Hydrogen bonding probes electron density variations at the basic center in substituted alkyl benzoates: Theory and experiment

2021 ◽  
Author(s):  
Diana Cheshmedzhieva ◽  
Sonia Ilieva ◽  
Boriana Hadjieva ◽  
Boris Galabov
Keyword(s):  
Hydrogen Bonding ◽  
Electron Density ◽  
Basic Center ◽  
Theory And Experiment

scholarly journals Electron generation in water induced by magnetic effect and its impact on dissolved oxygen concentration

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Augustine Chung Wei Yap ◽  
Hwang Sheng Lee ◽  
Joo Ling Loo ◽  
Nuruol Syuhadaa Mohd
Keyword(s):  
Water Quality ◽  
Hydrogen Bonding ◽  
Dissolved Oxygen ◽  
Electron Density ◽  
Water Flow ◽  
Magnetic Effect ◽  
Water Quality Control ◽  
Electron Generation ◽  
Magnetic Effects ◽  
Do Concentration

AbstractpH, oxidation-reduction potential (ORP) and dissolved oxygen (DO) concentration are important parameters in water quality surveillance and treatment. The changes of these parameters are associated with electron density in water. Several techniques including electrolysis and catalysis which require redox reactions and electron exchange are employed to improve these parameters. In recent years, studies reported that magnetic effects can impart considerable changes on the pH, ORP and DO concentration of water. However, the correlation between electron density and magnetic effects on these parameters has yet to be disclosed despite the fact that increased electron density in water could improve water’s reductive properties, heat capacity and hydrogen bonding characteristics. In this study, the magnetic effects on pH, ORP and DO concentration were investigated using different magnets arrangements and water flow rates based on reversed electric motor principle. Results showed that the improvement of pH, ORP and DO concentration from 5.40–5.42 to 5.58–5.62 (+ 3.5%), 392 to 365 mV (− 6.9%), and 7.30 to 7.71 mg L− 1 (+ 5.6%), respectively were achieved using combined variables of non-reversed polarity magnet arrangement (1000–1500 G magnetic strength) and water flow rate of 0.1–0.5 mL s− 1. Such decrement in ORP value also corresponded to 8.0 × 1013 number of electron generation in water. Furthermore, Raman analysis revealed that magnetic effect could strengthen the intermolecular hydrogen bonding of water molecules and favor formation of smaller water clusters. The findings of this study could contribute to potential applications in aquaculture, water quality control and treatment of cancer attributed to free radical induced-oxidative stress.

scholarly journals Electron generation in water induced by magnetic effect and its impact on dissolved oxygen concentration

2021 ◽  
Author(s):  
Augustine Chung Wei Yap ◽  
Hwang Sheng Lee ◽  
Joo Ling Loo ◽  
Nuruol Syuhadaa Mohd
Keyword(s):  
Water Quality ◽  
Hydrogen Bonding ◽  
Dissolved Oxygen ◽  
Electron Density ◽  
Water Flow ◽  
Magnetic Effect ◽  
Water Quality Control ◽  
Electron Generation ◽  
Magnetic Effects ◽  
Do Concentration

Abstract pH, oxidation-reduction potential (ORP) and dissolved oxygen (DO) concentration are important parameters in water quality surveillance and treatment. The changes of these parameters are associated with electron density in water. Several techniques including electrolysis and catalysis which require redox reactions and electron exchange are employed to improve these parameters. In recent years, studies reported that magnetic effects can impart considerable changes on the pH, ORP and DO concentration of water. However, the correlation between electron density and magnetic effects on these parameters has yet to be disclosed despite the fact that increased electron density in water could improve water’s reductive properties, heat capacity and hydrogen bonding characteristics. In this study, the magnetic effects on pH, ORP and DO concentration were investigated using different magnets arrangements and water flow rates based on reversed electric motor principle. Results showed that the improvement of pH, ORP and DO concentration from 5.40–5.42 to 5.58–5.62 (+ 3.5%), 392 to 365 mV (-6.9%), and 7.30 to 7.71 mg L− 1 (+ 5.6%), respectively were achieved using combined variables of non-reversed polarity magnet arrangement (1000–1500 G magnetic strength) and water flow rate of 0.1–0.5 mL s− 1. Such decrement in ORP value also corresponded to 8.0 × 1013 number of electron generation in water. Furthermore, Raman analysis revealed that magnetic effect could strengthen the intermolecular hydrogen bonding of water molecules and favor formation of smaller water clusters. The findings of this study could contribute to potential applications in aquaculture, water quality control and treatment of cancer attributed to free radical induced-oxidative stress.

A topological analysis of the interion interactions of tetraphenylphosphonium squarate

2006 ◽  
Vol 84 (5) ◽  
pp. 804-811 ◽  
Author(s):  
David Wolstenholme ◽  
Manuel AS Aquino ◽  
T Stanley Cameron ◽  
Joseph D Ferrara ◽  
Katherine N Robertson
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Electron Density ◽  
Intermolecular Interactions ◽  
Critical Points ◽  
Topological Analysis ◽  
Van Der Waals ◽  
Van Der Waals Interactions ◽  
Multipole Refinement ◽  
Diverse Interactions

