The Cambridge Structural Database (CSD) contains a complete record of all published organic and metal–organic small-molecule crystal structures. The database has been in operation for over 50 years and continues to be the primary means of sharing structural chemistry data and knowledge across disciplines. As well as structures that are made public to support scientific articles, it includes many structures published directly as CSD Communications. All structures are processed both computationally and by expert structural chemistry editors prior to entering the database. A key component of this processing is the reliable association of the chemical identity of the structure studied with the experimental data. This important step helps ensure that data is widely discoverable and readily reusable. Content is further enriched through selective inclusion of additional experimental data. Entries are available to anyone through free CSD community web services. Linking services developed and maintained by the CCDC, combined with the use of standard identifiers, facilitate discovery from other resources. Data can also be accessed through CCDC and third party software applications and through an application programming interface.

https://journals.iucr.org/b/issues/2016/02/00/bm5086/bm5086.pdf

The Cambridge Structural Database

https://pubs.rsc.org/en/content/articlepdf/2019/NP/C8NP00092A

Marine natural products.

Graphene’s success has shown that it is possible to create stable, single and few-atom-thick layers of van der Waals materials, and also that these materials can exhibit fascinating and technologically useful properties. Here we review the state-of-the-art of 2D materials beyond graphene. Initially, we will outline the different chemical classes of 2D materials and discuss the various strategies to prepare single-layer, few-layer, and multilayer assembly materials in solution, on substrates, and on the wafer scale. Additionally, we present an experimental guide for identifying and characterizing single-layer-thick materials, as well as outlining emerging techniques that yield both local and global information. We describe the differences that occur in the electronic structure between the bulk and the single layer and discuss various methods of tuning their electronic properties by manipulating the surface. Finally, we highlight the properties and advantages of single-, few-, and many-layer 2D materials in...

/pdf/progress-challenges-and-opportunities-in-two-dimensional-1sweg4hljr.pdf

Progress, Challenges, and Opportunities in Two-Dimensional Materials Beyond Graphene

Images and force measurements taken by an atomic‐force microscope (AFM) depend greatly on the properties of the spring and tip used to probe the sample’s surface. In this article, we describe a simple, nondestructive procedure for measuring the force constant, resonant frequency, and quality factor of an AFM cantilever spring and the effective radius of curvature of an AFM tip. Our procedure uses the AFM itself and does not require additional equipment.

Calibration of atomic‐force microscope tips

http://experimentationlab.berkeley.edu/sites/default/files/AFMImages/butt_AFM.pdf

Force measurements with the atomic force microscope: Technique, interpretation and applications

With the scanning tunneling microscope (STM) it became possible to perform controlled manipulations down to the scale of small molecules and single atoms, leading to the fascinating aspect of creating manmade structures on atomic scale. Here we present a short review of our work in the last five years on atomic scale manipulation investigations. Upon soft lateral manipulation of adsorbed species, in which only tip/particle forces are used, three different manipulation modes (pushing, pulling, sliding) can be discerned. We show that also manipulation of highly coordinated native substrate atoms is possible and demonstrate the application of these techniques as local analytic and synthetic chemistry tools with important consequences on surface structure research. Vertical manipulation of Xe and CO is presented, leading to improved imaging and even chemical contrast with deliberately functionalized tips. For the transfer of CO it is shown that beside tip voltage current effects play also an important role. This is also the case for the dissociation of molecules. With CO transferred deliberately to the tip we have also succeeded to perform vibrational spectroscopy on single molecules. Furthermore, first experiments aiming for the transfer of all manipulation modes to thin insulating films are described.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/%28SICI%291438-5171%28200004%291%3A1%3C79%3A%3AAID-SIMO79%3E3.0.CO%3B2-R

Controlled manipulation of atoms and small molecules with a low temperature scanning tunneling microscope

We show charge-state manipulation of single Au adatoms on 2-11 monolayer (ML) thick NaCl films on Cu surfaces by attaching or detaching single electrons via the tip of an atomic force microscope (AFM). Tristate charge control (neutral, negatively charged, and positively charged) is achieved. On Cu(100) and Cu(111) supports, charge tristability is achieved independently of the NaCl layer thickness. In contrast, on Cu(311), only Au anions are stable on the thinnest NaCl films, but neutral and positive charge states become sufficiently long lived on films thicker than 4 ML to allow AFM-based charge-state-manipulation experiments.

/pdf/manipulation-of-the-charge-state-of-single-au-atoms-on-1ps31g0nns.pdf

Manipulation of the charge state of single Au atoms on insulating multilayer films.

Ultrathin insulating films on metal substrates are unique systems for using a scanning tunneling microscope to study the electronic properties of single atoms and molecules that are electronically decoupled from the metallic substrate. Individual gold atoms on an ultrathin insulating sodium chloride film supported by a copper surface exhibit two different charge states, which are stabilized by the large ionic polarizability of the film. The charge state and associated physical and chemical properties such as diffusion can be controlled by adding or removing a single electron to or from the adatom with a scanning tunneling microscope tip. The simple physical mechanism behind the charge bistability in this case suggests that this is a common phenomenon for adsorbates on polar insulating films. In the case of molecules on ultrathin NaCl films, the electronic decoupling allows the direct imaging of the unperturbed molecular orbitals, as will be shown in the case of individual pentacene molecules.

Scanning tunneling microscopy of adsorbates on insulating films. From the imaging of individual molecular orbitals to the manipulation of the charge state

Selective bond breaking of single iodobenzene molecules with a scanning tunneling microscope tip

The nanostencil is a tool for resistless lithography. It allows the direct patterning of complex nanometer-sized structures composed of a wide range of materials in an ultrahigh vacuum environment. This is combined with state-of-the-art scanning probe microscopy techniques (atomic force microscopy, scanning tunneling microscopy) and an electronic four-point probe. Moreover, all these capabilities are in situ and autoaligned in the field of view. The direct patterning is based on the shadow-mask technique and allows multimask processes in a static and dynamic manner.

Gerhard Meyer

Papers

Controlled manipulation of atoms and small molecules with a low temperature scanning tunneling microscope

Manipulation of the charge state of single Au atoms on insulating multilayer films.

Scanning tunneling microscopy of adsorbates on insulating films. From the imaging of individual molecular orbitals to the manipulation of the charge state

Selective bond breaking of single iodobenzene molecules with a scanning tunneling microscope tip

All-in-one static and dynamic nanostencil atomic force microscopy/scanning tunneling microscopy system