Overview of the activity of the G.M.J. Schmidt Minerva Center for
Supramolecular Architectures for the years 2005 and 2006
R. Tenne, Director
World Without Weapons
P. Picasso, 1962
Friction ( monolayer )
Au
+
NH3
Topography ( bilayer )
Au
+
NH3
+
NH3
C20
Si
OH
CH3 OH
O Si O Si
OH
OH
OH
OH CH3
Topography ( colloidal gold pattern )
Shantang Liu & Rivka Maoz (2001)
2001)
S. Liu et al., Nano Lett.
Lett. 2004,
2004, 4, 845
Prof. J. Sagiv: Constructive Lithography of self-assembled mono(multi)layers (World Without
Weapons, Picasso)
Dr. Ernesto Joselevich: Torsional nanoelectromechanical device based on a gold pedal attached to a
carbon nanotube
Dr. Roy Bar-Ziv: Patterning DNA with a micron precision for in-vitro transcription-translocation of
proteins on Si (glass) chip (The creation of Adam by Michelangelo, Sistine Chapel, Rome
1
a. Introduction
a.1. General
This is the second biannual report of the G.M.J. Schmidt Minerva Center during its
second term, which started in 2002. During this period the center has witnessed a surge of
activity and it supported numerous collaborations between the relevant scientists at the
WIS and German research groups. These collaborations are summarized below, together
with the joint scientific publications which ensued and the numerous visits of students
and researchers which were supported by the center. The financial report of the center is
attached as an appendix to this scientific report.
a.2. The Beirat
The current director of the center (R. Tenne) is about to step down and will be replaced
by Prof. David Cahen the new (as of 1.4.07) chairperson of the Department of Materials
and Interfaces at the Weizmann Institute of Science. David has a long history of
extremely fruitful collaborations with German science. His current strong collaboration
with Prof. Eberhard Umbach from Würzburg University (vide infra) on organic/inorganic
interfaces makes his leadership role in the center both timely and scientifically very
crucial for the success of the center. To secure the continuity of leadership, Prof. Sam
Safran, who finished recently his term as a senior vice resident of the WIS, and was
involved in the Minerva Center Beirat during its first term, will rejoin the current Beirat
of the center.
The Beirat is directed by Prof. Hans-Jürgen Butt of the MPI-Mainz, and includes also
Prof. W. Tremel (University of Mainz) and P. Fratzl (MPI-Gölm) on the German side. On
the Israeli side Profs. D. Milstein (Organic Chemistry-WIS), I. Talmon (Chemical
Engineering-Technion) and S. Vega (Chemical Physics-WIS) will continue to serve on
the Beirat.
a.3. The scientific objectives
The scientific objectives of the center are mainly two: 1. to promote collaborations
among German and Israeli scientists in the area of supramolecular chemistry and
nanoscale science in its broadest meaning; 2. to provide means for the direct contacts
between students and young researchers from the two countries in the general area of
supramolecular chemistry. In addition to these two main objectives, the center seeks to
enhance the overall scientific activity in this field at the Weizmann Institute. To fulfill
these goals, the Center has been involved in the following activities.
b. Support for scientific activities
The present account is quite general, with details of the supported items given in the
financial report.
b.1. Support for scientific visits
The Center supported visits of senior German and a few non-German scientists in the
WIS. Three outstanding collaborations deserve special notice
1. The periodical visits of Profs. Umbach (Würtzburg University) and Antoine Kahn
(Princeton University) at the WIS during the last three years are outstanding example of
how the center can in fact catalyze and promote a unique kind of collaboration between
WIS scientists (Prof. D. Cahen, Prof. R. Naaman and Dr. L. Kronik) and elite German
2
and US research groups in the field of organized molecular assemblies on semiconductor
surfaces.
2. Another outstanding example is the recent collaboration established between the
groups of Prof. Knut Urban, the director of the Ernst Ruska Center for high resolution
electron microscopy in the research center of Jülich; the theory group of Prof. Gotthard
Seifert of the TU Dresden and the nanomaterials synthesis group of Prof. R. Tenne
(WIS). The joint research program is concerned with the elucidation of the structure of
MoS2 nanooctahedra. The group of Prof. Urban (Dr. L. Houben) will pay its second visit
at the WIS next month, while Mrs. M. Bar-Sadan a Ph.D. student in Tenne’s group has
visited Jülich and Dresden twice and established a very thorough collaboration. This
collaboration became so effective that Mrs. Bar-Sadan has decided to spend her Post-Doc
stint in Urban’s lab in order to learn the Cs corrected Ultra HRTEM and make it a central
piece of her future scientific career.
3. Prof. Peter Fratzl visited the WIS for the first time during the 6th Minerva Student
Symposium in 2005 (he visited the WIS again in 2006). As a result of this visit a very
extensive collaboration was established between his laboratory and two laboratories at
the WIS: the group of Prof. H.D. Wagner dealing with the nanomechanics of teeth; and
the group of Prof. Michael Elbaum, both of the Materials and Interfaces Department.
Prof. Elbaum spent his sabbatical (2006) in Fratzl lab, while his wife who graduated from
Prof. Steve Weiner group (Structural Biology-WIS) spent a post-doc period in the same
lab. Moreover, Dr. Paul Zaslansky, another graduate of Weiner lab is spending now a
post-doc stint in Fratzl lab. He is organizing a joint Minerva School on bioinspired
materials in Gölm which will take place at the end of May jointly with the 7th Minerva
students symposium.
Obviously these three unique kinds of collaborations would not be possible without the
modest support of the Minerva Center. In the detailed scientific report below various
other collaborative programs which were based on mutual visits are described.
In addition to that the center provides support for visits of senior visitors in the field of
activity of the center from other countries. Thus Prof. (Sir) Fraser Stoddart (UCLA) spent
here three days. Prof. Brahat Bushan (Ohio State), an expert in surface science and
tribology lectured here. Prof. P.-G. DeGennes (Nobel Laureate) visited us and gave a
lecture on polymer physics with the support of the center. Dr. Jeremy Sloan an expert in
high resolution TEM imaging of nanomaterials (Oxford University). Prof. Lian Mao
Peng (Peking University-Beijing) gave a talk on nanomanipulation of carbon nanotubes
within the TEM. More recently, Prof. R. Dunin-Borkowski (Cambridge University)
visited here and gave a talk on high-resolution electron holography. Prof. (Sir) Richard
Friend (Cambridge University) is to visit us next month with the support of the center.
The center provide support to the annual visits of Prof. Tamar Seidman (Northewestern
University), who collaborates with Prof. Ron Naaman on calculations of the charge
transport in molecular electronics. Prof. Howard Katz (former president of the MRS and
currently of the IUMRS) visited us last year and gave a talk on organic transistors.
b.2. Support for visits of the Center’s students in Germany and elsewhere
It is worthwhile mentioning the last summer visit of Ms. Shani Eliyahu in the laboratory
of Prof. Andreas Offenhäusser in the Forschungszentrum Jülich and Prof. Ralf
Wehrspohn at Paderborn University. Shani is an M.Sc. student in Prof. Israel
3
Rubinstein’s group at the Materials and Interfaces Dept. of the WIS. Rubinstein knows
Prof. A. Offenhäusser from the period where they spent their post-doc stint in Prof. Allen
Bard’s lab in the US, long time ago. During the 6th Minerva student symposium in 2005
at the WIS, they discussed possible joint work and decided to start working jointly on a
new idea, which led to the above visit.
Another noticeable example in this respect is the post-doctoral work of Dr. Thorsten Auth
in the group of Prof. Sam Safran (WIS).
b.3. Small research grants
Like in the past, the center continues to provide small research grants, which usually
amounts to about half an annual fellowship for a Ph.D. student (7500 Euro), with
preference (but not exclusive) support to laboratories which demonstrate strong
collaboration with German laboratories.
b.4. Fellowships
The Center provided also partial support for fellowships of students, post-docs and
research associates. One of the missions of the center is to promote collaboration between
young research scientists from Germany and Israel. An outstanding example in this
connection is the support given to Dr. Leeor Kronik, A DFT theorist, who collaborates
with Prof. Eberhard Umbach (Würtzburg University) and Dr. Stephan Kümmel from the
University of Bayreuth). Stephan and Leeor know each other from their joint post-doc
work with Jim Chelikowki in the US. Recently, they contributed a major research article
to Rev. Modern Phys., the physics journal with the highest impact factor (close to 30).
