The Influence of the Comonomer Ratio and Reaction Temperature on the Mechanical, Thermal, and Morphological Properties of Lignin Oil-Sulfur Composites.

Although lignin is a plentiful biomass resource, it continually exists as an underutilized component of biomass material. Elemental sulfur is another abundant yet underutilized commodity produced as a by-product resulting from the refining of fossil fuels. The current study presents a strategy for preparing five durable composites via a simple one-pot synthesis involving the reaction of lignin oil and elemental sulfur.

Durable composites by vulcanization of oleyl-esterified lignin.

Productive utilization of lignocellulosic biomass is critical to the continued advancement of human civilization. Whereas the cellulose component can be efficiently upconverted to automotive fuel-grade ethanol, the lack of upconversion methods for the lignin component constitutes one of the grand challenges facing science. Lignin is an attractive feedstock for structural applications, in which its highly-crosslinked architecture can endow composite structures with high strengths.

High strength composites from low-value animal coproducts and industrial waste sulfur.

Herein we report high strength composites prepared by reaction of sulfur, plant oils (either canola oil or sunflower oil) and brown grease. Brown grease is a high-volume, low value animal fat rendering coproduct that represents one of the most underutilized products of agricultural animal processing. Chemically, brown grease is primarily comprised of triglycerides and fatty acids.

Sterically crowded 1,4-diiodobenzene as a precursor to difunctional hypervalent iodine compounds.

A bulky 1,4-di-iodobenzene having four adjacent -Bu-CH group (Ar') substituents (1) was used to prepare the di-hypervalent iodine compound 1,4-[I(OAc)]-2,3,5,6-Ar'-C (2). Despite the steric encumbrance of the iodine center by the flanking aryl substituents, compound 2 undergoes ready cyclization under mild conditions (excess CFCOOH at 55 °C, 30 min) to afford a dicyclic di-iodonium di-triflate salt 3. The single crystal structures of compounds 2 and 3 were examined and compared to the formerly characterized precursor 1.

Investigating the suitability of poly tetraarylphosphonium based anion exchange membranes for electrochemical applications.

Anion exchange membranes (AEMs) are becoming increasingly common in electrochemical energy conversion and storage systems around the world (EES). Proton-/cation-exchange membranes (which conduct positive charged ions such as H or Na) have historically been used in many devices such as fuel cells, electrolysers, and redox flow batteries. High capital costs and the use of noble metal catalysts are two of the current major disadvantages of polymer electrolyte membrane (PEM)-based systems.

Recent advances in starch-based films toward food packaging applications: Physicochemical, mechanical, and functional properties.

Interest in starch-based films has increased precipitously in response to a growing demand for more sustainable and environmentally sourced food packaging materials. Starch is an optimal candidate for these applications given its ability to form thermoplastic materials and films with affordable and often sustainably sourced plasticizers like those produced as waste byproducts by biodiesel and agricultural industries. Starch is also globally ubiquitous, affordable, and environmentally benign.

Durable, acid-resistant copolymers from industrial by-product sulfur and microbially-produced tyrosine.

The search for alternative feedstocks to replace petrochemical polymers has centered on plant-derived monomer feedstocks. Alternatives to agricultural feedstock production should also be pursued, especially considering the ecological damage caused by modern agricultural practices. Herein, l-tyrosine produced on an industrial scale by was derivatized with olefins to give tetraallyltyrosine.

Highly Luminescent Heavier Main Group Analogues of Boron-Dipyrromethene.

The preparation and photophysical properties of two heavier main group element analogues of boron-dipyrromethene (BODIPY) chromophores are described. Specifically, we have prepared dipyrrin complexes of dichlorogallate (GADIPY) or phenylphosphenium (PHODIPY) units. Whereas cationic PHODIPY is labile, decomposing to a phosphine over time, GADIPY is readily prepared in good yield as a crystalline solid having moderate air- and water-stability.

Thermally-healable network solids of sulfur-crosslinked poly(4-allyloxystyrene).

