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Recently, the development of olefin metathesis polymerization advanced the field of polymer synthesis. Simply put, the reorganization of substituents on their double bonds between two olefins in the presence of a catalyst is known as the olefin metathesis reaction. The use of metathesis reaction for polymer synthesis is called olefin metathesis polymerization.
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Ziegler–Natta polymerization is another form of addition or chain‐growth polymerization used for synthesizing linear polymers over branched polymers. The catalyst used for polymerization is the Ziegler–Natta catalyst, named after Karl Ziegler and Giulio Natta, who developed it in 1953. This catalyst is an organometallic complex of titanium tetrachloride and triethyl aluminum, with the active form of the catalyst being an alkyl titanium compound. Using the Ziegler–Natta...
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Ring-opening metathesis polymerization or ROMP involves strained cycloalkenes as starting materials. The mechanism of ROMP proceeds by reacting cycloalkene with Grubbs catalyst to give metallacyclobutane intermediate which undergoes a ring-opening reaction to form new carbene. The new carbene reacts with another molecule of cycloalkene. Repetition of these steps leads to the formation of an unsaturated open-chain polymer product. All these steps are reversible, however, relieving the ring...
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The skeletal structure of polymers synthesized via radical polymerization is always branched. For example, the polymerization of ethylene by radical polymerization results in a low-density grade of polyethylene with a heavily branched skeletal structure. Here, the radical site abstracts hydrogen from the growing chain, and the radical site shifts from the end (a primary carbon center) to anywhere within the growing chain (a secondary carbon center). Consequently, the part of the chain from the...
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Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
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Reversible hydrogen-bonded polymerization regulated by allosteric metal templation.

Tangxin Xiao1, Weiwei Zhong, Weiwei Yang

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This study introduces a novel method to control supramolecular polymerization using potassium ions. Adding K+ induces a U-shape conformation, forming cyclic dimers, which can be reversed by water extraction, offering dynamic control over polymer assembly.

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Area of Science:

  • Supramolecular Chemistry
  • Polymer Science
  • Chemical Biology

Background:

  • Allosteric regulation is crucial in biological systems but underexplored in supramolecular polymerization.
  • Understanding allosteric control can lead to novel dynamic materials and molecular devices.

Purpose of the Study:

  • To design and synthesize ditopic UPy derivatives capable of supramolecular polymerization via quadruple hydrogen bonding.
  • To investigate the allosteric control of this supramolecular polymerization using metal ions, specifically K+.
  • To demonstrate the reversible nature of the polymerization process.

Main Methods:

  • Synthesis of ditopic UPy derivatives featuring acyclic crown ether-like spacers.
  • Investigation of supramolecular polymerization through quadruple hydrogen bonding.
  • Induction of conformational changes and subsequent polymerization modulation via K+ coordination.
  • Reversal of polymerization through water extraction to remove K+.

Main Results:

  • Successfully synthesized UPy derivatives that form supramolecular polymers.
  • Demonstrated that K+ coordination induces a U-shape molecular conformation.
  • Observed the reconfiguring of UPy sites leading to the formation of discrete cyclic dimers.
  • Showed that the supramolecular polymerization is reversible upon removal of K+ via water extraction.

Conclusions:

  • Ditopic UPy derivatives with specific spacers enable controllable supramolecular polymerization.
  • Potassium ions act as allosteric effectors, reversibly modulating supramolecular assembly.
  • This work provides a new strategy for dynamic control in supramolecular polymerization, with potential applications in responsive materials.