The center supported the mutual visits of Dr. Kümmel here and that of Leeor’s studentMr. Amir Nathan, in this and other labs in Germany. Furthermore, the center supported
this joint work with a partial fellowship to Mr. Amir Nathan.
b.5. Support for equipment
A few grants of up to 10,000 Euro were allocated in partial support of upgrading the
scientific equipment of some WIS laboratories. The Center has allocated partial support
to some unique pieces of equipment, like the cryostat for CW X-band EPR spectrometer
(Prof. D. Goldfarb); optical microscope and camera (H.D. Wagner). The Minerva Center
gave a modest support towards the modernization of the powder diffraction laboratory,
which plays a vital role in the work of many scientists of the Center.
b.6. Support for student’s participation in conferences
The Center gave partial support to students who took part in local conferences related to
the activity of the Center, like the Annual Israel Chemical Society meeting. It also
provided support to a few symposia which were organized by members of the Center, or
affiliated with the center’s activity. Recognition to the center was given in each case. It is
worthwhile mentioning the mini-symposium organized by Profs. Sam Safran and Jacob
Klein in November 2006 with the participation of renowned sceitists, like Prof. P.G. deGennes (Nobel Laureate) and Prof. C. Bustamante (UC Berkeley) and Prof. E. Sackmann
(University of Munich). This mini-symposium gathered experts from the entire world
b.7. Support for the joint Minerva Students’ Symposia series
One of the foremost activities of the Center was the biannual students’ symposia. The 6th
biannual symposia on the topic of “Molecular-based devices” took place in 2005 at the
WIS. About 15 students and about 5 senior scientists came from Germany to attend ths
4
symposium. These series of symposia are jointly organized with the Reimund Stadler
Minerva Center of Ben-Gurion University in Beer Sheba. The 7th symposium in this
series will take place between 29.5-3.6.07 in the Harnackhaus in Berlin. This symposium
will be organized in conjunction with the Minerva School for “Bio-Inspired Materials”
which is organized by Prof. Fratzl’s lab (Dr. Paul Zaslansky). It is expected that the
support of the Center to this series will increase in the near future.
c. Scientific reports of specific groups associated with the Center
c.1. Dr. Milko van der Boom, Department of Organic Chemistry
The research within my group at the Department of Organic Chemistry at the Weizmann
Institute of Science is positioned at the interface of the following disciplines:
coordination/organometallic chemistry and chemistry of materials. This includes
chromophore design, synthetic methodology/mechanistic studies, synthesis and
characterization, thin film assemblies, patterning and prototype device formation. Its
multidisciplinary character is unique within Israel and attracts M.Sc. and Ph.D. students
with a variety of backgrounds. It is meant to function as a bridge between solution and
interface research. The research topics are closely linked to a broad array of methods to
elucidate structure, reaction mechanism, bonding and physicochemical properties of
molecular-based materials.
Support of the G.M.J. Schmidt Minerva Center allowed us to study the formation of new
metal complexes. Detailed mechanistic studies in solution are necessary to develop new
molecular building blocks for our thin film chemistry. In addition, we have studied the
physicochemical properties of series of new metal-chromophore based monolayers.
Metal-to-ligand charge transfer is known to significantly enhance the optical
(non)linearity and can be controlled as a function of the metal oxidation state. We have
shown that this property can be utilized to study electron transfer at the solution-interface
and to form monolayer-based chemical sensors and memory elements. The generous
support of the center has been acknowledged in 16 poster presentations in Israel and in 15
academic seminars and conference talks in the United States, Israel, Swiss, Italy, The
Netherlands and Germany. Three articles have been submitted to the Journal of the
American Chemical Society. Our German collaborators (Jürgen Heck, Sigurd Schrader
and John A. Gladysz) continue to play a significant role in terms of advice and
performing various analyses. I organized a Minerva Conference “Advances and Trends
on Organic Chemistry” at the Weizmann Institute of Science, December 9-12, 2006 See
details in Sec. d of this report).
Our group will continue to work with various German scientists. For instance, I invited
Prof. Dr. Manfred T. Reetz (Max-Planck-Institut für Kohlenforschung) to give a talk on a
one-day symposium at the Weizmann Institute on December 2, 2007.
I currently collaborate with the following German groups: 1. Prof. Dr. Jürgen Heck
(University of Hamburg), http://www.chemie.uni-hamburg.de/ac/AKs/Heck/. 2. Prof. Dr.
Sigurd Schrader (University of Applied Sciences Wildau), http://www.tfhwildau.de/iplpt/. 3. Prof. John A. Gladysz, University of Erlangen,
http://www.chemie.uni-erlangen.de/gladysz/
5
I was the chairperson of the Minerva symposium “Advances and Trends on Organic
Chemistry” at the Weizmann Institute of Science, December 9-12, 2006. This meeting
was attended by ~200 participants. German speakers included: Helmut Schwarz (TU
Berlin), Lutz H. Gade (University of Heidelberg), Lutz Ackermann (University of
Munchen), Jürgen Heck (University of Hamburg), John A. Gladysz (University of
Erlangen), Janet Blümel (University of Heidelberg), Carsten Bolm (University of
Aachen) and Holger Braunschweig (University of Würzburg). About 10 German and 50
Israeli students presented posters. In this opportunity, Professor Helmut Schwarz
presented also a lecture for our faculty colloquium series.
List of papers with acknowledgment to the center
1. T. Gupta and M.E. van der Boom, Monolayer-based sensor for selective optical recognition of iron(III)
via electron transfer processes, submitted.
2. Control of aryl–halide bond activation by platinum ring-walking, O. Zenkina, M. Altman, L.J.W.
Shimon, and M.E. van der Boom, submitted.
3. R. Yerushalmi, M.E. van der Boom, and H. Cohen, Non-contact detection of chemical-site capacitance,
submitted.
c.2. Prof. S.A. Safran, Department of Materials and Interfaces
c.2.a. We show theoretically how ATP-induced dissociations of spectrin filaments in the
cytoskeleton network of red blood cells (RBC) can explain in a unified manner both the
measured fluctuation amplitude as well as the observed shape transformations. The
number of these ATP-induced defects can be dramatically increased by external stresses
such as those present when RBC must pass through small capillaries. We predict that the
actin freed from these defects is the physical origin of the activation of the CFTR
membrane-bound protein and the subsequent release of ATP by RBC subjected to
deformations. The theory can be tested by experiments that measure the correlation
between variations in the binding of actin to spectrin, the activity of CFTR, and the
amount of ATP released. For further details, consider publication o. 1 in the list below.
c.2.b. Cells play an active role in the maintenance of mechanical homeostasis within
tissues and their response to elastic forces is also important for tissue engineering. We
predict the collective response of an ensemble of contractile cells in a three-dimensional
elastic medium to externally applied strain fields. Motivated by experiment, we model the
cells as polarizable force dipoles that change their orientation in response to the local
elastic strain. The analogy between the mechanical response of these systems and the
dielectric response of polar molecules is used to calculate the elastic response function,
analogous to the dielectric constant. We use this analogy to evaluate the average cell
orientation, the mean polarization stress and the effective elastic constants of the material,
as a function of the cell concentration and matrix properties. For further details, see Refs.
2 and 3 in the list below.
c.2.c.We predict the fluctuation spectrum of the bilayer membrane of the red blood cell
using a continuum, coupled membrane theory that includes the excluded volume
interaction between the bilayer and the two-dimensional, spectrin cytoskeleton. In our
model, a homogeneous, external pressure maintains an average distance between the
bilayer and the skeleton, eliminating the need to consider the discrete anchor proteins that
provide the coupling in actual cells. We find that, despite of the complex microstructure
of bilayer and cytoskeleton in a real cell, the fluctuations with wavelengths >400nm are
6
well described by the fluctuations of a single, polymerized membrane (provided that
there are no inhomogeneities in the microstructure). The model is applied to the
fluctuation data of discocytes ('normal' red blood cells), a stomatocyte, and an echinocyte.
The elastic parameters of the membrane and the effective temperature due to active
effects can be extracted from the experiments. For more details, consider publications 4
and 5 in the list below.
List of papers with acknowledgment to the center
1. N.S. Gov and S.A. Safran, Red Blood Cell Membrane Fluctuations and Shape Controlled by
ATP-Induced Cytoskeletal Defects, Biophys. Journal 88, 1859–1874 (2005).
2. A. Besser and S. A. Safran, Force-Induced Adsorption and Anisotropic Growth of Focal Adhesions,
Biophys. Journa, 90, 3469–3484 2006).
3. A. Zemel, B. Bischofs, and S. A. Safran, Active Elasticity of Gels with Contractile Cells, Phys. Rev. Lett.
97, 128103 (2006)
4. T. Auth, S. A. Safran and N. Gov, Thermal fluctuations of coupled fluid and solid membranes,
submitted.
5. T. Auth, S. A. Safran and N. Gov, Coupled membrane model for red blood cell fluctuations, submitted.
Mr. A. Besser was a visiting student (7 months) from Heidelberg while Mr. B. Bischofs
came for only a short visit here.
c.3. Prof. M. Lahav, Department of Materials and Interfaces
This work was aimed at challenging reports claiming to have demonstrated the Parity
Violating Energetic Difference (PVED) between enantiomorphous D- and L-crystals.
Apart from PVED, the presence of minute quantities and differing profiles of impurities
incorporated during their different history of preparation will affect the physical
properties of D- and L-crystals. These impurities are anticipated to play a much greater
role in affecting crystallization behavior than PVED. The effect of impurities on the
growth and dissolution of enantiomorphous crystals is illustrated with some
representative examples. Shinitzky et al. (2002) reported recently dramatic differences in
the growth and dissolution properties of the D- and L-crystals of tyrosine. We have
repeated these experiments using commercial samples from different sources and
employing a validated enantioselective gas chromatographic technique. We attribute
Shinitzky's findings either to the use of inappropriate analytical techniques for the
determination of enantiomeric composition and/or to the presence of unidentified
contaminants in the commercial tyrosine samples. Related caveats hold also for the
recently published claims by Shinitzky (2006) and Scolnik et al. (2006) to have observed
experimentally PVED between enantiomeric helices of poly-glutamic acid composed of
24 repeating units.
