Amphiphilic Molecular Motors for Responsive Aggregation in Water

Abstract

The novel concept of amphiphilic molecular motors that self-assemble into responsive supramolecular nanotubes in water is presented. The dynamic function of the molecular motor units inside the supramolecular assemblies was studied using UV-vis absorption spectroscopy and cryo-transmission electron microscopy (cryo-TEM) microscopy. Reorganization between distinct, well-defined nanotubes and vesicles can be reversibly induced by light, going through the rotation cycle of the motor, i.e. driven by alternate photochemical and thermal isomerization steps in the system. This is the first example in which a molecular rotary motor shows self-assembly in an aqueous medium with full retention of its functionality, paving the way to increasingly complex, highly dynamic artificial nanosystems in water.

Designing dynamic functional molecular systems

“…Photoisomerization does not cause a large change in dipole, but a pronounced change in structure, which can manifest itself in, for example, a different packing behavior in membranes. 31 The mixing of DOPC (1,2-dioleoyl-sn-glycero-3-phosphocholine) and an amphiphilic motor in an 1:1 ratio in water resulted in the formation of a nanotubular self-assembly (Fig. 6a).…”

“…Adapted with permission from Ref. 31 , American Chemical Society, 2016. b) Out-of-equilibrium formation of helicate with P handedness. Adapted with permission from Ref.…”

Allosteric Regulation of the Rotational Speed in a Light-Driven Molecular Motor

“…10 They have been applied to control a wide variety of processes, such as self-assembly, 11 substrate binding, 12 wettability, 13 and gel formation. 14 In these motors, repetitive unidirectional rotation is accomplished through sequential photochemical and thermal isomerization steps (Scheme 1A).…”

Light‐Gated Rotation in a Molecular Motor Functionalized with a Dithienylethene Switch

“…Promising applications have been demonstrated in nanotechnology,11, 46, 47 catalysis,48, 49 and anion binding,50, 51 amongst others. Unidirectional rotation is achieved by sequential photochemical E – Z isomerization and thermal helix inversion steps (Scheme 1 a).…”