Network polymers of sulfur and poly(4-allyloxystyrene), PAOS ( = percent by mass sulfur, where is varied from 10-99), were prepared by reaction between poly(4-allyloxystyrene) with thermal homolytic ring-opened S in a thiol-ene-type reaction. The extent to which sulfur content and crosslinking influence thermal/mechanical properties was assessed. Network materials having sulfur content below 50% were found to be thermosets, whereas those having >90% sulfur content are thermally healable and remeltable.

Convenient route to tetraarylphosphonium polyelectrolytes via metal-catalysed P-C coupling polymerisation of aryl dihalides and diphenylphosphine.

A P-C bond-forming reaction has been applied to the convenient preparation of tetraarylphosphonium polyelectrolytes (TPELs) from aryl dihalides and diphenylphosphine. A TPEL having a thermal decomposition temperature of 460 °C that is also stable to heating at 65 °C in 6 M NaOH(aq) for at least 24 h has been prepared by this method.

Comparison of 1,4-distyrylfluorene and 1,4-distyrylbenzene analogues: synthesis, structure, electrochemistry and photophysics.

A series of nine 1,4-distyrylfluorene derivatives (2) functionalized with substituents of variable electrondonating or -accepting capabilities was synthesised. The photophysical properties of the molecules were investigated, including UV/vis absorption, photoluminescence emission, and fluorescence quantum yields. Photophysical properties of chromophores 2 were found to exhibit significant solvatochromic effects, especially in the Stokes shift and photoluminescence maxima.

Naphthoxaphospholes as examples of fluorescent phospha-acenes.

Seven new fluorescent 2-R-naphtho[2,3-d]oxaphospholes (R-NOPs) (4a–g; R = tBu (a), Ad (b), C(6)H(5) (c), 4-MeC(6)H(4) (d), 4-ClC(6)H(4) (e), 4-BrC(6)H(4) (f ), 4-MeOC(6)H(4) (g)), have been synthesized by cyclocondensation reactions of benzimidoyl chlorides with 3-phosphino-2-naphthol (3). The compounds were characterized by multinuclear NMR, UV-vis, and fluorescence spectroscopy. Compounds 4a–d and 4g were characterized by cyclic voltammetry experiments.

Photochemically-induced dioxygenase-type CO-release reactivity of group 12 metal flavonolate complexes.

Exposure of 3-hydroxyflavonolate complexes of the group 12 metals to UV light under aerobic conditions results in oxidative carbon-carbon bond cleavage and CO release. This reactivity is novel in that it occurs under mild reaction conditions and suggests that light-induced CO-release reactivity involving metal flavonolate species may be possible in biological systems.

Poly(p-phenylenevinylene) Derivatives with Defined Conjugation Segments and Post-Polymerization Modification with Sterically Enshrouded Chromophores.

Two poly(p-phenylenevinylene) derivative alternating copolymers (P1-I and P2-I) have been prepared featuring iodo substituents and m-phenylene units to periodically disrupt conjugation. P1-I was derivatized with various chromophores to yield P1a-f. In P1a-f, the chromophores were positioned within a sterically protected pocket shielding them from interchain interactions so that intrachain interactions between polymer segments could be observed.

Metal ion detection by luminescent 1,3-bis(dimethylaminomethyl) phenyl receptor-modified chromophores and cruciforms.

Chromophores ranging from simple small molecule π-conjugated systems comprised of phenylene ethynylene or fluorenylethynyl units to cross-conjugated Bunz-type cruciforms have been derivatized to include 1,3-bis(dimethylaminomethyl)phenyl moieties. The photophysical responsiveness of these diamino-substituted chromophores to metal ions has been examined. Both emission enhancement (turn-on) and ratiometric fluorescence detection of Cu(2+) and Zn(2+) ions have been achieved in THF.

Interchromophore orientation scaffolding by m-terphenyl oxacyclophanes.

Modular oxacyclophanes featuring m-terphenyl units scaffold inter-pi-system interaction in face-to-face stacked or orthogonal orientations, leading to distinct photophysical properties.

Bifunctional cross-conjugated luminescent phosphines and phosphine derivatives: phospha-cruciforms.

