Solvent effects on the visible absorption spectrum of crystal violet

1981 ◽  
Vol 59 (2) ◽  
pp. 191-194 ◽  
Author(s):  
J. Korppi-Tommola ◽  
R. W. Yip
Keyword(s):  
Crystal Violet ◽  
Visible Region ◽  
Ion Pair ◽  
Polar Solvents ◽  
Visible Absorption ◽  
Spectral Behaviour ◽  
Solute Interaction ◽  
Self Association ◽  
Solvent Molecules ◽  
Polar Solutions

Addition of polar solvents to non-polar solutions of crystal violet results in dramatic changes in the visible absorption spectra. The observed changes are explained in terms of crystal violet existing as an ion-pair in non-polar solutions and as a solvated ion in polar solutions.The spectrum of crystal violet in toluene and in acetone solution remains virtually unchanged over a wide temperature range. However in methanol, as was reported for ethanol (1), the short wavelength component of the absorption in the visible region disappears as the temperature is lowered. The spectral behaviour in alcoholic solutions suggests a decreasing solvent–solute interaction around the dye cation due to increased self-association of the solvent molecules as the temperature is decreased. Our observations have a direct application in interpreting some of the results of the photodynamics of crystal violet in solution.

Stereospecific 1,3-H Transfer of Indenols Proceeds via Persistent Ion-Pairs Anchored By NH···Pi Interactions

2018 ◽  
Author(s):  
David Ascough ◽  
Fernanda Duarte ◽  
Robert Paton
Keyword(s):  
Computational Analysis ◽  
Ion Pairs ◽  
Ion Pair ◽  
Hydrogen Atom Transfer ◽  
Polar Solvents ◽  
Chirality Transfer ◽  
Activation Barriers ◽  
Sense And Avoid ◽  
Phase Dynamics ◽  
Pi Interactions

The base-catalyzed rearrangement of arylindenols is a rare example of a suprafacial [1,3]-hydrogen atom transfer. The mechanism has been proposed to proceed via sequential [1,5]-sigmatropic shifts, which occur in a selective sense and avoid an achiral intermediate. A computational analysis using quantum chemistry casts serious doubt on these suggestions: these pathways have enormous activation barriers and in constrast to what is observed experimentally, they overwhelmingly favor a racemic product. Instead we propose that a suprafacial [1,3]-prototopic shift occurs in a two-step deprotonation/reprotonation sequence. This mechanism is favored by 15 kcal mol<sup>-1</sup> over that previously proposed. Most importantly, this is also consistent with stereospecificity since reprotonation occurs rapidly on the same p-face. We have used explicitly-solvated molecular dynamics studies to study the persistence and condensed-phase dynamics of the intermediate ion-pair formed in this reaction. Chirality transfer is the result of a particularly resilient contact ion-pair, held together by electrostatic attraction and a critical NH···p interaction which ensures that this species has an appreciable lifetime even in polar solvents such as DMSO and MeOH.

Solvation and redox properties of [Co(en)3]3+-[Co(en)3]2+ system

1980 ◽  
Vol 45 (2) ◽  
pp. 335-338 ◽  
Author(s):  
Adéla Kotočová ◽  
Ulrich Mayer
Keyword(s):  
Hydrogen Bond ◽  
Lewis Acid ◽  
Specific Interaction ◽  
Redox Properties ◽  
Solvation Effect ◽  
Interacting Particles ◽  
Acid Base ◽  
Polar Solvents ◽  
Oxidation Reduction ◽  
Solvent Molecules

The solvation effect of a number of nonaqueous polar solvents was studied on the oxidation-reduction properties of the [Co(en)3]3+-[Co(en)3]2+ system. Interactions of these ions with the solvent molecules are discussed in terms of their coordination, which is accompanied by a specific interaction of the Lewis acid-base type, namely formation of a hydrogen bond between the interacting particles. This is the main controlling factor of the redox properties of the studied system.

Influence of Electron Injection Rate in Triphenylamine Based Dye for Dye-Sensitized Solar Cells: A First Principle Study

2019 ◽  
Vol 233 (9) ◽  
pp. 1247-1259
Author(s):  
Madhu Prakasam
Keyword(s):  
Solar Cells ◽  
Absorption Spectra ◽  
Density Functional ◽  
Dye Sensitized Solar Cells ◽  
Visible Region ◽  
Electron Injection ◽  
Injection Rate ◽  
Visible Absorption ◽  
Dye Sensitized ◽  
Sensitized Solar Cells

Abstract In this work, we systematically investigate the impacts of electron-donor based on Triphenylamine (TPA). The Geometry structure, energy levels, light-harvesting ability and ultraviolet-visible absorption spectra were calculated by using Density Functional Theory (DFT) and Time-Dependent-DFT. The electron injection rate of the TPA-N(CH3)2 based dyes has 0.71 eV for high among the dye sensitizer. The First and Second order Hyperpolarizability of the 11.95 × 10−30 e.s.u and 12195.54 a.u, respectively for TPA-N(CH3)2 based dye. The calculated absorption spectra were showed in the ultra-violet visible region for power conversion region. The study reveals that the electron transfer character of TPA-N(CH3)2 based dyes can be made suitable for applications in Dye-Sensitized Solar Cells.

