Absorption Spectra Of Crystal Violet Research Articles

First-Principles Modeling of the Absorption Spectrum of Crystal Violet in Solution: The Importance of Environmentally Driven Symmetry Breaking.

Theoretical spectroscopy plays a crucial role in understanding the properties of the materials and molecules. One of the most promising methods for computing optical spectra of chromophores embedded in complex environments from the first principles is the cumulant approach, where both (generally anharmonic) vibrational degrees of freedom and environmental interactions are explicitly accounted for. In this work, we verify the capabilities of the cumulant approach in describing the effect of complex environmental interactions on linear absorption spectra by studying Crystal Violet (CV) in different solvents. The experimental absorption spectrum of CV strongly depends on the nature of the solvent, indicating strong coupling to the condensed-phase environment. We demonstrate that these changes in absorption line shape are driven by an increased splitting between absorption bands of two low-lying excited states that is caused by a breaking of the D3 symmetry of the molecule and that in polar solvents, this symmetry breaking is mainly driven by electrostatic interactions with the condensed-phase environment rather than distortion of the structure of the molecule, in contrast with conclusions reached in a number of previous studies. Our results reveal the importance of explicitly including a counterion in the calculations in nonpolar solvents due to electrostatic interactions between CV and the ion. In polar solvents, these interactions are strongly reduced due to solvent screening effects, thus minimizing the symmetry breaking. Computed spectra in methanol are found to be in reasonable agreement with the experiment, demonstrating the strengths of the outlined approach in modeling strong environmental interactions.

Probing the reverse micelle environment with a cationic dye by varying oil and water content of micelles.

In the present work, spectroscopic properties of crystal violet (CV) within water-in-hexane sodium base (2-ethyl hexyl) sulfosuccinate (AOT) reverse micellar environment was investigated as a function of water contents (W = [H2O]/[AOT] = 6,10) in AOT and also function of mass fraction of nanodroplet (MFD = 0.01, 0.04, 0.07, and 0.1) by using UV/visible, and fluorescence techniques. A deviation in the absorption spectra of crystal violet at the high CV concentration (0.002 M) was observed in the AOT reversed micelles. The Quenching in the emission intensity of crystal violet at high CV concentration and blue shift in λmax of fluorescence of dye was observed as a function of MFD in AOT RMs. At high concentration of dye, molecules of CV can be reside interfacial region but near core of AOT. At low dye concentration, the CV molecules also can be in interfacial region but far from core. The Stokes shift of CV at high concentration decreased with mass fraction of nano-droplet (MFD), whereas at the low CV concentration, its variation often increased. The ratio of ground state to the excited state dipole moment of crystal violet dye also affected by the change in W values and MFD values. The change in dipole moment and stokes shift indicates the different environment around CV for different W and MFD values.

Application of soluble bio-organic substances (SBO) as photocatalysts for wastewater treatment: Sensitizing effect and photo-Fenton-like process

Soluble bio-organic substances (SBO) isolated from urban biorefuses have been investigated in photocatalytic processes for wastewater treatment using a cationic dye, namely crystal violet (CV) as target compound. The SBO have been found to enhance the photobleaching of CV solutions with an optimal SBO concentration of ca. 20mgL−1. Mechanistic investigation based on chemical probes and changes in the absorption spectrum of CV in the presence of SBO seems to indicate that a complex formed between sensitizer and substrate plays a major role in the process. SBO have also been tested for the implementation of photo-Fenton processes at circumneutral media: the observed pseudo first order rate constants for CV decoloration was higher for UV/SBO/Fe(II)/H2O2 (5.5×10−3min−1) than for UV/Fe(II)/H2O2 (1.5×10−3min−1). A modified mechanism, in which HO are less relevant that at the acidic medium, is in agreement with results of experiments carried out with chemical probes.

Effect of sodium dodecyl benzene sulfonate on the absorption spectrum and determination of crystal violet in aqueous solution

Abstract The effect of sodium dodecyl benzene sulfonate (SDBS) on the absorption spectrum of crystal violet (CV) in an aqueous solution was studied by spectrophotometry. The results showed that when the SDBS concentration was lower than the critical micelle concentration (CMC), the absorption spectrum of CV was altered significantly. However, the effect was eliminated when the SDBS concentration was higher than the CMC, and the absorption maximum of the solution gradually reached that of a SDBS-free CV solution. A new method was thus proposed for the determination of the CV concentration in an aqueous solution containing an anionic surfactant. Under the optimal conditions, i.e., a detection wavelength of 584 nm, a SDBS concentration of 4.8 mmol L−1 and a reaction time of 1 h, the linear range of the method was 0.16 × 10−2 mmol L−1–1.6 mmol L−1.

Use of Spectra Resolution Methodology to Investigate Surfactant/β-Cyclodextrin Mixed Systems

A study of the spectral behavior of crystal violet in mixed systems formed by hexadecyltrimethylammonium chloride (CTACl) and beta-cyclodextrin (beta-CD) has been carried out. The spectra resolution methodology was used to decompose the absorption spectra of crystal violet in the sum of constituent sub-bands centered at 17,953, 16,807, and 16,474 cm(-1). The sub-bands centered at upsilon = 17,953 and 16,807 cm(-1) correspond to planar and pyramidal isomers of the dye in water and the same isomers associated with the cyclodextrin and micelle. The sub-band centered at upsilon = 16,474 cm(-1) is due to the formation of an inclusion complex between the dye and the cyclodextrin, where solvation of the carbocation takes place through the hydroxyl groups of the cyclodextrin and the association of the crystal violet to micelles of CTACl through the formation of ion pairs in the Stern layer. The results obtained in the mixed systems are compatible with the results obtained in the previously studied simple systems, thus supporting the situation where interactions do not exist between cyclodextrins and micelles once these have formed.

