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Relevant π-hole tetrel bonding interactions in ethyl 2-triazolyl-2-oxoacetate derivatives: Hirshfeld surface analysis and DFT calculations

CrystEngComm, 2020, Advance Article
DOI: 10.1039/D0CE00335B, Paper
Muhammad Naeem Ahmed, Khawaja Ansar Yasin, Shahid Aziz, Saba Urooge Khan, Muhammad Nawaz Tahir, Diego Mauricio Gil, Antonio Frontera
We report the synthesis and X-ray characterization of four triazole derivatives that include an α-ketoester functionality and two phenyl substituents. The compounds form self-assembled dimers in the solid state establishing two symmetrically equivalent O⋯π-hole interactions.
To cite this article before page numbers are assigned, use the DOI form of citation above.
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Kollam bids to plug loopholes at check-post

Procedure for issuing passes for people from other States expedited




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Ludhiana faces medicine shortage as wholesale supply stops




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To combat COVID-19, Amritsar administration installs disinfection tunnel in wholesale market




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Coronavirus | What turned Koyambedu, Chennai’s popular wholesale complex market, into a COVID-19 hotspot?

Why has Koyambedu been so badly affected in all stages of the pandemic response?








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Whole-mol­ecule disorder of the Schiff base compound 4-chloro-N-(4-nitro­benzyl­idene)aniline: crystal structure and Hirshfeld surface analysis

In the crystal of the title Schiff base compound, C13H9ClN2O2, [CNBA; systematic name: (E)-N-(4-chloro­phen­yl)-1-(4-nitro­phen­yl)methanimine], the CNBA mol­ecule shows whole-mol­ecule disorder (occupancy ratio 0.65:0.35), with the disorder components related by a twofold rotation about the shorter axis of the mol­ecule. The aromatic rings are inclined to each other by 39.3 (5)° in the major component and by 35.7 (9)° in the minor component. In the crystal, C—H⋯O hydrogen bonds predominate in linking the major components, while weak C—H⋯Cl inter­actions predominate in linking the minor components. The result is the formation of corrugated layers lying parallel to the ac plane. The crystal packing was analysed using Hirshfeld surface analysis and compared with related structures.




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Intra­molecular 1,5-S⋯N σ-hole inter­action in (E)-N'-(pyridin-4-yl­methyl­idene)thio­phene-2-carbohydrazide

The title compound, C11H9N3OS, (I), crystallizes in the monoclinic space group P21/n. The mol­ecular conformation is nearly planar and features an intra­molecular chalcogen bond between the thio­phene S and the imine N atoms. Within the crystal, the strongest inter­actions between mol­ecules are the N—H⋯O hydrogen bonds, which organize them into inversion dimers. The dimers are linked through short C—H⋯N contacts and are stacked into layers propagating in the (001) plane. The crystal structure features π–π stacking between the pyridine aromatic ring and the azomethine double bond. The calculated energies of pairwise inter­molecular inter­actions within the stacks are considerably larger than those found for the inter­actions between the layers.




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Comparing the backfilling of mesoporous titania thin films with hole conductors of different sizes sharing the same mass density

Efficient infiltration of a mesoporous titania matrix with conducting organic polymers or small molecules is one key challenge to overcome for hybrid photovoltaic devices. A quantitative analysis of the backfilling efficiency with time-of-flight grazing incidence small-angle neutron scattering (ToF-GISANS) and scanning electron microscopy (SEM) measurements is presented. Differences in the morphology due to the backfilling of mesoporous titania thin films are compared for the macromolecule poly[4,8-bis­(5-(2-ethyl­hexyl)­thio­phen-2-yl)benzo[1,2-b;4,5-b']di­thio­phene-2,6-diyl-alt-(4-(2-ethyl­hexyl)-3-fluoro­thieno[3,4-b]thio­phene-)-2-carboxyl­ate-2-6-diyl)] (PTB7-Th) and the heavy-element containing small molecule 2-pinacol­boronate-3-phenyl­phen­anthro[9,10-b]telluro­phene (PhenTe-BPinPh). Hence, a 1.7 times higher backfilling efficiency of almost 70% is achieved for the small molecule PhenTe-BPinPh compared with the polymer PTB7-Th despite sharing the same volumetric mass density. The precise characterization of structural changes due to backfilling reveals that the volumetric density of backfilled materials plays a minor role in obtaining good backfilling efficiencies and interfaces with large surface contact.




