The dire need to reduce the atmospheric carbon dioxide(CO_(2))concentration has attracted worldwide attention to the capture of this greenhouse gas and its conversion into useful chemicals.Nevertheless,it is still dif...The dire need to reduce the atmospheric carbon dioxide(CO_(2))concentration has attracted worldwide attention to the capture of this greenhouse gas and its conversion into useful chemicals.Nevertheless,it is still difficult to achieve variable-temperature and humid-condition adsorption with mild condition fixation of CO_(2)in metal–organic frameworks(MOFs)due to difficulties in positioning assorted taskspecific sites.We introduced open metal site(OMS),hydrogen-bond operative functionality,and free amine moiety inside the pore wall of a mixed-ligand robust Cd(Ⅱ)framework.Two-fold interpenetration generated high-density acid–base functionalization promotes appreciable CO_(2)adsorption in the vipfree structure at elevated temperature with considerable MOF–CO_(2)interaction.The aqua-robust MOF exhibits minimum loss in CO_(2)uptake during multiple capture–release cycles under variable temperature and retains the adsorption capacities even upon exposure to 75%RH.The atomistic-level snapshots of temperature-induced inclusion of gas molecules inside this microporous vessel are rationalized from simulation studies,and portray diverse CO_(2)-philic sites.Particularly,the four-fold increased CO_(2)adsorption compared to that of an un-functionalized MOF validates the prime role of pore surface engineering.Moreover,the CO_(2)selectivity shows a drastic improvement upon gradually increasing the temperature,attaining a CO_(2)/N_(2)value of 380 at 313 K.The framework further demonstrates solvent-free CO_(2)conversion to cyclic carbonates in high yield with broad substrate scope and satisfactory reusability under less harsh conditions and in a rather short time.In addition to typical OMS/co-catalyst synergism,the mutual participation of antagonistic active sites in substrate interaction and activation is validated by juxtaposing the performance of a urea-free isoskeletal framework and by the relative fluorescence modification in the presence of epoxide.The results corroborate the unique organic-functionality-mediated cycloaddition mechanism,which provides important structure–function synergy in this unconventional route to nonredox CO_(2)fixation.展开更多
基金UGC,Delhi,for providing a senior research fellowship.P.P.M.acknowledges the DST-SERB(grant no.CRG/2021/002529)the CSIR(grant no.MLP-0054)+4 种基金the DST-SERB(grant no.CRG/2021/002529)DST(DST/TM/EWO/MI/CCUS/21(C1)CSIR(grant no.MLP-0054)support from AESD&CIF(CSMCRI)Nilanjan Seal for valuable suggestions.CSMCRI communication no.161/2022.
文摘The dire need to reduce the atmospheric carbon dioxide(CO_(2))concentration has attracted worldwide attention to the capture of this greenhouse gas and its conversion into useful chemicals.Nevertheless,it is still difficult to achieve variable-temperature and humid-condition adsorption with mild condition fixation of CO_(2)in metal–organic frameworks(MOFs)due to difficulties in positioning assorted taskspecific sites.We introduced open metal site(OMS),hydrogen-bond operative functionality,and free amine moiety inside the pore wall of a mixed-ligand robust Cd(Ⅱ)framework.Two-fold interpenetration generated high-density acid–base functionalization promotes appreciable CO_(2)adsorption in the vipfree structure at elevated temperature with considerable MOF–CO_(2)interaction.The aqua-robust MOF exhibits minimum loss in CO_(2)uptake during multiple capture–release cycles under variable temperature and retains the adsorption capacities even upon exposure to 75%RH.The atomistic-level snapshots of temperature-induced inclusion of gas molecules inside this microporous vessel are rationalized from simulation studies,and portray diverse CO_(2)-philic sites.Particularly,the four-fold increased CO_(2)adsorption compared to that of an un-functionalized MOF validates the prime role of pore surface engineering.Moreover,the CO_(2)selectivity shows a drastic improvement upon gradually increasing the temperature,attaining a CO_(2)/N_(2)value of 380 at 313 K.The framework further demonstrates solvent-free CO_(2)conversion to cyclic carbonates in high yield with broad substrate scope and satisfactory reusability under less harsh conditions and in a rather short time.In addition to typical OMS/co-catalyst synergism,the mutual participation of antagonistic active sites in substrate interaction and activation is validated by juxtaposing the performance of a urea-free isoskeletal framework and by the relative fluorescence modification in the presence of epoxide.The results corroborate the unique organic-functionality-mediated cycloaddition mechanism,which provides important structure–function synergy in this unconventional route to nonredox CO_(2)fixation.
