Journal articleNature · June 2026
Mechanical failure is a marked limitation for plastics used in structural, protective and coating applications. In particular, perforation under high-rate deformation is difficult to mitigate through conventional molecular design1,2. Cross-linki ...
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Journal articleACS macro letters · March 2026
Machine-readable line notations such as SMILES are rapidly gaining popularity as a means of storing, searching, and analyzing chemical information. Within the SMILES framework, BigSMILES was developed to represent the stochastic connectivity characteristic ...
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Journal articleNature chemistry · February 2026
Customizing the toughness of polymer networks independently of their chemical composition and topology remains an unsolved challenge. Traditionally, polymer network toughening is achieved by using specialized monomers or solvents or adding secondary networ ...
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Journal articleJournal of the American Chemical Society · January 2026
Nanoparticles derived from plant viruses and bacteriophages are self-assembling structures that can be functionalized for broad applications in drug delivery, vaccine formulation, and imaging, as well as the engineering of nanomaterials, and nanoscale temp ...
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Journal articleMacromolecules · December 23, 2025
Polymer networks are complex materials with a broad distribution of molecular states, making it challenging to establish direct connections between the structure of individual network components and macroscopic material behavior. Recent advancements in mec ...
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Journal articleJournal of the American Chemical Society · December 2025
The reactivity of four-membered carbocycle mechanophores, such as cyclobutane (CB), cyclobutene (CBE), and benzocyclobutene (BCB), has been explored in the context of fundamental reaction mechanisms and the manipulation of polymer network properties. Despi ...
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Journal articleSoft matter · November 2025
Elastomeric materials are widely used in industrial application sectors including construction, automotives, soft robotics, and biomedicine. Light-based three-dimensional (3D) printing enables the manufacturing of elastomeric polymer networks with geometri ...
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Journal articleNature Synthesis · October 1, 2025
The ultimate realization of top-down atomic manipulation is to push or pull molecules in a way that changes their function, such as catalysis. The forces in a stretched polymer distort molecular conformation in ways that couple to reactivity, but the use o ...
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Journal articleACS central science · October 2025
Mechanophores are molecules that undergo chemical changes in response to mechanical force, offering unique opportunities in chemistry, materials science, and drug delivery. However, many potential mechanophores remain unexplored. For example, ferrocenes ar ...
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Journal articleACS central science · October 2025
The stretchability (ability to be elongated) and toughness (capacity to absorb energy before breaking) of polymer network materials, such as elastomers and hydrogels, often determine their utility and lifetime. Direct correlations between the molecular beh ...
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Journal articleJournal of the American Chemical Society · August 2025
Herein, we report that molecular tension generated by the swelling of a polyacrylate network containing a chiral [Biphep]Rh(I) catalyst as a tension-bearing, bis-tethered cross-linker enhances the enantioselectivity of hydrogenation of methyl 2-acetamidoac ...
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Journal articleMacromolecules · June 10, 2025
Oxy-substituted gem-dihalocyclopropanes (gDHCs) have recently found utility as mechanoacids for the generation of HCl or HF following force-assisted ring opening along polymer backbones. Here, we employ single-molecule force spectroscopy (SMFS) to quantify ...
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Journal articleNature Sustainability · June 1, 2025
Natural rubber has many uses in a variety of industries, enabled by ‘crosslinking’ between its tangled polymers, which creates elasticity. But rubber can crack and suffer fatigue. It is now shown that reducing the crosslink density in highly entangled natu ...
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Journal articleChemical science · April 2025
Symmetry forbidden reactions are notoriously difficult to study experimentally, for the simple reason that their competing symmetry allowed pathways typically dominate. Covalent polymer mechanochemistry offers an opportunity to broaden access to symmetry f ...
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Journal articleJournal of the mechanics and physics of solids · February 2025
The design and functionality of polymeric materials hinge on failure resistance. While molecular-level details drive crack evolution in polymer networks, the connection between individual chain scission and bulk failure remains unclear and difficult to pro ...
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Journal articleJournal of the American Chemical Society · February 2025
The tearing of a polymer network arises from mechanochemically coupled bond-breaking events in the backbone of a polymer chain. An emerging research area is the identification of molecular strategies for network toughening, such as the strategic placement ...
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Journal articleInorganic chemistry · January 2025
Transition metal mechanophores exhibiting force-activated spin-crossover are attractive design targets, yet large-scale discovery of them has not been pursued due in large part to the time-consuming nature of trial-and-error experiments. Instead, we levera ...
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Journal articleJournal of the American Chemical Society · January 2025
Understanding structure-mechanical activity relationships (SMARs) in polymer mechanochemistry is essential for the rational design of mechanophores with desired properties, yet SMARs in noncovalent mechanical transformations remain relatively underexplored ...
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Journal articlePolymer Chemistry · November 20, 2024
We report that differences in ring strain enthalpy between cis and trans isomers of sila-cycloheptene provide a driving force for both polymerization and depolymerization via olefin metathesis. A need for new methods to reintroduce the low-strain isomer in ...
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Journal articleMacromolecules · November 12, 2024
With microstructures that typically favor crystallization at low temperatures, commercial polybutadiene elastomers often suffer from poor toughness and limited elongation when utilized in applications near room temperature. By controlling competition betwe ...
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Journal articleAdvanced materials (Deerfield Beach, Fla.) · November 2024
Thermoset toughness and deconstructability are often opposing features; simultaneously improving both without sacrificing other mechanical properties (e.g., stiffness and tensile strength) is difficult, but, if achieved, could enhance the usage lifetime an ...
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Journal articleJournal of the American Chemical Society · November 2024
When multiple reaction steps occur before thermal equilibration, kinetic energy from one reaction step can influence overall product distributions in ways that are not well predicted by transition state theory. An understanding of how the structural featur ...
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Journal articleChem · October 10, 2024
Mechanical force drives distinct chemical reactions; yet, its vectoral nature results in complicated coupling with reaction trajectories. Here, we utilize a physical organic model inspired by the classical Morse potential and its differential forms to iden ...
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Journal articleMaterials Today Chemistry · June 1, 2024
Plant virus-like particles (VLPs) are biocompatible, non-infectious nanomaterials with promising applications as immunotherapeutics and vaccines. However, slow-release VLP formulations are needed to achieve long-term efficacy without repeated administratio ...
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Journal articleJournal of the American Chemical Society · May 2024
In recent decades, more than 100 different mechanophores with a broad range of activation forces have been developed. For various applications of mechanophores in polymer materials, it is crucial to selectively activate the mechanophores with high efficien ...
