The Nobel Prize winner re-published "JACS": a completely light-controlled "super gel"

As a highly organized assembly, supramolecular polymers are very important research contents in the fields of chemistry, biology and materials science.
Its rich functions can be used to construct sensors, electronic devices and biomedical materials.
Supramolecular polymers tend to form various gels.
The current research on supramolecular polymers mainly focuses on their stimulus response properties, such as controlling the polymerization and depolymerization of monomers through external stimuli, such as light, ultrasound, and chemical stimuli, so as to develop stimulus-responsive and adaptable materials.
Among these stimulus signals, because light is a non-invasive stimulus method and has a high temporal and spatial resolution, it has been valued in this field and has become the most potential external stimulus method.
The most common way to use light to control supramolecular systems is through the photoisomerization of molecules.
Most recent studies on supramolecular assembly have focused on the response characteristics of light-regulated aggregate formation and deconstruction, such as sol-gel conversion, volume, and morphological changes.
In light-responsive supramolecular polymers, the reversibility of polymerization is often achieved through light stimulation and subsequent thermal relaxation of photoisomerized fragments.
Few reports have completely used light to regulate the formation of supramolecular polymers.
And disaggregation, and changes in the macroscopic properties of the corresponding materials.
? For this reason, the Nobel Prize winner, the team of Professor Ben L.
Feringa of the University of Groningen in the Netherlands used a light-responsive rigid styrene molecule with two urea fragments as a monomer, and made it cis-trans heterogeneous through different wavelengths of light.
Structured, so that the polymerization and depolymerization of monomers can be controlled reversibly through light, and finally a sol-gel transition material that can be completely controlled by light is realized.
The structure was published on "JACS" under the title "From Photoinduced Supramolecular Polymerization to Responsive Organogels".
Highlights of the article: 1.
The use of rigid diurea styrene monomer, due to its higher light stability, is less prone to thermal relaxation than traditional photoisomerization materials, which will cause the polymer to spontaneously disintegrate.
Through experiments, it is found that the light stability of the monomer is cis:trans = 33:67 after being irradiated with 365 nm wavelength light for 15 minutes, and after being irradiated with 385 nm wavelength light, the light stability is cis:tran ≥ 99: 1;? 2.
When the monomer molecule is in the cis form, the urea fragment only produces intramolecular hydrogen bonds.
After the light is converted to the trans form, intermolecular hydrogen bonds can be formed, thereby producing supramolecular polymers;? 3.
The solvent has a wide application range and strong gel forming ability.
In toluene solution, its critical polymerization concentration is 1.
3 mg/ml, and in tetrahydrofuran it is 3.
0 mg/ml.
It can be classified as "super gelling agent";? 4.
It has the ability to form gel in situ and gel-sol transition.
Using 385 nm light, the monomer can form a gel fiber within 10 minutes, and using 365 nm light for 30 minutes, the gel can be reversibly converted into a sol.
? Figure 1.
Reversible light transition of supramolecular polymers