| The protic ionic liquids(PILs)composed of alkylethylenediaminium cation with trifluoroacetic(TFA)/trifluoromethanesulfonate(TFS)anion have been previously studied.It has been revealed that they are hydrophilic and highly miscible with water as there are two amines in their polar group.The solubility of water in PILs with TFA and TFS are over 90 wt.%and 50 wt.%,respectively.The water content in PILs significantly effects the physicochemical properties of PILs.In order to reveal the relationship between the physicochemical properties and the micro-structure of PILs containing several water molecules,the hydrogen-bonding between the PILs and water molecules was investigated using the density functional theory(DFT)at M06-2X/6-311G(d,p)level.In addition,calcium complexes of hexanoylalaninate(HHex-ala)and octanoylalaninate(HOct-ala)were used for the preparations of CaCO3nano-particles,and the size,shape and size-distributions of the nano-particles were characterized by transmission electron microscope(TEM).The present study is composed of the following three parts.1)Hydrogen-bonding between protic ionic liquids composed of hexylethylenediaminium cation and TFA/TFS anion with water moleculesThe protic ionic liquids(PILs)composed of hexylethylenediaminium(HHex)cation and TFA/TFS anion forming[HHex][TFA]and[HHex][TFS]have been studied in our previous work.Here,the hydrogen-bonding between water molecules and[HHex][TFA]/[HHex][TFS]were investigated using the density functional theory(DFT)at M06-2X/6-311G(d,p)level.The configurations of[HHex][TFA]-n H2O(n=1,2,6)and[HHex][TFS]-n H2O(n=1,2,6)were designed and optimized,where the optimized structures are A1-A8 and S1-S8,respectively.The results of interaction energy,vibration spectra,the second-order perturbation,electron density and the analysis of the reduced density gradient(RDG)show that N—H···O,O—H···N and O—H···O type hydrogen bonds were formed between PILs and n H2O.In the experimental study,the electric conductivity increases while the viscosity decreases with increasing water content of the PILs.It may be due to the ionicity and mobility of PILs increase with an increase in water content of the PILs.In the light of the micro-structure of PILs,the reason of decrease of electric conductivity is due to the interaction between the cation and anion weakened by the formation of hydrogen-bonding between PILs and n H2O.As a result,the hydrogen-bonding between the PILs and water molecules strengthens with increasing the number of water molecules.The hydrogen-bonding in[HHex][TFS]-n H2O is stronger than that in[HHex][TFA]-n H2O.2)Comprising 2-ethylhexylethylenediaminium cation coupled with TFA or TFS anion and water moleculesThe hydrogen-bonding between the cation and anion of PILs consisting of2-ethylhexylethylenediaminium(HEt Hex)cation and TFA or TFS anion forming[HEt Hex][TFA]and[HEt Hex][TFS]have been studied.The hydrogen-bonding between water and PILs with[HHex]+were studied in chapter one.In order to see the effect of alkylchain size on the hydrogen-bonding between PILs and water molecules,we here took up the ethyl-hexyl derivative in the cationic side of PIL using the DFT at M06-2X/6-311G(d,p)level in this study.The configurations of[HEt Hex][TFA]-n H2O(n=1,2,6)and[HEt Hex][TFS]-n H2O(n=1,2,6)were designed and optimized.The optimized configurations are B1-B8 and C1-C8 respectively.The results of the?E0BSSE,??,E(2),?cand analysis of RDG show that N—H···O,O—H···N and O—H···O type hydrogen bonds are formed between PILs and n H2O.In the experimental study,the electric conductivity increases and the viscosity decreases with increasing water content in the PILs because of the ionicity and mobility of PILs increase with enhancing water content in the PILs.On the bases of the micro-structure of PILs,the decrease of electric conductivity can be attributed to the weakening of the cation-anion interaction by the formation of hydrogen-bonding between PILs and n H2O.The hydrogen-bonding is stronger for[HEt Hex][TFS]-n H2O than that for[HEt Hex][TFA]-n H2O.For comparison,the hydrogen-bonding between the water molecules and the PILs containing TFA anion is stronger for[HHex][TFA]-n H2O than for[HEt Hex][TFA]-n H2O.On the other hand,for the PILs containing TFS anion,the hydrogen-bonding between the PIL and H2O is stronger in[HEt Hex][TFS]-n H2O than in[HHex][TFS]-n H2O.3)Preparation of CaCO3 nano-particles using Ca(Hex-ala)2and Ca(Oct-ala)2complexesThe Ca(Hex-ala)2 and Ca(Oct-ala)2complexes were prepared by the reaction,HHex-ala(Hexanoylalanine)+Ca(OH)2 and HOct-ala(Octanoylalanine)+Ca(OH)2,respectively.The purity of Ca(II)complexes was confirmed using FI-IR spectra,13C-NMR spectra and CHN elemental analysis.The CaCO3nano-particles were synthesized by the purge of CO2gas into aqueous Ca(II)complex solution.The size,morphology and size-distribution of CaCO3nano-particles were characterized by TEM and the results were as follows.The sizes of CaCO3nano-particles prepared by Ca(Hex-ala)2and Ca(Oct-ala)2are about 18 nm and 25 nm,respectively.The particles were spherical and the size-distributions were uniform. |
PDF Full Text Request