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Journal articleJournal of Polymer Science · April 1, 2024
Single-molecule force spectroscopy is a powerful tool for the quantitative investigation of the biophysics, polymer physics and mechanochemistry of individual polymer strands. One limitation of this technique is that the attachment between the tip of the a ...
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Journal articleJournal of the American Chemical Society · April 2024
Polymers that release small molecules in response to mechanical force are promising candidates as next-generation on-demand delivery systems. Despite advancements in the development of mechanophores for releasing diverse payloads through careful molecular ...
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Journal articleJournal of the American Chemical Society · April 2024
Hydrogen fluoride (HF) is a versatile reagent for material transformation, with applications in self-immolative polymers, remodeled siloxanes, and degradable polymers. The responsive in situ generation of HF in materials therefore holds promise for ...
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Journal articleChemical communications (Cambridge, England) · April 2024
Second row elements in small- and medium-rings modulate strain. Herein we report the synthesis of two novel oligosilyl-containing cycloalkynes that exhibit angle-strain, as observed by X-ray crystallography. However, the angle-strained sila-cyclooctynes ar ...
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Journal articleChemcatchem · March 8, 2024
The reactivity and selectivity of a transition metal catalyst is intimately related to its ligand-sphere geometry, and, in many cases, the ideal ligand geometry for one step of a catalytic cycle is poorly matched to the ideal ligand geometry for another. F ...
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Journal articleNano letters · March 2024
Many virus-like particles (VLPs) have good chemical, thermal, and mechanical stabilities compared to those of other biologics. However, their stability needs to be improved for the commercialization and use in translation of VLP-based materials. We develop ...
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Journal articleRsc Applied Polymers · February 20, 2024
Flexible and lightweight sensors can assess their environment for a broad range of applications that include wearables for health monitoring and soft robotics. While 2D and 3D printing enables control over sensor design in multiple dimensions, customizabil ...
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Journal articleJournal of the American Chemical Society · February 2024
Polymers that amplify a transient external stimulus into changes in their morphology, physical state, or properties continue to be desirable targets for a range of applications. Here, we report a polymer comprising an acid-sensitive, hydrolytically unstabl ...
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Journal articleJournal of the American Chemical Society · February 2024
The spiropyran mechanophore (SP) is employed as a reporter of molecular tension in a wide range of polymer matrices, but the influence of surrounding environment on the force-coupled kinetics of its ring opening has not been quantified. Here, we report sin ...
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Journal articleJournal of the American Chemical Society · January 2024
Pterodactylane is a [4]-ladderane with substituents on the central rung. Comparing the mechanochemistry of the [4]-ladderane structure when pulled from the central rung versus the end rung revealed a striking difference in the threshold force of mechanoact ...
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Journal articleJphys Materials · January 1, 2024
Soft materials are usually defined as materials made of mesoscopic entities, often self-organised, sensitive to thermal fluctuations and to weak perturbations. Archetypal examples are colloids, polymers, amphiphiles, liquid crystals, foams. The importance ...
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Journal articleACS macro letters · December 2023
The fracture of polymer networks is tied to the molecular behavior of strands within the network, yet the specific molecular-level processes that determine the mechanical limits of a network remain elusive. Here, the question of reactivity-guided fracture ...
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Journal articlePolymer · October 20, 2023
Polymers comprising polybutadiene backbones with 2,6-bis(1′-methyl-benzimidazolyl)pyridine (MeBip) sidechains were crosslinked by complexation with two different metal salts, either with copper(II) trifluoromethanosulfonate or with iron(II) trifluoromethan ...
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Journal articleAdvanced materials (Deerfield Beach, Fla.) · October 2023
Most elastomers undergo strain-induced crystallization (SIC) under tension; as individual chains are held rigidly in a fixed position by an applied strain, their alignment along the strain field results in a shift from strain-hardening (SH) to SIC. A simil ...
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Journal articleJournal of the American Chemical Society · October 2023
Metal-organic cages/polyhedra (MOCs) are versatile building blocks for advanced polymer networks with properties that synergistically blend those of traditional polymers and crystalline frameworks. Nevertheless, constructing polyMOCs from very stable Pt(II ...
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Journal articleMacromolecules · September 12, 2023
Four unsaturated poly(carbooligosilane)s (P1-P4) were prepared via acyclic diene metathesis polycondensation of new oligosilane diene monomers (1-4). These novel polymers with varying main-chain Si incorporation have high trans internal olefin stereochemis ...
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Journal articleOrganometallics · August 14, 2023
We have analyzed the rate of C(sp2)-C(sp2) reductive elimination from nickel(II) bis(2,4,6-trifluorophenyl) complexes (P-P)Ni(2,4,6-C6H2F3)2 containing either MeOBiPhep (3a) or a macrocyclic ...
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Journal articleNature communications · August 2023
Allosteric control of reaction thermodynamics is well understood, but the mechanisms by which changes in local geometries of receptor sites lower activation reaction barriers in electronically uncoupled, remote reaction moieties remain relatively unexplore ...
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Journal articleScience (New York, N.Y.) · June 2023
The mechanical properties of covalent polymer networks often arise from the permanent end-linking or cross-linking of polymer strands, and molecular linkers that break more easily would likely produce materials that require less energy to tear. We report t ...
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Journal articleJournal of the American Chemical Society · May 2023
The cis- and trans-isomers of a silacycloheptene were selectively synthesized by the alkylation of a silyl dianion, a novel approach to strained cycloalkenes. The trans-silacycloheptene (trans-SiCH) was significantly more strain ...
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Journal articleMacromolecules · March 28, 2023
We present a modified Lake-Thomas theory that accounts for the molecular details of network connectivity upon crack propagation in polymer networks. This theory includes not only the energy stored in the breaking network strands (bridging strands) but also ...
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Journal articleBiomaterials · March 2023
Many biologics have a short plasma half-life, and their conjugation to polyethylene glycol (PEG) is commonly used to solve this problem. However, the improvement in the plasma half-life of PEGylated drugs' is at an asymptote because the development of bran ...
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Journal articleMaterials horizons · February 2023
Recent work has demonstrated that force-triggered mechanochemical reactions within a polymeric material are capable of inducing measurable changes in macroscopic material properties, but examples of bulk property changes without irreversible changes in sha ...
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Journal articleFaraday discussions · January 2023
This paper provides a summary of the Faraday Discussions meeting on "Mechanochemistry: fundamentals, applications, and future" in the context of broad themes whose exploration might contribute to a unified framework of mechanochemical phenomena. ...
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Journal articleJournal of the American Chemical Society · January 2023
Over the past 20 years, the field of polymer mechanochemistry has amassed a toolbox of mechanophores that translate mechanical energy into a variety of functional responses ranging from color change to small-molecule release. These productive chemical chan ...
