Double Rotors with Fluxional Axles: Domino Rotation and Azide–Alkyne Huisgen Cycloaddition Catalysis

Abstract

The simple preparation of the multicomponent devices [Cu4(A)2]4+ and [Cu2(A)(B)]2+, both rotors with fluxional axles undergoing domino rotation, highlights the potential of self‐sorting. The concept of domino rotation requires the interconversion of axle and rotator, allowing the spatiotemporal decoupling of two degenerate exchange processes in [Cu4(A)2]4+ occurring at 142 kHz. Addition of two equiv of B to rotor [Cu4(A)2]4+ afforded the heteromeric two‐axle rotor [Cu2(A)(B)]2+ with two distinct exchange processes (64.0 kHz and 0.55 Hz). The motion requiring a pyridine→zinc porphyrin bond cleavage is 1.2×105 times faster than that operating via a terpyridine→[Cu(phenAr2)]+ rupture. Finally, both rotors are catalysts due to their copper(I) content. The fast domino rotor (142 kHz) was shown to suppress product inhibition in the catalysis of the azide–alkyne Huisgen cycloaddition.

A Switchable Catalyst Duo for Acyl Transfer Proximity Catalysis and Regulation of Substrate Selectivity

“…At room temperature, the two distinct sets of phenanthroline signals clearly indicated slow exchange of the terpyridine arm between both copper(I)‐loaded phenanthrolines. A cross‐correlation between proton 9c‐H of the copper(I)‐loaded phenanthroline (at 6.96 ppm) and proton 9‐H of the HETTAP‐complexed phenanthroline signal (at 6.38 ppm) in the 1 H‐ 1 H ROESY experiment allowed measurement of the slow exchange [15] . The activation parameters for the exchange were determined at 298 K ( k =1.34 s −1 and Δ G ≠ 298 =72.6 kJ mol −1 ) (Supporting Information, Figure S42).…”

Kooperative Effekte in schaltbarer Katalyse: Verbesserung der Doppel‐Click‐Reaktionsausbeuten von symmetrischen Rotaxanen

“…In früheren Arbeiten hatten wir bereits gezeigt, dass Kupfer(I)-beladene Phenanthroline vom Typ[Cu(phenAr 2 )] + in der Lage waren, Cyclopropanierungen [5b] und Clickreaktionen zu katalysieren. [2d] Ebenso sollten die exponierten Kupfer(I)-Ionen im Dimer [FeCu 2 (1) 2 )] 4+ (Zustand II) in der Lage sein, Bisethinyl-terminierte Pseudorotaxane mit sperrigen Stoppern über ein Click-Protokoll [16] zu [2]Rotaxanen umzuwandeln. Für den Komplex [Cu 2 ( 1) 2 ] 2+ wurde keine katalytische Aktivität erwartet, da die verkapselten Kupfer(I)-Ionen unreaktiv sein sollten.…”

“…Im Einzelnen (Abbildung 2), wenn eine 1:5:4-Mischung von 2a (oder 2b), DB24C8 und 3 bei 40 8 8CinGegenwart des geschlossenen Komplexes [Cu 2 ( 1 (1) 2 )] 4+ (10 mol %) in Gegenwart von 2a, DB24C8 und 3 in einem 1:5:4-Verhältnis. Das Erwärmen von Zustand II für15hbei 40 8 8Clieferte reproduzierbare Mengen an [2]Rotaxan 4a (zwei unabhängige Durchläufe). Verbrauchte Mengen an Substraten wurden zugegeben (siehe grünes Sternchen).…”

Cooperative Effects in Switchable Catalysis: Enhancing Double‐Click Reaction Yield of Symmetrical Rotaxanes

“…Inspired by Nature,chemists have increasingly developed switchable catalysts that are of great use for ON/OFF or UP/ DOWN regulation [1,2] and thus of great promise for autonomous networked reaction systems. [3] Va rious protocols have been used for the activation of switchable catalysts,f or instance the exposure/hiding of the active site(s) in rotaxanes, [4] the unlocking/self-locking [5] of switchable frameworks, and the weak-link approach.…”