Rotational Studies On Potential Oxygen-bearing Interstellar Molecules And Their Complexes

Oxygen as one of an important element for life molecules,has much higher abundance in interstellar medium.Water are adsorbed on dust surface in the form of ice and are detected in several sources in the form of gas.Therefore,the rotational studies and astronomical detections on potential oxygen-bearing interstellar molecules can not only help us understand the properties of those molecules,but also promote the studies of the origin of life,the evolution of stars and the mechanism of interstellar molecular formation;The studies of their complexs with water can promote the understanding of the interact forms of the similar molecular systems.More than 200 interstellar molecules have been detected,in which,there are about 60 oxygen-bearing interstellar molecules,including alcohols,ketones,acids,ethers,amides and so on.At present,the rotational transition lines of molecules can be measured by using the most reliable experimental technique—Fourier transform microwave spectroscopy.The comparison between the experimental and the astronomical observation transition lines is the basis for confirming the molecule.In addition,accurate molecular structure,molecular dynamics and intarmolecular/intermolecular non-covalent interaction can be obtained by using transform microwave spectroscopy.In this paper,three potential oxygen-bearing interstellar systems were studied by rotational spectra:4-hydroxy-2-butanone monomer and 4-hydroxy-2-butanone-water complex,2-（Trifluoromethyl）acrylic acid monomer and 2-（Trifluoromethyl）acrylic acid-water complex as well as 1,3-Thiazolidin-2-one monomer.（1）The 4-hydroxy-2-butanone monomer and its complex with water were calculated by quantum chemical calculation.With the aid of the theoretical prediction,the rotational spectra of the 4-hydroxy-2-butanone monomer and its complex were measured by Fourier transform microwave spectroscopy.The spectroscopic parameters of the most stable conformer/isomer were obtanted by rotational assigned,which helping to determine the accurate structure parameters and non-covalent interactions.（2）With the aid of the quantum chemical calculation,the rotational spectra of2-（Trifluoromethyl）acrylic acid monomer and its complex were measured by Fourier transform microwave spectroscopy.Two stable comformers/isomers were observed for the monomer and the complex,respectively.Based on the rotational constants of the complex,the partial r₀structure was determined.The intramolecular and intermolecular non-covalent interactions of the monomer and the complex were analyzed,respectively.The population between two conformations/isomers of monomer and complex was calculated,respectively.（3）According to the predictions from quantum chemical calculation,the rotational spectrum of the monomer was measured by Fourier transform microwave spectroscopy.One comformer was observed.The small theoretical calculation error on the rotational constants of the monomer proved the theoretical calculation structure is quite accurate.The complex was also calculated at the same level of theory.In addition,the optimal action site between the monomer and water as well as the non-covalent interactions of each isomers of the complex were analyzed based on the quantum chemical calculation.It is proved that the complex is more likely to exist in the form of isomer I.