Contributions of experimental and selected theoretical charge-density research to medicinal chemistry are reviewed; combining experimental methods from high-resolution small-molecule and macromolecular crystallography with theory proves to be fruitful.

London soil pollution worst on former Blitz bomb sites  Chemistry World

The title compound, C15H13BrO2S, comprises three different substituents bound to a central (and chiral) methine-C atom, i.e. (4-bromo­phen­yl)sulfanyl, benzaldehyde and meth­oxy residues: crystal symmetry generates a racemic mixture. A twist in the mol­ecule is evident about the methine-C—C(carbon­yl) bond as evidenced by the O—C—C—O torsion angle of −20.8 (7)°. The dihedral angle between the bromo­benzene and phenyl rings is 43.2 (2)°, with the former disposed to lie over the oxygen atoms. The most prominent feature of the packing is the formation of helical supra­molecular chains as a result of methyl- and methine-C—H⋯O(carbon­yl) inter­actions. The chains assemble into a three-dimensional architecture without directional inter­actions between them. The nature of the weak points of contacts has been probed by a combination of Hirshfeld surface analysis, non-covalent inter­action plots and inter­action energy calculations. These point to the importance of weaker H⋯H and C—H⋯C inter­actions in the consolidation of the structure.

The di-substituted acetyl­ene residue in the title compound, C11H11NO3, is capped at either end by di-methyl­hydroxy and 4-nitro­benzene groups; the nitro substituent is close to co-planar with the ring to which it is attached [dihedral angle = 9.4 (3)°]. The most prominent feature of the mol­ecular packing is the formation, via hy­droxy-O—H⋯O(hy­droxy) hydrogen bonds, of hexa­meric clusters about a site of symmetry overline{3}. The aggregates are sustained by 12-membered {⋯OH}6 synthons and have the shape of a flattened chair. The clusters are connected into a three-dimensional architecture by benzene-C—H⋯O(nitro) inter­actions, involving both nitro-O atoms. The aforementioned inter­actions are readily identified in the calculated Hirshfeld surface. Computational chemistry indicates there is a significant energy, primarily electrostatic in nature, associated with the hy­droxy-O—H⋯O(hy­droxy) hydrogen bonds. Dispersion forces are more important in the other identified but, weaker inter­molecular contacts.

A cadmium germanium arsenide compound, Cd3Ge2As4, was synthesized using a double-containment fused quartz ampoule method within a rocking furnace and a melt-quench technique. The crystal structure was determined from single-crystal X-ray diffraction (SC-XRD), scanning and transmission electron microscopies (i.e. SEM, STEM, and TEM), and selected area diffraction (SAD) and confirmed with electron backscatter diffraction (EBSD). The chemistry was verified with electron energy loss spectroscopy (EELS).

The refinement of biomolecular crystallographic models relies on geometric restraints to help to address the paucity of experimental data typical in these experiments. Limitations in these restraints can degrade the quality of the resulting atomic models. Here, an integration of the full all-atom Amber molecular-dynamics force field into Phenix crystallographic refinement is presented, which enables more complete modeling of biomolecular chemistry. The advantages of the force field include a carefully derived set of torsion-angle potentials, an extensive and flexible set of atom types, Lennard–Jones treatment of nonbonded interactions and a full treatment of crystalline electrostatics. The new combined method was tested against conventional geometry restraints for over 22 000 protein structures. Structures refined with the new method show substantially improved model quality. On average, Ramachandran and rotamer scores are somewhat better, clashscores and MolProbity scores are significantly improved, and the modeling of electrostatics leads to structures that exhibit more, and more correct, hydrogen bonds than those refined using traditional geometry restraints. In general it is found that model improvements are greatest at lower resolutions, prompting plans to add the Amber target function to real-space refinement for use in electron cryo-microscopy. This work opens the door to the future development of more advanced applications such as Amber-based ensemble refinement, quantum-mechanical representation of active sites and improved geometric restraints for simulated annealing.

