Supramolecular Organization in Confined Nanospaces

Abstract

Empty spaces are abhorred by nature, which immediately rushes in to fill the void. Humans have learnt pretty well how to make ordered empty nanocontainers, and to get useful products out of them. When such an order is imparted to molecules, new properties may appear, often yielding advanced applications. This review illustrates how the organized void space inherently present in various materials: zeolites, clathrates, mesoporous silica/organosilica, and metal organic frameworks (MOF), for example, can be exploited to create confined, organized, and self-assembled supramolecular structures of low dimensionality. Features of the confining matrices relevant to organization are presented with special focus on molecular-level aspects. Selected examples of confined supramolecular assemblies - from small molecules to quantum dots or luminescent species - are aimed to show the complexity and potential of this approach. Natural confinement (minerals) and hyperconfinement (high pressure) provide further opportunities to understand and master the atomistic-level interactions governing supramolecular organization under nanospace restrictions.

The Nature and Catalytic Function of Cation Sites in Zeolites: a Computational Perspective

“…[5] The three-dimensional crystalline frameworks of zeolites are represented by networks of molecular-sized channels and cages comprised of corner-shared tetrahedral [TO 4 ] (T = Si or Al) primary building blocks. [6] By varying the connectivity of such building blocks families of microporous materials with different topologies can be obtained. A negative charge can be introduced onto the framework via the isomorphous substitution of a framework tetravalent silicon by a trivalent aluminum atom.…”

Stepwise Evolution of Molecular Nanoaggregates Inside the Pores of a Highly Flexible Metal–Organic Framework

“…Thei ncoming liquid will simultaneously interact with the sponge and the outcoming content, while the sponge will progressively change its shape to accommodate the flowing liquid. Here we downsize the scale by 7orders of magnitude,and monitor, at the nanoscale, the structural evolution of molecular aggregates of eugenol inside the pores of aMOF pristinely filled with DMF.MOFs or, more generally,h ollow molecular structures that are capable of guest inclusion are an area of raising interest in the last decades [1][2][3] and lie at the forefront of the modern supramolecular structural chemistry. [4] Originally studied in solution, [5,6] this concept has subsequently been applied using solid systems, [7] by exploiting robust nanoporous crystals [8] as suitable molecular-scale containers for small molecular guests.…”

Unravelling the High-Pressure Behaviour of Dye-Zeolite L Hybrid Materials

“…The nanometric-scale geometry of zeolite pore systems allows the intensive use of zeolites in several fields such as in molecular separation processes and in heterogeneous catalysis [3,4]. Such ongoing progress in applications has been accompanied, in the latest years, by a deeper molecular-level understanding of the confined photoactive assemblies, which has been achieved through computational modelling [44][45][46][47][48][49][50], often combined with multi-technique experimental analyses [45,[50][51][52][53][54][55][56][57]. The key role of water in tuning the organization of the confined chromophores has been revealed [45,46,58], as well as the stabilizing effect of potassium cations in composites with carbonyl dyes [44,57,59].…”

“…The high-pressure behaviour of zeolites has been intensively studied in the last 15 years, as documented in various reviews [50,[60][61][62][63][64][65][66], both with pore penetrating and non-penetrating pressure transmitting media (PTM). One reason for this interest is that high pressures, combined with the confining environments of nanometric pores, may reveal unexpected chemical phenomena (e.g., pressure-induced hydration [67][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82], ionic conductivity [83], guest exchange [84][85][86][87][88], or realization of new materials otherwise unattainable [89][90][91][92][93][94][95][96][97]).…”