hydrogen bond strength
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2021 ◽  
Vol 22 (10) ◽  
pp. 4446-4457
Author(s):  
Fasih Bintang Ilhami ◽  
Ya-Tang Yang ◽  
Ai-Wei Lee ◽  
Yu-Hsuan Chiao ◽  
Jem-Kun Chen ◽  
...  

Author(s):  
Atheni Konar ◽  
Tandra Sarkar ◽  
Indrani Chakraborty ◽  
Nirmal Chandra Sukul ◽  
Dipanwita Majumdar ◽  
...  

Objective: To decipher the nature of water structure in two ultrahigh diluted (UHD) homeopathic drugs by Laser Raman Spectroscopy. Method: Two homeopathic drugs Calcarea carbonica (Calc.) and Sepia officinalis (Sep.) in 8cH, 202cH, and 1002cH and their diluent medium 90% ethanol in 8cH and 202cH were used in the present study. Laser Raman spectra of all the samples were obtained in the wave number region of 2400 – 4200 cm-1. The intensity ratio at vibration frequencies between 3200 and 3420 (R1) and that between 3620 and 3420 (R2) were calculated for each UHD of the samples. Results: The spectra show a marked difference in intensities in the stretching vibrations of CH and OH groups of all the samples. R1 values for three UHDs of Calc. and Sep. show negative and positive relationships, respectively. In the case of R2 values, the relationship in three UHDs is 81002 for Calc., and 8> 202 < 1002 for Sep. In the case of control (ethanol UHDs) both R1 and R2 show a negative relationship. Conclusion: R1 denotes a relative number of OH groups with strong and weak hydrogen bonds. R2 indicates the relative number of OH groups with broken and weak H-bonds. Therefore, the UHDs of the two drugs and the control are different from each other with respect to hydrogen bond strength of OH groups and the number of free OH groups or non-hydrogen bonded water molecules.


Author(s):  
Tandra Sarkar ◽  
Atheni Konar ◽  
Nirmal Chandra Sukul ◽  
Achintya Singha ◽  
Anirban Sukul

Objective: To confirm that free water molecules and hydrogen bond strength of OH groups underlie difference between two homeopathic drugs at ultrahigh dilution (UHD). Method: FTIR and Laser Raman spectra of UHDs of X-ray and Magnetis Poli Ambo were obtained in the wave number regions of 2400-4000 cm-1 and 2400-4200 cm-1, respectively. Mother tincture (MT) were prepared by exposing ethanol water to X-radiation for X-ray and magnetic field for Magnetis. Spectra of the reference water and the three UHDs of Ethanol were also taken. All the samples were in water-ethanol solution in which the ethanol content was 25%. For FTIR the difference spectrum (absorbance of a UHD minus absorbance of reference water) was obtained after normalization of the spectrum at 3410 cm-1. For Raman spectra the intensity ratio at vibration frequencies between 3200 and 3420 cm-1 (R1), and that between 3620 and 3420 cm-1 (R2), were calculated for each UHD. The intensity at 3600 cm-1 in the difference spectra (FTIR) represents the number of free water molecules in UHDs. R2 values in Raman scattering suggest the same thing. Results: The data in both cases follow almost a similar pattern of difference among the UHDs studied here. For example, X-ray: FTIR 14


Author(s):  
Atheni Konar ◽  
Tandra Sarkar ◽  
Nirmal Chandra Sukul ◽  
Anirban Sukul