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Structural and functional characterization of CMP-N-acetylneuraminate synthetase from Vibrio cholerae

Several pathogenic bacteria utilize sialic acid, including host-derived N-acetylneuraminic acid (Neu5Ac), in at least two ways: they use it as a nutrient source and as a host-evasion strategy by coating themselves with Neu5Ac. Given the significant role of sialic acid in pathogenesis and host-gut colonization by various pathogenic bacteria, including Neisseria meningitidis, Haemophilus influenzae, Pasteurella multocida and Vibrio cholerae, several enzymes of the sialic acid catabolic, biosynthetic and incorporation pathways are considered to be potential drug targets. In this work, findings on the structural and functional characterization of CMP-N-acetylneuraminate synthetase (CMAS), a key enzyme in the incorporation pathway, from Vibrio cholerae are reported. CMAS catalyzes the synthesis of CMP-sialic acid by utilizing CTP and sialic acid. Crystal structures of the apo and the CDP-bound forms of the enzyme were determined, which allowed the identification of the metal cofactor Mg2+ in the active site interacting with CDP and the invariant Asp215 residue. While open and closed structural forms of the enzyme from eukaryotic and other bacterial species have already been characterized, a partially closed structure of V. cholerae CMAS (VcCMAS) observed upon CDP binding, representing an intermediate state, is reported here. The kinetic data suggest that VcCMAS is capable of activating the two most common sialic acid derivatives, Neu5Ac and Neu5Gc. Amino-acid sequence and structural comparison of the active site of VcCMAS with those of eukaryotic and other bacterial counterparts reveal a diverse hydrophobic pocket that interacts with the C5 substituents of sialic acid. Analyses of the thermodynamic signatures obtained from the binding of the nucleotide (CTP) and the product (CMP-sialic acid) to VcCMAS provide fundamental information on the energetics of the binding process.




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Synchrotron multimodal imaging in a whole cell reveals lipid droplet core organization

A lipid droplet (LD) core of a cell consists mainly of neutral lipids, triacylglycerols and/or steryl esters (SEs). The structuration of these lipids inside the core is still under debate. Lipid segregation inside LDs has been observed but is sometimes suggested to be an artefact of LD isolation and chemical fixation. LD imaging in their native state and in unaltered cellular environments appears essential to overcome these possible technical pitfalls. Here, imaging techniques for ultrastructural study of native LDs in cellulo are provided and it is shown that LDs are organized structures. Cryo soft X-ray tomography and deep-ultraviolet (DUV) transmittance imaging are showing a partitioning of SEs at the periphery of the LD core. Furthermore, DUV transmittance and tryptophan/tyrosine auto-fluorescence imaging on living cells are combined to obtain complementary information on cell chemical contents. This multimodal approach paves the way for a new label-free organelle imaging technique in living cells.




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Quantitative three-dimensional nondestructive imaging of whole anaerobic ammonium-oxidizing bacteria

Anaerobic ammonium-oxidizing (anammox) bacteria play a key role in the global nitrogen cycle and in nitrogenous wastewater treatment. The anammox bacteria ultrastructure is unique and distinctly different from that of other prokaryotic cells. The morphological structure of an organism is related to its function; however, research on the ultrastructure of intact anammox bacteria is lacking. In this study, in situ three-dimensional nondestructive ultrastructure imaging of a whole anammox cell was performed using synchrotron soft X-ray tomography (SXT) and the total variation-based simultaneous algebraic reconstruction technique (TV-SART). Statistical and quantitative analyses of the intact anammox bacteria were performed. High soft X-ray absorption composition inside anammoxosome was detected and verified to be relevant to iron-binding protein. On this basis, the shape adaptation of the anammox bacteria response to iron was explored.




