Autocatalysis and Oriented Attachment Direct the Synthesis of a Metal–Organic Framework

Abstract

Synthesis of porous, covalent crystals such as zeolites and metal–organic frameworks (MOFs) cannot be described adequately using existing crystallization theories. Even with the development of state-of-the-art experimental and computational tools, the identification of primary mechanisms of nucleation and growth of MOFs remains elusive. Here, using time-resolved in-situ X-ray scattering coupled with a six-parameter microkinetic model consisting of ∼1 billion reactions and up to ∼100 000 metal nodes, we identify autocatalysis and oriented attachment as previously unrecognized mechanisms of nucleation and growth of the MOF UiO-66. The secondary building unit (SBU) formation follows an autocatalytic initiation reaction driven by a self-templating mechanism. The induction time of MOF nucleation is determined by the relative rate of SBU attachment (chain extension) and the initiation reaction, whereas the MOF growth is primarily driven by the oriented attachment of reactive MOF crystals. The average size and polydispersity of MOFs are controlled by surface stabilization. Finally, the microkinetic model developed here is generalizable to different MOFs and other multicomponent systems.

Fatty acid capped, metal oxo clusters as the smallest conceivable nanocrystal prototypes

“…23 Group 4 MOFs are based on group 4 metal oxo clusters that act as secondary building units (or nodes) in the MOF framework. 5,[24][25][26][27][28] Apart from the typical Zr6, and Hf6 oxo clusters used in MOFs, many discrete group 4 oxo clusters exist with different nuclearities. 2,29 Discrete group 4 oxo clusters are conceptually close to colloidal oxide nanocrystals and share some features with them.…”

“…23 Group 4 MOFs are based on group 4 metal oxo clusters that act as secondary building units (or nodes) in the MOF framework. 5,24–28 Apart from the typical Zr6 , and Hf6 oxo clusters used in MOFs, many discrete group 4 oxo clusters exist with different nuclearities. 2,29…”

Gaining Structural Control by Modification of Polymerization Rate in Ring-Opening Polymerization-Induced Crystallization-Driven Self-Assembly

“…Additionally, the time to maximum turbidity is substantially different for the fast polymerization and slow polymerization samples taking ∼0.15 and 12 h, respectively. The turbidity data appears to be sigmoidal, which has been observed in a variety of self-assembly processes. − Therefore, the data was modeled as a logistic function (eq ). where L is the maximum value of the function, m is the intercept, x 0 is the x value of the steepness point of the curve, and k quantifies the steepness of the sigmodal curve.…”

Three-Step Mechanism of Antisolvent Crystallization

“…Antisolvent crystallization is commonly used for diverse materials such as organic, − inorganic, − and protein crystals, , metal–organic and covalent organic frameworks, − and nanomaterials . Primarily, antisolvent is used to reduce the solubility of solute and increase the chemical potential of the solution.…”