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Journal articleAiche Annual Meeting Conference Proceedings · January 1, 2023
The mechanical properties of a polymer network reflect the collective behavior of all of the constituent strands within the network. These strands comprise a distribution of states, and a central question is how the deformation and tension experienced by a ...
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Journal articleFrontiers in Virology · January 1, 2023
Plant virus-based nanoparticles (VNPs) offer a bioinspired approach to the delivery of drugs and imaging agents. The chemical addressability, biocompatibility, and scalable manufacturability of VNPs make them a promising alternative to synthetic delivery p ...
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Journal articleJournal of the American Chemical Society · December 2022
We report the mechanochemical reactivity of the highly strained pentacyclic hydrocarbon cubane. The mechanical reactivity of cubane is explored for three regioisomers with 1,2-, 1,3-, and 1,4-substituted pulling attachments. Whereas all compounds can be ac ...
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Journal articleACS Catalysis · November 18, 2022
Here we quantify the regio- chemo-, and enantioselectivity of the hydroformylation of 1-alkenes catalyzed by Rh(I) complexes containing chiral macrocyclic biaryl bis(phosphine) ligands as a function of mechanical force applied to the biaryl backbone of the ...
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Journal articleJournal of Rheology · November 1, 2022
The linear rheological properties of supramolecular polymer networks formed by mixtures of two different bis-Pd(II) cross-linkers with poly(4-vinylpyridine) in dimethyl sulfoxide are examined. The changes in storage and loss moduli of the networks with mix ...
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Journal articleChemical science · October 2022
As a machine-recognizable representation of polymer connectivity, BigSMILES line notation extends SMILES from deterministic to stochastic structures. The same framework that allows BigSMILES to accommodate stochastic covalent connectivity can be extended t ...
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Journal articleSynlett · May 16, 2022
The mechanically induced symmetry-allowed disrotatory ring openings of cis- and trans-gem-dichlorocyclopropane (gDCC) diesters are demonstrated through sonication and single-molecule force spectroscopy (SMFS) studies. In contrast to the previously reported ...
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Journal articleJournal of the American Chemical Society · March 2022
The intermolecular interactions of noble gases in biological systems are associated with numerous biochemical responses, including apoptosis, inflammation, anesthesia, analgesia, and neuroprotection. The molecular modes of action underlying these responses ...
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Journal articleScience (New York, N.Y.) · October 2021
The utility and lifetime of materials made from polymer networks, including hydrogels, depend on their capacity to stretch and resist tearing. In gels and elastomers, those mechanical properties are often limited by the covalent chemical structure of the p ...
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Journal articleJournal of the American Chemical Society · August 2021
Recent research on the mechanochemistry of metallocene mechanophores has shed light on the force-responsiveness of these thermally and chemically stable organometallic compounds. In this work, we report a combination of experimental and computational studi ...
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Journal articleJournal of the American Chemical Society · August 2021
We have recently reported a series of ladder-type cyclobutane mechanophores, polymers of which can transform from nonconjugated structures to conjugated structures and change many properties at once. These multicyclic mechanophores, namely, exo-ladd ...
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Journal articleChemical science · August 2021
Coupled mechanical forces are known to drive a range of covalent chemical reactions, but the effect of mechanical force applied to a spectator ligand on transition metal reactivity is relatively unexplored. Here we quantify the rate of C(sp2)-C( ...
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Journal articleJournal of the American Chemical Society · April 2021
Mechanochemical reactions that lead to an increase in polymer contour length have the potential to serve as covalent synthetic mimics of the mechanical unfolding of noncovalent "stored length" domains in structural proteins. Here we report the force-depend ...
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Journal articleChemical reviews · April 2021
Polymer networks are complex systems consisting of molecular components. Whereas the properties of the individual components are typically well understood by most chemists, translating that chemical insight into polymer networks themselves is limited by th ...
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Journal articleJournal of chemical information and modeling · March 2021
Polymers are stochastic materials that represent distributions of different molecules. In general, to quantify the distribution, polymer researchers rely on a series of chemical characterizations that each reveal partial information on the distribution. Ho ...
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Journal articleJournal of the American Chemical Society · March 2021
Woodward and Hoffman once jested that a very powerful Maxwell demon could seize a molecule of cyclobutene at its methylene groups and tear it open in a disrotatory fashion to obtain butadiene (Woodward, R. B.; Hoffmann, R. The Conservation of Orbital Symme ...
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Journal articleJournal of the American Chemical Society · March 2021
The fracture of rubbery polymer networks involves a series of molecular events, beginning with conformational changes along the polymer backbone and culminating with a chain scission reaction. Here, we report covalent polymer gels in which the macroscopic ...
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Journal articleJournal of the American Chemical Society · February 2021
Metal-complexed N-heterocyclic carbene (NHC) mechanophores are latent reactants and catalysts for a range of mechanically driven chemical responses, but mechanochemical scission of the metal-NHC bond has not been experimentally characterized. Here we repor ...
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Journal articleMacromolecular rapid communications · January 2021
Molecular force probes that generate optical responses to critical levels of mechanical stress (mechanochromophores) are increasingly attractive tools for identifying molecular sites that are most prone to failure. Here, a coumarin dimer mechanophore whose ...
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Journal articleMacromolecular rapid communications · January 2021
Featured Publication
The molecular processes that accompany dynamic mechanical response to large deformations at high strain rate (≈1000 s-1 or higher) underlie the early stages of damage in materials, but understanding of material response in this regime is typical ...
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Journal articleNature Reviews Materials · January 1, 2021
The use of mechanical forces to chemically transform polymers dates back decades. In recent years, the use of mechanochemistry to direct constructive transformations in polymers has resulted in a range of engineered molecular responses that span optical, m ...
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Journal articleNature chemistry · January 2021
Mechanophores can be used to produce strain-dependent covalent chemical responses in polymeric materials, including stress strengthening, stress sensing and network remodelling. In general, it is desirable for mechanophores to be inert in the absence of fo ...
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Journal articleJournal of the American Chemical Society · October 2020
Here, we report the effect of force applied to the biaryl backbone of a bisphosphine ligand on the rate of oxidative addition of bromobenzene to a ligand-coordinated palladium center. Local compressive and tensile forces on the order of 100 pN were generat ...
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Journal articleNature communications · October 2020
Featured Publication
The mechanical degradation of polymers is typically limited to a single chain scission per triggering chain stretching event, and the loss of stress transfer that results from the scission limits the extent of degradation that can be achieved. Here, we rep ...
