Theoretical Study Of Strueture Property Of Ionic Liquids And Their Interaction With Micromolecule

Ionic Liquids（ILs）, duing to their unique properties and solvent capabilities, havearoused wide concern and much potential utility value investigation have been carried out.Quantum chemical calculations studies structure, properties and catalysis mechanism ofionic liquids theoretically at the molecular and electronic level. In this artical, theconstitutive property and spectroscopy of the ionic liquid N-ethyl yridiniumbromide（[EPy]Br）, the constitutive property of trimethylphenylammoniumhexafluorphosphate（[PhNMe₃][PF₆]） and the interaction of sulfur dioxide andtrimethylphenylammonium hexafluorphosphate have been calculated by quantumchemistry.1. The constitutive property and spectroscopy have been calculated by densityfunction theory（DTF） B3LYP、 B3PW91and （ab initio）HF at6-31G+（d,p） and6-311G+（d,p） level for the ionic liquid N-ethyl yridinium bromide（[EPy]Br）. Theassignment of atomic charge and the IR spectra have been respectively obtained byNatural Bond Orbital（NBO） analysis and vibration analysis. Compared experimental IRfrequency and calculated. And then this paper sumed up and analysed vibrationfrequencies.The results show that some charges have transferred between the anion andcation and IR characteristic spectrum of theoretical calculation is consistent withexperimental result for the B3PW91and HF methods using the6-311G+（d,p）.2. The constitutive property have been calculated by density function theory（DTF）B3LYP at6-31G+（d） level for the ionic liquid trimethylphenylammoniumhexafluorphosphate （[PhNMe₃][PF₆]） and compared three different optimized structure.The assignment of atomic charge have been obtained by Natural Bond Orbital（NBO）analysis, and the interaction of anion-cation pair have been obtained by second-orderperturbative energy analysis. The results show that the anionic distributed in the threeareas around cation, the hydrogen bond existed between anion-cation pair, and somecharges have transferred between the anion and cation mainly through the interaction ofLP_F�'σ^*_C-H.3. The complex of molecules geometry of anion, cation and ion pairs respectivelywith the SO₂have been calculated by density function theory（DTF） B3LYP at6-31G+（d）level；the hydrogen bond existed between the hydrogen atoms of cation and oxygen atomsof SO₂by analysis, and were the oxygen atoms more close to the N-methyl side chain ismore stable; when SO₂and anion have effects, there is an interaction between S atom and F atom, and the infrared spectrum split out a new vibrating peaks that indicate theadsorption effect of SO₂and PF₆^-between physical adsorption and chemistry adsorption;SO₂and ion pair [PhNMe₃][PF₆] can form a variety of complex, SO₂can occur interactionalone with cation but can not with anion alone, the most stable complex structure is SO₂with anion and cation common occurrence; because of SO₂, the charge distribution werechanged, the hydrogen bonding strength between the anion and cation were weakened, butthe number of hydrogen bond has increased, and overall tend to be more stable.