Terahertz spectroscopy and weak interaction analysis of cinnamic acid derivatives
The absorption peaks of three cinnamic acid derivatives(CADs):p-coumaric acid(PCA),trans o-coumaric acid(OCA),and 4-fluorocinnamic acid(4-FCA)were measured using terahertz time-domain spectroscopy(THz-TDS)in the range of 0.5-3.5 THz.To identify the origins of the THz absorption peaks in the three samples,the density functional theory(DFT)was employed along with the vibrational mode automatic relevance determination(VMARD)method.Additionally,the molecular force field energy decomposition analysis(EDA-FF)was used to analyze the forms of weak intermolecular forces in the molecular systems.Visualization analysis was conducted through the visual-ization of molecular dynamics(VMD)using atom coloring to study the contribution types and strengths of weak inter-molecular forces by atoms in the molecular systems.This combination of THz-TDS,DFT,VMARD,and EDA-FF methods not only effectively distinguishes organic molecules with structural isomers or structural similarities but also provides valuable reference data for uncovering their biochemical functionalities.
terahertz time-domain spectroscopydensity functional theorycinnamic acid derivativesvibrational modesenergy decomposition analysis based on forcefield