Unidirectional Photoinduced Shuttling in a Rotaxane with a Symmetric Stilbene Dumbbell

Abstract

Die Hantel rauf und runter: Der Cyclodextrin‐Makrocyclus bewegt sich bei Photoisomerisierung des Stilben‐Rotaxans in genau eine Richtung (siehe Schema). Mit diesem Verhalten ermöglichen die beschriebenen und ähnliche Rotaxane Rückschlüsse auf Mechanismen des Hin‐und‐Herbewegens bei molekularen Maschinen.

Fate of photoexcited trans-aminostilbenes

“…Trans-aminostilbenes are a class of p-donor-acceptor (D-A) systems that have been investigated as fluorescent probes [1][2][3][4][5][6], cell imaging dyes [7][8][9], and the active materials in a variety of optoelectronic devices such as organic light-emitting diodes [10,11], dye-sensitized solar cells [12][13][14], nonlinear optics [15][16][17][18][19][20], and molecular switches [21,22]. These applications are all associated with the electronically excited states, in which the lowest singlet excited state (S 1 ) possesses a significant degree of charge separation as a result of intramolecular charge-transfer (ICT) from the amino to the stilbene moiety upon photoexcitation.…”

Structural, energetic, and dynamical properties of rotaxanes constituted of α-cyclodextrins and an azobenzene chain

“…The molecular components are not covalently linked and bulky stoppers bound to the ends of the linear component prevent dissociation of the complex. Because the macrocyles are not covalently linked to the chain, rotaxanes can be used as molecular motors [1][2][3][4] or molecular switches [5][6][7][8][9][10][11][12].…”

“…Cyclodextrins (CDs) are macrocyclic structures used to synthetise rotaxanes [1,2,7,9,10,[12][13][14][15]. CDs are well known cyclic oligosaccharides formed by 6, 7, or 8 a-D-glucose named a-, b-, or g-CD, respectively [16].…”

A Rapidly Shuttling Copper‐Complexed [2]Rotaxane with Three Different Chelating Groups in Its Axis

“…[15][16][17][18][19][20][21][22] Most of these previously reported systems were two-geometry compounds, which were able to switch between a stable five-coordinate copper(II) complex where the copper(II) center is coordinated to a bidentate and a tridentate chelate and a second form, which is a four-coordinate copper(I) complex. [17b] Molecular "shuttles" [23][24][25][26][27][28][29][30] represent the archetype of molecular machines and, equally importantly, they are often used in the fabrication of real devices. A rare example of a three-geometry system was reported in 1996, and was based on a [2]catenane that consisted of two identical rings, each ring incorporating two different chelating units (a bi-and a tridentate ligand).…”

“…The copper center could thus be four-, five-, or six-coordinate. [17b] Molecular "shuttles" [23][24][25][26][27][28][29][30] represent the archetype of molecular machines and, equally importantly, they are often used in the fabrication of real devices. [9] The shuttle-like [2]rotaxanes reported to date are two-station systems.…”