Highly Efficient Extraction of Sulfate with a Tripodal Hexa-urea Receptor

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1、CommunicationsDOI:10.1002/anie.201004461AnionRecognitionHighlyEfficientExtractionofSulfateIonswithaTripodalHexaureaReceptor**ChuandongJia,BiaoWu,*ShaoguangLi,XiaojuanHuang,QilongZhao,Qian-ShuLi,*andXiao-JuanYangThedesignofartificialreceptorsforsulfateionsisofgreatethyl)amine)hasal

2、sobeenfoundtoencapsulatethesulfate[8]interestbecauseoftheimportanceofsulfateionsinenviron-ionina2:1(host/guest)ratio.Althoughsaturatedcoordi-[1]mentalandbiologicalsystems.Oneoftheapplicationsofnation(12hydrogenbonds)forsulfateandphosphateionshassulfateionreceptorsisextractionofthe

3、sulfateionfrombeenachievedbythesereceptors,thecomplementarityfor[2]nitrate-richmixturesintheremediationofnuclearwaste.theionsisnotoptimalinmostcases.CalculationshaveBasedonliquid–liquidanionexchangetechnology,extractiondemonstratedthattheoptimalsaturatedcoordinationmodeofsulfateio

4、nsfromanaqueoustoanorganicphasewasforsulfateionsisbindinginatetrahedralcavitywith12[2b][9]realizedbyusingmacrocyclicreceptors.Inparticular,thehydrogenbondsalongtheedges.Inthisregard,theideal22distributionratio(Dsulfate=[SO4)]org/[SO4)]aq)canreachsulfateionreceptorwouldpossessaco

5、mplementarytetrahe-technologicallyusefulvalues(>1)whenafluorinatedcal-dralcavitysurroundedby12optimallyarrangedbindingsites.[2c]ixpyrrolisused.However,highconcentrations(about1000Thechelateeffectmayalsoplayanimportantroleinthe2timesSO4)ofthereceptorwereneededinthiscasetohost–gues

6、tbindingaffinitybecauseofthefavorablecontri-ensureapplicableextraction.Hence,theextractionefficiencybutionsfrombothentropyandenthalpy.Asatypicalexample2+hasyettobeimprovedforsulfateionextractants.Thisaimisofthechelateeffect,theCocomplexofthebidentateligand8quitechallengingbecauseo

7、ftheextremelylargehydration1,2-diaminoethaneis10timesmorestablethanthatofthe12[10]energyofthesulfateion(DGh=1080kJmolforSO4unidentateligandammonia.Moreover,thehexadentate1[3]comparedto300kJmolforNO3)accordingtotheligandethylenediaminetetraaceticacid(EDTA)displays[4]Hofmeiste

8、rseries,aswellasthehighnitrate/su