List of papers with acknowledgment to the center
1. M. Lahav, I. Weissbuch, E. Shavit, C. Reiner, G.J. Nicholson, V. Schurig (Univ Tubingen), Parity
violating energetic difference and enantiomorphous crystalsp-caveats; reinvestigation of tyrosine
crystallization, Origin Life Evolution Biosphere 36, 151-170 (2006).
c.4. Prof. M. Elbaum, Department of Materials and Interfaces
The works in my lab at the Weizmann Institute center on molecular exchange in the cell
between the nucleus and the cytoplasm. Building on a background in physics of soft
condensed matter, we approach this fundamental problem in cell biology with an
approach based on biophysics and materials science. Three publications were supported
7
by the Gerhard M.J. Schmidt Minerva Center for Supramolecular Architecture in the
period 2005 – 2006 (listed below). Briefly, these address the interaction of the
biochemical machinery of nuclear import with cytoplasmic delivery along microtubules,
the interaction of the major nucleocytoplasmic transport receptor protein importin beta
with its regulating GTPase Ran, and the regulation of interaction between DNA and an
essential virulence protein of Agrobacterium tumefaciens. This organism is able to
deliver foreign genes to plant cells by a process akin to bacterial conjugation. The paper
was noted in the Faculty of 1000. In addition, a new and, in my opinion, conceptually
very important work on the physical underpinnings of protein import to the nucleus is
currently in review.
During the period March 2006 through February 2007 I was on sabbatical in Potsdam,
Germany. Through the month of September I worked with the group of Dr. Gerd
Schneider at the BESSY synchrotron in Berlin, where a new instrument for X-ray
microscopy is being installed. I believe that my prior experience with electron
microscopy and tomography made a useful contribution. I had several sessions of use on
the existing microscope, where I was able to scan a fair number of samples for feasibility
of biological imaging with soft x-rays. We collected beautiful datasets from nematodes
and single-celled ciliates. During the summer, however, it was decided to advance the
planned upgrade of the microscopy beamline from September 2007 to September 2006 so
my active participation ended then. In hopes of continuation I wrote a proposal to GIF
with Dr. Schneider on biological applications of the X-ray microscope, with a focus on
Agrobacterium tumefaciens.
From October I worked at the Max Planck Institute of Colloids and Interfaces, in the
Biomaterials Department with Prof. Peter Fratzl. There I studied the organization of
cellulose in a common sea grass, Zostera marina. As rooted but boyant plants, the force
due to gravity is inverted with respect to terrestrial species. Its tape-like leaves, 4-5 mm
wide, less than half a mm thick, and as much as a meter long, show remarkable
mechanical strength in the presence of waves and tidal currents. I characterized the
structural, chemical, and mechanical properties of fiber cells in the leaf using the many
tools available at the MPI. The study was very rewarding and a manuscript is in
preparation.
During the year I also built new contacts in Germany, particularly at the Max Planck
Institute of Molecular Plant Physiology on the same campus, and at the MPI of Molecular
Cell Biology and Development in Dresden.
Presently, I receive a grant from the Minerva Research Foundation for a project on threedimensional particle tracking microscopy. This is in collaboration with Prof. Ulrich
Kubitscheck at the University of Bonn. He and I share a common interest in biophysics of
the cell nucleus, and we have met many times at conferences, at his new home this year,
and at his previous lab in Muenster. In addition, I am organizing a Minerva-sponsored
meeting this coming November on biological motility, from molecules to animals, in
collaboration with Prof. Orly Reiner from the Molecular Genetics Department at WIS,
and Prof. Eckhard Mandelkow from the Max-Planck Arbeitsgruppen für strukturelle
Molekularbiologie in Hamburg.
List of papers with acknowledgment to the center and papers relevant to the center activity
8
1. D. Frenkiel-Krispin, S.G. Wolf, S. Albeck, T. Unger, Y. Peleg, J. Jacobovitch, Y. Michael, S. Daube, M.
Sharon, C.V. Robinson, D.I. Svergun, D. Fass, T. Tzfira, and M. Elbaum, Plant transformation by
Agrobacterium tumefaciens: Modulation of single-stranded DNA-VirE2 complex assembly by VirE1, J
Biol Chem. 282, 3458-64 (2007).
2. M. Elbaum, Polymers in the pore, Science 314, 766-7 (2006) (invited commentary).
3. C. Fradin, D. Zbaida, and M. Elbaum, Dissociation of nuclear import cargo complexes by the protein
Ran: a fluorescence correlation spectroscopy study, C R Biol. 328, 1073-1082 (2005).
4. H. Salman, A. Abu-Arish# , S. Oliel, A. Loyter, J. Klafter, R. Granek, and M. Elbaum, Nuclear
localization signal peptides induce molecular delivery along microtubules, Biophys J 89: 2134-2145 (2005).
5. J. Li, S.G. Wolf, M. Elbaum, and T. Tzfira, Exploring cargo transport mechanics in the type IV secretion
systems, Trends Microbiol 13, 295-298 (2005) (perspective).
c.5. Prof. I. Rubinstein, Department of Materials and Interfaces
In July-August 2006 my M.Sc. student Shani Eliyahu spent approx. two months in
Germany as a recipient of a North Rhine-Westfalia fellowship. Shani stayed in two
laboratories: (i) Prof. Andreas Offenhäusser, Forschungszentrum Jülich; (ii) Prof. Ralf
Wehrspohn, Paderborn University. In Jülich Shani worked on the preparation of nanopillared gold surfaces to be used for improved contact with neuronal cells. In Paderborn
Shani worked on template synthesis of polymeric nanotubes. Figure 1 shows a nanopillared gold surface prepared by Shani in Jülich.
Other scientific activities in Germany:
On February 1-3, 2006, I participated in an evaluation panel of the Deutsche
Forschungsgemeinschaft (DFG) Priority Program on “Nanowires and Nanotubes - From
Controlled Synthesis to Functions” (Bad Honnef, Germany).
On November 20-21, 2006, I participated in a review panel of the Deutsche
Forschungsgemeinschaft (DFG) Excellence Initiative on “Molecular Function and
Interaction” (Frankfurt, Germany).
9
Figure 1. Gold nano-pillars prepared by template synthesis, shown at two magnifications. Preparation
procedure: A Si wafer was sequentially coated (by evaporation) with Ti (10 nm), Au (200 nm), and Al (500
nm). The Al was anodized under controlled conditions to provide a nanoporous alumina layer on the Au.
The Au electrode was then used as a cathode for electrodeposition of Au nano-pillars in the alumina
membrane pores. The membrane template was then dissolved in NaOH.
Experiment carried out by Shani Eliyahu at the Forschungszentrum Jülich.
List of papers with acknowledgment to the center
1. T. Sehayek, T. Bendikov, A. Vaskevich, I. Rubinstein, Au-Pd Alloy Gradients Prepared by Laterally
Controlled Template Synthesis, Adv. Funct. Mater. 16, 693-698 (2006).
c.6. Dr. S.R. Cohen, Head of the Scanning Probe Microscopy Lab (associate member of
the Center)
In a continuation of the microscopic determination of mechanical properties of individual
WS2 nanotubes, the shear behavior of multiwalled nanotubes were investigated in the
scanning probe microscope (SPM). By proper choice of geometry, and knowledge of the
bending modulus from previous experiments [1], 3-point bending tests [2] were exploited
to extract the shear component which could be directly related to sliding between the
layers of the multiwalled nanotube. First-principles calculations performed by the group
of Gotthard Seifert of Univ. Dresden provided a basis for distinguishing between in-plane
shear and sliding [3]. The facile sliding under shear of these nanotubes, leads to a large
anisotropy between the bending and shear moduli, a feature which distinguishes these
structures from carbon nantubes. The results have important implications for proposed
tribological applications [4].
1. a. I. Kaplan-Ashiri, S.R. Cohen, K. Gartsman, V. Ivanovskaya, T. Heine, G. Seifert, I. Wiesel, H.D.
Wagner, and R. Tenne, On the mechanical behavior of WS2 nanotubes under axial tension and compression, Proc.
Natl. Acad. Sci. 103, 523-528 (2006); b. I. Kaplan-Ashiri, S.R. Cohen, K. Gartsman, R. Rosentsveig, G.
Seifert, and R. Tenne, Mechanical behavior of WS2 nanotubes, J. Mater. Res. 19, 454-459 (2004).
2. D.A. Walters, L.M. Ericson, M.J. Casavant, J. Liu, D.T. Colbert, K.A. Smith, and R.E. Smalley, Appl.
Phys. Lett. 74, 3803-3805 (1999); B. Wu, A. Heidelberg, and J.J. Boland, Nature Materials 4, 525-529
(2005).
3. L. Zhechkov, T. Heine, S. Patchkovskii, G. Seifert, and H.A. Duarte, An efficient a posteriori treatment
for dispersion interaction in density-functional-based tight binding, J. Chem. Theory Comput. 1, 841-847
(2005).
