Diffusion Control in the in Situ Synthesis of Iconic Metal–Organic Frameworks within an Ionic Polymer Matrix

Abstract

Ionic polymers that possess ion-exchangeable sites have been shown to be a greatly useful platform to fabricate mixed matrices (MMs) where metal-organic frameworks (MOFs) can be in situ synthesized, although the in situ synthesis of MOF has been rarely studied. In this study, alginate (ALG), an anionic green polymer that possesses metal-ion-exchangeable sites, is employed as a platform of MMs for the in situ synthesis of iconic MOFs, HKUST-1, and MOF-74(Zn). We demonstrate for the first time that the sequential order of supplying MOF ingredients (metal ion and deprotonated ligand) into the alginate matrix leads to substantially different results because of a difference in the diffusion of the MOF components. For the examples examined, whereas the infusion of BTC ligand into Cu-exchanged ALG engendered the eggshell-shaped HKUST-1 layers on the surface of MM spheres, the infusion of Cu ions into BTC-included alginate engendered the high dispersivity and junction contact of HKUST-1 crystals in the alginate matrix. This fundamental property has been exploited to fabricate a flexible MOF-containing mixed matrix membrane by coincorporating poly(vinyl alcohol). Using two molecular dyes, namely, methylene blue and rhodamine 6G, further, we show that this in situ strategy is suitable for fabricating an MOF-MM that exhibits size-selective molecular uptake.

Strategies for Overcoming Defects of HKUST‐1 and Its Relevant Applications

“…As a typical product through in situ synthesis shown in Figure , the HKUST‐1 mixed matrices show size selectivity to separate MB from rhodamine 6G, thus this material was applied to synthesize a selective membrane by adding poly(vinyl alcohol). At present, this strategy has been proved adoptable and efficient in MOF‐74 and HKUST‐1 and has a potential to be appropriate for other MOFs …”

“…In situ synthesis of HKUST‐1 in alginate polymer matrix via two routes with different adding orders: route A showed ligand‐diffusional and route B showed metal ion‐diffusional. Reproduced with permission . Copyright 2018, American Chemical Society.…”

Metal–Organic Framework Hybrid Materials and Their Applications

“…In situ growth approach involves the growth of MOF crystals via solvothermal/hydrothermal reactions of the metal salts and ligands in the presence of another material. During the synthesis, the second material generally serves as a structure directing agent, leading to oriented growth of MOF crystals [77,78]. Hybrid materials obtained by in situ growth approach usually have ordered morphology and/or hierarchical structure, which are useful features for applications such as gas storage and small molecule separations [17,[79][80][81].…”

The Antibacterial Mechanism of Zn(II) Frame Supported on Alginate Membrane

“…As a unique framework material, metal-organic frameworks (MOFs) have a wide range of applications due to their high porosity, adjustable structure, high chemical stability, and good biocompatibility (such as adsorption, separation, catalysis, electricity chemistry, biomedicine). [10][11][12][13][14][15][16][17] Recent studies have shown that some MOFs also have good anti-bacterial properties 18,19 and good medical value, [20][21][22] including the classic zeolite imidazolate skeleton (ZIF-8), which can respond to decomposition and release Zn(II) in the acidic environment of bacterial infection. As a bactericidal factor, Zn(II) can damage cell membranes and cause cell death.…”