Multiscale Structural Control of Linked Metal-Organic Polyhedra Gel by Aging-Induced Linkage-Reorganization

Assembly of permanently porous metal-organic cages with functional polymers forms soft supramolecular networks featuring both porosity and processability. However, the amorphous nature of such soft materials complicates their characterization and thus limits structural control. Here we demonstrated that aging is an effective strategy to control the hierarchical network of supramolecular gels, which are assembled from organic ligands as linkers and metal-organic polyhedra (MOP) as junctions. Normally, the initial gel formation by rapid gelation leads to a kinetically trapped structure with low controllability. Through a controlled post-synthetic aging process, we show that it is possible to tune the network of the linked MOP gel over multiple length scales. This process allows control on the molecular-scale rearrangement of interlinking MOPs, mesoscale fusion of colloidal particles and macroscale densification of the whole colloidal network. In this work we elucidate the relationships between the gel properties, such as porosity and rheology, and their hierarchical structures, which suggest that porosity measurement can be used as a powerful tool to characterize the microscale structural transition of the amorphous gels. This aging strategy can be applied in other supramolecular polymer systems particularly containing kinetically controlled structures and shows an opportunity to engineer the structure and porosity of amorphous porous soft materials for further applications.

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Spatiotemporal Control of Supramolecular Polymerization and Gelation of Metal-Organic Polyhedra

10.26434/chemrxiv.13414646.v1 ◽

2020 ◽

Author(s):

alexandre legrand ◽

Li-Hao Liu ◽

Philipp Royla ◽

Takuma Aoyama ◽

Gavin Craig ◽

...

Keyword(s):

Acid Concentration ◽

Self Assembly ◽

Colloidal Particles ◽

Soft Materials ◽

Supramolecular Materials ◽

Time Resolved ◽

Colloidal Gel ◽

Metal Organic ◽

Spatiotemporal Control ◽

Gel Network

In coordination-based supramolecular materials such as metallogels, simultaneous temporal and spatial control of their assembly remains challenging. Here, we demonstrate that the combination of light with acids as stimuli allows for the spatiotemporal control over the architectures, mechanical properties, and shape of porous soft materials based on metal-organic polyhedra (MOPs). First, we show that the formation of a colloidal gel network from a preformed kinetically trapped MOP solution can be triggered upon addition of trifluoroacetic acid (TFA), and that acid concentration determines the reaction kinetics. As determined by time-resolved dynamic light scattering, UV-vis absorption and 1H NMR spectroscopies and rheology measurements, the consequences of the increase in acid concentration are (i) an increase in the cross-linking between MOPs; (ii) a growth in the size of the colloidal particles forming the gel network; (iii) an increase in the density of the colloidal network; and (iv) a decrease in the ductility and stiffness of the resulting gel. We then demonstrate that irradiation of a dispersed photoacid generator, pyranine, allows the spatiotemporal control of the gel formation by locally triggering the self-assembly process. Using this methodology, we show that the gel can be patterned into a desired shape. Such precise positioning of the assembled structures, combined with the stable and permanent porosity of MOPs, could allow their integration into devices for applications such as sensing, separation, catalysis, or drug release.

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Understanding of the Multiscale Self-Assembly of Metal-Organic Polyhedra Towards Functionally Graded Porous Gels

10.26434/chemrxiv.9746177.v1 ◽

2019 ◽

Author(s):

alexandre legrand ◽

Gavin A. Craig ◽

Mickaele Bonneau ◽

Saori Minami ◽

Kenji Urayama ◽

...