The tetraphenylphosphonium squarate salt crystallizes with a number of diverse interactions, which all have the potential to be classified as hydrogen bonds. The squarate anions are found as dimers linked by O-H···O interactions. The multipole refinement of the tetraphenylphosphonium squarate was performed using the Hansen–Coppens model followed by topological analysis of its intermolecular interactions. A total of 28 interactions were found among the symmetry related molecules, which include a number of C-H···Cπ, C-H···O, and C-H···H-C interactions, along with the O-H···O interaction. With the criteria for hydrogen bonding proposed by Popelier and Koch, it is possible to determine which of these interactions are hydrogen bonds and which are van der Waals interactions. Both linear and exponentially dependent correlations can be seen for the properties of the bond critical points involving the intermolecular interactions that fulfill these criteria. All this leads to a better understanding of the role that hydrogen bonds play in the formation of small organic compounds.Key words: electron density, multiple refinement, hydrogen bonds.

scholarly journals Crystal structure of pentakis(ethylenediamine-κ2N,N′)lanthanum(III) trichloride–ethylenediamine–dichloromethane (1/1/1)

2014 ◽  
Vol 70 (11) ◽  
pp. 424-426 ◽  
Author(s):  
Hope T. Sartain ◽  
Richard J. Staples ◽  
Shannon M. Biros
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Electron Density ◽  
Inversion Center ◽  
Asymmetric Unit ◽  
Acta Cryst ◽  
Bypass Procedure ◽  
Hydrogen Bonding Network ◽  
Additional Hydrogen

We report here the crystal structure of a ten-coordinate lanthanum(III) metal coordinated by five bidentate ethylenediamine ligands, [La(C2H8N2)5]Cl3·C2H8N2·CH2Cl2. One free ethylenediamine molecule and three Cl−anions are also located in the asymmetric unit. The overall structure is held together by an extensive hydrogen-bonding network between the Cl−anions and the NH groups on the metal-bound ethylenediamine ligands. The free ethylenediamine molecule is held in an ordered position by additional hydrogen bonds involving both the chlorides and –NH groups on the metal-bound ligands. One highly disordered molecule of dichloromethane is located on an inversion center; however, all attempts to model this disorder were unsuccessful. The electron density in this space was removed using the BYPASS procedure [van der Sluis & Spek (1990).Acta Cryst.A46, 194–201].

Topological analysis of electron density and the electrostatic properties of isoniazid: an experimental and theoretical study

2014 ◽  
Vol 70 (2) ◽  
pp. 331-341 ◽  
Author(s):  
Gnanasekaran Rajalakshmi ◽  
Venkatesha R. Hathwar ◽  
Poomani Kumaradhas
Keyword(s):  
Hydrogen Bonding ◽  
Charge Density ◽  
Electron Density ◽  
Topological Analysis ◽  
Bond Critical Point ◽  
Potential Region ◽  
Electrostatic Properties ◽  
Structural And Electronic Properties ◽  
Density Analysis ◽  
Mycobacterial Cell Wall

Isoniazid (isonicotinohydrazide) is an important first-line antitubercular drug that targets the InhA enzyme which synthesizes the critical component of the mycobacterial cell wall. An experimental charge-density analysis of isoniazid has been performed to understand its structural and electronic properties in the solid state. A high-resolution single-crystal X-ray intensity data has been collected at 90 K. An aspherical multipole refinement was carried out to explore the topological and electrostatic properties of the isoniazid molecule. The experimental results were compared with the theoretical charge-density calculations performed usingCRYSTAL09with the B3LYP/6-31G** method. A topological analysis of the electron density reveals that the Laplacian of electron density of the N—N bond is significantly less negative, which indicates that the charges at the b.c.p. (bond-critical point) of the bond are least accumulated, and so the bond is considered to be weak. As expected, a strong negative electrostatic potential region is present in the vicinity of the O1, N1 and N3 atoms, which are the reactive locations of the molecule. The C—H...N, C—H...O and N—H...N types of intermolecular hydrogen-bonding interactions stabilize the crystal structure. The topological analysis of the electron density on hydrogen bonding shows the strength of intermolecular interactions.

THE EFFECT OF SUBSTITUTION ON STRUCTURE, INTRAMOLECULAR HYDROGEN BONDING STRENGTH, ELECTRON DENSITY AND RESONANCE IN 3-AMINO 2-IMINOMETHYL ACRYL ALDEHYDE

2012 ◽  
Vol 11 (05) ◽  
pp. 925-939 ◽  
Author(s):  
HEIDAR RAISSI ◽  
MAHDI YOOSEFIAN ◽  
FARIBA MOLLANIA ◽  
FARZANEH FARZAD
Keyword(s):  
Hydrogen Bonding ◽  
Electron Density ◽  
Population Analysis ◽  
Intramolecular Hydrogen Bonding ◽  
Analysis Data ◽  
Covalent Character ◽  
Hydrogen Bonding Interactions ◽  
Hydrogen Bond Strength ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bonding Strength

B3LYP/6-311++G** calculations have been carried out to simulate the influence of substitutions in position R1 and R2 of 3-amino 2-iminomethyl acryl aldehyde on intramolecular hydrogen bond strength. The following substituents are taken into considerations: CN, NO2, Cl, F, CH3, CHO, NH2, C2H5, SH, SCH3, CF3 and CH3CO and their vibrational frequencies are calculated at the same level of theory. Quantum theory of "Atoms in Molecules" and Natural Bond Orbitals method were applied to analyzed H-bond interactions. The electron density (ρ) and Laplacian (∇2ρ) properties, estimated by AIM calculations, indicate that N⋯H bond possesses low ρ and positive ∇2ρ values which are in agreement with electrostatic character of the HBs, whereas N–H bonds have covalent character (∇2ρ < 0). Natural population analysis data, the electron density and Laplacian properties, as well as, ν (N-H) and γ (N-H) have been used to evaluate the hydrogen bonding interactions.

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