Related Experiment Video
Updated: Sep 9, 2025
11:09
Constructing Thioether/Vinyl Sulfide-tethered Helical Peptides Via Photo-induced Thiol-ene/yne Hydrothiolation
Published on: August 1, 2018
10.8K
Photodimerization-Mediated Intramolecular Cross-Linking of Thermoresponsive Dendronized Cyclodextrin-Based
Yue Yuan1, Songbin Wu1, Yuqiang Chen1
1International Joint Laboratory of Biomimetic and Smart Polymers, School of Materials Science and Engineering, Shanghai University, Shanghai, China.
Macromolecular Rapid Communications
|August 28, 2025
Summary
We created novel single-chain nanoparticles using intramolecular cross-linking of polyrotaxanes (PRXs). This process utilizes photodimerization within thermoresponsive dendronized structures, yielding unique stimuli-responsive polymers.
Area of Science:
- Polymer Chemistry
- Materials Science
- Supramolecular Chemistry
Background:
- Mechanically interlocked polymers, such as polyrotaxanes (PRXs), offer unique structural possibilities.
- Intramolecular cross-linking is a key strategy for developing advanced single-chain nanoparticles.
- Thermoresponsive polymers are desirable for applications requiring stimuli-controlled behavior.
Purpose of the Study:
- To report the intramolecular cross-linking of thermoresponsive dendronized cyclodextrin-based PRXs.
- To investigate the role of dendritic confinement in mediating photodimerization for cross-linking.
- To explore the impact of cross-linking on the thermoresponsive properties of these PRXs.
Main Methods:
- Synthesis of dendronized polyrotaxanes (PRXs) with polyethylene glycol axles and cinnamate-cored dendritic oligo(ethylene glycol)s (OEGs).
- Photodimerization of cinnamate moieties within dendritic OEGs in aqueous solutions to induce intramolecular cross-linking.
- Characterization of thermoresponsive behavior and phase transitions of both native and cross-linked PRXs.
Main Results:
- Efficient intramolecular cross-linking of dendronized PRXs was achieved via photodimerization, controlled by PRX architecture and solvation.
- Dendronized PRXs exhibited characteristic thermoresponsive behavior due to dendritic OEG dehydration and aggregation.
- Photodimerization significantly increased phase transition temperatures and retarded aggregation, forming smaller coacervates.
Conclusions:
- Intramolecularly cross-linked dendronized PRXs represent a novel class of stimuli-responsive materials.
- Dendritic confinement effectively mediates photodimerization for controlled single-chain nanoparticle formation.
- These materials offer unique architectures and tunable thermoresponsiveness for diverse applications.
Keywords:
dendritic topologyintramolecularly cross‐linked polymerpolyrotaxanestimuli‐responsive polymerMore Related Videos
Related Concept Videos
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
2.4K
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
2.4K
01:16Cycloaddition Reactions: MO Requirements for Thermal Activation
3.7K
Thermal cycloadditions are reactions where the source of activation energy needed to initiate the reaction is provided in the form of heat. A typical example of a thermally-allowed cycloaddition is the Diels–Alder reaction, which is a [4 + 2] cycloaddition. In contrast, a [2 + 2] cycloaddition is thermally forbidden.
3.7K
01:26Photochemical Electrocyclic Reactions: Stereochemistry
1.9K
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
1.9K
01:17Thermal Electrocyclic Reactions: Stereochemistry
2.1K
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
2.1K
01:12Cycloaddition Reactions: MO Requirements for Photochemical Activation
2.2K
Some cycloaddition reactions are activated by heat, while others are initiated by light. For example, a [2 + 2] cycloaddition between two ethylene molecules occurs only in the presence of light. It is photochemically allowed but thermally forbidden.
2.2K
![[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F12417.jpg&w=3840&q=75)
01:16[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
10.5K
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
10.5K