Thermodynamics-of-metal-organic-frameworks

Thermodynamicsofmetal-organicframeworksDiWu,AlexandraNavrotskynPeterA.RockThermochemistryLaboratoryandNEATORU,UniversityofCalifornia,Davis,OneShieldsAvenue,Davis,CA95616,USAarticleinfoArticlehistory:Received8April2014Receivedinrevisedform10June2014Accepted11June2014Keywords:Metal-organicframeworkThermodynamicsCalorimetryEnergeticsGuest–hostinteractionandconfinementAdsorptionabstractAlthoughtherehavebeenextensivestudiesoverthepastdecadeinthesynthesisandapplicationofmetal-organicframeworks(MOFs),investigationoftheirthermodynamicstabilityandoftheenergeticsofguest–hostinteractionshasbeenmuchmorelimited.Thisreviewsummarizesrecentprogressinexperimental(calorimetric)determinationofthethermodynamicsofMOFmaterials.TheenthalpiesofMOFsrelativetodensephaseassemblagessuggestonlymodestmetastability,withageneralincreaseofenthalpywithincreasingmolarvolume,whichbecomeslesspronouncedathigherporosity.Theenergylandscapeofnanoporousmaterials(inorganicandhybrid)consistsofapairofparallelpatternswithinafairlynarrowrangeofmetastabilityof5–30kJpermoleoftetrahedrainzeolitesandmesoporoussilicasorpermoleofmetalinMOFs.Thusstrongthermodynamicinstabilitydoesnotseemtolimitframeworkformation.Therearestronginteractionswithinthechemisorptionrangeforsmallmolecule–MOFinteractionswithdefinedchemicalbindingatthemetalcentersorotherspecificlocations.Coexistenceofsurfacebindingandconfinementcanleadtomuchstrongerguest–hostinteractions.&2014ElsevierInc.Allrightsreserved.1.IntroductionDevelopmentsinsyntheticchemistryandmaterialsscienceenablefabricationofmetal-organicframeworks(MOFs)withextre-melyhighsurfaceareas,hugeaccessibleporosityandtunablechemicalproperties[1–3].Duetotheseuniqueproperties,MOFsareconsideredtohaveapromisingfutureforapplicationinenergystorage[4–9],catalysis[10–13],adsorption/separation[14,15],mole-cularsensing[16–18]andmedicine[19–21].Sofarmorethansixthousanddistinctstructureshavebeendeveloped[1](seeFig.1forsomeexamplesofstructures).Thesestructuresconsistofmetalcentersconnectedbyorganiclinker