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Journal articleChemical science · September 2020
Featured Publication
The mechanical strength of individual polymer chains is believed to underlie a number of performance metrics in bulk materials, including adhesion and fracture toughness. Methods by which the intrinsic molecular strength of the constituents of a given poly ...
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Journal articleAngewandte Chemie (International ed. in English) · February 2020
Photoresponsive materials that change in response to light have been studied for a range of applications. These materials are often metastable during irradiation, returning to their pre-irradiated state after removal of the light source. Herein, we report ...
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Journal articleJournal of the American Chemical Society · February 2020
Degradable polymers are desirable for the replacement of conventional organic polymers that persist in the environment, but they often suffer from the unintentional scission of the degradable functionalities on the polymer backbone, which diminishes polyme ...
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Journal articleJournal of the American Chemical Society · January 2020
Mechanically coupled proton transduction offers potential for stress-responsive polymeric materials whose properties can be switched via acid-triggered coloration, polymerization/cross-linking, or degradation. The utility of currently available mechanoacid ...
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Journal articlePolymer Chemistry · December 21, 2019
The authors apologise for an incorrect structure that was presented in Fig. 10. During the preparation of Fig. 10, the authors included unlabeled bonds that indicated vinylic methyl groups instead of hydrogen atoms on the ladderene compounds. The corrected ...
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Journal articlePolymer Chemistry · November 28, 2019
Herein, we report a strategy for additive manufacturing of a mechanochemically active silicone ink primarily composed of PDMS microbeads. Extruded, stable structures of cured microbeads were held together with a "bridging material" comprising uncured PDMS ...
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Journal articleMacromolecules · November 26, 2019
We report the mechanochemical activity of copolymers formed through the radical addition polymerization of cyclobutene carboxylates that are fused to larger rings. The fused ring repeats act as stored-length mechanophores along the polymer backbone, and so ...
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Journal articleChemical communications (Cambridge, England) · October 2019
Clarifying the correlation between the chemical structure of mechanophores and their mechanical reactivity informs the design of mechanochemical systems. One specific correlation that has received much recent attention is that between stereoisomerism and m ...
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Journal articleThe journal of physical chemistry. B · October 2019
The cis-to-trans isomerization of azobenzene is accelerated in a bulk PDMS elastomer under uniaxial tension. The kinetics are cleanly described by a single-exponential first-order process (k = 2.7 × 10-5 s-1) in the absence of ...
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Journal articleACS central science · September 2019
Having a compact yet robust structurally based identifier or representation system is a key enabling factor for efficient sharing and dissemination of research results within the chemistry community, and such systems lay down the essential foundations for ...
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Journal articleMacromolecules · August 27, 2019
Recent successes in covalent polymer mechanochemistry might more easily be translated to stress-responsive bulk materials if easily scalable and minimalist mechanophores were identified. Epoxides represent attractive modifications of unsaturated polymer ba ...
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Journal articleJournal of the American Chemical Society · July 2019
Cyclic polymers containing multiple gem-dichlorocyclopropane (gDCC) mechanophores along their backbone were prepared using ring expansion metathesis polymerization. The mechanochemistry of the cyclic polymers was investigated using pulsed ult ...
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Journal articleAdvanced materials (Deerfield Beach, Fla.) · June 2019
Biological tissues are multiresponsive and functional, and similar properties might be possible in synthetic systems by merging responsive polymers with hierarchical soft architectures. For example, mechanochromic polymers have applications in force-respon ...
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Journal articleChemical science · May 2019
Recent reports have shown that ferrocene displays an unexpected combination of force-free stability and mechanochemical activity, as it acts as the preferred site of chain scission along the backbone of highly extended polymer chains. This observation rais ...
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Journal articleMacromolecules · April 9, 2019
We present a conceptual framework for adding molecular details of chain extension and force-coupled bond dissociation to the Lake-Thomas model of tear energy in rubbery crack propagation. Incorporating data reported from single-molecule force spectroscopy ...
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Journal articleOrganic Chemistry Frontiers · April 7, 2019
The encapsulation of guests in supramolecular capsules has long been used to trap reactive intermediates and enhance or reduce the kinetic stability of reactants, and alter the products of chemical reactions that occur within the capsule interior. In recen ...
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Journal articleMolecules (Basel, Switzerland) · February 2019
Several technologies can be used for measuring strains of soft materials under high rate impact conditions. These technologies include high speed tensile test, split Hopkinson pressure bar test, digital image correlation and high speed X-ray imaging. Howev ...
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Journal articleMacromolecules · November 27, 2018
We report the preparation of cyclic ferrocenyl olefins with various substituents and different ring sizes by ring-closing metathesis (RCM). These ferrocene-containing monomers were subject to ring-opening metathesis polymerization (ROMP), leading to main-c ...
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Journal articleJournal of the American Chemical Society · November 2018
Mechanochromic force probes, including spiropyran derivatives, have proven to be useful in visualizing the stress/strain distribution and fracture behavior in polymeric materials. Here, we report the macroscopic response of silicone elastomers including cr ...
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Journal articleJournal of the American Chemical Society · October 2018
We report the effect of substituents on the force-induced reactivity of a spiropyran mechanophore. Using single molecule force spectroscopy, force-rate behavior was determined for a series of spiropyran derivatives substituted with H, Br, or NO2 ...
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Journal articleACS macro letters · October 2018
Ferrocene is classically regarded as being highly inert owing to the large dissociation energy of metal-cyclopentadienyl (Cp) bonds. We show that the Fe-Cp bond in ferrocene is the preferential site of mechanochemical scission in the pulsed ultrasonication ...
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Journal articleACS applied materials & interfaces · September 2018
Soft and stretchable electronics are promising for a variety of applications such as wearable electronics, human-machine interfaces, and soft robotics. These devices, which are often encased in elastomeric materials, maintain or adjust their functionality ...
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Journal articlePolymer Chemistry · July 14, 2018
The development of multi-mechanophore polymers (MMPs) has empowered new methodologies for observing, quantifying, and exploiting mechanochemical transformations. For example, techniques such as single molecule force spectroscopy and pulsed ultrasound can b ...
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Journal articleJournal of Polymer Science Part A Polymer Chemistry · July 1, 2018
A series of poly(methyl acrylates) incorporating a disulfide center was subjected to four different stimuli to cleave the SS bond, as the weakest member of the chain. Four polymers with molecular weights in the range of 25–93 kDa were synthesized via Cu-b ...
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Journal articleThe journal of physical chemistry. B · July 2018
The formation of permanent structures upon mild red laser illumination in transparent polydiene solutions is examined in the case of gem-dichlorocyclopropanated polybutadiene ( gDCC-PB) polymers bearing 15% functional units of the dichlorocyclopropane grou ...
