Carbohydrate-based sensors, that specifically detect sugar binding molecules or cells, are increasingly important in medical diagnostic and drug screening. Here we demonstrate that cantilever arrays functionalized with different mannosides allow the real-time detection of several Escherichia coli strains in solution. Cantilever deflection is thereby dependent on the bacterial strain studied and the glycan used as the sensing molecule. The cantilevers exhibit specific and reproducible deflection with a sensitivity range over four orders of magnitude.

Molecular building blocks interacting at the nanoscale organize spontaneously into stable monolayers that display intriguing long-range ordering motifs on the surface of atomic substrates. The patterning process, if appropriately controlled, represents a viable route to manufacture practical nanodevices. With this goal in mind, we seek to capture the salient features of the self-assembly process by means of an interaction-site model. The geometry of the building blocks, the symmetry of the underlying substrate, and the strength and range of interactions encode the self-assembly process. By means of Monte Carlo simulations, we have predicted an ample variety of ordering motifs which nicely reproduce the experimental results. Here, we explore in detail the phase behavior of the system in terms of the temperature and the lattice constant of the underlying substrate.

An interaction-site model can a priori predict molecular self-organisation on a new substrate in Monte Carlo simulations. This is experimentally confirmed with scanning tunnelling microscopy on Fréchet dendrons of a pentacontane template. Local and global ordering motifs, inclusion molecules and a rotated unit cell are correctly predicted.

Carbohydrates are important mediators of many biological processes that underlie cellular communication and disease mechanisms. Therapeutic agents include carbohydrate-based vaccines and the potent anti-viral protein Cyanovirin-N (CV-N). CV-N acts by specifically binding the carbohydrate structures decorating the cell surface of deadly viruses including human immunodeficiency virus (HI-V) or Ebola. In search for new carbohydrate-binding proteins and the development of sensors that exploit carbohydrate-protein interactions the label-free cantilever array technique can provides a fast, parallel and low-cost approach.

To date, heterogeneous patterns on surfaces could assemble either in host guest or templated structures only. A Frechet-type dendron now shows both classes of ordering and thus connects both assembly types. Depending on the type of interaction with the guest molecule, saturated adamantane is included in an existing host structure, while aromatic coronene templates a new molecular ordering.

Advances in carbohydrate sequencing technologies have revealed the tremendous complexity of the glycome. This complexity reflects the structural and chemical diversity of carbohydrates and is greater than that of proteins and oligonucleotides. The next step in understanding the biological function of carbohydrates requires the identification and quantification of carbohydrate interactions with other biomolecules, in particular, with proteins. To this end, we have developed a cantilever array biosensor with a self-assembling carbohydrate-based sensing layer that selectively and sensitively detects carbohydrate protein binding interactions. Specifically, we examined binding of mannosides and the protein cyanovirin-N, which binds and blocks the human immunodeficiency virus (HIV). Cyanovirin-N binding to immobilized oligomannosides on the cantilever resulted In mechanical surface stress that Is transduced into a mechanical force and cantilever bending. The degree and duration of cantilever deflection correlates with the interaction's strength, and comparative binding experiments reveal molecular binding preferences. This study establishes that carbohydrate-based cantilever biosensors are a robust, label-free, and scalable means to analyze carbohydrate-protein interactions and to detect picomolar concentrations of carbohydrate-binding proteins.

Scanning tunneling microscopy (STM) images of self-organized monolayers of Frechet dendrons display a variety of two-dimensional ordering motifs, which are influenced by engineering the molecular interactions. An interaction-site model condenses the essential molecular properties determined by molecular mechanics modeling, which in a Monte Carlo approach successfully predicts the various ordering motifs. This confirms that geometry as well as a few salient weak interaction sites encode these structural motifs.

Self-organized monolayers of highly flexible Frechet dendrons were deposited on graphite surfaces by solution casting. Scanning tunneling microscopy (STM) reveals an unprecedented variety of patterns with up to seven stable hierarchical ordering motifs allowing us to use these molecules as a versatile model system. The essential molecular properties determined by molecular mechanics simulations are condensed to a coarse grained interaction-site model of various chain configurations. In a Monte Carlo approach with random starting configurations, the experimental pattern diversity can be reproduced in all facets of the local and global ordering. Based on an energy analysis of the Monte Carlo and molecular mechanics modeling, the thermodynamically most stable pattern is predicted and shown to coincide with the pattern which dominates the STM images after several hours or upon moderate heating.

The surfaces of a ten years aged crystal and a freshly prepared κ-(BEDT-TTF)2Cu(NCS)2 crystal were compared by scanning tunneling microscopy (STM). The molecularly-resolved STM images of the bc plane of the crystals agree with each other and with the electronic contrast obtained by new density functional theory (DFT) based simulations. Even after ten years STM images of the molecular stacking of BEDT-TTF display a variation in brightness at the positions of different molecules. We attribute this symmetry breaking concerning the brightness in the STM images of the otherwise equivalent BEDT-TTF dimers to the electronic states of a relaxed surface.