Drugs in ultra-high dilution (UHD) are used in homeopathy. Lactose is used as a binding medium for UHD drugs. FTIR and Raman spectroscopy revealed that although devoid of molecules of the starting substance, different UHD drugs exhibit different amounts of free water molecules and variation in hydrogen bond strength. The aim of the present study was to establish whether specific water structures in UHD could specifically modify the water structure in lactose, particularly the water of crystallization. 3 UHD’s (potencies), 30cH, 200cH and 1000cH, of 2 drugs, Natrum muriaticum and Sulphur were mixed to lactose samples separately. Differential scanning calorimetry (DSC) of the samples was measured. The thermograms of potencies mixed to lactose differed from each other with respect to temperature and enthalpy associated with the removal of water of crystallization from lactose. We believe that the tested UHD modified the water structure in lactose thereby changing the enthalpy for the removal of water of crystallization. Different levels of thermal energy are needed to remove both free water molecules and water of crystallization from lactose. UHD’s also contributed to the change in enthalpy associated with the removal of water of crystallization from lactose. The tested UHD might have modified the number and strength of hydrogen bonds in the crystal structure of lactose. Specific water structures in liquid aqueous ethanol medium are transferable to the solid medium(lactose).


2021 ◽  
Author(s):  
Rahul Gera ◽  
Huib Bakker ◽  
Ricardo Franklin ◽  
Uriel N. Morzan ◽  
Gabriele Falciani ◽  
...  

We study the properties of the interface of water and the surfactant Hexaethylene Glycol Monododecyl Ether (C12E6)<br>with a combination of Heterodyne-Detected Vibrational Sum Frequency Generation (HD-VSFG), Kelvin-Probe measurements, and Molecular Dynamics (MD) simulations. We observe that the addition of C12E6 close to the critical micelle concentration (CMC), induces a drastic hydrogen bond strength enhancement of the water molecules close to the interface, as well as a flip in their net orientation. The mutual orientation of the water and C12E6 molecules, leads to the emergence of a broad (~ 3 nm) interface with a large electric field of ~ 1V/nm, as evidenced by the Kelvin-Probe measurements and MD simulations. Our findings may open the door for the design of novel electric-field tuned catalytic and light harvesting systems anchored at water-surfactant air interface. <br>


2021 ◽  
Author(s):  
Rahul Gera ◽  
Huib Bakker ◽  
Ricardo Franklin ◽  
Uriel N. Morzan ◽  
Gabriele Falciani ◽  
...  

We study the properties of the interface of water and the surfactant Hexaethylene Glycol Monododecyl Ether (C12E6)<br>with a combination of Heterodyne-Detected Vibrational Sum Frequency Generation (HD-VSFG), Kelvin-Probe measurements, and Molecular Dynamics (MD) simulations. We observe that the addition of C12E6 close to the critical micelle concentration (CMC), induces a drastic hydrogen bond strength enhancement of the water molecules close to the interface, as well as a flip in their net orientation. The mutual orientation of the water and C12E6 molecules, leads to the emergence of a broad (~ 3 nm) interface with a large electric field of ~ 1V/nm, as evidenced by the Kelvin-Probe measurements and MD simulations. Our findings may open the door for the design of novel electric-field tuned catalytic and light harvesting systems anchored at water-surfactant air interface. <br>


Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 627
Author(s):  
Michael R. Reynolds ◽  
Fraser S. Pick ◽  
John J. Hayward ◽  
John F. Trant

Anions are important hydrogen bond acceptors in a range of biological, chemical, environmental and medical molecular recognition processes. These interactions have been exploited for the design and synthesis of ditopic resorcinarenes as the hydrogen bond strength can be tuned through the modification of the substituent at the 2-position. However, many potentially useful compounds, especially those incorporating electron-withdrawing functionalities, have not been prepared due to the challenge of their synthesis: their incorporation slows resorcinarene formation that is accessed by electrophilic aromatic substitution. As part of our broader campaign to employ resorcinarenes as selective recognition elements, we need access to these specialized materials. In this article, we report a straightforward synthetic pathway for obtaining a 2-(carboxymethyl)-resorcinarene, and resorcinarene esters in general. We discuss the unusual conformation it adopts and propose that this arises from the electron-withdrawing nature of the ester substituents that renders them better hydrogen bond acceptors than the phenols, ensuring that each of them acts as a donor only. Density Functional Theory (DFT) calculations show that this conformation arises as a consequence of the unusual configurational isomerism of this compound and interruption of the archetypal hydrogen bonding by the ester functionality.


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