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Stretching a segment of a polymer beyond its contour length makes its (primarily backbone) bonds more dissociatively labile, which enables polymer mechanochemistry. Integrating some backbone bonds into suitably designed molecular moieties yields mechanistically and kinetically diverse chemistry, which is becoming increasingly exploitable. Examples include, most prominently, attempts to improve mechanical properties of bulk polymers, as well as prospective applications in drug delivery and synthesis. This review aims to highlight an emerging effort to apply the concepts and experimental tools of mechanochemistry to fundamental physical questions in soft matter. A succinct summary of the state‐of‐the‐knowledge of the field, with emphasis on foundational concepts and generalizable observations, is followed by analysis of 3 recent examples of mechanochemistry yielding molecular‐level details of elastomer failure, macromolecular chain dynamics in elongational flows and kinetic allostery. We conclude with reasons to assume that the highlighted approaches are generalizable to a broader range of physical problems than considered to date. [ABSTRACT FROM AUTHOR]

The exciting field of polymer mechanochemistry has made great empirical progress in discovering reactions in which a stretching force accelerates scission of strained bonds using single molecule force spectroscopy and ultrasonication experiments. Understanding why these reactions happen, i.e., the fundamental physical processes that govern coupling of macroscopic motion to chemical reactions, as well as discovering other patterns of mechanochemical reactivity require complementary techniques, which permit a much more detailed characterization of reaction mechanisms and the distribution of force in reacting molecules than are achievable in SMFS or ultrasonication. A molecular force probe allows the specific pattern of molecular strain that is responsible for localized reactions in stretched polymers to be reproduced accurately in non-polymeric substrates using molecular design rather than atomistically intractable collective motions of millions of atoms comprising macroscopic motion. In this review, we highlight the necessary features of a useful molecular force probe and describe their realization in stiff stilbene macrocycles. We describe how studying these macrocycles using classical tools of physical organic chemistry has allowed detailed characterizations of mechanochemical reactivity, explain some of the most unexpected insights enabled by these probes, and speculate how they may guide the next stage of mechanochemistry. [ABSTRACT FROM AUTHOR]

The electrochemical behavior of multilayer films formed by iron porphyrins deposited on an edge plane graphite electrode has been examined under anaerobic conditions. In the scan rate interval (1-250 mV/s) where the electrode reaction is reversible, CV diagrams of these films demonstrate substantial deviations from ideality in broadening and separation of the peaks. A model that describes the observed behavior is proposed by taking into account the potential distribution at the electrode/film interface and the concentration dependence of surface activity coefficients. The peak separation is described in terms of the electric double layer that affects the potential difference driving the electrode reaction. The effective potential difference deviates from the applied value due to the potential distribution across the film. The interfacial potential distribution depends on the ionic concentration inside the film. When different ionic concentrations are assumed for oxidation and reduction, different shifts from the applied potential lead to a hysteresis of the peaks. The peak broadening is modeled by using the lattice theory expression for the surface activity coefficients. The model shows that the midpoint potentials of the redox centers depend on the ionic concentration inside the film. At low ionic concentrations, they are remarkably close to the midpoints of the cytochrome c oxidase heme [a.sub.3]/[Cu.sub.B] site.

Research has been conducted on the terminal oxidases. The preparation of the biomimetic models, such as cytochrome c oxidase and related enzymes, for the binuclear heme/trisimidazole active site of these oxidases is described.

Results describe structural characterization of two lithium chloride complexes. Data indicate their structural characteristics differ depending on the presence of or absence of water in the compounds.

A method is described for quantifying the restoring force of a constrained small molecule and relating its reactivity to this force. The studies have shown that restoring force is a size-invariant measure of molecular strain, unlike strain energy.

Several density functional theory calculations are conducted to explain the impact of the functional, basis set, and zero-point energy corrections on the structural parameters, the lowest energy quintet and triplet states of model hemes. The computational variables are found to be extremely important in determining the structure of these hemes.

The kinetics and the mechanism of electrocatalytic reduction of common peroxidic oxidants are reported. At ferric-Fe-(NMe) and Fe(Ac), catalytic reduction of KHSO5, PAA and CPBA is substantially faster than reduction of H2O2, which is comparable to that of TBHP.

A great deal of creative effort is expended in designing, synthesizing, and studying functional models of enzymes involved in oxygen transport, storage and utilization. Such work has provided a significant body of new information relevant to chemistry and the structure, reactivity relationship within the binding pockets of myoglobin and hemoglobin.

We report a series of organic fluorophores that undergo selective self-sensitized photooxidation upon light irradiation in air accompanied by a change of fluorescence from yellow to blue on the seconds timescale. The distinct emission changes allow the ratiometric quantitation of O2 concentration. [ABSTRACT FROM AUTHOR]