scholarly journals ANÁLISIS DE COMPONENTES PRINCIPALES DE IMÁGENES MULTIESPECTRALES EN EL ÁMBITO DEL ARTE RUPESTRE

2017 ◽  
Author(s):  
Berta Carrión-Ruiz ◽  
José Luis Lerma
Keyword(s):  
Principal Component Analysis ◽  
Near Infrared ◽  
Rock Art ◽  
Visible Region ◽  
Principal Component ◽  
Optical Filters ◽  
Infrared Region ◽  
Spectral Behaviour ◽  
Near Infrared Region ◽  
Art Analysis

This paper tackles principal component analysis (PCA) in images that include wavelengths between 380-1000 nm. Our approach is focussed on taking advantage of the potencial of ultraviolet and infrarred images, in combination with the visible ones, to improve documentation process and rock art analysis. In this way, we want to improve the discrimination between pigment and support rock, and analyse the spectral behaviour of rock art paintings in the ultraviolet and infrared regions. Three images were used, one image from the ultraviolet (UV) region, one from the visible region (VIS) and another one from the near infrared region (NIR). Optical filters coupled to the camera optics were used to take the images. These filters capture specific wavelengths excluding radiation that we are not interested in registering. Finally, PCA is applied to the acquired images. The results obtained demonstrate the PCA usefulness with imagery in this field and also it is possible to extract some conclusions about the correspondent paint pigments.http://dx.doi.org/10.4995/CIGeo2017.2017.6597

scholarly journals Determination of the dipole moments of some polar liquids dissolved in polar solvents

1969 ◽  
Vol 47 (20) ◽  
pp. 3767-3771 ◽  
Author(s):  
H. A. Rizk ◽  
N. Youssef ◽  
H. Grace
Keyword(s):  
Dipole Moments ◽  
Butyl Alcohol ◽  
Polar Solvents ◽  
Tert Butyl ◽  
Tert Butyl Alcohol ◽  
Initial Decrease ◽  
Interacting Systems ◽  
Solvent Molecules ◽  
Onsager Equation

The application of a modified form of the Onsager equation at the condition of infinite dilution of a polar solute in a polar solvent leads to reasonable dipole moments for water, pyridine, acetone, tert-butyl alcohol, n-butyl alcohol, and β-octyl alcohol, except in the case of water in tert-butyl alcohol at 30 and 40 °C and the case of acetone in n-butyl alcohol at 30 to 50 °C. The initial decrease of the dielectric constant of solvent by addition of solute in each of these two cases is associated with a reduction in the Kirkwood g-factor of solute. In all 12 systems investigated, strong hydrogen bonding occurs between solute and solvent molecules and often between solvent molecules themselves. It is thought that this equation must fail when short-range interactions assume predominant importance, but why it works so well for those cases which are also strongly interacting systems is not clear.

Photoreduction of Dye with Noble Metal Gold Permeated with Metal Oxide Titania

2020 ◽  
Vol 20 (6) ◽  
pp. 3896-3901 ◽  
Author(s):  
Jyoti Bansal ◽  
A. K. Hafiz ◽  
Shailesh Narain Sharma
Keyword(s):  
Metal Oxide ◽  
Noble Metals ◽  
Irradiation Time ◽  
Visible Region ◽  
Visible Absorption ◽  
Photo Degradation ◽  
Sunlight Irradiation ◽  
Tunable Bandgap ◽  
Photo Response ◽  
Uv Visible

Photoactive degradation of textile malachite green (MG), methylene blue (MB) dyes has been permeated on metal oxide TiO2 nanoparticles under sunlight. Semiconductor photocatalysis is a promising method for removal of toxic chemicals from wastewater produced by industry. Due to tunable bandgap, TiO2 among various semiconductor studied mostly. Large band gap (UV active) and recombination of exciton in TiO2 less active in photo degradation. Noble metals such as gold nanoparticles deposited on TiO2 surface increased the optical activity and to shift optical response to visible region. Degradation detail has been carried out by characterisation such as XRD, UV-Vis, PL, TEM, and SEM for MG and MB textile dyes under sunlight irradiation. UV-visible absorption spectra and PL spectra shows that photo-response of as prepared sample is extended from UV to visible region. PL intensity decreases with increases in concentration of Au nanoparticles, decreases in intensity in optical spectra of Au–TiO2 composites shows that charge transfer process dominates. Au–TiO2 plays an essential role in enhancing photocatalytical activity. Decolorization optimization depends on catalyst concentration, Dye concentration, light intensity and, irradiation time.

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