“Conformational Simulation” of Sulfamethizole by Molecular Complexation and Insights from Charge Density Analysis: Role of Intramolecular S···O Chalcogen Bonding

2015 ◽  
Vol 15 (5) ◽  
pp. 2110-2118 ◽  
Author(s):  
Sajesh P. Thomas ◽  
Srimukh Prasad K. P. Veccham ◽  
Louis J. Farrugia ◽  
T. N. Guru Row
Keyword(s):  
Charge Density ◽  
Molecular Complexation ◽  
Density Analysis

Charge Density Analysis of 2-Pyridineformamide N(4)-Methylthiosemicarbazone (Z′ = 4): Role of an Enhanced N–H···S Thioureido Dimer

2017 ◽  
Vol 17 (6) ◽  
pp. 2993-3004 ◽  
Author(s):  
Bojana M. Francuski ◽  
Sladjana B. Novaković ◽  
Djordje D. Francuski ◽  
Goran A. Bogdanović
Keyword(s):  
Charge Density ◽  
Density Analysis

ChemInform Abstract: Crystal Structure and Charge Density Analysis of Ca(BH4)2.

ChemInform ◽  
2010 ◽  
Vol 41 (13) ◽  
Author(s):  
T. Noritake ◽  
M. Aoki ◽  
M. Matsumoto ◽  
K. Miwa ◽  
S. Towata ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Charge Density ◽  
Density Analysis

scholarly journals Deciphering the Role of π-Interactions in Polyelectrolyte Complexes Using Rationally Designed Peptides

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2074
Author(s):  
Sara Tabandeh ◽  
Cristina Elisabeth Lemus ◽  
Lorraine Leon
Keyword(s):  
Hydrogen Bonding ◽  
Phase Separation ◽  
Liquid Phase ◽  
Charge Density ◽  
Secondary Structures ◽  
Liquid Phase Separation ◽  
Polyelectrolyte Complexes ◽  
Π Interactions ◽  
Liquid Liquid Phase Separation

Electrostatic interactions, and specifically π-interactions play a significant role in the liquid-liquid phase separation of proteins and formation of membraneless organelles/or biological condensates. Sequence patterning of peptides allows creating protein-like structures and controlling the chemistry and interactions of the mimetic molecules. A library of oppositely charged polypeptides was designed and synthesized to investigate the role of π-interactions on phase separation and secondary structures of polyelectrolyte complexes. Phenylalanine was chosen as the π-containing residue and was used together with lysine or glutamic acid in the design of positively or negatively charged sequences. The effect of charge density and also the substitution of fluorine on the phenylalanine ring, known to disrupt π-interactions, were investigated. Characterization analysis using MALDI-TOF mass spectroscopy, H NMR, and circular dichroism (CD) confirmed the molecular structure and chiral pattern of peptide sequences. Despite an alternating sequence of chirality previously shown to promote liquid-liquid phase separation, complexes appeared as solid precipitates, suggesting strong interactions between the sequence pairs. The secondary structures of sequence pairs showed the formation of hydrogen-bonded structures with a β-sheet signal in FTIR spectroscopy. The presence of fluorine decreased hydrogen bonding due to its inhibitory effect on π-interactions. π-interactions resulted in enhanced stability of complexes against salt, and higher critical salt concentrations for complexes with more π-containing amino acids. Furthermore, UV-vis spectroscopy showed that sequences containing π-interactions and increased charge density encapsulated a small charged molecule with π-bonds with high efficiency. These findings highlight the interplay between ionic, hydrophobic, hydrogen bonding, and π-interactions in polyelectrolyte complex formation and enhance our understanding of phase separation phenomena in protein-like structures.

