Recurring groups of atoms in molecules are surrounded by specific canonical distributions of electrons. Deviations from these distributions reveal unrealistic molecular geometries. Here, we show how canonical electron densities can be combined with classical electron densities derived from X-ray diffraction experiments to drive the real space refinement of crystal structures. The refinement process generally yields superior molecular models with reduced excess electron densities and improved stereochemistry without compromising the agreement between molecular models and experimental data.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3234344 | PMC |
| http://dx.doi.org/10.1016/j.str.2011.10.011 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
FeS@BC prepared from natural pyrite and biomass as peroxydisulfate activator for sulfadiazine degradation.
Environ Res
January 2025
School of Environment and Energy Engineering, Anhui Jianzhu University, Hefei, 230601, China.
The efficient degradation of SAs is a significant challenge for the treatment of wastewater. To address this, the FeS@BC was prepared by calcining a mixture of pyrite and biomass, and used to activate peroxydisulfate (PDS) to degrade sulfadiazine (SDZ). The effect of carbon sources (wheat straw, rice husk, and corn cob) on catalytic activity of FeS@BC were investigated by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), total Fe dissolution and free radical quantification.
View Article and Find Full Text PDFGreater Influence of Density on the Electrical Properties of an Organic Semiconductor Glass Compared to Molecular Orientation.
J Phys Chem B
January 2025
Department of Chemistry, Sungkyunkwan University, Suwon 16419, Republic of Korea.
Physical vapor deposition is widely used in the fabrication of organic light-emitting diodes and has the potential to adjust the density and orientation through substrate temperature control, which may lead to enhanced electrical performance. However, it is unclear whether this enhanced property is because of the horizontal molecular orientation or the increased density. The effects of the density and orientation on the electrical properties of a potential electron transport material, (3-dibenzo[c,h]acridin-7-yl)phenyl)diphenylphosphine oxide (TPPO-dibenzacridine), were investigated.
View Article and Find Full Text PDFCavitation and Other Deformation Instabilities in Plastic Deformation of Semicrystalline Polyethylene Modified with Paraffin Wax.
Polymers (Basel)
January 2025
Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363 Lodz, Poland.
The deformation behavior and instabilities occurring during the drawing of high-density polyethylene (HDPE) were investigated using wide- and small-angle X-ray scattering (WAXS and SAXS) and scanning electron microscopy (SEM) in plain HDPE and paraffin wax- and/or chloroform-modified samples. In contrast to neat HDPE, the modified materials demonstrated strongly suppressed cavitation. However, regardless of cavitation, the tensile deformation of all samples was found to be governed by crystallographic mechanisms active in the crystalline lamellae, supported by shear in the amorphous layers, i.
View Article and Find Full Text PDFHigh-Density Polyethylene-Polypropylene Blends: Examining the Relationship Between Nano/Microscale Phase Separation and Thermomechanical Properties.
Polymers (Basel)
January 2025
School of Engineering, Institute for Materials and Processes, The University of Edinburgh, Sanderson Building, King's Buildings, Edinburgh EH9 3FB, UK.
The phase separation of high-density polyethylene (HDPE)-polypropylene (PP) blends was studied using atomic force microscopy in tapping mode to obtain height and phase images. The results are compared with those from scanning electron microscopy imaging and are connected to the thermomechanical properties of the blends, characterised through differential scanning calorimetry, dynamic mechanical analysis (DMA), and tensile testing. Pure PP, as well as 10:90 and 20:80 weight ratio HDPE-PP blends, showed a homogeneous morphology, but the 25:75 HDPE-PP blends exhibited a sub-micrometre droplet-matrix structure, and the 50:50 HDPE-PP blends displayed a more complex co-continuous nano/microphase-separated structure.
View Article and Find Full Text PDFAn Electrochemical Dopamine Assay with Cobalt Oxide Palatinose Carbon Dots.
Molecules
January 2025
Department of Chemistry, Middle Tennessee State University, 440 Friendship Street, Murfreesboro, TN 37132, USA.
Elevated dopamine (DA) levels in urine denote neuroblastoma, a pediatric cancer. Saccharide-derived carbon dots (CDs) were applied to assay DA detection in simulated urine (SU) while delineating the effects of graphene defect density on electrocatalytic activity. CDs were hydrothermally synthesized to vary graphene defect densities using sucrose, raffinose, and palatinose, depositing them onto glassy carbon electrodes (GCEs).
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!