The three probes of the structure of matter (X-rays, neutrons and electrons) in biology have complementary properties and strengths. The balance between these three probes within their strengths and weaknesses is perceived to change, even dramatically so at times. For the study of combined states of order and disorder, NMR crystallography is also applicable. Of course, to understand biological systems the required perspectives are surely physiologically relevant temperatures and relevant chemical conditions, as well as a minimal perturbation owing to the needs of the probe itself. These remain very tough challenges because, for example, cryoEM by its very nature will never be performed at room temperature, crystallization often requires nonphysiological chemical conditions, and X-rays and electrons cause beam damage. However, integrated structural biology techniques and functional assays provide a package towards physiological relevance of any given study. Reporting of protein crystal structures, and their associated database entries, could usefully indicate how close to the biological situation they are, as discussed in detail in this feature article.

Over 170 molecules have been detected in space, from simple diatomic molecules like CO to complex organic molecules with over 70 atoms, such as fullerene. […]

The post Astronomers explore the rich chemistry surrounding an evolved star appeared first on Smithsonian Insider.

A research team from the Smithsonian and Arizona State University have developed a new, non-destructive method using spectroscopic analysis to help unravel the complex chemistry […]

The post Feathers yield mysteries of pigment chemistry to spectroscopic analysis appeared first on Smithsonian Insider.

Astronomers had a mystery on their hands. No matter where they looked, from inside the Milky Way to distant galaxies, they observed a puzzling glow […]

The post GBT Detection Unlocks Exploration of ‘Aromatic’ Interstellar Chemistry appeared first on Smithsonian Insider.

Increasing energy demands and expanding industrial and agricultural activities worldwide are changing the composition of the atmosphere and contributing to major global challenges like climate change and air pollution. The study of atmospheric chemistry plays a key role in understanding and responding to these challenges, and research in this field has been successful in guiding policies to improve air quality in urban areas and reduce acid rain and stratospheric ozone depletion.

Researchers have developed the first biology-based model to predict the sub-lethal effects of chemical mixtures on organisms. Sub-lethal effects do not cause death but can damage processes such as growth and reproduction. The model provided accurate predictions of the sub-lethal impacts of a chemical mixture on water fleas.

Although there have been significant advances in the understanding and monitoring of atmospheric processes in the last decade, a recent study suggests that uncertainties in their assessment continue to grow and more complex studies are required to understand the precise relationship between atmospheric chemicals, such as air pollutants, and climate change.

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An international research team jointly led by NTU Singapore, the U.S. Department of Energy's (DOE) Argonne National Laboratory and Germany's Deutsches Elektronen-Synchrotron (DESY) has for the first time observed the ultrafast formation and then breakdown of the water ion that is created when water is exposed to ionising radiation....

Artist Iori Tomita explores the natural art of the skeletal system by exploiting clever chemistry tricks. See how it's done.

Want to Make Medicines Greener? It’s in the Chemistry

When you're attracted to someone, you might realize it right from the start. They make you feel special or they make your face curl into a smile each time they're around.

Dr. Pares-Matos parlays decades of academic experience into her role with the University of Puerto Rico at Mayaguez

Dr. Sørensen channels years of expertise into his executive positions with KU Dyes and FRS-Systems

Kristin Grayce McGary's new book "Know Your Blood, Know Your Health" launches April 7, 2020

Deloitte national managing director Kim Christfort talks about the different personality styles in an organization and the challenges of bringing them together. Her firm has developed a classification system to help companies better understand personality styles and capitalize on their cognitive diversity. She and Suzanne M. Johnson Vickberg coauthored the article, "Pioneers, Drivers, Integrators, and Guardians" in the March-April 2017 issue of Harvard Business Review.

Starting November 1 the University of Michigan Library has access to the new version of chemistry database SciFinder — SciFinder-n. In fact, both will be accessible to our users with the same login and password information.

