Hydrogen‐Bonded Open‐Framework with Pyridyl‐Decorated Channels: Straightforward Preparation and Insight into Its Affinity for Acidic Molecules in Solution

Abstract

A hydrogen-bonded open framework with pores decorated by pyridyl groups was constructed by off-charge-stoichiometry assembly of protonated tetrakis(4-pyridyloxymethyl)methane and [Al(oxalate) ] , which are the H-bond donor and acceptor of ionic H-bond interactions, respectively. This supramolecular porous architecture (SPA-2) has 1 nm-large pores interconnected in 3D with large solvent-accessible void (53 %). It demonstrated remarkable affinity for acidic organic molecules in solution, which was investigated by means of various carboxylic acids including larger drug molecules. Competing sorption between acetic acid and its halogenated homologues evidenced good selectivity of the porous material for the halogenated acids. The gathered results, including a series of guest@SPA-2 crystal structures and HRMAS-NMR spectra, suggest that the efficient sorption exhibited by the material relies not only on an acid-base interaction. The facile release of these guest molecules under neutral conditions makes this SPA a carrier of acidic molecules.

Controlled Growth of Ag Nanocrystals in a H‐Bonded Open Framework

“…The majority of the reported H‐bonded frameworks are purely organic systems known as HOF (H‐bonded organic framework). They are formed typically by homo‐assemblage of neutral molecules but related architectures have also been achieved following a bimolecular approach with charged H‐donor and H‐acceptor units, including metal complexes . An interesting feature of the latter is the reinforcement of the H‐bond by the Coulombic interaction resulting in a robust and predictable supramolecular assemblage pattern …”

“…Dealing with Ag + , formation of AgCl appeared as an interesting option because it can be easily photo‐reduced to Ag metal. This approach proved efficient using SPA‐2, a supramolecular porous architecture containing chloride anions in its channels …”

“…They are formed typically by homo-assemblage of neutralmolecules but related architectures have also been achieved following ab imolecular approach with charged H-donora nd H-acceptor units, including metal complexes. [4,[17][18][19] An interesting feature of the latter is the reinforcement of the H-bond by the Coulombic interaction resultingi narobust and predictable supramolecular assemblage pattern. [20,21] MOF and COF frameworks have been combinedw ith inorganic nanoparticles (NPs) to reach hybrid materials for which the confined space and sieving properties of the microporous component add to the property of the inorganic species to gain selectivity in catalysis or in sensinga pplications, for instance.…”

“…This approachp roved efficient using SPA-2, as upramolecular porous architecture containing chlorideanions in its channels. [19] The templating matrix, SPA-2, is characterized by 1nm-large poresi nterconnected in the three directions of space. The framework results from assemblage in a1 :1 ratio of [Al(oxalate) 3 ] 3À andp rotonated tetrakis(4-pyridyl-oxymethyl)methane, [H 4 Tpy] 4 + ,r espectively the H-bond acceptora nd donor.O nly three pyridinium of the [H 4 Tpy] 4 + units are involved in Hbondsw ith the oxalate moieties, the fourth is outsidet his network,p ointing towards the channels pace (SchemeS1, Supporting Information (SI)).…”

Structural reorganization in a hydrogen-bonded organic framework

“…18 This organic molecule displays four exodentate functionalities in a rectangular planar disposition (C2h symmetry) well-suited to direct selfassembly in two dimensions ( Figure 1 (Table SI4), similar to those reported for other H-bonded organic frameworks. [22][23][24][25] Packing of the anionic grid-like layers is controlled by strong ππ stacking between neighbouring aromatic rings. The rings feature a parallel offset arrangement with inter-centroid distances close to 3.5 Å ( Figure SI20).…”