Dynamic Constitutional Systems

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Dynamic constitutional materials for self-instructed membranes

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Proc. Natl. Acad. Sci., 2009, 106(20), 8117-8122.

Microp. Mesop. Mat. 2011, 140, 51-57.

Chem. Eur.J. 2008, 14, 1776-1783.

Constitutional self-instructed membranes were developed and used for mimicking the adaptive structural functionality of natural ion-channel systems. These membranes are based on dynamic hybrid materials in which the self-organized columnar macrocycles are reversibly connected with the mesoporous silica through hydrophobic interactions (Figure 3). From the conceptual point of view these membranes express a synergistic adaptive behaviour: the simultaneous binding of the cation and its anion would be a case of "homotropic allosteric interactions" as time it increases the transport efficiency by a selective evolving process towards the fittest ion-channel.

Generation of directional ion-conduction pathways which can be morphologically tuned by alkali salts templating within Dynamic hybrid materials by the hydrophobic confinement of ureido-macrocyclic receptors within silica mesopores.  It embodies a reorganization of the membrane configuration evolving an improved response in the presence of the solute that produced this change in the first place.

Dynamic inside-pore constitutional resolution of the systems arrays under the pressure of the driving forces :(a) internal structural/ constitutional stabilization or (b) in response to a external target.

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Rubbery Organic Frameworks (ROFs) – constitutional routes toward dynameric membranes

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Chem. Commun., 2012, 48, 6827-6829

Chem. Commun., 2012, 48, 7398-7400

Israel J. Chem. 2013, 53(1-2), 97-101.

Chem. Commun., 2012, 48(94) 11546-11548

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The dynamic self-assembly of the components may allow the flow of structural information from molecular level toward nanoscale dimensions. Understanding and controlling such up-scale propagation of structural information, might offer the potential to impose further precise order at the mesoscale and new routes to obtain highly ordered ultradense arrays over macroscopic distances. Within this context, the dynamic covalent polymers or dynamers, generated from reversibly interacting monomers, offer the possibility to generate homogeneous systems with addressable domains based on structural relationships within the former monomers. In dynamers, the components self-assemble reversibly, in such a fashion that their external hypersurfaces might be able to maximize of all structure/energy combinations via their constitutional affinity. In such scenario the adaptive self-assembly might override defects and use the topography only as a guide to the formation/orientation of the segregated domains of different behaviours, under the pressure of internal structural stabilization, the constitution (affinity), as an internal driving force. This would mediate the dynamic self-assembly of low-size and molecularly addressable domains toward the macroscopic membrane films in which the diffusional/selective percolation pathways might exist.

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Converging the structural behaviours of block co-polymers and of ultradense block co-dynamers controled at the molecular level

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For all these reasons we introduced some examples of dynameric membranes together with useful and simple methodologies for the simple fabrication of stable supported thin-layer or self-standing membrane films. We hope that the strategies revealed here to represent versatile and simple synthetic methodologies for the fabrication of dynameric membranes for ionic and gas separation purposes and presenting interesting permeabilities and controlled selectivity. Dynameric membrane materials presented here would also offer to membrane science perspectives towards self-fabricated devices that involve modification and control of the intrinsic structural properties of dynamic entities correlated with the dynamic features of the diffusional controlled transport. This might shed light new prospects for the future include the development of these original methodologies towards for such dynamic tunable materials, presenting a greater degree of structural complexity and their application to different membrane processes.

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Dynamic covalent, metallodynameric and supraomlecular/dynameric membrane systems may be easily generated avoiding time-consuming synthetic steps or complicate synthetic procedures. These open wide perspectives to imagine a fundamental transition from macromolecular design toward constitutional molecular selection approaches, which might push the limits and achieve the molecular limit of permeable membranes. Finally, the glassy/rubbery dynameric membranes presented here allow a high permeabilities and interesting permeselectivities for ionic/gas separation. Within this context the dynameric membranes show a strong potential. Prospects for the future include the development of these rubbery organic frameworks-ROFs as an alternative of highly performing metal organic frameworks-MOFs, towards novel dynamic systems, presenting a greater degree of structural complexity. They might provide new insights into the basic features that control the design of sharply selective materials for separation with applications in chemical separations, sensors or as storage-delivery devices.

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a) Synthesis and b) schematic representation of chain packing of dynameric membranes combining polyTHF, 1 (red line) and polyMePEG, 3 (green star), connected via isophthaldimine cores 1, (blue circle). It generates structural diversity of matrixes: (right) linear compact (high content of 2), (center) free volume matrix (maximum value of diffusivity at %3=0.33, and (left) highly cross-linked (high content of 3) c) images of self-standing dynameric membrane films of elastomeric behavior.