The Modular Synthesis of Functional Porous Coordination Networks

Abstract

Although numerous porous coordination networks have been synthesized to date, 1 the functionalization of the pores at will without changing the network frameworks is still a difficult task despite the high designability of organic ligand components. 2 This is because the porous network formation is very sensitive to the ligand structure. Namely, the introduction of even a small functional group to the ligand often brings about the formation of completely different, unpredictable network structures. We have previously synthesized a unique porous coordination network composed of two interpenetrating networks in which the pores are surrounded by aromatic bricks. 3 The bricks consist of alternatively layered 2,4,6tris(4-pyridyl)-1,3,5-triazine (1) and triphenylene (2a); the former, 1, forms infinite 3D network via coordination to ZnI 2 , whereas the latter, 2a, is involved in the 3D framework without forming any covalent or coordination bonds with other components. Here, we report that the noncovalently intercalated 2a in this porous complex can be replaced with functionalized triphenylenes 2b-f without causing any change in the porous network structure (Figure 1). In these porous complexes, intercalated triphenylenes 2a-f are regarded as the cartridges of functional groups. We emphasize that the facile control of the pore nature by simply replacing the cartridge provides a family of porous networks.The porous complex was prepared by treating triazine ligand 1 and triphenylene 2 with ZnI 2 in a nitrobenzene-methanol gradient solution and isolated as single crystals with the formula of {[(ZnI 2 ) 3 -(1) 2 (2)]‚x(C 6 H 5 NO 2 )‚y(CH 3 OH)} n (3), wherein the [(ZnI 2 ) 3 (1) 2 (2)] composite constitutes the porous framework whose pore is filled with nitrobenzene and methanol. For a typical procedure, the single crystals of {[(ZnI 2 ) 3 (1) 2 (2b)]‚4(C 6 H 5 NO 2 )} n (3b), having acidic phenolic pore, were grown from a triple-layered solution consisting of a methanol solution (0.5 mL) of ZnI 2 (0.03 mmol) as the top layer, methanol (0.5 mL) as the middle layer, and a nitrobenzene/ methanol solution (4:1, 5 mL) of 1 (0.02 mmol) and the cartridge molecule 2b (0.1 mmol) as the bottom layer. After 2 days, the crystals were grown and isolated by filtration in 47% yield (Scheme 1). In a similar way, the use of cartridge 2c afforded another porous complex 3c with the acidic phenolic hydroxyl group arrayed at different positions in the pore (27% yield). From cartridges 2d,e with a 2-or 1-NH 2 group on the triphenylene core, complexes 3d,e with a basic pore were formed (32% and 30% yields, respectively). Similarly, cartridge 2f with a polar NO 2 group gave a polar pore in 3f (18% yield).All the complexes 3a-f were characterized by X-ray crystallographic analysis and shown to have the identical porous network frameworks of [(ZnI 2 ) 3 (1) 2 (2)], whose pores were filled with nitrobenzene and, in the case of 2c, methanol (Supporting Information). All the porous complexes 3a-f have in fact two distinct pores,

Visualization of Solution Chemistry by X-ray Crystallography Using Porous Coordination Networks

“…16 We have developed a modular synthesis of a porous coordination network characterized by the noncovalent intercalation of aromatic substrates. 17,18 Complexation of 2,4,6-tris(4-pyridyl)-triazine (1) and ZnI 2 in the presence of aromatic guest molecules G, such as triphenylene and pyrene derivatives, affords porous coordination network [{(ZnI 2 ) 3 (1) 2 ¢(G)} n ] (hereafter denoted as PCN-2¢G) wherein aromatic guests G are intercalated between two ligands 1 by ππ stacking, thereby forming a columnar structure (Figure 2). When substituted triphenylenes are used as guests, the pores of coordination network PCN-2 are functionalized by the substituents, thus allowing reactions with incoming reagents through the pores.…”

X-ray Direct Observation of Reactions and Labile Species on the Basis of Crystal Design

“…We named this strategy "cartridge (modular) synthesis." 66 Various biporous networks were prepared by the cartridge method (Figure 20).…”

“…66 When a triphenylene was used as a cartridge, propane-2-ol was not encapsulated at all. However, a biporous coordination network modified by hydroxy groups successfully recognized propane-2-ol via hydrogen bond formation between alcohol and the hydroxy groups ( Figure 21).…”

Funktionalisierter Koordinationsraum in metall‐organischen Gerüsten

“…Viele dieser Anwendungen machen es jedoch erforderlich, dass sich die organischen Brü-ckenmoleküle selektiv nach Belieben und ohne Veränderung der Gesamtstruktureigenschaften des Gerüstes funktionalisieren lassen -dies ist keine leichte Aufgabe. [12,13] Die Gerüstbildung von MOFs ist hochempfindlich gegenüber den Reaktionsbedingungen, was die funktionellen Gruppen der organischen Brückenmoleküle einschließt. Insbesondere koordinierende Gruppen wie -OH, -NH 2 und -COOH können unter Solvothermalbedingungen offensichtlich den Gerüst-aufbau und damit die Bildung von Kristallisationskeimen sowie das Kristallwachstum mit nicht vorhersagbaren Ergebnissen beeinflussen.…”

“…Während die eine Komponente integraler Bestandteil des Gerüstes ist, liegt die andere eher lose gebunden vor und lässt sich sogar nach Aufbau der porösen, kristallinen Matrix noch austauschen. [13] Lassen Sie uns mit dem zweiten Beitrag beginnen. 2004 entdeckten Kawano et al ein biporöses MOF, das aus zwei sich gegenseitig durchdringenden Gerüsten auf der Grundlage aromatischer Bausteine besteht (Abbildung 1).…”