排序方式: 共有5条查询结果,搜索用时 0 毫秒
1
1.
Temperature-dependent electronic circular dichroism (CD) spectra are reported for (R)-(+)-3-methylcyclopentanone (R3MCP) in 34 solvents. Analysis of these data yielded the enthalpy and entropy differences between axial methyl and equatorial methyl conformers, the dominant conformers for R3MCP. The weakly absorbing n-->pi* transition exhibited a decrease in lambdamax as the solvent polarity increased. Vibrational CD fine structure of the n-->pi* transition was observed in the gas phase in addition to several of the solvents. Vapor-phase CD spectra were compared to both the solution-phase spectra and theoretical calculations of the axial and equatorial methyl conformers. Optical rotation (OR) measurements for R3MCP in cyclohexane solution in the visible region showed excellent agreement with OR DFT calculations of the equatorial and axial methyl conformers. Density functional calculations with B3LYP and the 6-13G* and aug-cc-pVDZ basis sets, which incorporate the solvent dielectric constant, yielded trends in thermodynamic quantities as a function of polarity and solvent dipole moments that are only weakly or not observed in experiments. 相似文献
2.
Watheq Al‐Basheer 《Journal of Physical Organic Chemistry》2016,29(1):14-20
High‐resolution infrared (IR) spectra of R‐(+)‐3‐methylcyclopentanone (R3MCP) in para‐hydrogen (pH2) crystal were recorded and compared with the corresponding IR spectra of R3MCP in Argon (Ar) isolation matrix as well as the IR spectra of the neat crystalline R3MCP at low deposition temperature of 4 ± 0.05 K. Moreover, IR spectra of R3MCP, hosted in pH2 crystal, were recorded using a high‐resolution Fourier transform IR spectrometer as a function of sample concentration and over the range 10–300 ppm. Furthermore, density functional theory calculations of simulated IR spectra for the optimized geometries of R3MCP equatorial‐methyl and axial‐methyl conformers are compared with experimental spectra for the purpose of investigating molecular conformation. Upon comparison between theoretical and experimental IR spectra, vibrational modes arising from equatorial and axial conformers have been successfully assigned and related to the individual conformer's structure. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
3.
Structural Chemistry - The electronic circular dichroism (CD) spectra as a function of temperature for R-(?+)-3-methylcyclohexanone (R3MCH) were reported in 11 solvents of wide polarity range... 相似文献
4.
Watheq Al-Basheer AbdulAziz Al-Jalal Khaled Gasmi 《Isotopes in environmental and health studies》2018,54(1):106-112
The 18O/16O and 2H/1H ratios of 18 water brands representing the most popular bottled water brands in the Saudi market were measured using a system based on the latest advancements in tunable off-axis integrated cavity output diode laser spectroscopy (OA-ICOS) in the near-infrared spectral region. Utilizing δ18O and the δ2H values of locally produced water samples, a meteoric water line (δ2H?=?7.84 δ18O?+?2.11) was extracted and found to be consistent with the slope of the global meteoric water line (GMWL) and the geographic location of Saudi Arabia. 相似文献
5.
Watheq Al-Basheer 《Journal of solution chemistry》2012,41(9):1495-1506
Density Functional Theory (DFT) calculations of infrared spectra for the optimized geometries of the R-(+)-3-methylcyclopentanone (R3MCP) equatorial-methyl and axial-methyl conformers were performed in eleven common solvents with a wide polarity range, within the framework of polarizable continuum model (PCM). The DFT correlation function type B3LYP, using a powerful basis set (aug-cc-pVDZ), yielded different linear correlations between solvent polarity and R3MCP equatorial and axial conformers for frequencies of IR modes, intensities, and enthalpies. DFT calculations of the dipole moments of R3MCP equatorial and axial conformer components in 3D were also carried out and found to have a linear correlation with the solvent polarity. An increasing trend for the hypsochromic (blue) shift in the equatorial conformer??s IR frequencies is observed, in comparison to bathochromic (red) shift for the axial-methyl conformer IR modes, as a function of the solvent polarity. 相似文献
1