Light-switchable Metal-Organic Cages

Supramolecular & Biomaterials Chemistr

Photoswitchable molecular tweezers: isomerization to control substrate binding, and what about vice versa?

NWOSupramolecular & Biomaterials Chemistr

Stiff‐Stilbene Photoswitches: From Fundamental Studies to Emergent Applications

Stiff‐stilbene, a sterically restricted fused ring analogue of stilbene, has been regularly used as a model compound in theoretical studies of stilbene photoisomerization. Lately, owing to its excellent photoswitching properties, it is increasingly being applied to reversibly control the properties and function of chemical as well as biological systems. Stiff‐stilbene photoswitches possess a number of advantageous properties including a high quantum yield for photoisomerization and a high thermal stability. Furthermore, they undergo a large geometrical change upon isomerization and their synthesis is straightforward. Herein, we provide an overview of the basic properties of stiff‐stilbene and of recent applications in supramolecular chemistry, catalysis, and biological systems.Supramolecular & Biomaterials Chemistr

Anion-induced reversible actuation of squaramide-crosslinked polymer gels

NWOSupramolecular & Biomaterials Chemistr

Push‐pull stiff‐stilbene: proton‐gated visible‐light photoswitching and acid‐catalyzed isomerization

Supramolecular & Biomaterials Chemistr

A photoswitchable macrocycle controls anion-templated pseudorotaxane formation and axle relocalization

Supramolecular & Biomaterials Chemistr

Supramolecular control of unidirectional rotary motion in a sterically overcrowded photoswitchable receptor

The control of molecular motion by external stimuli has attracted major interest in recent years. In order to achieve unidirectional rotational motion, intrinsically chiral light-driven molecular motors have been shown to be particularly versatile. We recently introduced a system in which unidirectional rotation is achieved in an achiral photoswitchable receptor upon binding of a chiral guest molecule. In order to gain detailed insight into the rotary steps, we present here a modified design in which the steric crowding is increased such that interconversion between the helical isomers of the (Z)-form of the receptor becomes very slow. DFT calculations support the increase in interconversion barrier. Furthermore, two diastereomeric complexes of the chiral guest bound to the (Z)-receptor are distinguished in the 1H NMR spectrum and the ratio between them slowly changes over time as a result of thermal helix inversion. On the other hand, no enrichment in one of the diastereomeric complexes is observed in the photochemical step. Our studies therefore unequivocally confirm that net rotation, induced by the chiral guest, takes place. This study affords an improved understanding of these dynamic supramolecular systems and expands the possibilities to control chirality transfer and motion at the molecular level, spurring developments of supramolecular recognition and information transfer at the nanoscale.Supramolecular & Biomaterials Chemistr

Photoswitching of halide-binding affinity and selectivity in dithienylethene-strapped calix[4]pyrrole

Supramolecular & Biomaterials Chemistr

Tuning of Morphology by Chirality in Self-Assembled Structures of Bis(Urea) Amphiphiles in Water

We present the synthesis and self‐assembly of a chiral bis(urea) amphiphile and show that chirality offers a remarkable level of control towards different morphologies. Upon self‐assembly in water, the molecular‐scale chiral information is translated to the mesoscopic level. Both enantiomers of the amphiphile self‐assemble into chiral twisted ribbons with opposite handedness, as supported by Cryo‐TEM and circular dichroism (CD) measurements. The system presents thermo‐responsive aggregation behavior and combined transmittance measurements, temperature‐dependent UV, CD, TEM, and micro‐differential scanning calorimetry (DSC) show that a ribbon‐to‐vesicles transition occurs upon heating. Remarkably, chirality allows easy control of morphology as the self‐assembly into distinct aggregates can be tuned by varying the enantiomeric excess of the amphiphile, giving access to flat sheets, helical ribbons, and twisted ribbons.Supramolecular & Biomaterials Chemistr

Photomodulation of transmembrane transport and potential by stiff-stilbene based bis(thio)ureas

NWOSupramolecular & Biomaterials Chemistr