Controlled Nucleation and Controlled Growth for Size Predicable Synthesis of Nanoscale Metal–Organic Frameworks (MOFs): A General and Scalable Approach

Abstract

Nanoscale metal-organic frameworks (nanoMOFs) are promising porous nanomaterials for diverse applications, such as catalysis,i maging,f unctional membranes,a nd drug delivery.A tt he nanoscale,t he sizeo fm aterials is critical for their properties and utility.H erein, as traightforwarda nd convenient strategy is developed for sizep recisely controlled synthesis of nanoMOFs.Unlike other approaches,this strategy can directly give nanoMOFs of predicable sizes within awide range without the time consuming trial-and-error process and without the addition of additives.I nt his approach, the preciseness of sizec ontrol is ensured by the separated and controlled nucleation and growth. The sizecontrolled synthesis of 9kinds of most widely studied nanoMOFs confirms the versatility of this strategy.More importantly,this approach can be utilized for scale-up synthesis of nanoMOFs with the same precise size control.Bytaking advantages of the nanosize,t he potential uses of metal-organic frameworks (MOFs) are broadened by nano-MOFs, [1] including application in biomedical sensing and imaging, [2] functional membranes, [3] thin film devices, [4] cancer therapy [5] and drug delivery. [6] Thes ize of nanomaterials is critical for their properties and utility.Asmall change of size within nanoscale (say,t ens of nanometers) may have ad ecisive impact on some properties of nanomaterials. [7] One widely studied example is the pivotal role of size in the biological properties of nanoparticles,s uch as cellular internalization and biodistribution. [8] Although great advances have been witnessed in synthesis and utilization of new MOFs over the past two decades,the understanding of size-property relationship of MOFs is still in infancyowing to the difficulty of controlling size for many MOFs.T he size effect has not been considered in most reports and the influence of size on many properties of nanoMOFs remains obscure.To modulate aMOF of known size to another specific size by reported approaches,s uch as modulated synthesis, [9] microwave assisted synthesis, [10] or microemulsion strategy, [2a, 11] at rial-and-error process is needed to optimize the reaction conditions (such as solvent, additive,t emperature), which is time and cost consuming and inefficient. Furthermore,t he change of reaction conditions or the addition of additives may influence the major properties of the products (such as crystallinity,porosity and stability). In some cases,the range of size control is limited by the narrow window of reaction conditions for producing products with acceptable performance.I na ddition, since the microemulsion strategy requires am ulticomponent system to form microemulsion droplets (generally consisting of water/oil/surfactant), the application scope of this approach is limited by the poor solubility of some ligands and the poor water stability of some MOFs. [11a] Based on the classical crystallization mechanism, the key to synthesize uniform nanocrystals is the separation of nucleation and growth. [12] Owing to the energy barri...

Three-step nucleation of metal–organic framework nanocrystals

“…Among several competing models that have been proposed to explain their nucleation and growth, two are the most prevalent. The first one follows the classical pathway, which stipulates that MOF crystals grow by the addition of monomers to spontaneously formed stable crystalline nuclei (28,29). The second pathway proposes that MOFs nucleate through a nonclassical route comprising multiple steps.…”

High-quality mesoporous SiO2 nanospheres via a confined jet impingement continuous microchannel reactor

“…3b), which can correspond to the three stages of LaMer's model (Fig. 3c) 25 . The rst stage (I) corresponds to the formation of micelle precursors, with little change in sequence parameters, indicating minimal density uctuations and aggregate formation.…”

“…When CTAB are further increased, the in uence of perforating agent concentration on particles is diminished (Fig S8). This phenomenon can be explained by liquid crystal templates theory [25][26][27] . The concentration of CTAB can directly affect the morphology of the liquid crystal template.…”

An investigation of affecting factors on MOF characteristics for biomedical applications: A systematic review

“…Hence, the final particle size is reduced, and more uniform nanoparticles will be obtained. In a study carried out by Wang et al, the supersaturation degree of reactions was controlled through a syringe pump to enter metal and ligand solutions separately at a specific feed rate into the reaction along with stirring [43].…”