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Journal articleJournal of Chemical Education · November 14, 2017
An easy-To-implement science outreach demonstration featuring a mechanically and photochemically color-changing polymer is described. The active polymeric material is a filled poly(dimethylsiloxane) (PDMS) elastomer that is covalently functionalized with s ...
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Journal articleChemphyschem : a European journal of chemical physics and physical chemistry · June 2017
Single-molecule force spectroscopy (SMFS) of multi-mechanophore polymers has been used to provide kinetic and mechanistic insights into mechanochemical reactions. Whereas biological systems have benefitted from force clamp spectroscopy, synthetic polymers ...
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Journal articleACS nano · April 2017
Silver nanowire (AgNW) networks are considered to be promising structures for use as flexible transparent electrodes for various optoelectronic devices. One important application of AgNW transparent electrodes is the flexible touch screens. However, the pe ...
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Journal articleAdvanced Functional Materials · December 27, 2016
Strain-induced light emission from mechanoluminescent cross-linkers in silica-filled poly(dimethylsiloxane) demonstrates that covalent bond scission contributes significantly to irreversible stress-softening upon the initial extension, known as the Mullins ...
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Journal articleNature communications · November 2016
Covalent polymer mechanochemistry offers promising opportunities for the control and engineering of reactivity. To date, covalent mechanochemistry has largely been limited to individual reactions, but it also presents potential for intricate reaction syste ...
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Journal articleAngewandte Chemie (International ed. in English) · October 2016
Topological molecular connections and structures, including physical entanglements in polymer networks, knots along polymer chains, and rotaxanes in sliding ring gels, have important consequences for the physical properties of polymeric materials. Often th ...
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Journal articleJournal of the American Chemical Society · August 2016
The mechanochemical activation of cis-gem-difluorocyclopropane (cis-gDFC) mechanophore in toluene was characterized with single-molecule force spectroscopy. Unlike previously reported behavior in methyl benzoate (MB), two transitions are observed in the fo ...
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Journal articlePolymer · February 10, 2016
Polymer bottlebrushes may be viewed as hairy flexible cylinders with a long backbone and a thick corona of densely grafted polymer chains. The corona not only controls the bottlebrush diameter, but also provides an additional drag force. We report the stud ...
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Journal articleThe Journal of organic chemistry · December 2015
Mechanical forces have previously been used to drive reactions along pathways that violate the orbital symmetry effects captured in the Woodward-Hoffmann rules. Here, we show that a polymer "lever arm effect" can provide a mechanical advantage in accelerat ...
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Journal articleThe Journal of organic chemistry · December 2015
The dynamics of reactions at or in the immediate vicinity of transition states are critical to reaction rates and product distributions, but direct experimental probes of those dynamics are rare. Here, s-trans, s-trans 1,3-diradicaloid transition states ar ...
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Journal articleACS applied materials & interfaces · October 2015
The functions of soft robotics are intimately tied to their form-channels and voids defined by an elastomeric superstructure that reversibly stores and releases mechanical energy to change shape, grip objects, and achieve complex motions. Here, we demonstr ...
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Journal articleMacromolecules · September 22, 2015
Structure-activity relationships in the mechanochemistry of gem-dichlorocyclopropane (gDCC)-based polymer solutions triggered by pulsed ultrasound are reported. Insights into the flow-induced mechanochemical transformations of gDCC mechanophores into the c ...
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Journal articleJournal of the American Chemical Society · September 2015
Mechanical forces, applied via covalent polymer mechanochemistry, have been used to bias reaction pathways and activate otherwise inaccessible reactions. Here, single-molecule polymer mechanochemistry is used to induce the disrotatory outward ring opening ...
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Journal articleRapid Prototyping Journal · August 17, 2015
Purpose - This paper aims to explore and demonstrate the ability to integrate entry-level additive manufacturing (AM) techniques with responsive polymers capable of mechanical to chemical energy transduction. This integration signifies the merger of AM and ...
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Journal articleJournal of the American Chemical Society · August 2015
The mechanical strength of scissile chemical bonds plays a role in material failure and in the mechanical activation of latent reactivity, but quantitative measures of mechanical strength are rare. Here, we report the relative mechanical strength of polyme ...
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Journal articleACS macro letters · August 2015
The mechanical stresses that materials experience during use can lead to aging and failure. Recent developments in covalent mechanochemistry have provided a mechanism by which those stresses can be channeled into constructive, rather than destructive, resp ...
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Journal articleJournal of the Mechanics and Physics of Solids · July 25, 2015
Abstract Mechanochemically responsive (MCR) polymers have been synthesized by incorporating mechanophores - molecules whose chemical reactions are triggered by mechanical force - into conventional polymer networks. Deformation of the MCR polymers applies f ...
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Journal articleChemical communications (Cambridge, England) · June 2015
Here we present a coumarin dimer (CD) mechanophore that, when embedded near the mid-chain of poly(methyl acrylate) polymers, activates under pulsed ultrasound conditions to yield coumarin chain-end functional polymers. Quantitative photochemical scission o ...
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Journal articleJournal of the American Chemical Society · May 2015
The mechanically accelerated ring-opening reaction of spiropyran to a colored merocyanine provides a useful method by which to image the molecular scale stress/strain distribution within a polymer, but the magnitude of the forces necessary for activation h ...
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Journal articleChemical science · April 2015
Force reactive functional groups, or mechanophores, have emerged as the basis of a potential strategy for sensing and countering stress-induced material failure. The general utility of this strategy is limited, however, because the levels of mechanophore a ...
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Journal articleNature chemistry · April 2015
Forbidden reactions, such as those that violate orbital symmetry effects as captured in the Woodward-Hoffmann rules, remain an ongoing challenge for experimental characterization, because when the competing allowed pathway is available the reactions are in ...
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Journal articleJournal of biomedical materials research. Part B, Applied biomaterials · February 2015
The tissue adhesive 2-octyl cyanoacrylate (OCA) was encapsulated in polyurethane microshells and incorporated into bone cement to form a catalyst free, self-healing bone cement comprised of all clinically approved components. The bending strength, modulus, ...
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Journal articleAngewandte Chemie (International ed. in English) · December 2014
A catalyst that couples a photoswitch to the biaryl backbone of a chiral bis(phosphine) ligand, thus allowing photochemical manipulation of ligand geometry without perturbing the electronic structure is reported. The changes in catalyst activity and select ...
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Journal articleJournal of the American Chemical Society · October 2014
Molecular mechanisms by which to increase the activity of a mechanophore might provide access to new chemical reactions and enhanced stress-responsive behavior in mechanochemically active polymeric materials. Here, single-molecule force spectroscopy reveal ...