Cross-conjugated bifunctional species including a phosphine, phosphine oxide, phosphine sulfide, phosphonium salt, phosphorus ylide and a gold(I) phosphine complex have been prepared. The photophysical characteristics of the series of compounds have been determined experimentally and are discussed/compared with simpler analogues lacking cross-conjugated branches and rationalized on the basis of DFT calculations.

Visible chromophore phosphines as functional elements of luminescent metallopolymers.

A general modular route to fluorophore-linked diphosphines from (4-iodophenyl)P(O)Ph(2) is described. The preparation of chromophoric diphosphine (LHP1) proceeded readily using this route. LHP1 was employed to prepare luminescent metallopolymers of platinum (P1) and palladium (P2) exhibiting modest degrees of polymerization (13-14) and extents of polymerization ( approximately 97%).

Steric coordination control of interchain interactions in conducting metallopolymers.

The solution processability of a conducting metallopolymer (CMP1) based on a 2,2'-bipyridyl (bipy) derivatized poly(p-phenylene vinylene) (PPV) backbone has been accomplished by the strategic placement of sterically demanding mesityl side chains. The enhanced solubility of CMP1 can be traced to the prevention of coordinative crosslinking between polymer chains. The sterically enforced 1:1 bipy/metal ratio was confirmed by job analysis of absorption spectroscopic titration data.

Covalently Scaffolded Inter-π-System Orientations in π-Conjugated Polymers and Small Molecule Models.

Organic π-conjugated polymers have emerged as one of the most fascinating classes of materials as they have found utility in a host of plastic electronics technologies. The distance between π-systems and their relative orientation dictate energy/charge transfer, conductivity, and photophysical properties of these materials in bulk. This Feature Article discusses π-conjugated polymers and model compounds in which specific inter-π-system interactions are covalently enforced and the effect that the scaffolding has on optoelectronic properties.

Poly(p-phenylene ethynylene) Incorporating Sterically Enshrouding m-Terphenyl Oxacyclophane Canopies.

A sterically encumbered m-terphenyl oxacyclophane substituted with two aryl iodide substituents has been prepared as a versatile monomer for the preparation of π-conjugated polymers. The monomer has been used to prepare a poly(p-phenylene ethynylene) derivative (P1) incorporating oxacyclophane units as canopies that shield one side of the π-system from inter-chain interactions. The photophysical properties of P1 in dilute solution compare well to those of a poly(p-phenylene ethynylene) derivative (P2) that lacks the canopy.

Canopied trans-chelating bis(N-heterocyclic carbene) ligand: synthesis, structure and catalysis.

The terphspan scaffold was employed to support a bis(N-heterocyclic carbene) ligand () that provides a m-terphenyl canopy over one side of its metal complexes. Single-crystal X-ray diffraction studies on a silver complex of {[Ag()]AgBr(2)}(2) revealed an unusual tetranuclear silver core with a Ag-Ag bond distance of 3.0241(8) A with as a trans-chelating ligand (C-Ag-C = 171 degrees ).

"Turn-on" fluorescent sensor for the selective detection of zinc ion by a sterically-encumbered bipyridyl-based receptor.

A sterically-encumbered 5,5'-distyryl-2,2'-bipyridyl derivative that enforces a 1:1 metal-to-ligand ratio acts as a selective turn-on sensor for Zn(2+) in THF.

Dizinc enzyme model/complexometric indicator pairs in indicator displacement assays for inorganic phosphates under physiological conditions.

A dizinc phosphohydrolase enzyme model complex employing the dinucleating ligand 2,6-bis-[(bis-pyridin-2-ylmethyl-amino)methyl]-4-methylphenol (L1) was tested for binding to a series of 11 commercially available complexometric indicators in aqueous N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) buffer at pH 7.4, with the aim of determining the applicability of these indicators in indicator displacement assays (IDAs) under physiological conditions. Dissociation constants (Kd) were determined for 11 indicator-Zn2L1 complexes, spanning 2 orders of magnitude from 2.