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1. Cation–π Interaction Assisted Molecule Attachment and Photocarrier Transfer in Rhodamine/Graphene Heterostructures

   https://doi.org/10.1002/admi.202000796  

   Liu, Bo; López‐González, Luis_E; Alamri, Mohammed; Velázquez‐Contrera, Enrique_F; Santacruz‐Ortega, Hisila; Wu, Judy_Z (June 2020, Advanced Materials Interfaces)

   Abstract Cation–π interactions between molecules and graphene are known to have a profound effect on the properties of the molecule/graphene nanohybrids and motivate this study to quantify the attachment of the rhodamine 6G (R6G) dye molecules on graphene and the photocarrier transfer channel formed across the R6G/graphene interface. By increasing the R6G areal density of the R6G on graphene field‐effect transistor (GFET) from 0 up to ≈3.6 × 10¹³cm⁻², a linear shift of the Dirac point of the graphene from originally 1.2 V (p‐doped) to −1 V (n‐doped) is revealed with increasing number of R6G molecules. This indicates that the attachment of the R6G molecules on graphene is determined by the cation–π interaction between the NH+ in R6G and π electrons in graphene. Furthermore, a linear dependence of the photoresponse on the R6G molecule concentration to 550 nm illumination is observed on the R6G/graphene nanohybrid, suggesting that the cation–π interaction controls the R6G attachment configuration to graphene to allow formation of identical photocarrier transfer channels. On R6G/graphene nanohybrid with 7.2 × 10⁷R6G molecules, high responsivity up to 5.15 × 10²A W⁻¹is obtained, suggesting molecule/graphene nanohybrids are promising for high‐performance optoelectronics. 

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2. Self‐Healable Poly(ionic liquid) Copolymers Driven by Polar and Dipolar Forces

   https://doi.org/10.1002/anie.202510066  

   Gaikwad, Samruddhi; Liu, Jiahui; Mashkow, Nyx; Urban, Marek W (August 2025, Angewandte Chemie International Edition)

   Abstract Commodity aliphatic and aromatic acrylic‐based copolymers self‐heal due to ubiquitouskey‐and‐lock,ring‐and‐lock, andfluorophilic‐σ‐lockvan der Waals (vdW) interactions. However, the role of these interactions in the presence of covalently copolymerized ionic liquid (IL) is not known. This study is driven by the hypothesis that covalently incorporated cation–anion pairs to form poly(ionic liquid) copolymers (PILCs) can perturb inter‐ or intra‐chain vdW interactions reflected in mechanical and electrical responses. To test this hypothesis, we synthesized a series of PILCs comprising of pentafluorostyrene (PFS) and imidazolium‐based IL monomers with variable‐length aliphatic tails (methyl and butyl). Using a combination of 2D¹H‐¹H and¹⁹F ‐¹⁹F NOESY NMR and FTIR measurements supplemented by molecular dynamic (MD) simulations, these studies demonstrate that preferentially alternating/random PILCs topologies facilitate self‐healing. The introduction of cation–anion moieties modifies thefluorophilic‐σ‐lockinteractions and, along with longer aliphatic tails ─(CH₂)₃CH₃covalently attached to the imidazolium cation, enhances cation‐anion mobility, thus faster recovery from mechanical damage occurs. These findings underline how precise control over dipolar and ionic interactions through copolymer composition enables self‐healing in PILCs. These insights may open pathways for designing sustainable, mechanically resilient materials for applications in energy storage and energy harvesting. 

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3. Differentiating Ligand Tailoring and Cation Incorporation as Strategies for Tuning Heterobimetallic Cerium Complexes

   https://doi.org/10.1002/chem.202500474  

   Mikeska, Emily_R; Blakemore, James_D (May 2025, Chemistry – A European Journal)

