As an effective alternative to Lewis-acid activation,hydrogen-bond donating(HBD)organo-catalysis represents a powerful construction tool for important classes of carbon-carbon bonds,wherein metal-organic frameworks(MO...As an effective alternative to Lewis-acid activation,hydrogen-bond donating(HBD)organo-catalysis represents a powerful construction tool for important classes of carbon-carbon bonds,wherein metal-organic frameworks(MOFs)alleviate issues like self-quenching,solubility and reactivity.However,sizeselectivity is rather challenging in such catalysis,while the status quo is still unexplored when both H-bonding and open-metal sites(OMS)are present together in a single system.The pillar-bilayer Cd(Ⅱ)MOF with a rare(3,8)-connected 2-nodal network upholds uni-directional microporous channels integrated with free-NH groups from the urea-moiety of the N,N-donor linker,and aqua-molecule bound[Cd_(3)(COO)_(6)]cluster.The activated framework allows the highly efficient Friedel-Crafts alkylation of indole and β-nitrostyrene under relatively mild conditions with low catalyst loading and no leaching.The strategically designed MOF exhibits unaltered activity over multiple catalytic cycles,and corroborates its effectivity towards a wide range of substituted electrophiles and nucleophiles.Importantly,suitably sized pores generated by two-fold interpenetration restrict the entry of a sterically encumbered substrate and result in poor conversion,demonstrating the rarest pore-fitting-induced size-selectivity.Given that this pore-engineered MOF contains both coordination unsaturated Cd(Ⅱ)centres and unbound-NH groups as active interaction sites,explicit proof of the interaction of the MOF functionality with the-NO_(2) group of the reactant is elaborated for the first time in light of the change in emission intensity of the framework in the presence of an electrophile,a judicious choice of substrate,and an in-depth comparison of the catalytic activity of an isostructural framework without a urea-moiety.These control experiments unprecedentedly authenticate urea-moiety-mediated two-point hydrogen bonding in the proposed catalytic route,and simultaneously exclude any major role for OMS at the SBU.Apart from pore-induced sizeexclusive reactions,this MOF exemplifies site-specific Friedel-Crafts alkylation,and paves the way to tailor-made engineering of advanced functionalities in contemporary materials for unconventional HBD reactions at the interface of structure-property synergies.展开更多
The multi-scaled pore networks of shale or tight reservoirs are considerably different from the conventional sandstone reservoirs.After hydraulic fracturing treatment,the spontaneous imbibition process plays an import...The multi-scaled pore networks of shale or tight reservoirs are considerably different from the conventional sandstone reservoirs.After hydraulic fracturing treatment,the spontaneous imbibition process plays an important role in the productivity of the horizontal wells.Applying the color-gradient model of Lattice Boltzmann Method(LBM)accelerated with parallel computing,we studied the countercurrent spontaneous imbibition process in two kinds of pore structures with different interlacing distributions of large and small pores.The effect of geometry configuration of pore arrays with different pore-scale and the capillary number Ca on the mechanism of counter-current spontaneous imbibition as well as the corresponding oil recovery factor are studied.We found that the wetting phase tends to invade the small pore array under small Ca in both types of geometry configurations of different pore arrays of four pore arrays zones.The wetting phase also tends to invade the pore array near the inlet for injecting the wetting phase no matter if it is a large pore array or small pore array except for the situation when the Ca is large to a certain value.In this situation,the small pore arrays show resistance to the wetting phase,so the wetting phase doesn't invade the small pore near the inlet,but invades the large pore preferentially.Both the geometry configurations of different pore arrays and Ca have a significant effect on the oil recovery factor.This work will help to solve the doubt about the selectivity of the multi-scaled pores of the wetting phase and the role of pores with different sizes in imbibition and oil draining in countercurrent spontaneous imbibition processes.展开更多
基金the DST-SERB(grant no.CRG/2021/002529)the CSIR(grant no.MLP-0028)+1 种基金support from AESD&CIF(CSMCRI).CSMCRI communication no.220/2021.
文摘As an effective alternative to Lewis-acid activation,hydrogen-bond donating(HBD)organo-catalysis represents a powerful construction tool for important classes of carbon-carbon bonds,wherein metal-organic frameworks(MOFs)alleviate issues like self-quenching,solubility and reactivity.However,sizeselectivity is rather challenging in such catalysis,while the status quo is still unexplored when both H-bonding and open-metal sites(OMS)are present together in a single system.The pillar-bilayer Cd(Ⅱ)MOF with a rare(3,8)-connected 2-nodal network upholds uni-directional microporous channels integrated with free-NH groups from the urea-moiety of the N,N-donor linker,and aqua-molecule bound[Cd_(3)(COO)_(6)]cluster.The activated framework allows the highly efficient Friedel-Crafts alkylation of indole and β-nitrostyrene under relatively mild conditions with low catalyst loading and no leaching.The strategically designed MOF exhibits unaltered activity over multiple catalytic cycles,and corroborates its effectivity towards a wide range of substituted electrophiles and nucleophiles.Importantly,suitably sized pores generated by two-fold interpenetration restrict the entry of a sterically encumbered substrate and result in poor conversion,demonstrating the rarest pore-fitting-induced size-selectivity.Given that this pore-engineered MOF contains both coordination unsaturated Cd(Ⅱ)centres and unbound-NH groups as active interaction sites,explicit proof of the interaction of the MOF functionality with the-NO_(2) group of the reactant is elaborated for the first time in light of the change in emission intensity of the framework in the presence of an electrophile,a judicious choice of substrate,and an in-depth comparison of the catalytic activity of an isostructural framework without a urea-moiety.These control experiments unprecedentedly authenticate urea-moiety-mediated two-point hydrogen bonding in the proposed catalytic route,and simultaneously exclude any major role for OMS at the SBU.Apart from pore-induced sizeexclusive reactions,this MOF exemplifies site-specific Friedel-Crafts alkylation,and paves the way to tailor-made engineering of advanced functionalities in contemporary materials for unconventional HBD reactions at the interface of structure-property synergies.
基金supported by the Joint foundation for enterprise innovation and development of the National Natural Science Foundation of China(U19B6003-03-04-03)by the Beijing Municipal Natural Science Foundation(No.2214077).
文摘The multi-scaled pore networks of shale or tight reservoirs are considerably different from the conventional sandstone reservoirs.After hydraulic fracturing treatment,the spontaneous imbibition process plays an important role in the productivity of the horizontal wells.Applying the color-gradient model of Lattice Boltzmann Method(LBM)accelerated with parallel computing,we studied the countercurrent spontaneous imbibition process in two kinds of pore structures with different interlacing distributions of large and small pores.The effect of geometry configuration of pore arrays with different pore-scale and the capillary number Ca on the mechanism of counter-current spontaneous imbibition as well as the corresponding oil recovery factor are studied.We found that the wetting phase tends to invade the small pore array under small Ca in both types of geometry configurations of different pore arrays of four pore arrays zones.The wetting phase also tends to invade the pore array near the inlet for injecting the wetting phase no matter if it is a large pore array or small pore array except for the situation when the Ca is large to a certain value.In this situation,the small pore arrays show resistance to the wetting phase,so the wetting phase doesn't invade the small pore near the inlet,but invades the large pore preferentially.Both the geometry configurations of different pore arrays and Ca have a significant effect on the oil recovery factor.This work will help to solve the doubt about the selectivity of the multi-scaled pores of the wetting phase and the role of pores with different sizes in imbibition and oil draining in countercurrent spontaneous imbibition processes.
