The Studies Of Double Metal Cyanide Complex Modified With Ligands

Since the first reported,Double Metal Cyanide Complex(DMC)has been drawn widespread attention for its superior catalytic performance and unique three-dimensional network structure.In order to improve the catalytic properties of DMC catalysts,increasing scholars have engaged in the studies of their modification.In this paper,the modification of DMC catalysts was carried out by the complexation of ligands.And corresponding researches were conducted about the structures,electrochemical properties of catalysts and the thermodynamic properties of the complexing process of Double Metal Cyanide Complex with ligands.First,we focused on the preparation of single crystal by the method of slow diffusion and solvothermal.And three kinds of single metal cyanide complexes single crystals,including Fe(CN)2(phen)2·1/2(2,2'-bipy)·H2O,Fe(CN)2(phen)2·3H2O,Mn(CN)6·3CI and a kind of single metal organic complexes single crystal MnCl2(phen)2 were finally obtained.And their information of structures was given by X-Ray Single Crystal Diffraction.Second,we prepared a series of Co/Fe DMC nano-particles containing different kinds of ligands,such as ionic liquids and quinoline derivatives,by stepwise added synthesis.And their compositions and structures were determined by Fourier transform infrared spectroscopy(FT-IR),elemental analysis,energy dispersive spectroscopy(EDS)and X-Ray powder diffraction(XRD),respectively.Then we discussed their properties in the respects of electrochemical by the Cyclic Voltammetry.At the same time,the modified Co/Fe DMC nano-particles were utilized as catalysts of the epoxidation of styrene.The results showed that the selectivity and stability were greatly enhanced when the Co/Fe DMC catalysts were modified by ionic liquids of TmaBF4 and BmimPF6.While catalytic properties of Co/Fe DMC catalysts modified by adding quinoline derivatives were not improved as expected.Third,the highlights of our research were the thermodynamic properties during the preparation of Co/Fe DMC nano-particles and the process of coordination between ligands and Co/Fe DMC particles by Isothermal Titration Calorimetry.Whether CoC12 or K3Fe(CN)6 was excess,the synthesis of Co/Fe DMC nano-particles was both exothermic processes with the increase in entropy,and they were driven by both entropy and enthalpy.In the presence of excess CoCl2,the binding between phenanthroline or 2,2'-bipy and Co/Fe DMC nano-particles manifested itself as an increase in entropy and an exothermic enthalpy,so it was also driven by both entropy and enthalpy.While in the case of excess K3Fe(CN)6,the coordination reaction of phenanthroline with Co/Fe DMC nano-particles was an exothermic process with a decrease in entropy,which indicated that the process was enthalpy-driven.Instead of coordination reaction,the reaction of Cs+ and particles was occurred with the Cs+positioned in interstitial lattice sites.It was enthalpy-driven exothermic process with a decrease in entropy.In addition,we produced corresponding Co/Fe DMC nana-particles by a peristaltic pump to simulate the synthesized conditions of Isothermal Titration Calorimetry.The catalytic properties of Co/Fe DMC catalysts modified by phen and 2,2'-bipy were improved in different degree.