Keyword(s):

Self Assembly ◽

Energy Transport ◽

Soft Materials ◽

Functionally Graded ◽

Colloidal Gels ◽

Time Resolved ◽

Colloidal Aggregation ◽

Synthetic Materials ◽

Multiple Length Scales ◽

Metal Organic

Spatial heterogeneity and gradients within porous materials are key for controlling their mechanical properties and mass/energy transport, both in biological and synthetic materials. However, it is still challenging to induce such complexity in well-defined microporous materials such as crystalline metal-organic frameworks (MOFs). Here we show a method to generate a continuous gradient of porosity over multiple length scales by taking advantage of the amorphous nature of supramolecular polymers based on metal-organic polyhedra (MOPs). First, we use time-resolved dynamic light scattering (TRDLS) to elucidate the mechanism of hierarchical self-assembly of MOPs into colloidal gels and to understand the relationship between the MOP concentrations and the architecture of the resulting colloidal networks. These features directly impact on the viscoelastic response of the gels and their mechanical strength. We then show that gradients of stiffness and porosity can be created within the gel by applying centrifugal force at the point of colloidal aggregation. These results with the creation of asymmetric and graded pore configuration in soft materials could lead to the emergence of advanced properties that are coupled to asymmetric molecule/ion transport as seen in biological systems.

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Controlled sequential assembly of metal-organic polyhedra into colloidal gels with high chemical complexity

10.33774/chemrxiv-2021-6dhhs ◽

2021 ◽

Author(s):

Min Ying Tsang ◽

Shun Tokuda ◽

Po-Chun Han ◽

Zaoming Wang ◽

Alexandre Legrand ◽

...

Keyword(s):

Colloidal Particles ◽

Soft Materials ◽

Chemical Components ◽

Colloidal System ◽

Synthetic Process ◽

Chemical Complexity ◽

Porous Networks ◽

Synthetic Strategy ◽

Colloidal Gel ◽

Metal Organic

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, we show a synthetic strategy to construct porous networks with multiple chemical components. By taking advantage of the hierarchical nature of a colloidal system based on metal-organic polyhedra (MOPs), we developed a two-step assembly process to form colloidal networks; assembling of MOPs with the organic linker to the formation of MOP network as a colloidal particle, followed by further connecting colloids by additional crosslinkers, leading to colloidal networks. This synthetic process allows not only for the use of different organic linkers for connecting MOPs and colloidal particles, respectively, but for assembling different colloidal particles formed by various MOPs. The proof-of-concept of this tuneable multivariate colloidal gel system offers an alternative to developing functional porous soft materials with multifunction.

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Spatiotemporal Control of Supramolecular Polymerization and Gelation of Metal-Organic Polyhedra

10.26434/chemrxiv.13414646 ◽

2020 ◽

Author(s):

alexandre legrand ◽

Li-Hao Liu ◽

Philipp Royla ◽

Takuma Aoyama ◽

Gavin Craig ◽

...

Keyword(s):

Acid Concentration ◽

Self Assembly ◽

Colloidal Particles ◽

Soft Materials ◽

Supramolecular Materials ◽

Time Resolved ◽

Colloidal Gel ◽

Metal Organic ◽

Spatiotemporal Control ◽

Gel Network

In coordination-based supramolecular materials such as metallogels, simultaneous temporal and spatial control of their assembly remains challenging. Here, we demonstrate that the combination of light with acids as stimuli allows for the spatiotemporal control over the architectures, mechanical properties, and shape of porous soft materials based on metal-organic polyhedra (MOPs). First, we show that the formation of a colloidal gel network from a preformed kinetically trapped MOP solution can be triggered upon addition of trifluoroacetic acid (TFA), and that acid concentration determines the reaction kinetics. As determined by time-resolved dynamic light scattering, UV-vis absorption and 1H NMR spectroscopies and rheology measurements, the consequences of the increase in acid concentration are (i) an increase in the cross-linking between MOPs; (ii) a growth in the size of the colloidal particles forming the gel network; (iii) an increase in the density of the colloidal network; and (iv) a decrease in the ductility and stiffness of the resulting gel. We then demonstrate that irradiation of a dispersed photoacid generator, pyranine, allows the spatiotemporal control of the gel formation by locally triggering the self-assembly process. Using this methodology, we show that the gel can be patterned into a desired shape. Such precise positioning of the assembled structures, combined with the stable and permanent porosity of MOPs, could allow their integration into devices for applications such as sensing, separation, catalysis, or drug release.