   Abstract Tuning of redox‐active complexes featuring metals with high coordination numbers by incorporation of secondary redox‐inactive cations has received far less attention than it deserves. Here, appending moderate steric bulk to a tripodal ligand framework has been tested for its influence on secondary‐cation‐driven structural and electrochemical tuning of cerium, a lanthanide that tends to adopt high coordination numbers. Aquasi‐C₃‐symmetric cerium(III) complex denoted[Ce]has been prepared that features pendant benzyloxy groups, and this work demonstrates that this species offers a site capable of binding single Na⁺or Ca²⁺ions. Electrochemical and UV‐visible spectroscopic studies reveal equilibrium binding affinity of[Ce]for Na⁺in acetonitrile solvent, contrasting with tight binding of all cations in all other previously studied systems of this type. The modulated cation binding can be attributed to the bulky benzyloxy groups, which impact the thermodynamics of cation binding but do not impede the formation of cerium centers with coordination number 8 upon binding of either Na⁺or Ca²⁺. The Ce(IV/III) reduction potential was found to be tunable under the equilibrium binding conditions, highlighting the potentially significant role that controlled structural changes can play in modulating the solution properties of heterobimetallic complexes. 

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4. Redirecting tropane alkaloid metabolism reveals pyrrolidine alkaloid diversity in Atropa belladonna

   https://doi.org/10.1111/nph.18651  

   Parks, Hannah M.; Cinelli, Maris A.; Bedewitz, Matthew A.; Grabar, Josh M.; Hurney, Steven M.; Walker, Kevin D.; Jones, A. Daniel; Barry, Cornelius S. (March 2023, New Phytologist)

   Summary Plant‐specialized metabolism is complex, with frequent examples of highly branched biosynthetic pathways, and shared chemical intermediates. As such, many plant‐specialized metabolic networks are poorly characterized.TheN‐methyl Δ¹‐pyrrolinium cation is a simple pyrrolidine alkaloid and precursor of pharmacologically important tropane alkaloids. Silencing of pyrrolidine ketide synthase (AbPyKS) in the roots ofAtropa belladonna(Deadly Nightshade) reduces tropane alkaloid abundance and causes highN‐methyl Δ¹‐pyrrolinium cation accumulation. The consequences of this metabolic shift on alkaloid metabolism are unknown. In this study, we utilized discovery metabolomics coupled withAbPyKSsilencing to reveal major changes in the root alkaloid metabolome ofA. belladonna.We discovered and annotated almost 40 pyrrolidine alkaloids that increase whenAbPyKSactivity is reduced. Suppression of phenyllactate biosynthesis, combined with metabolic engineeringin planta, and chemical synthesis indicates several of these pyrrolidines share a core structure formed through the nonenzymatic Mannich‐like decarboxylative condensation of theN‐methyl Δ¹‐pyrrolinium cation with 2‐O‐malonylphenyllactate. Decoration of this core scaffold through hydroxylation and glycosylation leads to mono‐ and dipyrrolidine alkaloid diversity.This study reveals the previously unknown complexity of theA. belladonnaroot metabolome and creates a foundation for future investigation into the biosynthesis, function, and potential utility of these novel alkaloids. 

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5. Not Limited to Iron: A Cobalt Heme–NO Model Facilitates N–N Coupling with External NO in the Presence of a Lewis Acid to Generate N ₂ O

   https://doi.org/10.1002/anie.201909137  

   Abucayon, Erwin G.; Khade, Rahul L.; Powell, Douglas R.; Zhang, Yong; Richter‐Addo, George B. (October 2019, Angewandte Chemie International Edition)

   Abstract Some bacterial heme proteins catalyze the coupling of two NO molecules to generate N₂O. We previously reported that a heme Fe–NO model engages in this N−N bond‐forming reaction with NO. We now demonstrate that (OEP)Co^II(NO) similarly reacts with 1 equiv of NO in the presence of the Lewis acids BX₃(X=F, C₆F₅) to generate N₂O. DFT calculations support retention of the Co^IIoxidation state for the experimentally observed adduct (OEP)Co^II(NO⋅BF₃), the presumed hyponitrite intermediate (P^.+)Co^II(ONNO⋅BF₃), and the porphyrin π‐radical cation by‐product of this reaction, and that the π‐radical cation formation likely occurs at the hyponitrite stage. In contrast, the Fe analogue undergoes a ferrous‐to‐ferric oxidation state conversion during this reaction. Our work shows that cobalt hemes are chemically competent to engage in the NO‐to‐N₂O conversion reaction. 

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