Chemically Recyclable Polyester Thermosets from Activated Adipic Acid and Renewable Polyols.

This study outlines a method for producing chemically recyclable crosslinked polyesters using renewable polyols-glycerol and sorbitol-combined with adipic acid (AA), which is transformed/activated into a polyanhydride mixture prior to use. A three-step procedure has been designed: 1) an acid-catalyzed reaction of AA with nontoxic isopropenyl acetate or acetic anhydride to form a crosslinking mixture (CLM) made of adipic-acetic mixed polyanhydrides; 2) a solvent- and additive-free process where glycerol or sorbitol, or a combination thereof, is reacted with the CLM to achieve a prepolymer, and 3) a casting/molding of the liquid viscous prepolymer to yield a thermoset as the end product. Different thermosets (eight examples) are prepared by changing the reagents ratio.

Solid-state NMR at natural isotopic abundance for bioenergy applications.

Lignocellulosic biomass offers a vast and renewable resource for biofuel production and carbon management solutions. The effective conversion of lignocellulosic biomass into economically competitive biofuels and bioproducts demands a comprehensive understanding of its complex structure and composition, often requiring a range of analytical tools to achieve meaningful insights. However, for the analysis of rigid solids, many traditional methods necessitate dissolution or chemical/physical modification of the sample, which limit our ability to capture an intact view of its structural components.

Remote chirality transfer in low-dimensional hybrid metal halide semiconductors.

In hybrid metal halide perovskites, chiroptical properties typically arise from structural symmetry breaking by incorporating a chiral A-site organic cation within the structure, which may limit the compositional space. Here we demonstrate highly efficient remote chirality transfer where chirality is imposed on an otherwise achiral hybrid metal halide semiconductor by a proximal chiral molecule that is not interspersed as part of the structure yet leads to large circular dichroism dissymmetry factors (g) of up to 10. Density functional theory calculations reveal that the transfer of stereochemical information from the chiral proximal molecule to the inorganic framework is mediated by selective interaction with divalent metal cations.

Site Disorder Drives Cyanide Dynamics and Fast Ion Transport in LiPSCN.

Halide argyrodite solid-state electrolytes of the general formula LiPS exhibit complex static and dynamic disorder that plays a crucial role in ion transport processes. Here, we unravel the rich interplay between site disorder and dynamics in the plastic crystal argyrodite LiPSCN and the impact on ion diffusion processes through a suite of experimental and computational methodologies, including temperature-dependent synchrotron powder X-ray diffraction, AC electrochemical impedance spectroscopy, Li solid-state NMR, and machine learning-assisted molecular dynamics simulations. Sulfide and (pseudo)halide site disorder between the two anion sublattices unilaterally improves long-range lithium diffusion irrespective of the (pseudo)halide identity, which demonstrates the importance of site disorder in dictating bulk ionic conductivity in the argyrodite family.

Synergistic Dual-Cure Reactions for the Fabrication of Thermosets by Chemical Heating.

Large composite structures, such as those used in wind energy applications, rely on the bulk polymerization of thermosets on an impressively large scale. To accomplish this, traditional thermoset polymerizations require both elevated temperatures (>100 °C) and extended cure durations (>5 h) for complete conversion, necessitating the use of oversize ovens or heated molds. In turn, these requirements lead to energy-intensive polymerizations, incurring high manufacturing costs and process emissions.

Atomistic, macromolecular model of the secondary cell wall informed by solid-state NMR.

Plant secondary cell walls (SCWs) are composed of a heterogeneous interplay of three major biopolymers: cellulose, hemicelluloses, and lignin. Details regarding specific intermolecular interactions and higher-order architecture of the SCW superstructure remain ambiguous. Here, we use solid-state nuclear magnetic resonance (ssNMR) measurements to infer refined details about the structural configuration, intermolecular interactions, and relative proximity of all three major biopolymers within air-dried wood.

Elastomeric vitrimers from designer polyhydroxyalkanoates with recyclability and biodegradability.

Cross-linked elastomers are stretchable materials that typically are not recyclable or biodegradable. Medium-chain-length polyhydroxyalkanoates (mcl-PHAs) are soft and ductile, making these bio-based polymers good candidates for biodegradable elastomers. Elasticity is commonly imparted by a cross-linked network structure, and covalent adaptable networks have emerged as a solution to prepare recyclable thermosets via triggered rearrangement of dynamic covalent bonds.