4. I. Kaplan-Ashiri, S.R. Cohen, Y. Wang, G. Seifert, H.D. Wagner, and R. Tenne, Interlayer shear
(Sliding) modulus of WS2 nanotubes, J. Phys. Chem. C, in press.
10
SPM image of a nanotube which was plastically deformed
by application of lateral force with the SPM. All data for
this work were ptaken at forces far below the failure limit.
List of papers with acknowledgment to the center
See Refs. 1a, 1b and 4 in the above list.
c.7. Dr. Leeor Kronik, Department of Materials and Interfaces
Organic monolayers organized on a (semi)conducting substrate exhibit unique collective
properties that do not exist in either the isolated molecules or the isolated substrate.
Recently, we have focused on two such collective effects: First, we showed that for polar
molecules, the electrostatic properties of a molecular monolayer adsorbed on a substrate
are diametrically opposite to those of an isolated polar molecule, adsorbed in the same
way on the same substrate. This was rationalized in terms of inter-molecular electrostatic
interactions, which reduce the effective dipole in the monolayer, and a superposition of
individual molecular dipoles which suppresses field penetration into the substrate for a
monolayer. This has led to several predictions on the role of order in monolayers which
are currently tested experimentally. Second, we showed that it is often insufficient to
describe the solid-state side of an organic/inorganic interface via a Bloch band picture
and the molecular side via a molecular orbital picture. Instead, a more nuanced picture,
which emphasizes interface induced gap states due to the "tailing out" of Bloch electrons
from the solid to the organic side, emerges. This picture was used to interpret
photoemission data of alkyl chains on Si quantitatively and assisted in reinterpreting the
mechanism of electron transport across the chains.
In a separate activity, we have been developing real-space methodologies for
understanding the properties of nano-clusters. We are in the process of extending these
advanced numerical tools so that we can use them for our monolayer work as well. In
parallel, we are developing new formal approaches that may increase the accuracy of our
computational work.
Collaborations with German Scientists that are sponsored by the center:
Prof. Dr. Eberhard Umbach, Universität Würzburg
Prof. Dr. Stephan Kümmel, Universiität Bayreuth
11
Collaborations with German Scientists that are not sponsored by the center:
Vlasta. Bonačić –Koutecký, Dept. of Chemistry, Humboldt Universität, Berlin
List of papers with acknowledgment to the center
1. O. Guliamov, L. Kronik, and K. A. Jackson, Photoelectron spectroscopy as a structural probe of
intermediate size clusters, J. Chem. Phys. 123, 204312 (2005).
2) A. Natan, Y. Zidon, Y. Shapira, and L. Kronik, Cooperative effects and dipole formation at
semiconductor/self-assembled-monolayer interfaces, Phys. Rev. B 73, 193310 (2006).
4) L. Kronik, A. Makmal, M. Tiago, M. M. G. Alemany, X. Huang, Y. Saad, and J. R. Chelikowsky,
PARSEC - the pseudopotential algorithm for real-space electronic structure calculations: recent advances
and novel applications to nanostructures, Phys. Stat. Solidi B (Feature Article) 243, 1063-1079 (2006).
3) N. Dori, M. Menon, L. Kilian, M. Sokolowski, L. Kronik, and E. Umbach, Valence Electronic Structure
of Gas Phase 3,4,9,10-perylene tetracarboxylic-acid-dianhydride (PTCDA): Experiment and Theory, Phys.
Rev. B 73, 195208 (2006).
4) A. Natan, L. Kronik, and Y. Shapira, Computing surface dipoles and potentials of self-assembled
monolayers from first principles, Appl. Surf. Sci. 252, 7608-7613 (2006).
5) L. Segev, A. Salomon, A. Natan, D. Cahen, L. Kronik, F. Amy, C. K. Chan, and A. Kahn, Electronic
structure of Si(111)-bound alkyl monolayers: theory and experiment, Phys. Rev. B 74, 165323 (2006).
7) D. Deutsch, A. Natan, Y. Shapira, and L. Kronik, Electrostatic properties of adsorbed polar molecules:
Opposite behavior of a single molecule and a molecular monolayer, J. Am. Chem. Soc. 129, 2989-2997
(2007).
c.8. Prof. R. Naaman, Department of Chemical Physics
Our group investigated the electronic properties of self-assembled structures. Specifically
we explored the self-assembling of InAs nanocrystals to GaAs substrates using different
organic molecules as linkers. The near IR fluorescence properties with and without codeposition with Au nanoparticles (NPs) was investigated. We demonstrated the ability to
control the binding of InAs/ZnSe core/shell NPs to GaAs substrate and exhibit the
usefulness of such a system by enhancing the photoluminescence (PL) from the InAs NPs
by coadsorbing them with gold NPs.
The combination of semiconductor NPs with their various size tunable properties,
together with the control over the binding molecules and the possibility to add gold NPs,
creates an arsenal of "nanotools" that allow us to self-assemble all its components into a
supramolecular system that has predesigned optical and electronic properties. This
scheme of combining metal and semiconductor NPs opens the possibility to couple light
to nano structures via plasmons.
We also developed a straightforward method for the self assembly of single walled
carbon nanotubes (SWNTs) between gold electrodes. The technique utilizes the
hybridization between short complementary DNA sequences located on metal contacts
and SWNTs. The new technique enables simple production of hundreds of devices with
high yields. The electrical characteristics are shown to depend strongly on the existence
of the chemical binding groups at the contacts as well as along the tubes. This technique
was used to drive the self assembly of SWNT-based field effect transistors (CNTFETs).
In principle, the devices made by this method behave like those made using direct metalcarbon nanotubes contacts. The inverse subthreshold slope of the CNTFETs depends on
the source-drain voltage applied to the device, confirming that the conductance of
CNTFETs is determined by the Schottky barriers at the interfaces between the CNTs and
12
the gold electrodes. This project was performed together with the group of Prof. Manfred
Kappes from Karlsruhe, Germany.
A
B
Schematic representation of DNA mediated deposition of a SWNT between 2 gold electrodes. (A) DNA
modified SWNT is reacted with (B) gold electrodes bearing the complementary oligonucleotides (yellow
dots represent thiol groups at the 3` of the capture sequences, used to assemble them on the gold
electrodes). (C) Hybridization between the complementary strands results in bridging the two electrodes by
the SWNT.
List of papers with acknowledgment to the center
1. M. Hazani, D. Shvarts, D. Peled, V. Sidorov, and R. Naaman, Self-assembled electrical circuits and their
electronic properties, Faraday Discuss. 134, 335 (2006).
2. Y. Paltiel, A. Haroni, U. Banin, O. Neuman, R. Naaman, Self-assembling of InAs nanocrystals on GaAsThe effect of electronic coupling and embedded gold nanoparticles on the photoluminescence, App. Phys.
Lett. 89, 033108 (2006).
3. G. Kopnov, Z. Vager, R. Naaman, New magnetic properties of silicon-silicon oxide interfaces Adv.
Mater. 19, 925-928 (2007).
c.9. Prof. Lia Adaddi, DEepartment of Structural Biology
The group of Prof Lia Addadi in the Dept. of Structural Biology is active in a number of
directions within the general framework of supramolecular architectures.
c.9.a. Mechanisms of biomineralization processes: specific projects concern: a) the
characterization of transient amorphous calcium carbonate phases and their subsequent
transformation into large stable calcite single crystals, such as in sea urchin larval
spicules, sea urchin teeth and mollusk shells; b) the assembly of guanine crystals into the
photonic crystals that provide fish skin and scales with their characteristic silvery sheen;
c) the continuously developing fish fins as a study model for bone formation; d) mollusk
shell nacreous and prismatic layers: comparing and contrasting mechanisms of composite
materials design (supported by a Minerva grant).
c.9.b. Antibodies that specifically recognize organized surfaces: specific projects
concern:
a) Antibodies recognizing amyloid fibers and the molecular structure of amyloid fibers;
b) antibodies recognizing organized lipid micro-domains in monolayers, bilayers and in
13
cell membranes; this also includes c) construction of a special humidified chamber that
will allow measurement of hydrated bilayer structures by GIXD (supported by the
Minerva Center).
c.9.c. Mechanisms of cell adhesion and organization: specific projects concern: a)
Characterization of thick hyaluronan pericellular coats (post-doctoral fellow Derk Joester
is a Minerva fellow); b) the mechanism of bone resorption in osteoclasts and the
architectural organization of the sealing zone
List of papers with acknowledgment to the center
1. R. Gueta, A. Natan, L. Addadi, S. Weiner, K. Refson and L. Kronik, Local atomic order and infrared
spectra of biogenic calcite, Angew Chem Int Ed, 46, 291 –294, (2007).
