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1. Covalent Organic Frameworks as Electrode Materials for Rechargeable Batteries

   https://doi.org/10.1055/s-0041-1723020  

   Wolfson, Eric R.; Moscarello, Erica M.; Haug, William K.; McGrier, Psaras L. (January 2021, Organic Materials)

   null (Ed.)

   Covalent organic frameworks (COFs) are an advanced class of crystalline porous polymers that have garnered significant interest due to their tunable properties and robust molecular architectures. As a result, COFs with energy-storage properties are of particular interest to the field of rechargeable battery electrode materials. However, investigation into COFs as candidates for energy-storage materials is still in its infancy. This review will highlight methods used to fabricate COFs used as electrode materials and discuss the factors that prove critical for their production. A collection of known COF-based energy-storage systems will be featured. In addition, the ability to utilize the storage properties of COFs for systems beyond traditional Li-ion batteries will be addressed. An outlook will address the current progress and remaining challenges facing the field to ultimately expand the scope of their applications. 

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2. Mechanochemical activation of an indole-fused 2H-benzopyran generates an acidochromic merocyanine dye enabling multicolor chromomorphic materials

   https://doi.org/10.1039/D5PY00746A  

   Sun, Yan; Granados_Razo, Wendy; Luo, Stella M; Osler, Skylar K; Robb, Maxwell J (August 2025, Polymer Chemistry)

   Molecular switches based on the 2H-1-benzopyran (chromene) scaffold have been widely developed for their desirable photochromic and mechanochromic properties. Extended π-conjugation is necessary to stabilize the ring-opened merocyanine dye at room temperature leading to efficient switching under ambient conditions. To this end, naphthopyrans represent a special class of benzo-annulated benzopyrans that have been studied extensively as both photoswitches and more recently as mechanophores, generating intensely colored merocyanine dyes upon exposure to ultraviolet light or mechanical force, respectively. Alternative annulation strategies with judicious heteroatom substitution have also been studied in the photochemistry literature, but the mechanochemistry of 2H-1-benzopyrans has yet to be explored. Here, we report the mechanochemical activation of an indole-fused 2H-1-benzopyran mechanophore that generates a yellow-colored merocyanine dye in polymers that is subsequently transformed to a purple-colored dye upon treatment with acid. Neutralization with base recovers the yellow-colored merocyanine isomer with trans exocyclic alkene geometry through an unusual acid-mediated alkene isomerization. This study expands the repertoire of mechanochromic mechanophores based on (hetero)annulated benzopyrans to enable multicolor chromomorphic behavior in response to both mechanical force and acid for applications in stimuli-responsive polymeric materials with complex switching properties. 

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3. Substrate Effects on Remote Optical Control of Pt Nanoparticle-Driven Olefin Hydrogenation

   https://doi.org/10.1021/acsanm.4c01787  

   Xie, Maichong; Slocik, Joseph M; Dennis, Patrick B; Knecht, Marc R (June 2024, ACS Applied Nano Materials)

   Bio-inspired approaches for materials synthesis and application are emerging as potentially sustainable approaches to achieve functional structures with selectively controlled properties (e.g., turn on catalysis). An attractive avenue to allow for selective functionality is optical stimulation; however, the ability to make nanomaterials light responsive for many applications remains challenging. One approach is to incorporate photoswitches into the surface adsorbed ligands which can stimulate a surface structural change that could have implications on the catalytic reactivity driven by the underlying metallic nanoparticle component. Herein were demonstrate the ability to drive optical switching of surface ligand overlayer structures on peptide-capped Pt nanoparticles. To this end, incorporation of an azobenzene unit into the surface-adsorbed peptide allows for the ability to optical reconfigure the ligand overlayer structure. This change results in direct manipulation of the catalytic properties of the Pt materials for olefin hydrogenation, which demonstrated changes in reactivity not only between different reagents, but also between the different ligand structures. Such results present information which could be used in the design of ligand interface structures to trigger specific reactivity control for a variety of reactions and materials for sustainable catalysis. 

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4. The luminescent and photophysical properties of covalent organic frameworks

   https://doi.org/10.1039/c9cs00807a  

   Haug, W. Karl; Moscarello, Erica M.; Wolfson, Eric R.; McGrier, Psaras L. (February 2020, Chemical Society Reviews)

   null (Ed.)

   Covalent organic frameworks (COFs) are an emerging class of crystalline porous polymers that have attracted significant attention due to their tunable properties and structural robustness. As a result, COFs with luminescent properties are of great interest for fields such as chemical sensing, solid-state light emitters, photocatalysis, and optoelectronics. However, the bottom-up synthesis of luminescent COF systems remains a challenge in the field due to an abundance of competing non-radiative pathways, including phenomena such as aggregate caused quenching (ACQ). To overcome these obstacles, there has been a burgeoning investigation into the luminescent and photophysical properties of COFs. This review will highlight methods used to fabricate luminescent COFs and discuss the factors that are critical for their production. A collection of known luminescent COF systems will be featured. In addition, the ability to utilize the photophysical properties of COFs for applications related to photocatalysis, solid-state light emitters, and chemical sensing will be addressed. An outlook will address the current progress and remaining challenges facing the field to ultimately expand the scope of their applications. 

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5. Efficient discovery of visible light-activated azoarene photoswitches with long half-lives using active search

   https://doi.org/10.33774/chemrxiv-2021-w32rs  

   Mukadum, F; Nguyen, Q; Adrion, D; Appleby, G; Chen, R; Dang, H; Chang, R; Garnett, R; Lopez, S (August 2021, ChemRxiv)

   null (Ed.)

   Photoswitches are molecules that undergo a reversible, structural isomerization after exposure to different wavelengths of light. The dynamic control offered by molecular photoswitches is favorable for applications in materials chemistry, photopharmacology, and catalysis. Ideal photoswitches absorb visible light and have long-lived metastable isomers. We used high throughput virtual screening to predict the absorption maxima (λmax) of the E-isomer and half-lives (t1/2) of the Z-isomer. However, computing the photophysical and kinetic properties of each entry of a virtual molecular library containing 103–106 entries with density functional theory is prohibitively time-consuming. We applied active search, a machine learning technique to intelligently search a chemical search space of 255991 photoswitches based on 29 known azoarenes and their derivatives. We iteratively trained the active search algorithm based on whether a candidate absorbed visible light (λmax > 450 nm). Active search was found to triple the discovery rate compared to random search. Further, we projected 1962 photoswitches to 2D using the Uniform Manifold Approximation and Projection (umap) algorithm and found that λmax depends on the core, which is tunable with substituents. We then incorporated a second stage of screening with to predict the stabilities of the Z-isomers for the top 1% of candidates. We identified four ideal photoswitches that concurrently satisfy λmax > 450 nm and t1/2 > 2 hours; the range of λmax and t1/2 range from 465 to 531 nm and hours to years, respectively. 

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