二氟尼柳/水滑石插层组装结构、氢键及水合特性的分子动力学模拟潘国祥倪哲明*王芳王建国李小年(浙江工业大学化学工程与材料学院,杭州310032摘要:采用分子动力学方法模拟二氟尼柳插层水滑石(DIF/LDHs的超分子结构,研究复合材料主客体间形成的氢键以及水合膨胀特性.结果表明,当水分子总数与DIF分子总数之比Nw≤3时,层间距dc保持基本恒定,约1.80nm;当Nw≥4时,层间距逐渐增大,且符合dc=1.2611Nw+13.63线性方程.随着水分子个数增加,水合能ΔUH逐渐增大.当Nw≤16时,由于ΔUH<-41.84kJ·mol-1,LDHs-DIF可以持续吸收水,从而使材料层间距不断膨胀.但当Nw≥24时,ΔUH>-41.84kJ·mol-1,此时LDHs-DIF层间不能再进一步水合,因此LDHs-DIF在水环境中膨胀具有一定的限度.水滑石层间存在复杂的氢键网络.DIF/LDHs水合过程中,水分子首先同步与层板和阴离子构成氢键;当阴离子趋于饱和后,水分子继续与层板形成氢键,并逐步发生L-W型氢键取代L-A型氢键,驱使阴离子向层间中央移动,与层板发生隔离;最后水分子在水滑石羟基表面形成有序结构化水层.关键词:分子动力学模拟;二氟尼柳/水滑石;氢键;水合中图分类号:O641MolecularDynamicsSimulationonStructure,Hydrogen-BondandHydrationPropertiesofDiflunisalIntercalatedLayeredDoubleHydroxidesPANGuo-XiangNIZhe-Ming*WANGFangWANGJian-GuoLIXiao-Nian(CollegeofChemicalEngineeringandMaterialsScience,ZhejiangUniversityofTechnology,Hangzhou310032,P.R.ChinaAbstract:Thesupramolecularstructureofdiflunisalintercalatedlayereddoublehydroxides(DIF/LDHswasmodeledbymoleculardynamics(MDmethods.Hydrogenbonding,hydrationandswellingpropertiesofDIF/LDHswereinvestigated.Theinterlayerspacingdcwasfoundtobeconstant(ca1.80nmwhenNw(theratioofthenumbersofwatermoleculetoDIF≤3.TheinterlayerspacingdcgraduallyincreasesasNw≥4andthisincreasefollowsthelinearequationdc=1.2611Nw+13.63.Thehydrationenergygraduallyincreasesasthewatercontentincreases.LDHs/DIFhydrateswhenNw≤16becausehydrationenergyΔUH<-41.84kJ·mol-1.AtNw≥24thehydrationofLDHs/DIFdoesnotoccurbecauseΔUH>-41.84kJ·mol-1.SwellingofLDHs/DIFisthuslimitedinanaqueousenvironment.TheinterlayerofDIF/LDHscontainsacomplexhydrogenbondingnetwork.ThehydrationofDIF/LDHsoccursasfollows:watermoleculesinitiallyformhydrogenbondwithlayersandanions.Whiletheanionsgraduallyreachasaturationstateandwatermoleculescontinuetoformhydrogenbondswiththehydroxylsofthelayers.TheL-WtypehydrogenbondgraduallysubstitutestheL-Atypehydrogenbondandtheanionsmovetothecenterofaninterlayerandthenseparatewiththelayers.Last,awell-orderedstructuralwaterlayerisformedonthesurfacehydroxylsofDIF/LDHs.KeyWords:Moleculardynamicssimulation;Diflunisal/layereddoublehydroxide;Hydrogen-bond;Hydration[Article]www.whxb.pku.edu.cn物理化学学报(WuliHuaxueXuebaoActaPhys.-Chim.Sin.,2009,25(2:223-228Received:August1,2008;Revised:October8,2008;PublishedonWeb:November26,2008.*Correspondingauthor.Email:jchx@zjut.edu.cn;Tel:+86571-88320373.浙江省自然科学基金(Y406069资助项目鬁EditorialofficeofActaPhysico-ChimicaSinicaFebruary223ActaPhys.-Chim.Sin.,2009Vol.25水滑石(简写为LDHs为典型的阴离子型层状材料,其化学式为[M2+1-xM3+x(OH2]x+An-x/n·mH2O(其中,M2+和M3+分别代表二价和三价金属阳离子,下标x为M3+/(M2++M3+金属离子摩尔比,An-代表层间阴离子[1].由于LDHs具有特殊的层状结构和层间离子的可交换性,可向层间引入新的客体阴离子,从而组装得到系列新型有机/无机复合材料,在催化、吸附、离子交换、药物缓释和功能助剂等领域得到广泛应用[2-5].水滑石作为新型的药物传输载体,可增强药物分子的扩散性能、热稳定性以及控制药物分子的释放速率[6,7].此外,水滑石呈碱性(pH值(10%悬浮液:7-9,具有较强的抗酸作用.其作为抗酸剂与非甾体抗消炎...