2. F. Nudelman, S. Weiner and L. Addadi, On the structure and mechanism of formation of mollusk shell
prismatic layer, Faraday Discussions, in press (2007)
3. L. Addadi, Y. Politi, F. Nudelman, and S. Weiner, Biomineralization design strategies and mechanisms
of mineral formation: Operating at the edge of instability, Proc. of ISSCG 13, in press (2007).
c.10. Prof. H. Daniel Wagner, Department of Materials & Interfaces
The objectives of our research projects are to measure and understand the mechanical
behavior of carbon nanotubes, and nanotubes-based composites obtained by embedding
these in polymers. The potential of the nanotubes as mechanical sensors in materials was
explored. In particular our research has focused on ways to measure interfacial adhesion
in nanocomposites, a most challenging endeavor. Biological composites in which the
hard phase is at the nanoscale (such as bone and dentin for example) are also being
investigated. A host of new results were recently generated:
1. Carbon nanotubes can be used as strain-sensors in polymers.
2. Carbon nanotubes effectively improve the mechanical properties of carbon nanotubebased composites based on thermosetting and thermoplastic matrices. This work is
performed jointly with Prof. Karl Schulte (Technical University Hamburg-Harburg) and
Dr Ingo Burgert (Max-Planck Institute, Golm). The figure shows a mechanical test of an
electrospun polymer fiber with carbon nanotubes.
In-situ SEM tensile test of an electrospun polymer fiber filled with carbon nanotubes: before (left) and after
breakdown
3. We have devised new methods for the measurement of interfacial properties (such as
the interfacial adhesion strength) in nanotube-polymer systems.
14
4. We have investigated the deformation and fracture behavior of various types of bone
and dentine viewed as hierarchical/anisotropic nanocomposites. These results are to be
used as input for building a mechanical model for the toughness incorporating several
hierarchical levels. This work is performed jointly with Prof. Peter Fratzl (Max-Planck
Institute, Gölm).
List of papers with acknowledgment to the center
1. L. Liu, A. H. Barber, S. Nuriel, H. D. Wagner, Mechanical properties of functionalized carbon
nanotube/PVA nanocomposites, Adv. Funct. Mater. 15, 975-980 (2005).
2. S. Nuriel, A. Katz, H. D. Wagner, Measuring fiber-matrix interfacial adhesion by means of a ‘drag-out’
micromechanical test, Composites A 36, 33-37 (2005).
3. A.H. Barber, S.R. Cohen, H. D. Wagner, External and internal wetting of carbon nanotubes with organic
liquids, Phys. Rev. B 71, 115443 (2005).
4. S. Nuriel, L. Liu, A.H. Barber, H.D. Wagner, Direct measurement of multiwall nanotube surface tension,
Chem. Phys. Lett. 404, 263-266 (2005).
5. J.D. Fidelus, E. Wiesel, F.H. Gojny, K. Schulte, H.D. Wagner, Thermo-mechanical properties of
randomly oriented carbon/epoxy nanocomposites, Composites A 36, 1555-1561 (2005).
6. L. Liu, H. D. Wagner, Rubbery and glassy epoxy resins reinforced with carbon nanotubes, Composites
Sci. & Tech. 65, 1861-1868 (2005).
7. A.H. Barber, I. Kaplan-Ashiri, S.R. Cohen, R. Tenne, and H.D. Wagner, Stochastic strength of
nanotubes: an appraisal of available data (Invited Paper for the 20th Anniversary of Composites Sci &
Tech.), Composites Sci. & Tech. 65 (2005), 2380-2384.
8. H.S. Gupta, W. Wagermaier, G.A. Zickler, D. Raz-Ben Aroush, S.S. Funari, P. Roschger, H.D. Wagner,
P. Fratzl, Nanoscale deformation mechanisms in bone, NanoLetters 5, 2108-2111(2005).
9. A.H. Barber, R. Andrews, L.S. Schadler, H.D. Wagner, On the tensile strength distribution of multiwalled carbon nanotubes, Appl. Phys. Lett. 87, 203106 (2005). [Selected to appear in the Virtual J.
Nanoscale Sci. & Tech., November 21, 2005].
10. L. Vaisman, G. Marom, H.D. Wagner, Dispersions of surface modified carbon nanotubes in watersoluble and –insoluble polymers, Adv. Funct. Mater. 16, 357-363 (2006).
11. A.H. Barber, S.R. Cohen, A. Eitan, L.S. Schadler, H.D. Wagner, Fracture transitions at carbon
nanotube-polymer interfaces, Adv. Mater. 18, 83-87 (2006).
12. H.S. Gupta, W. Wagermaier, G.A. Zickler, J. Hartmann, S.S. Funari, P. Roschger, H.D. Wagner, P.
Fratzl, Fibrillar level fracture in bone beyond the yield point, Int. J. Fracture 139, 425-436 (2006).
13. D. Raz-Ben Aroush, E. Maire, C. Gauthier, S. Youssef, P. Cloetens, H.D. Wagner, A study of fracture
of unidirectional composites using in-situ high-resolution synchrotron X-ray microtomography, Composites
Sci. & Tech. 66, 1348-1353 (2006).
14. A. Katz, M. Redlich, L. Rapoport, H.D. Wagner, R. Tenne, Self-lubricating coatings containing
fullerene-like WS2 nanoparticles for orthodontic wires and other possible medical applications, Tribol.
Lett. 21, 135-139 (2006).
15. H.S. Gupta, U. Stachewicz, W. Wagermaier, P. Roschger, H. D. Wagner, P. Fratzl, Mechanical
modulation at the lamellar level in osteonal bone, J. Mater. Res. 21, 1913-1921 (2006).
16. D. Raz-Ben Aroush, H.D. Wagner, Shear stress profile along a cell focal adhesion, Adv. Mater. 18,
1537-1540 (2006).
17. R. Elbaum, E. Tal, A. I. Perets, D. Oron, D. Ziskind, Y. Silberberg, H. D. Wagner, Dentin micro
architecture using harmonic generation microscopy, J. Dentistry 35, 150-155 (2007).
18. L. Vaisman, H.D. Wagner, G. Marom, The role of surfactants in dispersion of carbon nanotubes, Adv.
Colloid Inter. Sci. 128-130, 37-46 (2006).
19. L. Liu, H.D. Wagner, A comparison of the mechanical strength and stiffness of MWNT-PMMA and
MWNT-epoxy nanocomposites, Composite Inter., in press.
20. L. Vaisman, B. Larin, I. Davidi, E. Wachtel, G. Marom, H. D. Wagner, Processing and characterization
of extruded drawn MWNT-PAN composite filaments, Composites A, in press.
21. L. Liu, D. Tasis, M. Prato, H.D. Wagner, Tensile mechanics of electrospun MWNT/PMMA nanofibers,
Adv. Mater., in press.
22. L. Liu, M. Eder, I. Burgert, D. Tasis, M. Prato, H. D. Wagner, One-step electrospun nanofiber-based
composite ropes, Appl. Phys. Lett. 90, 083108 (2007).
15
c.11. Prof. R. Tenne, Department of Materials and Interfaces
c.11.a. With Prof. Ch. Thomsen, TU Berlin: The Raman spectrum of individual WS2
nanotubes is studied jointly with the group of Prof. Dr. Ch. Thomsen and his associate
Dr. P. M. Rafailov from the Technical University in Berlin and Dr. K. Gartsman from
here [1]. The first ms. has been recently published and work is in progress on a more
advanced study whereby coupling between mechanical and optical modes in individual
nanotubes are studied.
c.11.b. With Prof. Dr. M. Jansen of the MPI in Stuttgart and Prof. Dr. Seifert of the TU
Dresden:
Films of cesium oxides with approximately 2:1 Cs to O ratio (in addition to Ag) and at
~ monolayer level dimensions are widely utilized applied onto the surface of e.g. S-1
photocathodes, negative electron affinity (NEA) devices, and also discharge lamps,
television cameras, lasers, etc. These films reduce the work-function of the electrode
increasing thereby the electron emission currents and the long wavelength response of
these devices. A particular emphasis has been placed on the study of Cs1+xO for
applications in catalytic converters and optical fibers. The structure of these surface
layers deposited on photoemissive and NEA devices, has proved difficult to resolve and
interpret, partly due to the thinness of the film and the very high instability of Cs2O.
Furthermore, as these films are highly reactive and thin, they are damaged or destroyed
by short exposure to low vacuum. This stringent vacuum requirement increases the
difficulty and expenses of their manufacture and handling and prevents applications that
require periodic atmospheric exposures. Achieving stability enhancement of these films
has been a long standing goal.
In this collaboration two methods were investigated for the synthesis of closed-cage
Cs2O nanoparticles using ablation of Cs2O powder with laser [2,3] and focused sun light
[4]. A special environmental chamber (Fig. 1) was built to allow introduction of the
sample into the transmission electron microscope (TEM) without exposing the sample to
the ambient atmosphere. Fig. 2 shows the solar ablation set-up. Fig. 3 presents TEM
micrographs of two typical IF-Cs2O nanoparticles. It is remarkable that, due to their
closed cage structure, the nanoparticles are kinetically much more stable, and can be
exposed to the ambient atmosphere with only slow degradation of their structure.
16
Fig. 1. Environmental chamber allowing
introduction of air-sensitive samples to the
TEM without exposure to the environment.
Fig. 2. Ablation of Cs 2O powder with focused
sunlight
Fig. 3. Three typical closed cage (IF) nanoparticles of Cs2O obtained by solar ablation. The nanoparticles
could be taken out from the microscope and exposed to the ambient with gradual damage only.
c.11.c. With Prof. G. Seifert, TU Dresden (supported jointly with the GIF): Part of this
collaboration, which was dedicated to the mechanical behavior of WS2 nanotubes and
included also Prof. H.D. Wagner (see Sec.14), has been described in great detail by the
report of Dr. Sidney R. Cohen (Section c.6 and references 1a and b and 4 there) and will
not be repeated here.
