Control of the cavity size of flexible covalent cages by silver coordination to the peripheral binding sites

Abstract

The synthesis of covalent cages consisting of two porphyrins connected by four flexible spacers each incorporating two 1,2,3-triazolyl ligands is reported. Binding of four silver(I) to the peripheral ligands induces conformational changes in solution and locks the porphyrins in a face-to-face disposition.

Positive Allosteric Control of Guests Encapsulation by Metal Binding to Covalent Porphyrin Cages

“…In nonpolar solvent, external binding of the ligand to the zinc(II) porphyrins led to insoluble oligomers (Figure S11, Supporting Information). This result contrasts with the one obtained with DABCO, which was encapsulated quantitatively in cages 1 and 2 , in CH 2 Cl 2 and CH 2 Cl 2 /MeOH 9:1, respectively …”

“…To assess the ability of the cage to act as an allosteric receptor, guest molecules that can be trapped by coordination to the zinc(II) porphyrins or stabilized in between their large π‐electron rich core were considered. It must be noticed that cages 1 and 2 adopt a flattened conformation in a CH 2 Cl 2 /MeOH 9:1 mixture or even in solvents of higher polarity (DMSO, DMF) . This compact form stabilized by π–π interactions between the zinc(II) porphyrins was confirmed in the solid state with an X‐ray crystallographic structure of cage 2 .…”

“…Our previous work has focused on the synthesis of coordination and covalent architectures incorporating metalloporphyrins . In particular, flexible covalent cages incorporating orthogonal binding sites, metalloporphyrins and 1,2,3‐triazoles, were obtained using a DABCO‐templated copper(I)‐catalyzed alkyne‐azide reaction (DABCO=1,4‐diazabicyclo[2.2.2]octane).…”

“…In particular, flexible covalent cages incorporating orthogonal binding sites, metalloporphyrins and 1,2,3‐triazoles, were obtained using a DABCO‐templated copper(I)‐catalyzed alkyne‐azide reaction (DABCO=1,4‐diazabicyclo[2.2.2]octane). This templated synthesis enabled to perform simultaneously the macrocyclization reaction and the synthesis of four out of eight triazole ligands of the structure, therefore, limiting the synthetic effort to obtain these molecules . Protonation of both the porphyrins and the triazoles in the cages with two free‐base porphyrins has been shown to inflate the structures .…”

Kovalente organische Netzwerke und Käfigverbindungen: Design und Anwendungen von polymeren und diskreten organischen Gerüsten

“…[267] Eine sechsfache Williamson-Ethersynthese an den internen Hydroxygruppen in adamantoiden [4+ +6]-Käfigen ergab eine Reihe von funktionalisierten Strukturen in guten Ausbeuten, und die zugänglichen inneren Oberflächen konnten durch den sterischen Anspruch der Substituenten abgestimmt werden. [270] Die reversible Bindung von Ag I -Ionen an die internen Tr iazoleinheiten führte zu einer Versteifung von Käfiggeometrie und Kavität, was solche Systeme interessant füre ine allosterische Kontrolle der Käfigreaktivitätmacht. Porphyrinhaltige Käfige wurden über eine 1,4-Diazabicyclo-[2.2.2]octan(DABCO)-vermittelte und Cu I -katalysierte Azid-Alkin-Click-Reaktion synthetisiert.…”