Investigating the Atomic and Mesoscale Interactions that Facilitate Spider Silk Protein Pre-Assembly.

Black widow spider dragline silk is one of nature's high-performance biological polymers, exceeding the strength and toughness of most man-made materials including high tensile steel and Kevlar. Major ampullate (Ma), or dragline silk, is primarily comprised of two spidroin proteins (Sp) stored within the Ma gland. In the native gland environment, the MaSp1 and MaSp2 proteins self-associate to form hierarchical 200-300 nm superstructures despite being intrinsically disordered proteins (IDPs).

Hybrid Chemomechanical Plastics Recycling: Solvent-free, High-Speed Reactive Extrusion of Low-Density Polyethylene.

Low-density polyethylene (LDPE) is ubiquitous in the packaging industry owing to its flexibility, toughness, and low cost. However, it is typically contaminated with other materials, seriously limiting options for mechanical recycling. Interest in chemical recycling techniques such as pyrolysis and hydrothermal liquefaction is growing, but most of these processes face technoeconomic challenges that have limited commercial deployment.

Importance of suberin biopolymer in plant function, contributions to soil organic carbon and in the production of bio-derived energy and materials.

Suberin is a hydrophobic biopolymer of significance in the production of biomass-derived materials and in biogeochemical cycling in terrestrial ecosystems. Here, we describe suberin structure and biosynthesis, and its importance in biological (i.e.

Comparison of methodologies used to determine aromatic lignin unit ratios in lignocellulosic biomass.

Background: Multiple analytical methods have been developed to determine the ratios of aromatic lignin units, particularly the syringyl/guaiacyl (S/G) ratio, of lignin biopolymers in plant cell walls. Chemical degradation methods such as thioacidolysis produce aromatic lignin units that are released from certain linkages and may induce chemical changes rendering it difficult to distinguish and determine the source of specific aromatic lignin units released, as is the case with nitrobenzene oxidation methodology. NMR methods provide powerful tools used to analyze cell walls for lignin composition and linkage information.

Selective One-Dimensional C-C Spin-Diffusion Solid-State Nuclear Magnetic Resonance Methods to Probe Spatial Arrangements in Biopolymers Including Plant Cell Walls, Peptides, and Spider Silk.

Two-dimensional (2D) and 3D through-space C-C homonuclear spin-diffusion techniques are powerful solid-state nuclear magnetic resonance (NMR) tools for extracting structural information from C-enriched biomolecules, but necessarily long acquisition times restrict their applications. In this work, we explore the broad utility and underutilized power of a chemical shift-selective one-dimensional (1D) version of a 2D C-C spin-diffusion solid-state NMR technique. The method, which is called 1D dipolar-assisted rotational resonance (DARR) difference, is applied to a variety of biomaterials including lignocellulosic plant cell walls, microcrystalline peptide fMLF, and black widow dragline spider silk.

Probing the binding modes and dynamics of histidine on fumed silica surfaces by solid-state NMR.

Silica nanoparticles can be designed to exhibit a diverse range of morphologies (e.g. non-porous, mesoporous), physical properties (e.

Correction: Biosynthesis of the oxygenated diterpene nezukol in the medicinal plant Isodon rubescens is catalyzed by a pair of diterpene synthases.

[This corrects the article DOI: 10.1371/journal.pone.

Antioxidant Sensing by Spiropyrans: Substituent Effects and NMR Spectroscopic Studies.

The development of stimuli-responsive small molecules for probing biologically active antioxidants such as glutathione (GSH) has important ramifications in the detection of oxidative stress. An ideal sensor for biological applications should exhibit sufficient sensitivity and selectivity for detection at physiological concentrations and be reversible to allow continuous and dynamic monitoring of antioxidant levels. Designing a suitable sensor thus requires a detailed understanding of activation properties and mechanism of action.

H NMR Reveals Liquid State-Like Dynamics of Arene Guests Inside Hexameric Pyrogallol[4]arene Capsules in the Solid State.

The dynamics of guests in molecular encapsulation complexes have been studied extensively in solution, but the corresponding behavior of those guests when the capsules are present in the solid state is not as well understood. Here we report on comparative solution H and solid-state H NMR measurements of encapsulation complexes of fluorene(- ), fluoranthene(- ), and pyrene-(- ) in pyrogallol[4]arene hexamers assembled in the solid state by ball milling. In solution, the H spectra show that these rigid guests tumble and exchange positions quickly within the capsules' interiors, with the exception of pyrene, which has slower tumbling and positional exchange.

