High Pressure Raman Spectroscopy Investigation On Phase Stability Of Carboxylic Aromatic Hydrocarbons

Non-covalent interactions are weak interactions between molecules.There are many interactions that belong to non-covalent interactions.This article mainly deals with intermolecular interactions as non-covalent bonds in hydrogen bonds and ?-?stacking.The series of experiments that the interactions developed for the study subjects.At the same time,there are many kinds of these two interacting molecules,and representative carboxylic aromatic hydrocarbons are selected as research substances.The focus of research is on the properties of terephthalic acid and trimesic acid.The research method is to perform external actions on the molecules,which can enhance the interaction between molecules.The diamond-to-anvil(DAC)is used as a pressure-applying tool.High pressure can effectively change the molecular structure and interaction,and is an effective method to study the molecular under extreme conditions.The main purpose of this thesis is to study the phase stability of carboxylic aromatic hydrocarbons under high pressure.The interaction between hydrogen bonding and ?-? stacking is the main function to maintain phase stability.We carried out in-situ high pressure Raman measurements of terephthalic acid up to 15 GPa,the Raman spectrum did not observe abrupt changes in spectral lines.The theoretical simulation of the change in lattice parameters at high pressure indicates that the symmetry of hydrogen bonds is enhanced.And the Hirshfeld surface proves that intermolecular ?-? stacking interactions are also enhanced during the compression process.Under high pressure conditions,two interactions enhance the stability of terephthalic acid during compression.From high-pressure Raman experiments of terephthalic acid,we have shown that the stability of the maintaining molecules athigh pressure is mainly the result of a combination of hydrogen bond symmetry and enhancement of ?-? stacking interactions.In addition,we performed an in-situ Raman pressure of up to 8 GPa on trimesic acid.By analyzing Raman spectroscopy we learned that trimesic acid undergoes a phase transition at a pressure of 2 GPa,and that phase transitions is related to the trimesic acid hexagonal structure.