A strategy for the introduction of asymmetry into Frechet-type dendrons bearing n-alkyl chains is described. Starting from a methyl 3,5-dihydroxybenzoate core, 3,5-bis(octyloxyphenyl)methoxy and 3,5-bis(alkoxyphenyl)methoxy units are introduced in a stepwise manner. The method is illustrated by the syntheses of four representative compounds having mixed n-octyl/n-butyl, n-octyl/n-hexyl, n-octyl/n-heptyl and n-octyl/n-dodecyl substituents. The new compounds have been characterized by spectroscopic and mass spectrometric techniques. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).

A critical comparison of the two-dimensional and three-dimensional packing of Frechet-type dendrons in monolayers on HOPG and three-dimensional crystals, respectively, reveals a precise matching of the monolayer to sheets present in the bulk material.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Self‐organized molecular layers provide a promising route to constructing new (switchable) nanodevices and optimizing nanosensors. The design of such molecules involves control of structure and stabilization on the surface, as well as control of functionality. The search for a potentially universal “adapter”, which can control the self‐organization and stabilization on a particular type of surface, is a unique challenge. High‐quality nanoscale imaging using scanning tunneling microscopy (STM) provides the means to further such studies. This article reviews our recent STM work on single molecules, self‐assembled monolayers, and self‐organized monolayers, highlighting our application of a general “self‐organizer” for graphite surfaces, i.e., a Fréchet‐type dendron. How powerfully this self‐organizing motif can affect various central components (catalytic, switchable, redox‐active) on a graphite surface is addressed by analyzing self‐organized monolayers of nine different molecules, each containing at least one first‐ or second‐generation Fréchet‐type dendron. In molecular layers containing a “switchable” core, we can detect a large conformational change upon protonation with HCl gas. Last, but not least, the dynamic surface organization properties of the Fréchet‐type dendrons are described.

We describe the synthesis and a novel approach to the conformational analysis of 2,2'-bipyridines (bpy) bearing aromatic rich Frechet-type dendritic wedges of the first and second generation as substituents. The evaporation of solutions of these new ligands on graphite surfaces under ambient conditions results in the formation of self-organized monolayers. Scanning tunneling microscopy (STM) investigations of the monolayers under ambient conditions (air, 298 K) gave images at submolecular and near-atomic resolution. The analysis of the STM images includes the following processes: (i) identification and reproduction of potential homoconformational domains, (ii) exclusion of improper data using quality criteria for drift and feedback artifacts, (iii) compilation of running averages and checking for averaging artifacts, (iv) analysis of three-dimensional and contour plots, (v) calculation of the HOMO properties of the free molecules, and (vi) final conformational assignment based on all accessible information. Following this procedure, two different conformations could be assigned to domains observed in the monolayers of the first-generation (G1) and second-generation (G2) dendritic compounds. Homoconformational domains are observed side-by-side. The different conformations arise from syn or anti arrangements at the ether substituents. An additional conformational effect is found upon treating the G1 domains with HCl gas, when a partial rearrangement of the bpy from trans to cis occurs, concomitant with protonation.

A detailed STM study of monolayers of 3,5-bis[(3,5-bisoctyloxyphenyl)methyloxy]benzaldehyde and 3,5-bis[(3,5-bisoctyloxyphenyl)methyloxy]benzyl alcohol adsorbed on graphite is presented. Very highly resolved scanning tunnelling microscopy images are observed at room temperature in air allowing the analysis of the conformation of the adsorbed molecules. These long-chain alkyl-decorated Frechet-type dendrons are a powerful assembly motif and initially form a pattern based on trimeric units, assembled into hexagonal host structures with a pseudo-unit cell of seven molecules, one of which remains highly mobile. Over time, the supramolecular ordering changes from a trimeric into a dimeric pattern. The chirality arising from the adsorption onto a surface of the dendrons is discussed.

The compound 2,2': 6',2 ''-terpyridine-4'(1'H)-thione 1 has been prepared and structurally characterised; in both the solid state and in solution, the thione tautomer is dominant. Compound 1 is a key entry into 4'-sulfur-functionalised tpy ligands and a representative alkylation with an electrophilic Frechet dendrimer is presented and the structural characterisation of the new ligand 4 reported. Oxidation of 1 yields bis(2,2': 6',2 ''-terpyridin- 4'-yl) disulfide 2 which is a novel homoditopic tpy ligand and which forms a tetranuclear [ 4 + 4] iron (II) metallomacrocycle. Structural characterisation of 2 and preliminary data for the iron complex are presented.

Die Antwort liegt darunter: Metallosupramolekulare Kationen adsorbieren geordnet auf einer Kupferoberfläche, die zuvor mit einer Schicht aus Chloridionen modifiziert wurde. Diese Anionenschicht wirkt als Templat zweiter Ordnung, dessen Wechselwirkungen mit dem Kationen den Adsorptionsprozess bestimmen (siehe Schema).

The evaporation of solutions of dendron-functionalised 2,2'-bipyridines on a graphite surface gives highly ordered monolayers; near atomic resolution STM imaging has allowed a detailed conformational analysis to be made.