A primer solution for enhanced adhesion to a rigid substrate for aviation and aerospace applications includes an aminosilane-capped polyurethane prepolymer and a first solvent. The first solvent reacts with or modifies the surface of the rigid substrate, enabling the primer solution including the aminosilane-capped polyurethane prepolymer to become a part of the surface of the rigid substrate.

Biomaterials that support cell attachment and growth are provided. In one aspect, biomaterials are provided comprising a first polymer matrix comprising reactive amino moieties and a second polymer matrix that interpenetrates with the first polymer matrix, where the second polymer matrix comprises a poly(alkylene oxide) comprising two or more alkylene oxide oligomers joined by gamma-thioether carbonyl linkages. In another aspect, biomaterials are provided comprising at least one biopolymer comprising amino groups, thiol groups, and bifunctional modifiers connecting at least some of the amino groups to at least some of the thiol groups; and at least one poly(alkylene oxide) cross-linked to at least two thiol groups of the biopolymer. The biomaterials may further comprise a pharmacologically active agent or cells. Methods of administering such biomaterials to a patient in need thereof are also provided.

Electrochemical corrosion potential (ECP) probe assemblies may be used to monitor ECP of materials due to coolant chemistry in an operating nuclear reactor. Example embodiment assemblies include at least one ECP probe that detects ECP of potentially several different materials, a structural body providing a fluid flow path for the coolant over the ECP probes, and a signal transmitter that transmits or carries ECP data to an external receiver. The ECP probes may be of any number and/or type, so as to detect ECP for different component materials, including stainless steel, a zirconium alloys, etc. The ECP probes may further detect ECP due to ion concentration, pH, etc. The ECP data may be transmitted through wired or wireless signal transmitters. Example methods include installing and using example embodiment ECP probe assemblies in nuclear reactors and facilities.

Meet the determined young women who are working to break down barriers in the community and workforce, refusing to be defined by a stereotype.

Bananas too green, coffee too bitter, cookies too hard! Watch this clip to find out about the chemistry behind some clever food-preparation tricks that will solve these food crises. Discover the chemical elements, compounds and properties involved in getting some of our favourite foods to taste just right.

Want to know if an egg is rotten, why onions bring on tears and what makes green vegetables turn brown after cooking? Watch this clip to discover the chemistry behind these and other everyday problems. Find out about the chemical reactions, compounds and elements involved, and learn some simple chemistry-inspired solutions.

Caffeine is the world's most popular drug, but what is it and how does our body respond to its presence? Watch this clip to see the chemical structure of caffeine and the three compounds it metabolises into. Find out which receptor in the brain caffeine binds to, and the overall impacts it has on brain function and activity.

Do you know how glowsticks work? Watch this clip and discover the chemical reaction that takes place when you snap a glowstick and release the reactants. Find out about chemiluminescence in nature, when scientists first created glowing sticks and the chemical equation that describes the reaction. Can you guess which glowstick colour is the most challenging to create?

It’s not everyday we regurgitate a few old (and new!) chemistry jokes. How often do we tell them? Periodically. We told one the other day, but there was no reaction. Hahaha! Wait? How come nobody else is laughing? Ehem… well, anyways, here are a few more: When I first heard oxygen and magnesium got together […]

The post Top 20 Chemistry Jokes of Some Time appeared first on Funny & Jokes.

IBM scientists have developed a new approach to simulate molecules on a quantum computer that may one day help revolutionize chemistry and materials science. The scientists successfully used a seven-qubit quantum processor to address the molecular structure problem for beryllium hydride (BeH2) – the largest molecule simulated on a quantum computer to date. The results demonstrate a path of exploration for near-term quantum systems to enhance our understanding of complex chemical reactions that could lead to practical applications.

Documentary filmmaker Greg Barker has two new movies in one weekend: His narrative debut with Netflix biopic "Sérgio," and the Showtime doc "The Longest War."

(Bentham Science Publishers) This comprehensive review presented by researchers from K.S. Rangasamy College of Arts and Science, Tiruchengode, Tamil-Nadu, India, gives readers a brief overview of phytoconstituents, nutritional values and medicinal properties of the plant.

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