnol. 2010, 1, 75–93, doi:10.3762/bjnano.1.10

• on dipole–dipole-, hydrogen bond- or van der Waals interactions. They do usually not show covalent characteristics. Tensides can be characterized by their head groups via which they interact with metal atoms on the surface of the particles. We distinguish between tensides such as TOPO which has a