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Double Black-Hole Mystery: Dance Partners or Breakup Survivors?

Smithsonian astronomers have just discovered a rare example of a galaxy that appears to have a pair of giant black holes. Now they are trying to determine if those black holes are partners tied together by gravity, or if one of the two has been kicked out in a cosmic breakup.

The post Double Black-Hole Mystery: Dance Partners or Breakup Survivors? appeared first on Smithsonian Insider.




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Chandra X-ray Observatory finds youngest nearby black hole

Astronomers using NASA's Chandra X-ray Observatory have found evidence of the youngest black hole known to exist in our cosmic neighborhood. The 30-year-old object is a remnant of SN 1979C, a supernova in the galaxy M100 approximately 50 million light years from Earth.

The post Chandra X-ray Observatory finds youngest nearby black hole appeared first on Smithsonian Insider.




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Astronomers seek monster black hole gorging on a buffet of stars

According to new research by Nick Stone and Avi Loeb (Harvard-Smithsonian Center for Astrophysics), upcoming sky surveys might offer astronomers a way to catch a gorging black hole "in the act."

The post Astronomers seek monster black hole gorging on a buffet of stars appeared first on Smithsonian Insider.




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Chandra X-Ray Observatory finds massive black holes common in early universe

Using the deepest X-ray image ever taken, astronomers found the first direct evidence that massive black holes were common in the early universe. This discovery from NASA's Chandra X-ray Observatory shows that very young black holes grew more aggressively than previously thought, in tandem with the growth of their host galaxies.

The post Chandra X-Ray Observatory finds massive black holes common in early universe appeared first on Smithsonian Insider.




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Whole-genome analysis at center of effort to save Tasmanian devil

The whole-genome analysis of two Tasmanian devils—one that died of a new contagious cancer known as Devil Facial Tumor Disease (DFTD) and one healthy animal—is at the center of a new management strategy to help prevent the extinction of this species.

The post Whole-genome analysis at center of effort to save Tasmanian devil appeared first on Smithsonian Insider.




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Newly discovered supermassive black holes are just 160 million light years from Earth

Astronomers using NASA's Chandra X-ray Observatory discovered the first pair of supermassive black holes in a spiral galaxy similar to the Milky Way. Approximately 160 million light years from Earth, the pair is the nearest known such phenomenon.

The post Newly discovered supermassive black holes are just 160 million light years from Earth appeared first on Smithsonian Insider.




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New details on birth of black hole Cygnus X-1 revealed by Chandra X-ray Observatory

Astronomers are confident the Cygnus X-1 system contains a black hole, and with these latest studies they have remarkably precise values of its mass, spin, and distance from Earth.

The post New details on birth of black hole Cygnus X-1 revealed by Chandra X-ray Observatory appeared first on Smithsonian Insider.




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Black hole came from a shredded galaxy

Astronomers using NASA's Hubble Space Telescope have found a cluster of young, blue stars encircling the first intermediate-mass black hole ever discovered. The presence of the star cluster suggests that the black hole was once at the core of a now-disintegrated dwarf galaxy.

The post Black hole came from a shredded galaxy appeared first on Smithsonian Insider.




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X-ray flares observed by Chandra are asteroids being torn to pieces in a black hole

A new study provides a possible explanation for the mysterious flares. The suggestion is that there is a cloud around Sgr A* containing hundreds of trillions of asteroids and comets, which have been stripped from their parent stars.

The post X-ray flares observed by Chandra are asteroids being torn to pieces in a black hole appeared first on Smithsonian Insider.




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“Ordinary” black hole discovered in a galaxy 12-million-light-years away

An international team of scientists has discovered an ‘ordinary’ black hole in the galaxy Centaurus A. This is the first time that a normal-size black hole has been detected away from the immediate vicinity of our own Galaxy.

The post “Ordinary” black hole discovered in a galaxy 12-million-light-years away appeared first on Smithsonian Insider.




