Controlled Sequential Assembly of Metal–Organic Polyhedra into Colloidal Gels with High Chemical Complexity

Abstract

Assembling many chemical components into a material in a controlled manner is one of the biggest challenges in chemistry. Particularly, porous materials with multivariate character within their scaffolds are expected to demonstrate synergistic properties. In this study, a synthetic strategy to construct porous networks with multiple chemical components is shown. By taking advantage of the hierarchical nature of a colloidal system based on metal–organic polyhedra (MOPs), a two‐step assembly process to form colloidal networks is developed, assembling MOPs with the organic linker to form a MOP network as a colloidal particle, followed by further connection of colloids by additional cross‐linkers to construct colloidal networks. This synthetic process allows the use of different organic linkers not only for connecting MOPs and colloidal particles, respectively, but also for assembling different colloidal particles formed by various MOPs. The proof of concept of this tunable multivariate colloidal gel system offers an alternative to developing functional porous soft materials with multifunction.

Hierarchical porous metal–organic gels and derived materials: from fundamentals to potential applications

“…The understanding of the Rh 2 -MOG based gels is comparably advanced in this research field. Apart from the above mentioned examples on these Rh 2 -based MOGs, also the base induced gelation, 109 the aging induced linkage reorganization 19 and the preparation of heterogeneous composite gels 110 have been reported among others. 111 Lal and co-workers described the covalent crosslinking of MOPs.…”

Pore-Networked Soft Materials Based on Metal–Organic Polyhedra

“…Different linkers and CPPs based on different RhMOPs can be used in the gelation to afford a multicomponent colloidal gel. Reproduced with permission from ref . Copyright 2022 Wiley-VCH.…”

“…To further manipulate the MOP assembly, we divided the continuous self-assembly process into two separate steps, including the initial cross-linking of MOPs with the bisimidazole linkers to form MOP networks as colloidal nanoparticles (or CPPs) and the following connection of these CPPs by additional linkers to construct the overall colloidal network (Figure 5, bottom). 46 The key point of this strategy is the synthesis of CPPs with controlled size and vacant rhodium sites on their surface, allowing their further coordination with linkers at their interfaces to induce colloidal percolation for gel formation. This synthetic process permits the use of different linkers not only for connecting MOPs and CPPs, respectively, but also for assembling different CPPs formed by different MOPs.…”

“…By applying centrifugal force at this specific stage prior to the heat-induced gelation, a functionally graded or asymmetric gel can be obtained with the gradients of colloidal density, mechanical viscoelasticity, and porosity within the MOP network (Figure , top right). To further manipulate the MOP assembly, we divided the continuous self-assembly process into two separate steps, including the initial cross-linking of MOPs with the bisimidazole linkers to form MOP networks as colloidal nanoparticles (or CPPs) and the following connection of these CPPs by additional linkers to construct the overall colloidal network (Figure , bottom) . The key point of this strategy is the synthesis of CPPs with controlled size and vacant rhodium sites on their surface, allowing their further coordination with linkers at their interfaces to induce colloidal percolation for gel formation.…”

Polymer networks of imine-crosslinked metal–organic cages: tuneable viscoelasticity and iodine adsorption

“…9–11 MOCs can be viewed as preformed pores because their molecular nature engenders solubility and processability. 12 Thus, by functionalising their surface, MOCs can be utilised as building-blocks for porous gels, 13,14 utrathin films, 15 colloids 16 and liquids; 17 morphologies that are difficult to achieve for traditional porous solids. Importantly, the inherent porosity of the MOC is typically accessible within these diverse morphologies without the requirement of long-rage order.…”