Materials Literature
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This work uses neutron scattering to characterize a metastable crystalline phase of germanium recovered from high pressure. Such metastable phases of silicon and germanium exhibit interesting functionality. They could potentially yield a Si or Ge structure with ideal band gap characteristics for solar power conversion…
A significant problem in biological X-ray crystallography is the radiation chemistry caused by the incident X-ray beam. This produces both global and site-specific damage. Global damage manifests itself in the decay of the diffraction pattern and data processing parameters. Site specific damage targets glutamates, asp…
We present structural data and chemical decomposition studies for seven CuCN network structures that include protonated alkylethanolamine derivatives as guest cations. Each 3D anionic polymeric structure is built from cyanide-bridged Cu atoms and is distinct from the others. All structures include cuprophilic pairs of…
Single-crystal X-ray structure determination is a critical component to research programs in many science and engineering fields. Unlike other chemical characterization techniques that are commonly presented in considerable depth in undergraduate degree programs, most students receive, at best, a cursory overview of t…
Materials discovery can be accelerated by the development of synthesis methods and in-situ characterization techniques allowing for the rapid "screening" of multicomponent systems. However, the sluggish kinetics of solidstate reactions entails the necessity of high temperatures and long annealing times, often leading…
Solid solution (mixed crystal) is a crystal containing a second constituent (with a variable ratio) which fits into and is distributed in the lattice of the host crystal (IUPAC). It is widely found among inorganic substances, but rarely among organic compounds because it generally forms an amorphous solid or, at best,…
Modern crystallographic refinement methods treat each atom in a molecule as neutral with spherical electron density. Atoms, however, exhibit partial atomic charges arising from intramolecular forces via bonding. These partial charges are crucial for understanding electronic structure and bulk physical properties of mo…
The investigation of topologically non-trivial surface states is at the forefront of condensed matter physics and material science. Of particular interest is the concurrence of non-trivial topology with superconductivity which has sparked both fundamental questions about the intersection of these phenomena and reveale…
We studied the effect of pressure on atacamite, Cu2Cl(OH)3, to 8.79 GPa using single-crystal X-ray diffraction. Atacamite, crystallizes in orthorhombic space group Pnma with a = 6.0323(1) , b = 6.8672(2) , c = 9.1207(5) , V= 377.018(8) ^3, and Z = 4. The (OH)3Cl group forms a tetrahedron, O3Cl, with two H(2) atoms pos…
Of interest in understanding electronic structure, bulk physical properties, enthalpies of phase changes, dipole moments, and numerous other properties of molecules, is the determination of realistic partial atomic charges on atoms. Atoms may take on partial positive or negative charges due to polar covalent bonds, co…
Since it is not typically part of the syllabus for crystallagraphy courses, the topic of neutron diffraction can nicely be supplemented through summer schools. Even less discussed is a special application of neutron diffraction in the area of magnetism. I will discuss the summer schools that I have participated in aim…
Crystalline solids, such as metal, metal oxides, zeolites, and metal-organic frameworks (MOFs), have been intensively investigated both as traditional and state-of-the-art materials. They have been implemented in a wide range of applications from industrial use to laboratorial research. The applications are closely as…
The systematic introduction of automation in structural biology over the last decade has enabled the study of ever more challenging targets, and facilitated the use of crystallography in drug design. However, manual crystal mounting and processing methods are insufficient to exploit the full potential of modern synchr…
Amyloid protein aggregation is typically associated with neurodegenerative diseases such as Alzheimer's disease. However, not all amyloid proteins are pathogenic in their aggregated state. The neuronal cytoplasmic polyadenylation element binding (CPEB) protein has been shown to form "functional" amyloid aggregates in…
Intensity-based likelihood functions in crystallographic applications have the potential to enhance the quality of structures derived from marginal diffraction data. Their usage however is complicated by the ability to efficiently compute these targets functions. Here a numerical quadrature is developed that allows fo…
We present several problematic small-molecule structures that required non-routine handling of data collection, processing and/or structural refinement. The structure of an octahedral Ni(II) complex could not be properly refined until the crystal was identified as a pseudo-merohedral twin. A highly absorbing complex
The compounds with Spin-crossover (SCO) phenomenon have a reversible exchange between a low spin (LS) state that is stable at low temperatures and a high spin (HS) state that is stable at high temperatures. In general, the reversible process in solid systems is controlled by intermolecular cooperatives interactions Th…
Though macromolecular x-ray crystallography has long been the primary method for protein and nucleic acid structure solution, the technique is often first introduced at the graduate level. However, macromolecular structures are encountered frequently throughout the undergraduate biological sciences curriculum, but the…
Functional characterization of proteins requires insights into the interplay between structure and dynamics as a function of time. Classical approaches to X-ray crystallography via populating intermediate states by mutation or chemical trapping only provide static time-averaged data sets. Considering this, serial time…
Crystallography involves analysis of distances among points in several spaces: 3-dimensional real and reciprocal spaces, 1-, 2-, 3-, 4-, 5-, and 6-dimensional spaces of lattice parameters, and higher dimensional spaces in which those spaces may be embedded. In any or all of these spaces we may need to find one or more…