Structural And Spectral Studies Of Carotenoids In Solution

To our knowledge, carotenoids are one of the most abundant pigments found in nature. They are present in most organisms including humans.Carotenoids play an important role in photosynthesis, protection against various diseases in humans, etc.β-carotene, lycopene and canthaxanthin is the most attention and he most widely studied of the three ones of carotenoids. In particular,β-carotene has two main functions, i.e. photoprotection and photon harvesting in photosynthetic systems. Lycopene has functions defense aging and cancer prevention.Research on that they has been carried out extensively in physics, chemistry and biology. Carotenoids are the chemically simplyÏ€-conjugated polyene, is which the polyene chain consists of a sequences of carbon-carbon (CC) bonds (...-C=C-C=...), characterized by a strong electron-phonon (e-ph) coupling due to delocalizedÏ€electrons. They are the study of resonance Raman spectroscopy, optical nonlinear, the ideal molecular structure of the ideal sample, but also the realization of molecular wires and other important materials for optoelectronic devices. Therefore, the research has theoretical value and a bright application prospect. Carotenoids molecular nature of the great relationship between functional and molecular structures. In particular, this chain of molecular structure is closely related to molecular ordering properties and function.In the paper, UV-visible spectroscopy, Raman spectroscopy and Quantum computing are combined to investigate carotenoids in solution. It is worth mentioning that we introduce an important parameter-the Raman scattering cross section for analyzing Raman spectroscopy. Raman scattering cross section (RSCS) is an important parameter in the studies and applications of the Raman spectroscopy. It relates not only to the incident frequency and the structure of a scattered molecule but also to the environment where the scattered molecule is located. It is usually obtained bycomparing the Raman intensity of an unknown molecule with that of a standard molecule with known cross section.1. We study on Effect of the structural order of all-trans-β-carotene on the Raman scattering cross section at low concentrations. Using the technique of liquid-core optical fiber (LCOF), we measured the Raman scattering cross sections (RSCSs) of the carbon-carbon stretching vibrational modes of all-trans--carotene in carbon disulfide (CS₂) at concentrations ranging from 10^-6 to 10^-11 M. It was found that the RSCSs of all-trans-β-carotene were extremely high with decreasing concentration, and the absolute RSCS of C=C stretching modes of all-trans-β-carotene reached the value of 2.6×10^-20 cm² molecule_-1 Sr_-1 at 8×10^-11 M, which is larger than at 8×10-6 M by 4 orders of magnitude. A theoretical interpretation of the anomalous experimental results is given, which introduces a qualitative nonlinear model of coherent weakly damped electron-lattice vibrations in structural order of all-trans-β-carotene.2. Changing solvent is one of the basic research methods of Solvent effect. Solvent has relationship with the total energy of the compressed substance, and the phase structure and reaction way may be controlled by changing solvent because the interatomic distance can be reduced or increased during compression. UV-Visible absorption spectra and Raman spectra of canthaxanthin in different solvents. Our assignments and interpretations are supported by quantum mechanical calculations of structures, which are canthaxanthin/solvents complexes. Through the analysis of experimental and theoretical results, find the relationship between structure and properties. The combination of experimental Raman data with quantum mechanical calculation leads to a better knowledge of the nature of the hydrogen bonding and the structures of the studied hydrogen-bonded complexes. The micro-environmental and micro structures measurements for such molecules of the studied the complexes, while the method is also a powerful tool for such research.3. It is because of all the biological molecules are in the water environment to carry out its biological activity. Therefore, we measured in binary aqueous solutions of canthaxanthin in the Raman and UV-visible spectroscopy. First of all, because of the complex interaction between the ternary matter, our vibrational spectroscopic analysis on hydrogen-bonding between dimethyl sulfoxide and water comprises both experimental Raman spectra and ab initio calculations on structures of various dimethyl sulfoxide/water clusters with increasing water content.Later, we have established physical model for explaining the experimental results.At last, this method could be used as a suitable tool for investigating the structure and properties of biological molecules in aqueous environment.In summary, this work realized the combination of quantum mechanical calculation and molecular spectroscopic technique, and established physical model for explaining carotenoids in solution. This is a new technique to investigate carotenoids, and therefore opens a new approach to deeply explore physical and chemical issues.