Die Antwort liegt darunter: Metallosupramolekulare Kationen adsorbieren geordnet auf einer Kupferoberfläche, die zuvor mit einer Schicht aus Chloridionen modifiziert wurde. Diese Anionenschicht wirkt als Templat zweiter Ordnung, dessen Wechselwirkungen mit dem Kationen den Adsorptionsprozess bestimmen (siehe Schema).

Angewandte Chemie International EditionVolume 43, Issue 10 p. 1291-1294 Communication Second-Order Templation: Ordered Deposition of Supramolecular Squares on a Chloride-Covered Cu(100) Surface† Caroline Safarowsky Dipl.-Chem., Caroline Safarowsky Dipl.-Chem. Institut für Physikalische und Theoretische Chemie der Universität, Wegelerstrasse 12, 53115 Bonn, Germany, Fax: (+49) 228-732-551Search for more papers by this authorLeo Merz Dipl.-Chem., Leo Merz Dipl.-Chem. Institut für Physik der Universität, Klingelbergstrasse 82, 4056 Basel, SwitzerlandSearch for more papers by this authorAlexander Rang Dipl.-Chem., Alexander Rang Dipl.-Chem. Kekulé-Institut für Organische Chemie und Biochemie der Universität, Gerhard-Domagk-Strasse 1, 53121 Bonn, Germany, Fax: (+49) 228-735-662Search for more papers by this authorPeter Broekmann Dr., Peter Broekmann Dr. broekman@thch.uni-bonn.de Institut für Physikalische und Theoretische Chemie der Universität, Wegelerstrasse 12, 53115 Bonn, Germany, Fax: (+49) 228-732-551Search for more papers by this authorB. A. Hermann Prof. Dr., B. A. Hermann Prof. Dr. b.hermann@cens.de Institut für Physik der Universität, Klingelbergstrasse 82, 4056 Basel, Switzerland Present address: Walther-Meissner-Institut für Tieftemperaturforschung der Bayerischen Akademie der Wissenschaften und Fakultät für Physik/Center for Nano Science (CeNS) der LMU München, Walther-Meissner-Strasse 8, 85748 Garching, Germany, Fax: (+49) 89-289-14206Search for more papers by this authorChristoph A. Schalley Dr., Christoph A. Schalley Dr. c.schalley@uni-bonn.de Kekulé-Institut für Organische Chemie und Biochemie der Universität, Gerhard-Domagk-Strasse 1, 53121 Bonn, Germany, Fax: (+49) 228-735-662Search for more papers by this author Caroline Safarowsky Dipl.-Chem., Caroline Safarowsky Dipl.-Chem. Institut für Physikalische und Theoretische Chemie der Universität, Wegelerstrasse 12, 53115 Bonn, Germany, Fax: (+49) 228-732-551Search for more papers by this authorLeo Merz Dipl.-Chem., Leo Merz Dipl.-Chem. Institut für Physik der Universität, Klingelbergstrasse 82, 4056 Basel, SwitzerlandSearch for more papers by this authorAlexander Rang Dipl.-Chem., Alexander Rang Dipl.-Chem. Kekulé-Institut für Organische Chemie und Biochemie der Universität, Gerhard-Domagk-Strasse 1, 53121 Bonn, Germany, Fax: (+49) 228-735-662Search for more papers by this authorPeter Broekmann Dr., Peter Broekmann Dr. broekman@thch.uni-bonn.de Institut für Physikalische und Theoretische Chemie der Universität, Wegelerstrasse 12, 53115 Bonn, Germany, Fax: (+49) 228-732-551Search for more papers by this authorB. A. Hermann Prof. Dr., B. A. Hermann Prof. Dr. b.hermann@cens.de Institut für Physik der Universität, Klingelbergstrasse 82, 4056 Basel, Switzerland Present address: Walther-Meissner-Institut für Tieftemperaturforschung der Bayerischen Akademie der Wissenschaften und Fakultät für Physik/Center for Nano Science (CeNS) der LMU München, Walther-Meissner-Strasse 8, 85748 Garching, Germany, Fax: (+49) 89-289-14206Search for more papers by this authorChristoph A. Schalley Dr., Christoph A. Schalley Dr. c.schalley@uni-bonn.de Kekulé-Institut für Organische Chemie und Biochemie der Universität, Gerhard-Domagk-Strasse 1, 53121 Bonn, Germany, Fax: (+49) 228-735-662Search for more papers by this author First published: 25 February 2004 https://doi.org/10.1002/anie.200352968Citations: 65 † This work was supported by the SFB 624 of the Deutsche Forschungsgemeinschaft and the NRP 47 of the Swiss National Science Foundation. C.A.S. and B.A.H. gratefully acknowledge the Fonds der Chemischen Industrie and the BMBF for financial support. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract Beneath the surface lies the answer: Metallosupramolecular cations are deposited in an ordered manner on a copper surface, which had previously been covered with chloride ions. The anion layer acts as a second-order template, whose interactions with the cation determine the adsorption process (see scheme). Citing Literature Volume43, Issue10February 27, 2004Pages 1291-1294 RelatedInformation