Controlled Synthesis Of MOF-505 Analogues With High-performance

Metal-organic Frameworks(MOFs)are new porous crystalline solids resulting from that metal ions or metal clusters(usually termed as secondary building units,SUBs)are connected to multidentate organic ligands via metal coordination bonds.Compared to traditional porous materials such as zeolites,carbon materials and et al.MOFs are unprecedent in terms of their extraordinarily high porosities and surface areas,diverse structures and tunable pore properties.They will have potential applications in the storage of energy and environmental related gases(H2,CH4 and C2H2).In particular,MOFs possess one significant and unique feature of the structural fine-tunability and many MOFs as the platforms could be systematically investigated targeting very special properties.The MOF-505 like structure as a blueprint is one excellent platform.In this dissertation,we constructed novel MOF-505 analogues using different ligands with inserting amide and other functional groups with the focuses of improving MOFs'C2H2 and CH4 uptake capacities.In order to further deeply enrich our work and improve MOFs'performance for storage of C2H2,we replace the C?C functional group by the polar amide functional group and a new MOF-505 analogue,MOF-1 was successfully synthesized.Very interestingly,due to the improvement of the interaction between C2H2 and frameworks by the introduce of amide functional groups into the MOF-505 like structure,MOF-1 exhibits high C2H2 uptake of 222.4 cm3/g at 296 K and 1 bar which is greatly larger than the previous record of 201 cm3/g held by HKUST-1 at 295 K and 1 bar.Furthermore,the new and powerful absorption site of amide towards C2H2 has also been supported by Grand Canonical Monte Carlo(GCMC)and first-principles calculations.MOF-2 was synthesized to obtain balanced porosity and framework density and suitable cages for methane uptakes.The volumetric methane storage capacity was significantly improved from 195 cm3 cm-3 in PCN-14 to 204 cm3 cm-3 in MOF-2 at 35 bar,and 230 cm3 cm-3 to 245 cm3(STP)cm-3 at 65 bar.This is really remarkable,featuring MOF-2 as the unique MOF having the suitable pore size for methane volumetric storage.Although MOF-2 can significantly increase the methane uptakes,the effect on enhancing methane deliverable amounts are quite limited due to that MOF-2 also lead to higher methane uptakes under lower pressure of 5 bar.In order to increase the methane deliverable amounts,we replaced naphthalene with polar oxamide to get MOF-3.As we expected,MOF-3 exhibits much smaller methane uptake than MOF-3 at low pressure.The volumetric methane storage capacity was remarkably decreased from 73 cm3 cm-3 in PCN-14 to 53 cm3 cm-3 in MOF-3 at 5 bar and 298 K.Thus it exhibits a very high methane working capacity of 194 cm3 cm-3 via using a1ide as functional groups.Its exceptionally high methane storage and working capacity are rather surprising and very encouraging.We also combined phen rings and pyridine rings with amide to obtain MOF-4 and MOF-5.The deliverable CH4 capacity of MOF-4 and MOF-5 at 25? reach 197 and 178 cm3 cm-3 for adsorption at 65 bar,respectively,which are the highest reported so far.