Download Full-text

Understanding of the Multiscale Self-Assembly of Metal-Organic Polyhedra Towards Functionally Graded Porous Gels

10.26434/chemrxiv.9746177 ◽

2019 ◽

Author(s):

alexandre legrand ◽

Gavin A. Craig ◽

Mickaele Bonneau ◽

Saori Minami ◽

Kenji Urayama ◽

...

Keyword(s):

Self Assembly ◽

Energy Transport ◽

Soft Materials ◽

Functionally Graded ◽

Colloidal Gels ◽

Time Resolved ◽

Colloidal Aggregation ◽

Synthetic Materials ◽

Multiple Length Scales ◽

Metal Organic

Spatial heterogeneity and gradients within porous materials are key for controlling their mechanical properties and mass/energy transport, both in biological and synthetic materials. However, it is still challenging to induce such complexity in well-defined microporous materials such as crystalline metal-organic frameworks (MOFs). Here we show a method to generate a continuous gradient of porosity over multiple length scales by taking advantage of the amorphous nature of supramolecular polymers based on metal-organic polyhedra (MOPs). First, we use time-resolved dynamic light scattering (TRDLS) to elucidate the mechanism of hierarchical self-assembly of MOPs into colloidal gels and to understand the relationship between the MOP concentrations and the architecture of the resulting colloidal networks. These features directly impact on the viscoelastic response of the gels and their mechanical strength. We then show that gradients of stiffness and porosity can be created within the gel by applying centrifugal force at the point of colloidal aggregation. These results with the creation of asymmetric and graded pore configuration in soft materials could lead to the emergence of advanced properties that are coupled to asymmetric molecule/ion transport as seen in biological systems.

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Multiscale structural control of linked metal–organic polyhedra gel by aging-induced linkage-reorganization

Chemical Science ◽

10.1039/d1sc02883a ◽

2021 ◽

Vol 12 (38) ◽

pp. 12556-12563

Author(s):

Zaoming Wang ◽

Christian Villa Santos ◽

Alexandre Legrand ◽

Frederik Haase ◽

Yosuke Hara ◽

...

Keyword(s):

Structural Control ◽

Aging Process ◽

Length Scales ◽

Multiple Length Scales ◽

Metal Organic

By a controlled post-synthetic aging process, we demonstrate a protocol to induce the linkage reorganization in metal–organic polyhedra-linked gel networks, leading to the control of gel structures over multiple length scales and their properties.

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Biomimetic materials: An introduction

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100129735 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1020-1021 ◽

Cited By ~ 1

Author(s):

M. Sarikaya ◽

J. T. Staley ◽

I. A. Aksay

Keyword(s):

Self Assembly ◽

Structural Control ◽

Hierarchical Structures ◽

Ceramic Composites ◽

Advanced Materials ◽

Length Scale ◽

Spider Webs ◽

Biomimetic Materials ◽

Synthetic Materials ◽

All Ceramic

Biomimetics is an area of research in which the analysis of structures and functions of natural materials provide a source of inspiration for design and processing concepts for novel synthetic materials. Through biomimetics, it may be possible to establish structural control on a continuous length scale, resulting in superior structures able to withstand the requirements placed upon advanced materials. It is well recognized that biological systems efficiently produce complex and hierarchical structures on the molecular, micrometer, and macro scales with unique properties, and with greater structural control than is possible with synthetic materials. The dynamism of these systems allows the collection and transport of constituents; the nucleation, configuration, and growth of new structures by self-assembly; and the repair and replacement of old and damaged components. These materials include all-organic components such as spider webs and insect cuticles (Fig. 1); inorganic-organic composites, such as seashells (Fig. 2) and bones; all-ceramic composites, such as sea urchin teeth, spines, and other skeletal units (Fig. 3); and inorganic ultrafine magnetic and semiconducting particles produced by bacteria and algae, respectively (Fig. 4).

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