Environment effect on the electronic absorption spectra of crystal violet

The optical characterization and the influence of solvent–solvent interaction on the visible spectra of crystal violet were investigated. The spectroscopic measurements of the solvation of the dye in a polar nematic matrix and some isotropic solvents, mainly alcoholic systems, were correlated with the solvent properties as represented by their dielectric constants, ε, and dipole correlation factors, g. The interaction of the ionic dye with the anisotropic surrounding and with that of the isotropic solvents was investigated and compared. The solvent–solvent interactions can strongly influence the shape and intensity of absorption bands as well as solvent–solute and solute–solute interactions (i.e. dye aggregation, ion pair formation). Dichroic ratios R and degree of anisotropy S of this ionic dye in the liquid crystalline host were investigated by measuring the intensity of the absorption bands in the visible region of parallel aligned samples.

Visible absorption spectra of crystal violet in supercritical ethane–methanol solution

The effects of concentration and mole fraction of methanol in supercritical ethane on the absorption spectra of crystal violet (CV) were examined. Keeping the concentration of CV in the cell constant at 50 μmol l −1, both the methanol concentration (from 0.4 to 1.2 mol l −1) and pressure of ethane (from 60 to 150 bar) were varied. The degree of solvation of CV depends both on the mole fraction and concentration of cosolvent. The dimerization of CV was found to decrease with pressure, and with the ratio between methanol and CV concentrations.

Association Constant of Crystal Violet in Micellar Aggregates: Determination by Spectroscopic Techniques

The effects upon the absorption spectrum of Crystal Violet (CV) were used to determine the association constant of CV with different micellar aggregates.

Femtosecond spectral hole-burning of crystal violet in methanol. New evidence for ground state conformers

The absorption spectrum of crystal violet in methanol solution showed two spectral holes around 550 and 600 nm when using tunable femtosecond-pulse excitation. The formation of the 550 nm hole was delayed by 500 fs after the 600 nm hole was formed when the pumping wavelength was 598 nm. These findings support the presence of ground state conformational isomers, which have been the subject of controversy since 1942. A possible mechanism for the hole formation is proposed using a model having two ground states and one excited state.

Electrical conductivity and optical properties of sensitized poly[(N-benzyldiphenylamino)-methane] with crystal violet

Abstract The dark conductivity and photoconductivity of poly[( N -benzyldiphenylamino)methane] was greatly enhanced in the dark and in the visible region by the addition of a small amount of crystal violet having a molar ratio of monomer:dopant from 1:0.007 to 1:0.03. The current-voltage characteristics were studied in the dark and in the visible wavelength range, and the current increased superlinearly with the increase of doping level. The activation energies for dark conductivity and photoconductivity are 0.73-0.64eV and 0.71-0.60eV, respectively, at different doping levels. The dye, crystal violet, introduced a new photoresponse maximum at 580 nm corresponding to the absorption spectrum of crystal violet.

Metachromasy Bands of Disk-Like Guests in the Host Lyotropic Liquid Crystal Disodium Chromoglycate-Water

Abstract Electronic absorption spectra of Crystal Violet (CV), Malachite Green (MG) and Methylene Blue (MB) have been investigated in the 500–700 nm region using lecithin-water and disodium chromoglycate (DSCG)-water lyotropic liquid crystals as hosts. Metachromasy bands of CV and MG, indicative of associations of guest molecules, are observed even in the mesophase of the DSCG-water system, in spite of the suppression effect of the host which tends to reduce the degree of association of guest molecules with increasing host concentration. This contrasts with the case of a rod-like guest such as MB, where no indication of association of guest molecules is observed in the DSCG lyotropic mesophase. These spectral observations on the guests in the host DSCG lyotropic liquid crystal are explained in terms of some crucial structural parameter of the guests and a lyotropic columnar structure of the host such as that proposed by Attwood et al.

The temperature-dependent red-shift of the visible absorption spectra of crystal violet in alcohol solutions

The visible absorption spectrum of the triphenylmethane dye, crystal violet, in various alcohol solutions at several temperatures has been recorded and subsequently analyzed by computer fitting. The observed spectral changes do not sustain either the earlier temperature-dependent absorption results of Lewis and co-workers or the concept of two ground-state species in equilibrium.

Interaction of Crystal Violet and Polyanions in Aqueous Solution

Abstract The effect of several polyelectrolytes on the absorption spectrum of crystal violet (CV) has been studied over a wide range of pH. The following polymers were used: isotactic poly(methacrylic acid), PMAi; conventional poly(methacrylic acid), PMAc; a methacrylic acid (80%)-styrene (20%) copolymer, PMAS; and poly(styrene sulfonic acid), PSSA. Distinctly different effects were observed in the four cases. This has been interpreted in terms of a dependence of the degree and mode of binding of cationic dye molecules onto the polyacids on the hydrophobicity of the macroions.