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Journal articleAdvanced materials (Deerfield Beach, Fla.) · September 2014
Hydrogels and organogels made from polymer networks are widely used in biomedical applications and soft, active devices for which the ability to sustain large deformations is required. The strain at which polymer networks fracture is typically improved thr ...
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Journal articleNature communications · September 2014
Cephalopods can display dazzling patterns of colours by selectively contracting muscles to reversibly activate chromatophores--pigment-containing cells under their skins. Inspired by this novel colouring strategy found in nature, we design an electro-mecha ...
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Journal articleActa biomaterialia · August 2014
Hyaluronic acid (HA)-poly(ethylene glycol) (PEG) composite hydrogels have been widely studied for both cell delivery and soft tissue regeneration applications. A very broad range of physical and biological properties have been engineered into HA-PEG hydrog ...
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Journal articleACS macro letters · March 2014
Covalent mechanochemistry within bulk polymers typically occurs with irreversible deformation of the parent material. Here we show that embedding mechanophores into an elastomeric poly(dimethylsiloxane) (PDMS) network allows for covalent bond activation un ...
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Journal articleFaraday discussions · January 2014
The mechanochemical activation of covalent bonds in bulk polymers is often characterized by low conversions. Here we report that the activation of gem-dibromocyclopropane (gDBC) mechanophores embedded in a poly(1,4-butadiene) (PB) is enhanced when a centra ...
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Journal articleNature chemistry · September 2013
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High shear stresses are known to trigger destructive bond-scission reactions in polymers. Recent work has shown that the same shear forces can be used to accelerate non-destructive reactions in mechanophores along polymer backbones, and it is demonstrated ...
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Journal articleJournal of the American Chemical Society · September 2013
A primary goal of covalent mechanochemistry is to develop polymer bound mechanophores that undergo constructive transformations in response to otherwise destructive forces. The [2 + 2] cycloreversion of cyclobutane mechanophores has emerged as a versatile ...
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Journal articleNature chemistry · February 2013
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Mechanical forces along a polymer backbone can be used to bring about remarkable reactivity in embedded mechanically active functional groups, but little attention has been paid to how a given polymer backbone delivers that force to the reactant. Here, sin ...
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Journal articleBiomacromolecules · August 2012
The rheological properties of cysteine-containing elastin-like polypeptide (Cys-ELP) solutions and Cys-ELP hydrogels are reported. The Cys-ELP solutions exhibit a surprisingly high apparent viscosity at low shear rate. The high viscosity is attributed to t ...
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Journal articleJournal of the American Chemical Society · August 2012
Force-induced transformations of polymer-bound functionalities have the potential to produce a rich array of stress-responsive behavior. One area of particular interest is the activation of non-scissile mechanophores in which latent reactivity can be unvei ...
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Journal articleBiomaterials · July 2012
Protein-based biomaterials are an important class of materials for applications in biotechnology and medicine. The exquisite control of their composition, stereochemistry, and chain length offers unique opportunities to engineer biofunctionality, biocompat ...
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Journal articleJournal of the American Chemical Society · June 2012
Epoxidized polybutadiene and epoxidized polynorbornene were subjected to pulsed ultrasound in the presence of small molecules capable of being trapped by carbonyl ylides. When epoxidized polybutadiene was sonicated, there was no observable small molecule a ...
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Journal articlePolymer · February 28, 2012
In the past five years, the field of covalent polymer mechanochemistry has experienced a renaissance. Once limited to the simple scission of polymer chains, mechanical force can now be used to produce a wide array of productive chemistry. These outcomes ha ...
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Journal articleACS macro letters · January 2012
The high shear forces generated during the pulsed ultrasound of dilute polymer solutions lead to large tensile forces that are focused near the center of the polymer chain, but quantitative experimental evidence regarding the force distribution is rare. He ...
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Journal articleJournal of the American Chemical Society · November 2011
Perfluorocyclobutane (PFCB) polymer solutions were subjected to pulsed ultrasound, leading to mechanically induced chain scission and molecular weight degradation. (19)F NMR revealed that the new, mechanically generated end groups are trifluorovinyl ethers ...
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Journal articleThe journal of physical chemistry. A · September 2011
The forced extension of a DNA segment is studied in a series of steered molecular dynamics simulations, employing a broad range of pulling forces. Throughout the entire force range, the formation of a zipper-like (zip-) DNA structure is observed. In that s ...
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Journal articleMacromolecules · September 2011
The large amplitude oscillatory shear behavior of metallo-supramolecular polymer networks formed by adding bis-Pd(II) cross-linkers to poly(4-vinylpyridine) (PVP) in dimethyl sulfoxide (DMSO) solution is reported. The influence of scanning frequency, disso ...
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Journal articlePolymer Chemistry · July 1, 2011
We report the in situ growth of a thermoresponsive dumbbell-like polymer conjugate of a genetically engineered triblock elastin-like polypeptide (tELP). Atom transfer radical polymerization (ATRP) was used to directly grow a PEG-like polymer selectively fr ...
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Journal articleJournal of Materials Chemistry · June 21, 2011
Polybutadiene was functionalized with dibromo-, dichloro-, and bromochloro-carbene to give gem-dihalocyclopropanated (gDHC) polymers, in which the gDHCs act as mechanically activated functional groups or mechanophores. The polymers were extruded to determi ...
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Journal articleJournal of the American Chemical Society · March 2011
Tension along a polymer chain traps neighboring s-trans/s-trans-1,3-diradicals from the mechanically induced ring opening of gem-difluorocyclopropanes (gDFCs). The diradicals correspond to the transition states of the force-free thermal isomerization react ...
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Journal articleJournal of Materials Chemistry · February 14, 2011
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Current activity in, and future prospects for, the incorporation of mechanochemically active functional groups ("mechanophores") into polymers is reviewed. This area of research is treated in the context of two categories. The first category is the develop ...
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Journal articleJournal of biomedical materials research. Part A · February 2011
The goal of this review is to introduce the biomaterials community to the emerging field of self-healing materials, and also to suggest how one could utilize and modify self-healing approaches to develop new classes of biomaterials. A brief discussion of t ...
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Journal articleMacromolecules · January 2011
The linear rheological properties of networks formed by adding bis-Pd(II) cross-linkers to poly(4-vinylpyridine) (PVP) solution are examined, and the scaling law relationships between the zero shear viscosity (η(0)) of the networks versus the concentration ...
