Abstract-Experimental and theoretical investigations of tartaric acid isomers by terahertz spectroscopy and density functional theory

Tao Chen, Qin Zhang, Zhi Li, Xianhua Yin, Fangrong Hu,

https://www.sciencedirect.com/science/article/pii/S1386142518306334

The terahertz (THz) absorption spectra of l-, d-, and dl-tartaric acid have been measured in the frequency range from 0.2 to 2.0 THz by terahertz time-domain spectroscopy (THz-TDS). The characteristic absorption peaks of these three tartaric acid isomers were obtained, which showed remarkable difference between enantiomers (l- and d-tartaric acid) and the racemic compound (dl-tartaric acid) in their peak frequencies. In parallel with the experimental study, theoretical calculations on isolated-molecule and unit cell of tartaric acids using density functional theory (DFT) were also performed for simulating the experimental THz spectrum features, which were in good agreement with the experimental data. Results demonstrate that THz-TDS can distinguish the tiny diversity between tartaric acid chiral isomers and its racemic compound, and provided an effective method for molecular identification in biological and biomedical engineering.

Researchers at North Carolina State University Release New Data on Coenzymes

http://www.hispanicbusiness.com/2013/10/2/researchers_at_north_carolina_state_university.htm
By a News Reporter-Staff News Editor at Life Science Weekly--

Investigators publish new report on Enzymes and Coenzymes. According to news reporting originating from Raleigh, North Carolina, by NewsRx correspondents, research stated, "Terahertz (THz) absorption of biotin was simulated using the first principle and the density functional theory (DFT) both in the harmonic approximation and with corrections for the anharmonicity. Anharmonicity corrections were calculated using two different approaches."
Our news editors obtained a quote from the research from North Carolina State University, "First, the perturbation theory-based first principle calculations were performed to include third-and fourth-order anharmonicity corrections in atomic displacements to harmonic vibrational states. Second, the atom-centered density matrix propagation molecular dynamics model that provides a good energy conservation was used to calculate the atomic trajectories, velocities, and a dipolemoment time history of biotin at lowand room temperatures. Predicted low-THz lines agree well with the experimental spectra. The influence of the polyethylene (PE) matrix embedment on the THz spectra of biotin at the nanoscale was studied using the developed hybrid DFT/molecular mechanical approach."
According to the news editors, the research concluded: "While PE is almost transparent at THz frequencies, additional low-THz lines are predicted in the biotin/PE system, which reflects a dynamic interaction between biotin and a surrounding PE cavity."

For more information on this research see: Terahertz Spectra of Biotin Based on First Principle, Molecular Mechanical, and Hybrid Simulations. IEEE Transactions on Terahertz Science and Technology, 2013;3(4):357-362. IEEE Transactions on Terahertz Science and Technology can be contacted at: Ieee-Inst Electrical Electronics Engineers Inc,445 Hoes Lane, Piscataway, NJ 08855-4141, USA. (Institute of Electrical and Electronics Engineers - www.ieee.org/; IEEE Transactions on Terahertz Science and Technology - ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=5503871)

The news editors report that additional information may be obtained by contacting A. Bykhovski, North Carolina State University, Dept. of Elect & Comp Engn, Raleigh, NC 27695, United States (see also Enzymes and Coenzymes).
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