In another kind of collaboration between the two groups [5], the structure and energetics
of MoS2 nanooctahedra was investigated. Bulk synthesis of the IFs normally yields quasispherical nanoparticles with at least 20 molecular layers and outer diameters of greater
than 30 nm. In early work, the formation of hollow MoS2 clusters with octahedral or
tetrahedral shapes was often observed. Laser ablation was used to produce MoS2 nanooctahedra with diameters of 3–5 nm. These closed nanocages are the smallest Ifs (see
Fig.4). Herein, the small hollow nano-octahedra and the quasi-spherical nanoparticles
(diameters larger than 30 nm) are termed (inorganic) fullerenes and fullerene-like
nanoparticles, respectively. A detailed investigation of their structures and
physicochemical properties was undertaken. It was found that the MoS2 nanooctahedra
consisting of 3-5 molecular layers are stable in the range of 3-8 nm (103-105 atoms). In
contrast to the quasi-spherical nanoparticles, which are semiconducting, the
17
nanooctahedra are semimetallic. Much more research is needed to elucidate their
structure and properties in great detail.
For this to occur we have started a trilateral collaboration including, in addition Seifert
(TU Dresden and our laboratory, also the laboratory of Prof. Knut Urban (and Dr. Lothar
Houben), the director of the Ernst Ruska center for ultra-high resolution transmission
electron microscopy in the Research Center in Jülich. Frequent mutual visits of both
students and researchers and strong collaboration promises to bring this research to new
exciting heights.
Fig. 4. MoS2 nanooctahedra, which are considered to be the true fullerenes of MoS 2, produced by laser
ablation (above) and their calculated model (below)
List of papers with acknowledgment to the center
1. P.M. Rafailov, C. Thomsen, K. Gartsman, I. Kaplan-Ashiri, and R. Tenne, Orientation dependence of the
polarizability of an individual WS2 nanotube by resonant Raman spectroscopy, Phys. Rev. B, 72, No.
205436 (2005).
2. J. Solid State Chem, Electron microscopy, spectroscopy and first principles calculations of Cs2O, S.
Gemming, G. Seifert, C. Mühle, M. Jansen, A. Albu-Yaron, T. Arad, and R. Tenne, 178, 1190-1196
(2005).
3. A. Albu-Yaron, T. Arad, R. Popovitz-Biro, M. Bar-Sadan, Yehiam Prior, M. Jansen and R. Tenne,
Closed-cage (fullerene-like) structures of Cs 2O, Angew. Chem. Intl. Ed., 44, 4169-4172 (2005).
4. A. Albu-Yaron, T. Arad, R. Tenne, M. Levy, R. Popovitz-Biro, J.M. Gordon, D. Feuermann, E.A. Katz,
M. Jansen and C. Mühle, Synthesis of fullerene-like Cs 2O nanoparticles by concentrated sunlight, Adv.
Mater. 18, 2993–2996 (2006).
5. a. A.N. Enyashin, S. Gemming, M. Bar-Sadan, R. Popovitz-Biro, S.Y. Hong, Y. Prior, R. Tenne, and G.
Seifert, Structure and stability of molybdenum sulfide Fullerenes, Angew. Chem. Intl. Ed. 46, 623–627
18
(2007); b. Structure and stability of molybdenum sulfide fullerenes, M. Bar-Sadan, A.N. Enyashin, S.
Gemming, R. Popovitz-Biro, S.Y. Hong, Yehiam Prior, G. Seifert and R. Tenne, J. Phys. Chem. B 110,
25399-25410 (2006).
c.12. Prof. D. Cahen, Department of Materials and Interfaces
c.12.a. Charge transport through semiconductor-tethered molecular moieties: How alkyl
chain molecules are bound chemically to GaAs directly affects current transport through
GaAs/Alkyl/Hg junctions. We used two different binding groups, thiols that form an AsS bond and phosphonates with the much stronger Ga-O (actually Ga-O-P) bond.
Analyzing transport through the junctions as tunneling through a dielectric medium of
defined thickness, characterized by one barrier and the effective mass of the electronic
carrier, we find the main difference in the electronic properties between the two systems
to be the effective mass, 1.5-1.6 m(e) with thiols and 0.3 m(e) with phosphonates. The
latter value is similar to that found with, or predicted for, other systems. We ascribe this
difference primarily to less scattering of carriers by the Ga-O than by the As-S interface.
c.12.b. Electronic structure of semiconductor-organic moieties interfaces: We elucidate
the electronic structure of both filled and empty states of ordered alkyl chains bound to
the Si(111) surface by combining direct and inverse photoemission spectroscopy with
first principles calculations based on density functional theory. We identify both filled
and empty interface-induced gap states, distinguish between those and states extending
throughout the monolayer, and discuss the importance of these findings for interpreting
transport experiments through such monolayers
1. D. Cahen, A. Kahn, E. Umbach, Energetics of molecular interfaces, Mater. Today 8, 32-41 (2005).
2. F. Amy, C.K. Chan, W. Zhao, J. Hyung, M. Ono, T. Sueyoshi, S. Kera, G. Nesher, A. Salomon, L.
Segev, O. Seitz, H. Shpaisman, A. Schöll, M. Haeming, T. Boecking, D. Cahen, L. Kronik, N. Ueno, E.
Umbach and A. Kahn, Radiation damage to alkyl chain monolayers on semiconductor substrates
investigated by electron spectroscopy, J. Phys. Chem. B 110, 21826-21832 (2006).
List of papers with acknowledgment to the center:
1. H. Haick, J. Ghabboun, O. Niitsoo, H. Cohen, D. Cahen, A. Vilan , J. Hwang, A. Wan, F. Amy, A.
Kahn, Effect of molecular binding to semiconductor on metal /molecule/semiconductor junction behavior,
J. Phys. Chem. B 109, 9622-9630 (2005).
2. S. Ruehle, M. Greenshtein, S.G. Chen, A.Merson, H.Pizem, H. S. Sukenik, D. Cahen, A. Zaban,
Molecular adjustment of the electronic properties of nanoporous electrodes in dye sensitized solar cells,
J. Phys. Chem. B 109, 18907-13 (2005).
3. D. Cahen, A. Kahn, E. Umbach, Energetics of molecular interfaces, Mater. Today 8, 32-41 (2005).
4. H. Haick, M. Ambrico, T. Ligonzo, R. T. Tung, and D. Cahen, Controlling semiconductor/metal junction
barriers by incomplete, non-ideal molecular monolayers, J. Am. Chem. Soc. 128, 6854-6869 (2006).
5. O. Niitsoo, S. K. Sarkar, C. Pejoux1, S. Rühle, David Cahen, G. Hodes, Chemical bath deposited
CdSe/CdS-sensitized porous TiO2 solar cells, J. Photochem.Photobiol. 181, 306-313 (2006).
6. O. Seitz, T. Boecking, A. Salomon, J. J. Gooding, D. Cahen, Importance of monolayer quality for
interpreting current transport through organic molecules: Alkyls on oxide-free Si , Langmuir 22, 6915-6922
(2006).
7. F. Amy, C.K. Chan, W. Zhao, J. Hyung, M. Ono, T. Sueyoshi, S. Kera, G. Nesher, A. Salomon, L.
Segev, O. Seitz, H. Shpaisman, A. Schöll, M. Haeming, T. Boecking, D. Cahen, L. Kronik, N. Ueno, E.
Umbach and A. Kahn, Radiation damage to alkyl chain monolayers on semiconductor substrates
investigated by electron spectroscopy, J. Phys. Chem. B 110, 21826-21832 (2006).
8. L. Segev, A. Salomon, D. Cahen, L. Kronik*, F. Amy, C. K. Chan, A. Kahn, Electronic structure of
Si(111)-bound alkyl monolayers: theory and experiment, Phys. Rev. B 74, 165323 (2006).
9. A. Salomon, T. Boecking, J.J. Gooding, D. Cahen, How important is the interfacial chemical bond for
electron transport through alkyl chain monolayers?, Nano Letters 6, 2873-2876 (2006).
19
10. G. Nesher, H. Shpaisman, D. Cahen, Effect of chemical bond-type on electron transport in GaAschemical bond-alkyl/Hg junctions, J.Am. Chem. Soc. 129, 734-735 (2007).
c.13. Dr. E. Joselevich, Department of Materials and Interfaces
Our research focuses on the organization of molecular wires and one-dimensional
nanostructures, such as carbon nanotubes, inorganic nanowires and polymers, their
integration into functional nanosystems (mechanical, electronic, electromechanical,
optoelectronic, electromagnetic, etc.), and their characterization by mechanical and
electrical measurements at the nanometer scale. One of our major innovations has been
the development of epitaxial approaches to carbon nanotube organization denoted
’nanotube epitaxy, namely, the directed growth of carbon nanotubes by well-defined
crystal surfaces. We have identified three different modes of nanotube epitaxy: Latticedirected epitaxy (by atomic rows), ledge-directed epitaxy (by atomic steps) [1] and
graphoepitaxy (by nanofacets) [2]. In addition, we have combined these modes of
nanotube epitaxy with two types of external aligning forces: Electric field and gas flow.
