Investigation of intermolecular interactions in organic solutions by combining two-dimensional correlation Raman spectroscopy and DFT simulation: Example of methanol and Chloralkane

Effect of environmental factors on laccase-mediated 17β-estradiol coupling reaction

Hazardous 17β-estradiol (E2) with a higher estrogen effect, has attracted the attention of many scholars. How to transform and remove E2 in the environment becomes a research hotspot. This paper systematically explores the impacts of environmental elements like temperature, pH value, laccase concentration, humic acid concentration, and the type and concentration of metal ions on the laccase-catalyzed oxidation process of E2. The results show that the optimal environmental conditions for laccase-catalyzed oxidation of E2 are temperatures of 25 °C to 30 °C, pH values of 4 to 5, laccase concentration of 30 unit·L-1, no addition of humic acid, and the addition of Cu2+ at a density of 1 mmol·L-1. The conversion rate of E2 by laccase remained above 70%. The coupling products were formed through covalent coupling mechanisms mediated by functional groups such as C-C and C-O-C, with the main product being E2 dimers. E2 underwent chain extension polymerization during the reaction. Laccase has the potential to remediate E2 contaminated environment in a green and efficient manner.

Diverse Applications of Two-Dimensional Correlation Spectroscopy (2D-COS)

This second of the two-part series of a comprehensive survey review provides the diverse applications of two-dimensional correlation spectroscopy (2D-COS) covering different probes, perturbations, and systems in the last two years. Infrared spectroscopy has maintained its top popularity in 2D-COS over the past two years. Fluorescence spectroscopy is the second most frequently used analytical method, which has been heavily applied to the analysis of heavy metal binding, environmental, and solution systems. Various other analytical methods including laser-induced breakdown spectroscopy, dynamic mechanical analysis, differential scanning calorimetry, capillary electrophoresis, seismologic, and so on, have also been reported. In the last two years, concentration, composition, and pH are the main effects of perturbation used in the 2D-COS fields, as well as temperature. Environmental science is especially heavily studied using 2D-COS. This comprehensive survey review shows that 2D-COS undergoes continuous evolution and growth, marked by novel developments and successful applications across diverse scientific fields.

Tuning the Fermi resonance of pyridine using ethanol molecules

The Fermi resonance (FR) phenomenon is prevalent in infrared and Raman spectroscopy, and it can be observed in a variety of molecules. In particular, pyridine is a compound that has two Fermi doublets: ν₁ ∼ ν₁₂ and ν₁ + ν₆ ∼ ν₈. To analyze the effect of environmental changes on the FR, this study first investigated the Raman spectra of pyridine mixed with ethanol at different concentrations. Results indicated that the FR parameters exhibited a nonlinear dependence on the pyridine concentration fractions, and changing the concentration fraction of pyridine led to different hydrogen bond strengths. Second, the interaction mechanism of pyridine-ethanol binary solutions was analyzed by two-dimensional correlation Raman spectroscopy (2DCRS). In addition, high-pressure Raman spectra of a 50% pyridine-ethanol binary solution were measured up to a pressure of 19.65 GPa by a diamond anvil cell technique, and the phase transition of the binary solution occurred at 6.35 GPa. Finally, the impact of ethanol on the FR of pyridine was determined by deducing the FR parameters at different pressures. The turning point at 6.35 GPa was consistent with the Raman frequency-pressure relationships. The results demonstrated that changes in the intensity of ν₁ did not affect the FR of ν₁ + ν₆ ∼ ν₈, whereas the undisturbed frequency ν₁ still played a role in the FR. When the pressure was compressed to 13.36 GPa, the disappearance of the Raman peaks (ν₁ and ν₁') was attributed to the tuning of the molecular symmetry by pressure during the phase transition.

Generation of dual-supercontinuum coherent radiation in acetone mixed with carbon disulfide by stimulated Raman scattering

Stimulated Raman scattering (SRS) in a liquid has been a major focus of nonlinear optics. Traditional SRS generates single or cascaded Stokes components arising from spontaneous Raman noise. Herein, we report the formation mechanism of a specific spectrum-continuous spectroscopy technique based on SRS of mixed liquids. SRS of a mixed acetone and carbon disulfide solution is investigated by a pulsed Nd:YAG laser with a wavelength of 532 nm. Two remarkably asymmetric broadened SRS lines are obtained. When the volume ratio is 7:3, the broadened spectral bands are optimized. The supercontinuum spectroscopy phenomenon is explained by hydrogen bond formation, adjacent vibrational modes coupling, and laser-induced plasma generation. This technique has the potential to contribute to the development of a supercontinuum Raman laser.