More Like this

1. 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 (June 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. 

   more » « less
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. 

   more » « less
3. 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. 

   more » « less
4. Insight from Electrochemical Analysis in the Radical Cation State of a Monopyrrolotetrathiafulvalene‐Based [2]Rotaxane

   https://doi.org/10.1002/chem.202402377  

   Neumann, Mathias S; Flood, Amar H; Jeppesen, Jan O (September 2024, Chemistry – A European Journal)

   Abstract Mechanically interlocked molecules are a class of compounds used for controlling directional movement when barriers can be raised and lowered using external stimuli. Applied voltages can turn on redox states to alter electrostatic barriers but their use for directing motion requires knowledge of their impact on the kinetics. Herein, we make the first measurements on the movement of cyclobis(paraquat‐p‐phenylene) (CBPQT⁴⁺) across the radical‐cation state of monopyrrolotetrathiafulvalene (MPTTF) in a [2]rotaxane using variable scan‐rate electrochemistry. The [2]rotaxane is designed in a way that directs CBPQT⁴⁺to a high‐energy co‐conformation upon oxidation of MPTTF to either the radical cation (MPTTF⋅⁺) or the dication (MPTTF²⁺).¹H NMR spectroscopic investigations carried out in acetonitrile at 298 K showed direct interconversion to the thermodynamically more stable ground‐state co‐conformation with CBPQT⁴⁺moving across the oxidized MPTTF²⁺electrostatic barrier. The electrochemical studies revealed that interconversion takes place by movement of CBPQT⁴⁺across both the MPTTF^•+(19.3 kcal mol⁻¹) and MPTTF²⁺(18.7 kcal mol⁻¹) barriers. The outcome of our studies shows that MPTTF has three accessible redox states that can be used to kinetically control the movement of the ring component in mechanically interlocked molecules. 

   more » « less
5. Effect of iron redox ratio on the structures of boroaluminosilicate glasses

   https://doi.org/10.1111/jace.18685  

   Tuheen, Manzila I.; Sun, Wei; Du, Jincheng (December 2022, Journal of the American Ceramic Society)

   Abstract Iron oxide is commonly found in natural or industrial glass compositions and can exist as ferrous (Fe²⁺) or ferric (Fe³⁺) species, with their ratios depending on glass composition, temperature, pressure and the redox reactions during the glass forming process. The iron redox ratio plays an important role on silicate glass structures and consequently various properties. This work aims to study the effect of iron oxide, and particularly the iron redox ratio, on the structures of borosilicate and boroaluminosilicate glasses using molecular dynamics simulations with newly developed iron potential parameters that are compatible with the borosilicate potentials. The results provide detailed cation coordination states of both iron species and the effect of redox ratio on boron coordination and other structural features. Particularly, competition for charge compensating modifier cations (such as Na⁺) among the fourfold‐coordinated cations such as B³⁺, Al³⁺, and Fe³⁺is investigated by calculating the cation–cation pair distribution functions and coordination preferential ratios. The results show that the trivalent ferric ions, with a shorter Fe–O bond distance and better defined first coordiation shell with mainly four‐fold coordination, act as a glass former whereas the divalent ferrous ions mainly play the role of glass modifier. The ferrous/ferric ratio (Fe²⁺/Fe³⁺) was found to affect the glass chemistry and hence glass properties by regulating the amount of four‐coordinated boron, the fraction of non‐briding oxygen and other features. The results are compared with available experimental data to gain insights of the complex structures and charge compensation schemes of the glass system. 

   more » « less