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Steady diet of binary star partners makes black holes grow “supermassive”

A new study by astrophysicists at the University of Utah and the Smithsonian Astrophysical Observatory in Cambridge, Mass., has found a new explanation for the growth of supermassive black holes: they repeatedly capture and swallow single stars from pairs of stars that get too close.

The post Steady diet of binary star partners makes black holes grow “supermassive” appeared first on Smithsonian Insider.




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Smithsonian astronomers and colleagues to photograph black hole at our galaxy’s heart

Smithsonian astronomers have joined their colleagues from other observatories in a daring new venture: to photograph the giant black hole at the heart of our Milky Way galaxy.

The post Smithsonian astronomers and colleagues to photograph black hole at our galaxy’s heart appeared first on Smithsonian Insider.




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Astronomers witness black hole outburst in Spiral Galaxy M83

An extraordinary outburst produced by a black hole in a nearby galaxy has provided direct evidence for a population of old, volatile stellar black holes.

The post Astronomers witness black hole outburst in Spiral Galaxy M83 appeared first on Smithsonian Insider.




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Scientists catch black hole in a feeding frenzy

Supermassive black holes snack infrequently, making the recent discovery of a black hole in the act of feeding all the more exciting to astronomers.

The post Scientists catch black hole in a feeding frenzy appeared first on Smithsonian Insider.




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Giant black hole kicked out of home galaxy

Astronomers have found strong evidence that a massive black hole is being ejected from its host galaxy at a speed of several million miles per hour.

The post Giant black hole kicked out of home galaxy appeared first on Smithsonian Insider.




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Save your local fishing hole

Last summer and this spring Boy Scout Arthur Carlton-Jones (shown here), working in conjunction with researchers at the Smithsonian Environmental Research Center in Edgewater, Md., […]

The post Save your local fishing hole appeared first on Smithsonian Insider.




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Black hole growth found to be out of synch

A new study of Chandra data has revealed two nearby galaxies whose supermassive black holes are growing faster than the galaxies themselves.

The post Black hole growth found to be out of synch appeared first on Smithsonian Insider.





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Black-hole powered jets plow into galaxy

This composite image of a galaxy illustrates how the intense gravity of a super massive black hole can be tapped to generate immense power. The image […]

The post Black-hole powered jets plow into galaxy appeared first on Smithsonian Insider.




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Chandra X-ray Observatory turns up black hole bonanza in galaxy next door

Using data from NASA’s Chandra X-ray Observatory, astronomers have discovered an unprecedented bonanza of black holes in the Andromeda Galaxy, one of the nearest galaxies […]

The post Chandra X-ray Observatory turns up black hole bonanza in galaxy next door appeared first on Smithsonian Insider.





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Dark matter guides growth of supermassive black holes

Every massive galaxy has a black hole at its center, and the heftier the galaxy, the bigger its black hole. But why are the two […]

The post Dark matter guides growth of supermassive black holes appeared first on Smithsonian Insider.



  • Science & Nature
  • Space
  • astronomy
  • astrophysics
  • Center for Astrophysics | Harvard & Smithsonian
  • Smithsonian Astrophysical Observatory

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Coming soon: Vacancy at the crawdad hole?

Yabbies, mudbugs, crayfish, crawdads, call them what you will, but one-third of the world’s crayfish species are facing extinction according to a recent report by […]

The post Coming soon: Vacancy at the crawdad hole? appeared first on Smithsonian Insider.





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Event Horizon Telescope Reveals Magnetic Fields at Milky Way’s Central Black Hole

Most people think of black holes as giant vacuum cleaners sucking in everything that gets too close. But the supermassive black holes at the centers […]

The post Event Horizon Telescope Reveals Magnetic Fields at Milky Way’s Central Black Hole appeared first on Smithsonian Insider.




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Ligo’s Twin Black Holes Might Have Been Born Inside a Single Star

On September 14, 2015, the Laser Interferometer Gravitational-wave Observatory (LIGO) detected gravitational waves from the merger of two black holes 29 and 36 times the […]

The post Ligo’s Twin Black Holes Might Have Been Born Inside a Single Star appeared first on Smithsonian Insider.