This has enabled us to achieve a variety of previously unattainable morphologies of
nanotubes arrays, including straight, kinked, wavy, crossed, serpentine and looped. [3,4]
A second important contribution (see picture in front page) has been the first study of the
effect of torsion on the electronic properties of carbon nanotubes, which led to the
observation of torsional electromechanical quantum oscillations in carbon nanotubes [5].
We found that continuously varying the chirality of a nanotube by mechanical torsion [6]
can induce conductance oscillations, which can be attributed to metal-semiconductor
periodic transitions. The phenomenon is observed in multi-walled carbon nanotubes,
where both the torque and the current are shown to be carried predominantly by the
outermost nanotube wall. The oscillation period with torsion is consistent with the
theoretical shifting of the corners of the first Brillouin zone of graphene across different
subbands allowed in the nanotube. Beyond a critical torsion, the conductance irreversibly
drops due to torsional failure, allowing us to determine for the first time the torsional
strength of carbon nanotubes. Our results suggest that carbon nanotubes could be used as
self-sensing torsional springs for nanoelectromechanical systems.
1. A. Ismach, L. Segev, E. Wachtel, and E. Joselevich, Atomic-step-templated formation of single wall
carbon nanotube patterns, Angew Chem Int Ed 43, 6140-6143 (2004).
2. A. Ismach, D. Kantorovich, and E. Joselevich, Carbon nanotube graphoepitaxy: Highly oriented growth
by faceted nanosteps, J Am Chem Soc 127, 11554-11555 (2005).
3. E. Joselevich, H.J. Dai, J. Liu, K. Hata, and A. Windle, Carbon Nanotube Synthesis and Organization.
Top Appl Phys 2007, submitted.
4. A. Ismach and E. Joselevich, Orthogonal self-assembly of carbon nanotube crossbar architectures by
simultaneous graphoepitaxy and field-directed growth, Nano Lett 6, 1706-1710 (2006).
5. T. Cohen-Karni, L. Segev, O. Srur-Lavi, S.R. Cohen, and E. Joselevich, Torsional electromechanical
quantum oscillations in carbon nanotubes, Nature Nanotechnology 1, 36-41(2006).
6. E. Joselevich, Twisting nanotubes: From torsion to chirality, ChemPhysChem 7, 1405-1407 (2006).
c.14. Dr. R. Bar-Ziv, Department of Materials and Interfaces
Biochip platforms that work as artificial cells are attractive for fundamental system
biology studies, medical diagnostics, interrogation of biological processes, and for the
production of important biomolecules. However, to match the complexity of nature, the
biochips need to be designed such that proteins, DNA, and other important biological
20
components can be located in specific, spatially well-resolved regions on the chips. This
allows these devices to mimic the complex, sequential, and often cascaded events
involved in biological processes. We have recently designed a molecule called “daisy”
that is able to bind genes onto chips in miniature patterned arrays, demonstrating thereby
in vitro transcription and translation on a chip [1] (see also figure on the coverpage).
We have been able to use the daisy to pattern tiny regions of double-stranded DNA onto
silicon dioxide surfaces. Indeed, these immobilized genes are able to conduct their
fucntionality on patterned silicon substrates without the need for living cells. These
biochips can act as protein microtraps, selectively trapping specific proteins from crude
cell extracts with high spatial resolution. Moreover, the gene sequences immobilized on
the biochips can be used for the on-chip production of proteins by
transcription/translation processes such as those occurring within cells. We have also
demonstrated the integration of these systems with microfluidics [2]. Integration with
flow systems is of interest for the fabrication of miniature assembly lines on chips,
wherein proteins can be synthesized on the chips and transported to their final
destinations through microfluidic channels. In a remarkable demonstration of the utility
of the daisy approach, the researchers have patterned two different genes as alternating
stripes on a biochip.
The protein synthesized on one stripe diffuses to the second stripe where it regulates the
synthesis of a second protein. More complex artificial gene circuits can be envisioned by
extending this protocol, and thus the biochips may be able to carry out complex cascaded
information-processing functions, mimicking those in living organisms. This approach is
a first step towards functional cell-free biochemical factories for synthesizing
biomolecules and decision-making modules. Placing genes close to one another on a
surface provides opportunities not available in bulk solution by allowing communication
between individual gene sequences in these artificial cells.
1. A. Buxboim, M. Bar-Dagan, V. Frydman, D. Zbaida, M. Morpurgo, and R. Bar-Ziv, A single-step lightdirected interface for cell-free gene circuits, Small (2006).
2. T. Beatus, T. Tlusty and R. Bar-Ziv, Phonons in a 1D microfluidic crystal of droplets, Nature Physics 2,
743-748, (2006).
c.15. Prof. Avi Shanzer, Department of Organic Chemistry
The group’s efforts of the last years were devoted to:
(i) Further development of biomimetic analogs to natural iron-carriers particularly those
associated with pathogenic bacteria Yersinia enterocolitica and various Vibrio strains
(Vibrio Cholerea, Vibrio parahemaliticuse etc.). In the first we identified a synthetic
analog that recognize the FoxA receptor in Y. enterocholitica and was able to induce
growth and proliferation. In the Vibrio strains we identified three synthetic analogs with
recognition ability and suggest the construction of a diagnostic kit for the identification of
these pathogens (common in developing countries) in water sources.
(ii) A new subject in our lab that reach maturity is the use of simple chemicals as
processing units capable of responding to external stimuli by performing elementary
logic-gate functions and consequently algebraic functions as ADDITION and
SUBTRUCTION of two and three information bits (chemical) we introduced a RESET
capabilities following each computation thus, a true computation with molecules or a
simple MOLECULATORS was introduced.
21
(iii) A new project that at its early beginning involves the synthesis of polylanthanide
chiral complexes for the formation of multi-Lanthanide clusters exhibiting circular
polarized luminescence emissions and unique magnetic properties.
List of papers with acknowledgment to the center
1. H. Kornreich-Leshem, C. Ziv, E. Gumienna-Kontecka, R. Arad-Yellin, Y. Chen, M. Elhabiri, A.-M.
Albrecht-Gary, Y. Hadar, and A. Shanzer, Ferrioxamine B analogues: targeting the FoxA uptake system in
the pathogenic Yersinia enterocolitica, J. Am. Chem. Soc. 127, 1137-1145 (2005).
2. D. Margulies, G. Melman, and A. Shanzer, Fluorescein as a model molecular calculator with reset
capability, Nature Mater. 4, 768-771 (2005).
3. O. Abed, M. Wanunu, A. Vaskevich, R. Arad-Yellin, A. Shanzer, and I. Rubinstein, Reversible Binding
of Gold Nanoparticles to Polymeric Solid Supports, Chem. Mater. 18, 1247-1260 (2006).
4. D. Margulies, G. Melman, and A. Shanzer, A Molecular Full-Adder and Full-Subtractor, an Additional
Step toward a Moleculator, J. Am. Chem. Soc. 128, 4865-4871 (2006).
5. D. Margulies, C.E. Felder, G. Melman, and A. Shanzer, A molecular keypad lock: a photochemical
device capable of authorizing password entries, J. Am. Chem. Soc. 129, 347-354 (2007).
6. R. Kikkeri, T. Hassan, N. Humbert, E. Gumienna-Kontecka, R. Arad-Yellin, G. Melman, M. Elhabiri,
A.-M. Albrecht-Gary, and A. Shanzer, Toward Iron Sensors: Bioinspired Tripods Based on Fluorescent
Phenol-oxazoline Coordination Sites, Inorg. Chem. 46, 2485-2497 (2007).
7. K. Raghavendra, M. Galina, L. Gregory, and A. Shanzer, Chirality within chirality: tri-lanthanide
complex integrating right- and left-handed ligand orientation, submitted.
c.16. Prof. Daniella Goldfarb, Department of Chemical Physics
Collaborations with German Scientists
Frank Neese, Physical and Theoretical Chemistry, U. Bonn
Klaus Möbius, Department of Physics, Free University Berlin
Gunnar Jeschke, Department of Chemistry, University of Konstanz
Herbert Zimmermann , MPI fur Medical Research, Heidelberg
Support given by the Center for a cryostat for CW X-band EPR spectrometer, 4-300 K
This is an application for a cryostat for cryogenic temperatures for continuous wave
(CW) that fits both the old Varian E12 spectrometer in my laboratory and the two Bruker
X-band spectrometers of the Chemical Research Support Department of the Faculty of
Chemistry. Our pulsed EPR spectrometer is equipped with a cryostat but this set up
cannot be used with the CW spectrometers due to different cavity constructions. Our
work evolves around transition metal centers and occasionally the relaxation times are
just too short and echoes cannot be observed even at 4 K. In other cases the echo-detected
EPR spectrum (this is how EPR spectra are measured in the pulse mode) are highly
distorted due to the nuclear modulation effect and one must measure the CW-EPR
spectrum to get the correct lineshape.
List of papers with acknowledgment to the center
22
1. S. Ruthstein, J. Schmidt, E. Kesselman, Y. Talmon, and D. Goldfarb, Resolving the evolution of the
micellar structures in solution during the formation of mesoporous SBA-15, J. Am. Chem. Soc. 128, 33663374 (2006).
