Ultraviolet-visible spectroscopy (UV-Vis), which is also known as ultraviolet-visible molecular absorption spectroscopy, uses a continuous spectrum of electromagnetic waves in the ultraviolet-visible region as a light source to illuminate samples. The UV-Vis spectrum is produced by the transition of valence electrons and has been widely applied to study the relative intensity of light absorption by substance molecules. Qualitative analysis can be carried out using UV-Vis spectrum, and quantitative analysis is also able to be completed according to Lambert-Beer law.
Figure 1. Experimental UV-vis spectrum of [Pt2Ag23Cl7(PPh3)10] (black) compared with the excitation energies and oscillator strengths calculated by TD-DFT for [Pt2Ag23Cl7(PPh3)10] (red). (Bootharaju, M. S.; et al. 2017)
It is possible to determine whether the molecular framework of organic compounds contains conjugated structural systems, such as C=C-C=C, C=C-C=O, benzene ring, etc.
If the organic compound has no obvious absorption peak in the ultraviolet-visible region, but the impurity has a strong absorption in the ultraviolet region, the purity of the compound can be determined by UV-Vis spectrum.
• Determination of isomers
• Determination of steric hindrance
• Determination of hydrogen bond strength
It has a greater impact on the UV-Vis spectrum of the solute molecule when the solvent molecule associates with the solute molecule to form a hydrogen bond.
Alfa Chemistry has established a validated process for UV-Vis spectrum prediction:
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