Functional characterization of the cytochrome P450 monooxygenase CYP71AU87 indicates a role in marrubiin biosynthesis in the medicinal plant Marrubium vulgare.

Background: Horehound (Marrubium vulgare) is a medicinal plant whose signature bioactive compounds, marrubiin and related furanoid diterpenoid lactones, have potential applications for the treatment of cardiovascular diseases and type II diabetes. Lack of scalable plant cultivation and the complex metabolite profile of M. vulgare limit access to marrubiin via extraction from plant biomass.

Hierarchical spidroin micellar nanoparticles as the fundamental precursors of spider silks.

Many natural silks produced by spiders and insects are unique materials in their exceptional toughness and tensile strength, while being lightweight and biodegradable-properties that are currently unparalleled in synthetic materials. Myriad approaches have been attempted to prepare artificial silks from recombinant spider silk spidroins but have each failed to achieve the advantageous properties of the natural material. This is because of an incomplete understanding of the in vivo spidroin-to-fiber spinning process and, particularly, because of a lack of knowledge of the true morphological nature of spidroin nanostructures in the precursor dope solution and the mechanisms by which these nanostructures transform into micrometer-scale silk fibers.

Functional Diversity of Diterpene Synthases in the Biofuel Crop Switchgrass.

Diterpenoids constitute a diverse class of metabolites with critical functions in plant development, defense, and ecological adaptation. Major monocot crops, such as maize () and rice (), deploy diverse blends of specialized diterpenoids as core components of biotic and abiotic stress resilience. Here, we describe the genome-wide identification and functional characterization of stress-related diterpene synthases (diTPSs) in the dedicated bioenergy crop switchgrass ().

Condensed Tannin Reacts with SO during Wine Aging, Yielding Flavan-3-ol Sulfonates.

Numerous monomeric and oligomeric flavanol sulfonation products were observed in 10 wines. Levels of 0.85-20.

Mechanically induced pyrogallol[4]arene hexamer assembly in the solid state extends the scope of molecular encapsulation.

Pyrogallol[4]arene hexamers are hydrogen-bonded molecular capsules of exceptional kinetic stability that can entrap small molecule guests indefinitely, without exchange, at ambient temperatures. Here, we report on the use of a ball mill to induce self-assembly of the capsule components and the guests in the solid state. Stoichiometric amounts of pyrogallol[4]arene and a guest, which can be an arene, alkane, amine, or carboxylic acid, were milled at 30 Hz for fixed durations, dissolved, and characterization by NMR.

Discovery, Biosynthesis and Stress-Related Accumulation of Dolabradiene-Derived Defenses in Maize.

Terpenoids are a major component of maize () chemical defenses that mediate responses to herbivores, pathogens, and other environmental challenges. Here, we describe the biosynthesis and elicited production of a class of maize diterpenoids, named dolabralexins. Dolabralexin biosynthesis involves the sequential activity of two diterpene synthases, -COPALYL DIPHOSPHATE SYNTHASE (ZmAN2) and KAURENE SYNTHASE-LIKE4 (ZmKSL4).

Cell Migration and Bone Formation from Mesenchymal Stem Cell Spheroids in Alginate Hydrogels Are Regulated by Adhesive Ligand Density.

The adhesion and migration of cells entrapped in engineered materials is regulated by available adhesive ligands. Although mesenchymal stem cell (MSC) spheroids injected into damaged tissues promote repair, their transplantation in biomaterials which regulate cell migration from the aggregate may further enhance their therapeutic potential. Alginate hydrogels were modified with Arginine-Glycine-Aspartic acid (RGD) at increasing concentrations, and osteogenically induced human MSC spheroids were entrapped to assess cell migration, survival, and differentiation.

Synthesis of Benzodihydrofurans by Asymmetric C-H Insertion Reactions of Donor/Donor Rhodium Carbenes.

Metal carbenes appended with two electron-donating groups, known as "donor/donor" carbenes, undergo diastereo- and enantioselective rhodium-catalyzed C-H insertion reactions with ether substrates to form benzodihydrofurans. Unlike the reactions of metal carbenes with electron-withdrawing groups attached, the attenuated electrophilicity enables these reactions to be conducted in Lewis basic solvents (e.g.