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Our Galaxy’s Black Hole is Spewing Planet-size “Spitballs”

Every few thousand years, an unlucky star wanders too close to the black hole at the center of the Milky Way. The black hole’s powerful […]

The post Our Galaxy’s Black Hole is Spewing Planet-size “Spitballs” appeared first on Smithsonian Insider.



  • Science & Nature
  • Space
  • Center for Astrophysics | Harvard & Smithsonian
  • Milky Way
  • Smithsonian Astrophysical Observatory


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Cosmic filament probes our galaxy’s giant black hole

The center of our Galaxy has been intensely studied for many years, but it still harbors surprises for scientists. A snake-like structure lurking near our […]

The post Cosmic filament probes our galaxy’s giant black hole appeared first on Smithsonian Insider.




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Black hole blasts may transform “Mini-Neptunes” into rocky worlds

A team of astrophysicists and planetary scientists has predicted that Neptune-like planets located near the center of the Milky Way galaxy have been transformed into […]

The post Black hole blasts may transform “Mini-Neptunes” into rocky worlds appeared first on Smithsonian Insider.




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Black Holes, just two numbers is all you need…

Black holes sound wildly complicated. After all, there are all sorts of bizarre things going on: intense gravity, the warping of the fabric of space, the distortion of time itself. But when it comes to describing black holes, it comes down to just two numbers: the mass of the black hole and its spin. That’s right. Everything you physically need to describe a black hole is found in just these two numbers.

The post Black Holes, just two numbers is all you need… appeared first on Smithsonian Insider.




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With signing of insurance bill, Lyft, Uber ridesharing loophole comes to an end

AB 2293 bans drivers from using their personal policies and mandates that drivers have to be covered from the moment they turn on their app and look for customers.; Credit: Photo by Daniel X. O'Neil via Flickr Creative Commons

Amid all the talk about cutting-edge technology, much of Uber and Lyft’s success actually owes to that fact the ride-sharing companies have been able to exploit a basic loophole: The companies foist the cost of insurance on their drivers, but the drivers' insurance companies don’t know they are underwriting cars for hire, and even if drivers wanted to be honest and get a policy that would cover ride-sharing, they couldn’t, because no such policy exists.

AB-2293, introduced by Assemblywoman Susan Bonilla (D-Concord) and signed into law Wednesday by Governor Jerry Brown, tries to close the loophole by paving the way for insurance companies to offer hybrid personal/commercial policies by next summer.

Uber once derided the bill as a backroom deal between insurance companies and trial lawyers.

"The bill does nothing to enhance safety, yet compromises the transportation choices and entrepreneurial opportunities Uber offers Californians," the company wrote in a June blog post that encouraged customers to contact their representatives opposing the bill.

However, the company backed down and supported the legislation when Bonilla insurance requirements were lowered.

AB 2293 also specifically bans drivers from using their personal policies and mandates drivers have to be covered from the moment they turn on their app and look for customers, which is a response to the tragic accident on New Year's Eve in San Francisco when an UberX driver hit and killed a six year old child.

Uber argued that because the driver was waiting for a fare he wasn't working for the company at the time, so he wasn't covered by the company's insurance.




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Junior Miner Has Potential for 'Discovery Hole' on Mexican Prospect

Ron Struthers of Struthers' Research Report takes a look at the investment thesis for Ridgestone Mining.




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Low-carbon product design: look at the parts to improve the whole

Researchers have developed a method to identify the parts that contribute the most to a product's greenhouse gas (GHG) emissions and evaluate alternative design solutions. When applied to a LCD television, it showed that GHG emissions could be cut by 36 per cent by using alternative parts to those currently used.




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New ozone hole discovered over the Arctic

For the first time, scientists have identified an ‘ozone hole’ over the Arctic, in addition to the well-known ozone hole over the Antarctic. Unusually persistent low temperatures over the arctic in early 2011 caused an unprecedented amount of chemical destruction of stratospheric ozone there. The authors warn that this is likely to happen again, although it is presently difficult to predict when this might be.