Supramolecular Relay-Control of Organocatalysis with a Hemithioindigo-Based Molecular Motor

Abstract

Integration of individual molecular components such as molecular motors or switches into larger meta-functional systems represents a current challenge at the forefront of molecular machine research. Here we present a modular supramolecular approach to relay the photoinduced geometry changes of a hemithioindigo based molecular motor into catalytic efficiency of a chemical reaction. Using the intrinsic chemical nature of the motor for recognition of different hydrogenbonding organocatalysts a greater than 10-fold modulation in binding affinity is achieved upon photoisomerization. This change in affinity is then translated effectively into control of catalytic competence of the organocatalysts without direct interference by the motor. As an example the organocatalysed Michael addition reaction between nitrostyrene and 3-methoxy-dimethyl aniline was modulated in situ by visible light irradiation. Thus, dynamic and reversible remote control of catalytic processes by the switching capacity of a hemithioindigo molecular motor is established in a multicomponent chemical system. The high intrinsic modularity of this approach presents further advantages, e.g., for easy tailoring of conditions or facile exchange of catalysts and reactions. These results represent a first stepping stone into integrated chemical networks regulated by molecular machines in a fully dynamic way.

Designing light-driven rotary molecular motors

“…Light-driven rotary molecular motors have been used in many elds already, ranging from smart materials and surface anchoring, to catalysis and biomolecular technology. 43,84,85,129,145,[153][154][155] For effective integration into more complex, functional molecular systems, it is important to have an idea of which motor scaffold would be best tailored for each potential purpose.…”

“…Since then, these motors have been used in switchable catalysis, 84 functionalised for attachment to metal surfaces, 85 and the rotation of the motor has been used to bias and actively accelerate the rotation of a remotely attached biaryl axis. 86,87 In addition to their general design (vide supra), the Dube group has developed a few HTI-based motors that have an entirely different mode of rotation; these structures operate through the light-driven rotation of a single-bonded group about a central alkene bond.…”

Sulfoxide hemithioindigo tweezers – visible light addressable capture and release

“…1 ) 27,28 or hydrogen bonding driven recognition. 54 For example, we presented a bis-HTI receptor 1 that folds into a helix in its high affinity state in response to blue light irradiation and planarizes into a low affinity state after heating. 27 Subsequently we devised two different molecular tweezers 55–59 motives 2 and 3 that respond reversibly to the same wavelengths of light with opposite affinity changes.…”

All-Red-Light Photoswitching of Indirubin Controlled by Supramolecular Interactions

“…The most prominent photoswitches stilbenes, azobenzenes, spiropyranes, and diarylethenes have already led to countless applications and uses in fields spanning the molecular, material or biomedical sciences. They represent fundamental switching units for synthetic molecular machines, [1][2][3][4][5][6][7][8][9][10] photopharmacology, [11][12][13][14][15][16] light-controlled catalysts [17][18][19][20][21][22][23][24] or materials research [25][26][27][28][29][30] to name only a few examples. In their wake a number of novel molecular photoswitch architectures have been developed, 31 which bring a suite of different geometrical and electronic changes to the table greatly expanding the toolbox of molecular engineering.…”