Molecular Loop Lock: A Redox-Driven Molecular Machine Based on a Host-Stabilized Charge-Transfer Complex

✍ Scribed by Woo Sung Jeon; Eunju Kim; Young Ho Ko; Ilha Hwang; Jae Wook Lee; Soo-Young Kim; Hee-Joon Kim; Kimoon Kim

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 199 KB
• Volume: 44
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/anie.200461806

✦ Synopsis

Artificial molecular machines have received much attention in recent years because of their potential application in the creation of nanometer-scale molecular devices. [1,2] A wide variety of molecular machines such as shuttles, [3a] rotors, [3b] muscles, [3c] ratchets, [3d] pistons and cylinders, [3e] scissors, [3f] and elevators [3g] have been reported. Nevertheless, the design and synthesis of new molecular machines that are reminiscent of macroscopic machines would further widen the scope of this area of chemistry.

Cucurbit[8]uril (CB[8]), [4] a member of the host family cucurbit[n]uril, which has a cavity that is similar to that of gcyclodextrin, exhibits remarkable host-guest properties including the encapsulation of a hetero-guest-pair inside the cavity. [5] For example, it encapsulates methyl viologen (MV 2+ ) and 2,6-dihydroxynaphthalene (Np(OH) 2 ) inside the cavity to form the stable 1:1:1 complex 1 2+ . Formation of the complex is driven by the markedly enhanced charge-transfer (CT) interaction between the electron-deficient and electron-rich guest molecules inside the hydrophobic cavity of CB[8]. [5a] This discovery led us to build several novel supramolecular assemblies such as supramolecular amphiphiles that led to