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Journal articleJournal of the American Chemical Society · November 2010
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Single-molecule force spectroscopy is used to observe the irreversible extension of a gem-dibromocyclopropane (gDBC)-functionalized polybutadiene under tension, a process akin to polymer necking at a single-molecule level. The extension of close to 28% in ...
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Journal articleScience (New York, N.Y.) · August 2010
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Transition state structures are central to the rates and outcomes of chemical reactions, but their fleeting existence often leaves their properties to be inferred rather than observed. By treating polybutadiene with a difluorocarbene source, we embedded ge ...
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Journal articleThe journal of physical chemistry letters · June 2010
Molecular theories of shear thickening and shear thinning in associative polymer networks are typically united in that they involve a single kinetic parameter that describes the network -- a relaxation time that is related to the lifetime of the associativ ...
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Journal articleAustralian Journal of Chemistry · April 19, 2010
Single molecule atomic force microscopy (AFM) studies of oligonucleotide-based supramolecular polymers on surfaces are used to examine the molecular weight distribution of the polymers formed between a functionalized surface and an AFM tip as a function of ...
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Journal articleMacromolecules · April 2010
We report here the nonlinear rheological properties of metallo-supramolecular networks formed by the reversible cross-linking of semi-dilute unentangled solutions of poly(4-vinylpyridine) (PVP) in dimethyl sulfoxide (DMSO). The reversible cross-linkers are ...
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Journal articleMicrosc Res Tech · January 2010
Titanium is one of the most commonly used materials for implantable devices in humans. Scanning electron microscopy (SEM) serves as an important tool for imaging titanium surfaces and analyzing cells and other organic matter adhering to titanium implants. ...
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Journal articleThe Journal of organic chemistry · December 2009
The flexible, electropositive cavity of linear 1,4-diaryl-1,2,3-triazole oligomers provides a suitable host for complexation of various anions. The binding affinities for various combinations of oligomer and anion were determined by (1)H NMR titrations. Ef ...
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Journal articleJournal of the American Chemical Society · November 2009
This paper explores the contribution of solvation to the overall steric effects of S(N)2 reactions observed in solution. The reactions of chloride ion with a series of alkyl chloronitriles, RCH(CN)Cl (R = methyl, ethyl, isopropyl, tert-butyl) were investig ...
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Journal articleJournal of the American Chemical Society · August 2009
When gem-dichlorocyclopropane (gDCC) copolymers derived from polybutadiene are subjected to ultrasonication, the gDCCs undergo ring opening to form 2,3-dichloroalkenes. The reactivity is not observed in low-molecular-weight (6.5 kDa) copolymers or side-cha ...
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Journal articleColloids and surfaces. A, Physicochemical and engineering aspects · August 2009
Single-molecule force spectroscopy, as implemented in an atomic force microscope, provides a rarely-used method by which to monitor dynamic processes that occur near surfaces. Here, a methodology is presented and characterized that facilitates the study of ...
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Journal articleAngewandte Chemie (International ed. in English) · January 2009
Charging forward: Ionic interactions presented in a multivalent fashion in small-molecule ionic liquids lead to functional polymer-like materials (see picture) that are consistent with the formation of a supramolecular ionic network. For example, the ionic ...
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Journal articleLangmuir : the ACS journal of surfaces and colloids · May 2008
Polymer bridging between surfaces plays an important role in a range of fundamental processes in the material and life sciences. Bridges formed by main-chain reversible polymers differ from their covalent analogs in that they can dynamically adjust their s ...
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Journal articleJournal of the Royal Society, Interface · April 2007
A family of hybrid polymer gels is described, in which covalent cross-links create a permanent, stiff scaffold onto which reversible metal-ligand coordinative cross-links are added. The reversible metal-ligand interactions are shown to bear mechanical stre ...
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Journal articleLangmuir : the ACS journal of surfaces and colloids · February 2007
A combination of fluorescence spectroscopy and dynamic laser light scattering is used to investigate the relationship between the extent of hybridization on the surface of DNA-functionalized gold nanoparticles and the hydrodynamic radius (Rh) of the nanopa ...
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Journal articleLangmuir : the ACS journal of surfaces and colloids · February 2007
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Unlike the case of traditional covalent polymers, the entanglements that determine properties of supramolecular polymers are defined by very specific, intermolecular interactions. Recent work using modular molecular platforms to probe the mechanisms underl ...
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Journal articleJournal of Materials Chemistry · January 1, 2007
The precise manipulation of network percolation, combined with the previously reported effects of the kinetics of cross-linking interactions, provide a mechanism by which to optimize the stimulus-responsive mechanical properties of supramolecular gels. Spe ...
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Journal articleInorganic chemistry · December 2006
The thermodynamics of pyridine coordination in 1,4-phenylene-bridged binuclear palladium and platinum organometallic complexes [1,4-(MOTf)2-&{C6(CH2NR2)4-2,3,5,6}] (11, M =Pd, Pt; R =CH3, C2H5, R2 = -(CH2)5-) are measured by 1H NMR in DMSO-d6. The coordina ...
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Journal articleJournal of the American Chemical Society · March 2006
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The mechanochemistry of the bimolecular nucleophilic substitution of DMSO for substituted pyridines at a square-planar pincer Pd(II) center was investigated using single-molecule force spectroscopy (SMFS). The SMFS data are interpreted in terms of the Bell ...
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Journal articleMacromolecules · November 29, 2005
We report here the formation and dynamic mechanical properties of metallo-supramolecular networks formed by mixtures of bis-Pd(II) and Pt(II) cross-linkers with poly(4-vinylpyridine) in DMSO. Precise control over the dynamic mechanical properties of the bu ...
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Journal articleJournal of the American Chemical Society · October 2005
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Specific metal-ligand coordination between bis-Pd(II) and Pt(II) organometallic cross-linkers and poly(4-vinylpyridine) in DMSO defines a three-dimensional associative polymer network. Frequency-dependent dynamic mechanical moduli of a series of four diffe ...
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Journal articleJournal of the American Chemical Society · September 2005
Dynamic light scattering is used as a sensitive probe of hybridization on DNA-functionalized colloidal gold nanoparticles. When a target DNA strand possesses an 8 base "dangling end", duplex formation on the surface of the nanoparticles leads to an increas ...
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Journal articleAdvanced Materials · 2005
The compressive and adhesive mechanical properties of self-assembled polymer brushes were investigated using DNA-based modules. The effects of surface anchor density, association strength, and monomer flexibility on the properties were also investigated. R ...
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Journal articleJournal of the American Chemical Society · April 2004
This paper describes a simple strategy to biochemically manipulate a surface at the nanoscale by enzyme dip-pen nanolithography using an endonuclease (DNase I) that is directly patterned on a self-assembled monolayer presenting a terminal oligonucleotide. ...