2. D. Baute and D. Goldfarb, The interaction of nitrates with pluronic micelles and their role in the phase
formation of mesoporous materials, Submitted
c17. Prof. Jacob Sagiv, Department of Materials and Interfaces
We address the timely major problem of nanofabrication on the basis of a comprehensive
chemical approach that exploits spontaneous processes of template guided self-assembly
at solid fluid interfaces. Two central issues are in the focus of this research: (i) the precise
control of the three dimensional (3D) surface self-assembly of arbitrary nanoscale
architectures, according to a predefined design; (ii) the communication between a surface
self-assembled nanodevice and the outside macro world.
To this end, we rely on Constructive Lithography (see picture at front page) an
electrochemical surface patterning approach invented and advanced in this laboratory,
which allows non-destructive inscription or printing of chemical information on highly
ordered organic monolayers self-assembled on silicon. Constructive Lithography is
applicable on the full range of lateral length scales from nanometer to centimeter.
Stephanie Höppener was a postdoctoral Minerva Fellow coming from H. Fuchs' group in
Münster left in 2004 (coauthor of one of the papers in the list below).
List of papers with acknowledgment to the center
1. S. Höppener, R. Maoz, and J. Sagiv, Contact electrochemical replication of electrochemically printed
monolayer patterns, Adv. Mater. 18, 1286-1290 (2006).
2. H. Cohen, R. Maoz, and J. Sagiv, Transient charge accumulation in a capacitive self- assembled
monolayer, NanoLett. 6, 2462-2466 (2006).
3. D. Chowdhury, R. Maoz, and J. Sagiv, Wetting driven self-assembly as a new approach to template
guided fabrication of metal nanopatterns, submitted.
4. Post assembly chemical modification of a highly ordered organosilane multilayer: New insights into the
structure, bonding and chemical reactivity of self-assembling silane monolayers, K.Wen, R. Maoz, H.
Cohen, J. Sagiv, A. Gibaud, A. Desert, B.M. Ocko, to be submitted.
c.18. Prof. J. Klein, Department of Materials and Interfaces
This year we had help from the Minerva Center in organizing a high-powered
International 1-day Symposium (November 2006) on Soft Matter and Biomaterials,
where we hosted Prof. Erich Sackmann of Munich University, who was an invited
speaker, as well as other distinguished speakers. We also have the Center’s help in
hosting Prof. Joachim Spatz, University of Heidelberg, whom we invited to present a
seminar in our regular Soft Matter and Biomaterials seminar (March 2007). The Center’s
help was instrumental in facilitating these visits and the symposium. I enclose with this
report an electronic copy of the poster advertising our Minerva-Center-sponsored Soft
Matter and Biomaterials symposium.
c.19. Prof. gary Hodes, Depoartment of Materials and Interfaces
Light-induced chemically resolved electrical measurements (CREM) under controlled
23
electrical conditions were used to study photovoltaic effects at selected regions in
nanocrystalline CdSe-based films. The method, based on X-ray photoelectron
spectroscopy (XPS), possesses unique capabilities for exploring charge trapping and
charge transport mechanisms, combining spectrally filtered input signals with
photocurrent detection and with a powerful, site-selective, photovoltage probe.
CdSe was homogeneously deposited into nanoporous TiO2 films and used in liquid
junction photoelectrochemical solar cells. The effect of the deposition parameters on the
cell were studied, in particular differences between deposition mechanisms, which could
be controlled. CdSe deposition on a Cd-rich CdS film that was deposited first into the
TiO2 film, or selenization of the Cd-rich CdS layer with selenosulphate solution
improved the cell parameters. Photocurrent spectral response measurements indicated
photocurrent losses due to poor collection efficiencies, as shown by the strong spectral
dependence on illumination intensity. Cell efficiencies up to 2.8% under solar conditions
were obtained – the highest obtained for this type of porous, nanocrystalline
photoelectrochemical cell.
List of papers with acknowledgment to the center
1. O. Niitsoo, S.K. Sarkar, C. Pejoux, S. Rühle, D. Cahen, and G. Hodes, Chemical bath deposited
CdS/CdSe-sensitized porous TiO2 solar cells, J. Photochem.Photobiol. A, 181, 306-313 (2006).
2. H. Cohen, S.K. Sarkar and G. Hodes, Chemically resolved photovoltage measurements in CdSe
nanoparticle films, J. Phys. Chem. B 110, 25508-25513 (2006).
d. Reports on symposia under the auspices of the Schmidt Minerva Center
1. The 6th Minerva student symposium, Molecualr based devices, Weizmann Institute 68.3.05
Organizers: Neta Ggranit (WIS), Ifat Kaplan-Ashiri (WIS), Inga Vockenroth (MPIP
Mainz); Roman Shusterman (BGU)
24
List of invited speakers: Prof. P. Fratzl (MPI-Gölm), Prof. H.-J. Butt (MPI-Mainz), Prof.
W. Tremel (Mainz U), Prof. A. Offenhäser (Jülich), Prof. Michael Müller (Fraunhaufer I,
Stuttgart), Dr. Anne Bernheim-Groswasser (Ben-Gurion U), Dr. G. Frey (Technion),
Prof. R. Jelinek (Ben-Gurion U), Prof. R. Marks (Ben-Gurion U), Prof. N. Tessler
(Technion), Dr. M. van der Boom (WIS)
2. Workshop on Biological and Soft Matter, Weizmann Institute of Science
Organizers: Profs. J. Klein and S.A. Safran, Department of Materials and Interfaces
25
List of invited speakers (see the poster above)
Workshop of International Networks of Protein Engineering Centers (INPEC)
Organizer: Prof. J.L. Sussman, Department of Structural Biology
The Annual Meeting of the "International Networks of Protein Engineering Centers
(INPEC)" which took place in Nov 9-13, 2005, at Ein-Gedi (see: http://www.inpec.org.il)
was supported by the Center. The committee organizing this meeting spanned 3 faculties
and consists of: Prof. Yigal Burstein, Dr. Michal Harel, Dr. Jaime Prilusky, Prof. Gideon
Schreiber, Dr. Oneg Segal, Prof. Israel Silman, Prof. Dan Tawfik, and Prof. Joel L.
Sussman, all from the WIS. This INPEC meeting brought together some of the very top
figures in the field of Protein Engineering, from about 20 countries (see delegate lists at:
http://www.inpec.org.il/aboutINPEC.html). A significant number of the presentations at
this international meeting discussed nano machines.
In addition the G.M.J. Schmidt Minerva Center supports also the annual meetings of the
Israel Chemical Society and the Israel Vacuum (Materials) Society. The annual Israel
Chemical Society meeting gathers more than 900 experts of which 600 are students,
many of them presenting posters. The Israel Vacuum (Materials) Society gathers some
250 people, with about 150 students and about 150 posters. The Center supports the
venue of senior invited speakers from Germany. In addition, the Center supports 50% of
the registration fees of students which belong to the center. Center’s students are allowed
to register to these important meeting, pending upon presentation of a poster. In addition
the Center provides support for the participation of students in the annual Photovolatic
26
Conference (organized by Prof. D. Faimann) in the Sede Boqer campus of Ben-Gurion
University and in the annual meeting of the Polymer and Plastics Society meeting.
Support was also given to the 5 th European Conference on Computational Biology, which
took place recently in Eilat.
e. Future plans and conclusions
The scientific report for the past two years demonstrates the extensive scientific activity
that the Center promoted between Weizmann scientists and their counterparts in
Germany and in particular in the MPI in Mainz and Gölm, in the field of Supramolecular
Architectures and Nanoscale Science. We strongly believe that the modest support
provided by the center to nurture scientific collaborations is an extremely effective tool
for continuing to develop the intricate web of contacts between scientists of both
countries, especially among the young generation of scientists.
One of the greatest challenges of the Center is to educate the young students and the
young non-tenured researchers of both sides to better know each other, promoting
thereby bilateral collaborations. Therefore the series of the students’ biannual symposia
will continue, but they will diversify in their scope and the support provided by the
Center to these conferences will increase in order to allow greater participation of
students and young researchers from both countries. Special support will be given to
young tenure track researchers who initiate collaborations The Center will support visits
of scientists from Germany to conferences in Israel, provided they will visit the Institute
and give lecture on their work, with the hope that such visits can stimulate collaborations.
The center will be also involved proactively in a search of new collaborations, by sending
students and young researchers to working visits in Germany. We believe that by
diversifying and promoting those collaborations proactively, deeper scientific ties will
bind WIS scientists to their German colleagues in this field, using the modest support of
the GMJ Schmidt Minerva Center. A specific example will illustrate this idea, clearly.
Mrs. Maya Bar-Sadan, a student in Prof. Reshef Tenne here, decided recently to spend
her post-doc stint in the Ernst Ruska Center for High Resolution Electron Microscopy in
Jülich starting off in January 2008. This decision is a natural development of the deep
collaboration that has taken shape between Prof. Knut Urban’s lab and the WIS group,
which was nurtured by the Center. We hope that this is example is the swallow that
27
announces the spring and that other such collaborations will follow suit. We are involved
now in recruiting new assistant professors for the Department of Materials and Interfaces
and to other departments in the Faculty of Chemistry. These new recruits will have a
great impact on new research directions of the Center, as early as 2008.
28