成核
溶解度
过饱和度
降水
粒径
化学工程
粒子(生态学)
溶剂
水溶液
拉曼光谱
相(物质)
材料科学
化学
溶剂热合成
金属有机骨架
无机化学
结晶学
物理化学
有机化学
吸附
工程类
地质学
物理
海洋学
光学
气象学
作者
Heidemarie Embrechts,Martin Kriesten,Matthias Ermer,Wolfgang Peukert,Martin Hartmann,Monica Distaso
标识
DOI:10.1021/acs.cgd.9b01384
摘要
While it is well-known that the particle size of solvothermally synthesized metal–organic frameworks (MOFs) can be controlled by tuning the solvent composition, which affects the solubility of the linker and metal salt educts, the exact relationship between linker solubility, initial chemical coordination steps occurring in solution, and the resulting MOFs’ particle size has not yet been investigated. Here, we have studied the solvothermal synthesis of MIL-53(Al) in DMF and water/DMF mixtures with in situ Raman spectroscopy, which reveals the formation of intermediate prenucleation building unit (PNBU) species that consist of one linker molecule and one metal atom and self-assemble in solution to form MIL-53(Al). The concentration of PNBUs in solution prior to particle precipitation is dependent on the synthesis solvent ratio used and influences the MIL-53 particle size. Synthesis in pure DMF results in a high concentration of PNBUs in solution prior to MOF supersaturation and precipitation. This results in a large burst of MOF nucleation and the formation of nanosized MIL-53(Al) particles. Adding water to the DMF solution leads to reduced PNBU accumulation in solution prior to MOF precipitation due to the reduced linker solubility. The reduced accumulation of PNBUs prior to particle precipitation causes reduced nucleation and favors particle growth. The MIL-53(Al) particle size, in contrast, is independent of the MOF phase growth rate, which is highly dependent on the synthesis temperature.
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