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Journal articleMacromolecules · March 9, 2004
Duplex formation between DNA-based monomers creates linear, polymeric assemblies that resemble larger duplex DNA, but in which the main chain is defined by the reversible base pairing. These monomers provide a reversible polymer platform through which mole ...
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Journal articleJournal of the American Chemical Society · March 2004
Self-assembled polymers whose main chains are defined by reversible DNA base pairing form bridges between the tip of an atomic force microscope and substrate. The forces associated with the rupture of these assemblies are independent of polymer bridge leng ...
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Journal articleJournal of the American Chemical Society · December 2003
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A pair of homologous and soluble reversible polymers display nearly identical solution structures but dramatically different dissociation dynamics (1.0 vs ca. 100 s-1) along their main chains. The polymers are formed by organopalladium-pyridine coordinatio ...
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Journal articleAngewandte Chemie International Edition · November 4, 2002
Fundamental studies of reversible polymerizations can be achieved with intrinsically modular oligonucleotide-based monomers (OMs) comprised of oligonucleotide sequences that are covalently linked directly or through a synthetic spacer. The thermodynamics a ...
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Journal articleJournal of the American Chemical Society · July 2002
Self-assembled cylindrical capsule 1 is reversibly formed from dimerization of two tetraimide resorcinarenes. Studies of guest exchange involving host capsule 1 reveal a mechanistic continuum for exchange that depends on the structure of the guest. Kinetic ...
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Journal articleAngewandte Chemie (International ed. in English) · May 2002
Louis Kahn, architect of the Salk Institute in LaJolla, said "even a common, ordinary brick wants to be something more than it is". Suppose that were also true of molecules. We know that they can and do aggregate; they give complex structures, and by doing ...
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Journal articleScience (New York, N.Y.) · March 2002
Rates of SN2 reactions of chloride ion with methyl- and tert-butyl-substituted chloroacetonitrile were measured by using Fourier transform-ion cyclotron resonance spectrometry to follow the isotopic exchange reaction. Barrier heights for these reactions in ...
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Journal articleProceedings of the National Academy of Sciences of the United States of America · March 2002
Autocatalysis and chemical amplification are characteristic properties of living systems, and they give rise to behaviors such as increased sensitivity, responsiveness, and self-replication. Here we report a synthetic system in which a unique form of compa ...
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Journal articleNature · January 2002
Autocatalysis and chemical amplification are properties of living systems that can lead to increased responsiveness and to self-replication. Here we describe a synthetic system in which a unique form of reagent compartmentalization gives rise to nonlinear ...
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Journal articleJournal of the American Chemical Society · November 8, 2000
Herein we report the synthesis of a molecule that self-organizes through hydrogen bonds into discrete tetrameric capsular species, encapsulating large polycyclic guest molecules. The unique folded structure of the assembled state is determined by correlati ...
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Journal articleProceedings of the National Academy of Sciences of the United States of America · November 2000
Synthetic self-assembled systems combine responsiveness and reversibility with the ability to perform chemical tasks such as molecular recognition and catalysis. An unmet challenge is the construction of polymeric materials that, like nature's tubulin, are ...
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Journal articleJournal of the American Chemical Society · August 23, 2000
The kinetics and thermodynamics of multicomponent assembly in organic solution are investigated using fluorescence resonance energy transfer (FRET). Calix[4]arenes functionalized with ureas on their wider rims dimerize in organic solution, via intermolecul ...
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Journal articleJournal of the American Chemical Society · December 22, 1999
The translational energy dependence of several gas-phase S(N)2 and carbonyl addition-elimination reaction rate constants has been measured in an FT-ICR. The relative energy dependences of the reactions are qualitatively consistent with variations in the re ...
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Journal articleJournal of the American Chemical Society · July 21, 1999
Introduction of an ω-substituent (CN, Cl, or OH) onto a primary n- alkyl chloride significantly enhances the rate of S(N)2 chloride exchange in the gas phase. Trends in reactivity suggest that the rate acceleration depends primarily on through-space solvat ...
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Journal articleProceedings of the National Academy of Sciences of the United States of America · July 1999
Encapsulation complexes are reversibly formed assemblies in which small molecule guests are completely surrounded by large molecule hosts. The assemblies are held together by weak intermolecular forces and are dynamic: they form and dissipate on time scale ...
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Journal articleScience (New York, N.Y.) · March 1998
Nucleophilic displacement reactions (the SN2 reaction) of ions in the gas phase are a prototypical reaction system that allows a study of dynamics, mechanisms, and structure-energy relations. This article reviews aspects of the kinetics (especially the app ...
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Journal articleBerichte Der Bunsengesellschaft Physical Chemistry Chemical Physics · December 1, 1997
We have measured the translational energy dependence of a series of chloride exchange reactions in the gas phase. The translational energy dependence varies with the changes in the potential energy surfaces across the series of reactions in a manner that i ...
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Journal articleJournal of Physical Chemistry A · June 26, 1997
The kinetic energy distribution of trapped ions in an ion cyclotron resonance spectrometer (ICR) under a periodically phase-reversed rf potential is determined. At the operating pressures typical for the ICR (10-7-10-5 Torr), the ions ...
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Journal articleScience · June 6, 1997
The relative translational energy of one set of reactants in the gas- phase equilibrium between chloride ion and chloroacetonitrile 35Cl- + 37ClCH2CN ⇆ 37Cl- + 35ClCH2C ...
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Journal articleJournal of Physical Chemistry A · January 2, 1997
Branching between reaction channels in activated systems is often observed to vary with changes in the potential energy surface as Δln(k1/k2) ∝ Δ(ΔE‡1 - ΔE‡2). RRKM calculations demonstrate that in many, but not ...
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Journal articleJournal of Organic Chemistry · June 1, 1995
Adsorption of a variety of acids to chromatographic silica gel results in substantial enhancement of their catalytic activity–affording easily prepared, environmentally benign heterogeneous acids that are highly effective in mediating a number of processes ...
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Journal articleJournal of the Chemical Society Faraday Transactions · December 1, 1994
Diels-Alder reactions of ethene, acrolein and acrylonitrile with butadiene and its 1-methyl, 2-methyl and 2-cyano derivatives have been studied by self-consistent field intermolecular perturbation theory. The procedure is successful in reproducing the ster ...
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Journal articleJournal of the American Chemical Society · April 1, 1993
Appropriately prepared silica gel and alumina have been found to mediate the addition of HCl, HBr, and HI to alkenes. The technique has been rendered even more convenient by the use of various organic and inorganic halides that undergo hydrolysis in the pr ...
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