Revisiting the charge density analysis of 2,5-dichloro-1,4-benzoquinone at 20 K

2017 ◽  
Vol 73 (4) ◽  
pp. 654-659 ◽  
Author(s):  
Zhijie Chua ◽  
Bartosz Zarychta ◽  
Christopher G. Gianopoulos ◽  
Vladimir V. Zhurov ◽  
A. Alan Pinkerton
Keyword(s):  
Charge Density ◽  
Electron Density ◽  
Topological Analysis ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Total Electron Density ◽  
Total Electron ◽  
Structure Factors ◽  
Density Analysis ◽  
Experimental Charge Density

A high-resolution X-ray diffraction measurement of 2,5-dichloro-1,4-benzoquinone (DCBQ) at 20 K was carried out. The experimental charge density was modeled using the Hansen–Coppens multipolar expansion and the topology of the electron density was analyzed in terms of the quantum theory of atoms in molecules (QTAIM). Two different multipole models, predominantly differentiated by the treatment of the chlorine atom, were obtained. The experimental results have been compared to theoretical results in the form of a multipolar refinement against theoretical structure factors and through direct topological analysis of the electron density obtained from the optimized periodic wavefunction. The similarity of the properties of the total electron density in all cases demonstrates the robustness of the Hansen–Coppens formalism. All intra- and intermolecular interactions have been characterized.

scholarly journals Halogen bonding from charge-density analysis

2011 ◽  
Vol 67 (a1) ◽  
pp. C99-C100 ◽  
Author(s):  
E. Espinosa ◽  
T. T. T. Bui ◽  
S. Dahaoui ◽  
E. Aubert ◽  
C. Lecomte ◽  
...  
Keyword(s):  
Charge Density ◽  
Halogen Bonding ◽  
Density Analysis

Beyond Charge Density Matching: The Role of C–H···O Interactions in the Formation of Templated Vanadium Tellurites

2011 ◽  
Vol 11 (9) ◽  
pp. 4213-4219 ◽  
Author(s):  
Matthew D. Smith ◽  
Samuel M. Blau ◽  
Kelvin B. Chang ◽  
Matthias Zeller ◽  
Joshua Schrier ◽  
...  
Keyword(s):  
Charge Density

Ab initio charge density analysis of (B6C)2– and B4C3 species — How to describe the bonding pattern?

2006 ◽  
Vol 84 (5) ◽  
pp. 771-781 ◽  
Author(s):  
Cina Foroutan-Nejad ◽  
Gholam Hossein Shafiee ◽  
Abdolreza Sadjadi ◽  
Shant Shahbazian
Keyword(s):  
Quantum Theory ◽  
Carbon Atom ◽  
Charge Density ◽  
Ab Initio ◽  
Atoms In Molecules ◽  
Central Carbon Atom ◽  
B3lyp Method ◽  
Central Carbon ◽  
Density Analysis ◽  
Concrete Ring

In this study, a detailed topological charge density analysis based on the quantum theory of atoms in molecules (QTAIM) developed by Bader and co-workers, has been accomplished (using the B3LYP method) on the CB62– anion and three planar isomers of the C3B4 species, which had been first proposed by Exner and Schleyer as examples of molecules containing hexacoordinate carbon atoms. The analysis uncovers the strong (covalent) interactions of boron atoms as well as the "nondirectional" interaction of central carbon atom with those peripheral atoms. On the other hand, instabilities have been found in the topological networks of (B6C)2– and B4C3(para) species. A detailed investigation of these instabilities demonstrates that the topology of charge density has a floppy nature near the equilibrium geometries of the species under study. Thus, these species seems to be best described as complexes of a relatively concrete ring containing boron or carbon atoms and a central carbon atom that is confined in the plane of the molecule, but with nondirectional interactions with the surrounding atoms.Key words: hypervalency, hexacoordinate carbon, quantum theory of atoms in molecules, charge density analysis, ab initio methods.

Experimental charge-density analysis towards predictive materials science

2021 ◽  
Vol 4 (03) ◽  
pp. 50-71
Author(s):  
Leonardo Dos Santos ◽  
Bernardo L. Rodrigues ◽  
Camila B. Pinto
Keyword(s):  
Physical Properties ◽  
Charge Density ◽  
Materials Science ◽  
New Materials ◽  
Wide Applicability ◽  
Density Analysis ◽  
Properties Of Materials ◽  
A Charge ◽  
Experimental Charge Density

The ongoing increase in the number of experimental charge-density studies can be related to both the technological advancements and the wide applicability of the method. Regarding materials science, the understanding of bonding features and their relation to the physical properties of materials can not only provide means to optimize such properties, but also to predict and design new materials with the desired ones. In this tutorial, we describe the steps for a charge-density analysis, emphasizing the most relevant features and briefly discussing the applications of the method.

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