Carbon Dioxide Capture and Utilization with Isomeric Forms of Bis(amino)‐Tagged Zinc Bipyrazolate Metal–Organic Frameworks

Aimingatextendingthe taggedzinc bipyrazolatemetal–organicframeworks(MOFs)family,the ligand3,3’-di-amino-4,4’-bipyrazole (3,3’-H2L)has beensynthesizedingoodyield.The reaction withzinc(II)acetatehydrateled tothe relatedMOFZn(3,3’-L).The compoundis isostructuralwithits mono(amino) analogueZn(BPZNH2)and withZn(3,5-L),its isomericparentbuiltwith3,5-diamino-4,4’-bi-pyrazole. The texturalanalysishas unveiledits micro-/meso-porousnature,with aBET areaof 463 m2g@1.Its CO2adsorp-tion capacity (17.4wt.%CO2atpCO2=1bar andT=298 K)andisostericheatof adsorption(Qst=24.8 kJmol@1)arecomparableto that ofZn(3,5-L).BothZn(3,3’-L)andZn(3,5-L)havebeentestedas heterogeneous catalystsinthe reac-tionof CO2withthe epoxidesepichlorohydrin andepibro-mohydrintogive the correspondingcycliccarbonatesat393 KandpCO2=5bar undersolvent- and co-catalyst-freeconditions.In general, the conversions recordedare higherthanthosefoundforZn(BPZNH2), provingthat the insertionofanextraaminotagintheporesisbeneficialfortheepoxi-dationcatalysis. The bestcatalyticmatchhas beenobservedfor theZn(3,5-L)/epichlorohydrincouple,with64%conver-sionandaTOF of 5.3 mmol(carbonate)(mmolZn)@1h@1.Togainbetterinsightson the MOF-epoxide interaction,thecrystal structureofthe [epibromohydrin@Zn(3,3’-L)]adducthas beensolved,confirmingthe existence of Br···(H)@Nnon-bondinginteractions.To our knowledge,this studyrepre-sentsthe firststructuraldeterminationof a[epibromohy-drin@MOF] adduct.