Raman Spectroscopic Study On The Interaction Of Hydrogen Bond On Surface Tension And Viscosity Of Aqueous Solutions

It has been neglected due to the samey and intuitive characteristics of liquid water,despite it is the most important material in our life.There exists widely in various forms for the water,such as hydrate(flammable ice),binding water(protein,DNA),free water,surface / interface water(catalysis,water purification),etc.Even thouth the water plays an important role in several fields,including material science,energy,ecological environment,chemical industry,life science,biology,etc,the microstructure of liquid water as well as the relationship between macromolecules and their water environment were not exactly known.Indeed,it has become the challenging and scientific problems as for the understanding of the structure of liquid water and aqueous solution.The physical and chemical properties of the aqueous solution were affected by the hydrogen bonding directly,acted as the primary reason of molecular association of liquid water.Water as a universal solvent is usually presented in the form of aqueous solution in the nature.And it was found that the change of structures and properties is closely related to the microstructural and intermolecular interactions in the solution,mainly by having the difference between the pure solute molecules as well as the free water and water molecules together with solute molecules in the aqueous solution.Dimethyl sulfoxide(DMSO),acetonitrile,acetone and tetrahydrofuran(THF)were chosedas the formation of binary system as well as ternary system containing the DMSO / acetonitrile / water and DMSO / THF / water,respectively.Importantly,the typical hydrogen bonding exhibited.The varied characteristics of surface tension and viscosity of each aqueous solution system at different concentrations were investigated.In the meantime,the effect of hydrogen bonding of binary and ternary aqueous solution on the molecular structure and propreties were studied by using the in-situ nondestructive testing technology of the Raman spectrum.As a result,the information of the intermolecular hydrogen bond was obtained from the results of Raman spectrum.And the hydrogen bond interaction model was established in the aqueous solution and there showed the relationship between hydrogen bond and aqueous solution system from the molecular level.It was revealed that the macrophysical and chemical property of the aqueous solution was related to the hydrogen bonding.Afterwards,the results indicated that the surface tension of aqueous solution in four binary hydrogen bonding systems was influenced by the interaction of intermolecular hydrogen bonding with the variation of concentration.The action of hydrogen bonding in the mixed solution containing water molecule and solute molecule led to the phenmeonon of cluster.The results indicated that the strong hydrogen bonding affilitated to the decreasing values of surface tension.The experimental results of peak fitting from the OH-bond Raman peak of the water molecule showed that there exhibited the transformation of clustering structure with the various hydrogen bonding in the solution.Apparently,it was consistent with the consequences of experiment and calculation by Raman linewidth and empirical formula,individually.It was deduced that the viscosity of solution was obtained by the linewidth,as a function of viscosity and concentration,in a given concertration.Otherwise,the hydrogen bonding among the molecules has great effect on the increasing viscosity.Compared the hydrogen bonding of dimethyl sulfoxide-acetonitrile-water ternary system been studied to the binary system,there shifted the electron cloud of acetonitrile C?N bond being closed to carbon atom and S=O double bond in dimethyl sulfoxide being closed to sulfur atom.In the ternary system,there was a competition relation on the hydrogen bonding formed between the acetonitrile or dimethyl sulfoxide and water.Meanwhile,a new complex,showing the unique phenomenon that a water molecule was shared,was generated in the mixture of acetonitrile molecule,dimethyl sulfoxide molecule and water.However,this unique phenomenon is gradually disappeared with the increasing content of water.In addition,in the ternary system of tedimethyl sulfoxide-tetrahydrofuran-water,hydrogen bonding was formed between dimethyl sulfoxide or tetrahydrofuran and water.It was found that the hydrogen bonding in the former was stronger than that of latter.There exhibited increasing hydrogen bonding with the increase of amount of water between dimethyl sulfoxide and water.