Permanent Porosity Derived From the Self‐Assembly of Highly Luminescent Molecular Zinc Carbonate Nanoclusters

Abstract

Over the past two decades, crystalline microporous materials have attracted major interest, owing to their applications in gas sorption, separation, catalysis, and sensing. [1] Microporous crystalline materials can be constructed from coordinatively or covalently linked building blocks where rigid or semi-rigid molecular scaffolds separate void spaces of different size and geometry. Prominent examples of porous materials showing polymeric structures include zeolites, [2] hybrid metal-organic frameworks (MOFs) or porous coordination polymers (PCPs), [3] covalent organic frameworks (COFs), [4] and Hbonded supramolecular organic frameworks (SOFs). [5] The formation of bonding interactions between building units is an important factor that defines and controls the stability and robustness of these porous polymeric materials. However, discrete molecules may also pack in the solid state to form 3D assemblies that exhibit high permanent porosity. [6] The resulting noncovalent porous materials (NPMs) are distinct from the above polymeric systems, as they are held together by weak noncovalent crystal-packing forces. Modifications of structure by cocrystallization of different building blocks [7] can tune the microcavities in the solid state, and the material can thus conform to the shape or functionality of guest molecules. Moreover, these materials can be highly solubile, an important advantage in their processing to form porous thin films. [7a, 8] NPMs can exhibit extrinsic and/or intrinsic porosity. Intrinsic porosity is associated with the structure of the single-molecule-containing voids, clefts, or cavities, as has been demonstrated for calixarenes, [9] cucurbiturils, [10] cyclodextrins, [11] organic cage compounds, [6, 7a,c] or discrete small organic molecules. [12] In contrast, materials with extrinsic porosity are those where individual molecules pack in the solid-state to form structures with empty spaces between the individual molecules. As discrete molecules tend to form close-packed solids with minimal void volume, extrinsic porosity in NPMs remains a rare phenomenon. [12a, 13] The rational design and preparation of NPMs showing extrinsic porosity based on molecular metal complexes is highly challenging and few examples have been reported. [14] We have demonstrated previously that alkylzinc hydroxides RZnOH can be efficiently transformed into multinuclear alkyzinc carbonate nanoclusters [15] or nanomaterials, such as discrete nanoparticulate zinc carbonate aerogels [15] and ZnO nanoparticles. [16] As shown in Scheme 1 a, the reactivity of the RZnOH species can be rationalized in terms of the presence of both a proton-reactive Zn À C bond and CO 2 -reactive Zn À OH groups. We argued that introduction of an additional auxiliary ligand L to the RZnOH system, followed by CO 2 fixation, could lead to the formation of novel molecular building blocks for new extrinsic NPMs. Herein, we report such a strategy in which the construction of a nanosized cluster [Zn 10 (m 6 -CO 3 ) 4 (L) 12 ] (WUT-1; WUT = War...

tert‐Butyl(tert‐butoxy)zinc Hydroxides: Hybrid Models for Single‐Source Precursors of ZnO Nanocrystals

“…Based on our experience in the synthesis of alkylzinc alkoxides,8 hydroxides,6a–c,e, 8b and oxides,6d, 9 herein we describe the efficient synthesis of unique mixed tert ‐butyl( tert ‐butoxy)zinc hydroxide aggregates, [( t Bu) 4 Zn 4 (μ 3 ‐O t Bu) x (μ 3 ‐OH) 4− x ]. These compounds were obtained from a combination of the well‐defined molecular alkylzinc hydroxide [ t BuZn(μ 3 ‐OH)] 6 ( 1 6 )6e and the corresponding zinc alkoxide [ t BuZn(μ 3 ‐O t Bu)] 4 ( 2 4 ) 8a.…”

Experimental and Computational Insights into Carbon Dioxide Fixation by RZnOH Species

“…[9] Thus, aside from its fundamental novelty, organozinc hydroxides, in combination with CO 2 , have appeared as very promising precursors of zinc carbonate based functional materials.…”

“…These preliminary investigations provided the first example of a structurally characterized alkylzinc hydroxide, t BuZnOH ( 1 ),6 which, in the presence of CO 2 , can form different nanomaterials based on CO 3 2− as a templating ion, for example, ZnCO 3 nanoparticles (NPs) or discrete alkylzinc carbonate cluster 2 (Scheme ) 7. Moreover, the introduction of an auxiliary ligand, L, to the RZnOH system,8 followed by the reaction with CO 2 , led to the formation of the nanosized cluster [(L 2 Zn) 6 (ZnCO 3 ) 4 ] (L=deprotonated 8‐hydroxyquinoline; Scheme ), which self‐assembled into noncovalent porous material WUT‐1 9. Thus, aside from its fundamental novelty, organozinc hydroxides, in combination with CO 2 , have appeared as very promising precursors of zinc carbonate based functional materials.…”

Towards Extended Zinc Ethylsulfinate Networks by Stepwise Insertion of Sulfur Dioxide into Zn−C Bonds

“…As a part of our ongoing interest in the sequestration and activation of small molecules as well as in searching for new molecular building blocks for extended inorganic–organic networks, here we report on systematic investigations of the fundamental reactions involving Et 2 Zn and 1) gaseous SO 2 , 2) gaseous SO 2 with the assistance of Lewis bases (i.e., urotropine (hexamethylenetetramine, hmta) and 1,4‐diazabicyclo[2.2.2]octane (DABCO)), and 3) 1,4‐diazabicyclo[2.2.2]octane bis(sulfur dioxide) (DABSO) as a solid‐state source of SO 2 (Scheme ). These model reaction systems provided novel examples of structurally characterized organozinc ethylsulfinate based compounds and represent efficient tools for the preparation of extended zinc ethylsulfinate networks.…”