金属、配体和溶剂之间的协同性：基于密度泛函理论研究含双锌离子配合物催化磷酸二酯裂解的反应机理

densityfunctionaltheory(dft)-tao-perdew-staroverov-scuseria(tpss)functionalcalculationsondizinccomplex-mediatedphosphodiestercleavageindicateageneralbasecatalyticmechanism.2-hydroxylpropyl-4-nitrophenylphosphate(hpnp)favorsthebridgingoftwoznionsbytheformationoftwocoordinationbondsbetweenterminalphosphateoxygensandznions.thezn-boundhydroxidedeprotonatesthehydroxylonthesidechainofhpnpandconsequentlythealkoxideisstabilizedbycoordinationtoaznionandahydrogen-bondtozn-boundwater.awatermoleculeistightlyboundtotwoaminoprotonsinthebis(1,4,7-triazacyclononane)ligandandthisdeterminestheorientationofhpnpduringanucleophilicattacktoformatrigonalbipyramidalpo5intermediateanditalsoweakensthebondbetweenphosphorusandthephenolate,whichmakestheleavingofthelattereasier.thephenolateformedafterthecollapseofthefive-coordinatedphosphorusintermediateeasilycoordinatestoaznion.surprisingly,thestabilizingsolventeffectforthetransitionstateaftertheformationofthepo5intermediateismuchstronger(atleast42kj·mol-1)thanthatofallotherspeciesastheyhavesolvationenergiesthatfluctuatearound12.6kj·mol-1.thus,theoverallfreeenergybarrierforthisreactionafterreactant-bindingandbeforeproductreleaseisabout17.0kj·mol-1,whichistoolowtoberate-determining.therate-determiningstepisverylikelypartofthereleaseprocessoftheproducts.basedonvariouscalculations,wediscusspossiblereasonsforthedifferentcatalyticefficienciesofthedizinccomplexandtheenzymes.