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1. Conjugated Polymer for Implantable Electronics toward Clinical Application

   https://doi.org/10.1002/adhm.202001916  

   Liu, Yuxin; Feig, Vivian Rachel; Bao, Zhenan (April 2021, Advanced Healthcare Materials)

   null (Ed.)

   Owing to their excellent mechanical flexibility, mixed-conducting electrical property, and extraordinary chemical turnability, conjugated polymers have been demonstrated to be an ideal bioelectronic interface to deliver therapeutic effect in many different chronic diseases. This review article summarizes the latest advances in implantable electronics using conjugated polymers as electroactive materials and identifies remaining challenges and opportunities for developing electronic medicine. Examples of conjugated polymer-based bioelectronic devices are selectively reviewed in human clinical studies or animal studies with the potential for clinical adoption. The unique properties of conjugated polymers are highlighted and exemplified as potential solutions to address the specific challenges in electronic medicine. 

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2. Force Transduction Through Distant Force‐Bearing Regioisomeric Linkages Affects the Mechanochemical Reactivity of Cyclobutane

   https://doi.org/10.1002/anie.202406103  

   Flear, Erica_J; Horst, Maggie; Yang, Jinghui; Xia, Yan (July 2024, Angewandte Chemie International Edition)

   Abstract Fundamental understanding of mechanochemical reactivity is important for designing new mechanophores. Besides the core structure of mechanophores, substituents on a mechanophore can affect its mechanochemical reactivity through electronic stabilization of the intermediate or effectiveness of force transduction from the polymer backbone to the mechanophore. The latter factor represents a unique mechanical effect in considering polymer mechanochemistry. Here, we show that regioisomeric linkage that is not directly adjacent to the first cleaving bond in cyclobutane can still significantly affect the mechanochemical reactivity of the mechanophore. We synthesized three non‐scissile 1,2‐diphenyl cyclobutanes, varying their linkage to the polymer backbone via theo,m, orp‐position of the diphenyl substituents. Even though the regioisomers share the same substituted cyclobutane core structure and similar electronic stabilization of the diradical intermediate from cleaving the first C−C bond, thepisomer exhibited significantly higher mechanochemical reactivity than theoandmisomers. The observed difference in reactivity can be rationalized as the much more effective force transduction to the scissile bond through thep‐position than the other two substitution positions. These findings point to the importance of considering force‐bearing linkages that are more distant from the bond to be cleaved when incorporating mechanophores into polymer backbones. 

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3. Open‐Shell Donor–Acceptor Conjugated Polymers with High Electrical Conductivity

   https://doi.org/10.1002/adfm.201909805  

   Huang, Lifeng; Eedugurala, Naresh; Benasco, Anthony; Zhang, Song; Mayer, Kevin S.; Adams, Daniel J.; Fowler, Benjamin; Lockart, Molly M.; Saghayezhian, Mohammad; Tahir, Hamas; et al (May 2020, Advanced Functional Materials)

   Abstract Conductive polymers largely derive their electronic functionality from chemical doping, processes by which redox and charge‐transfer reactions form mobile carriers. While decades of research have demonstrated fundamentally new technologies that merge the unique functionality of these materials with the chemical versatility of macromolecules, doping and the resultant material properties are not ideal for many applications. Here, it is demonstrated that open‐shell conjugated polymers comprised of alternating cyclopentadithiophene and thiadiazoloquinoxaline units can achieve high electrical conductivities in their native “undoped” form. Spectroscopic, electrochemical, electron paramagnetic resonance, and magnetic susceptibility measurements demonstrate that this donor–acceptor architecture promotes very narrow bandgaps, strong electronic correlations, high‐spin ground states, and long‐range π‐delocalization. A comparative study of structural variants and processing methodologies demonstrates that the conductivity can be tuned up to 8.18 S cm⁻¹. This exceeds other neutral narrow bandgap conjugated polymers, many doped polymers, radical conductors, and is comparable to commercial grades of poly(styrene‐sulfonate)‐doped poly(3,4‐ethylenedioxythiophene). X‐ray and morphological studies trace the high conductivity to rigid backbone conformations emanating from strong π‐interactions and long‐range ordered structures formed through self‐organization that lead to a network of delocalized open‐shell sites in electronic communication. The results offer a new platform for the transport of charge in molecular systems. 

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4. Electron‐Deficient Conjugated Materials via p–π* Conjugation with Boron: Extending Monomers to Oligomers, Macrocycles, and Polymers

   https://doi.org/10.1002/chem.202003481  

   Yin, Xiaodong; Liu, Jun; Jäkle, Frieder (December 2020, Chemistry – A European Journal)

   Abstract The extension of conjugated organoboranes from monomeric species to oligomers, macrocycles, and polymers offers access to a plethora of fascinating new materials. The p–π* conjugation between empty orbitals on boron and the conjugated linkers not only affects the electronic structure and optical properties, but also enables mutual interactions between electron‐deficient boron centers. The unique properties of these electron‐deficient π‐conjugated systems are exploited in highly luminescent materials, organic optoelectronic devices, and sensing applications. 

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5. Boron‐Nitrogen Lewis Pairs in the Assembly of Supramolecular Macrocycles, Molecular Cages, Polymers, and 3D Materials

   https://doi.org/10.1002/anie.202313379  

   Chen, Beijia; Jäkle, Frieder (October 2023, Angewandte Chemie International Edition)

   Abstract Covering an exceptionally wide range of bond strengths, the dynamic nature and facile tunability of dative B−N bonds is highly attractive when it comes to the assembly of supramolecular polymers and materials. This Minireview offers an overview of advances in the development of functional materials where Lewis pairs (LPs) play a key role in their assembly and critically influence their properties. Specifically, we describe the reversible assembly of linear polymers with interesting optical, electronic and catalytic properties, discrete macrocycles and molecular cages that take up diverse guest molecules and undergo structural changes triggered by external stimuli, covalent organic frameworks (COFs) with intriguing interlocked structures that can embed and separate gases such as CO₂and acetylene, and soft polymer networks that serve as recyclable, self‐healing, and responsive thermosets, gels and elastomeric materials. 

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