Poly(arylene vinylene) Synthesis via a Precursor Step-Growth Polymerization Route Involving the Ramberg–Bäcklund Reaction as a Key Post-Chemical Modification Step

Architectural Editing of Polyesters and Polyurethanes via Palladium(II)-Catalyzed [3,3]-Sigmatropic Oxo-Rearrangements

Architecture underlies the thermomechanical properties of polymers. Yet, few strategies are available to tune a polymer's architecture after it is prepared without altering its chemical composition. The ability to edit the architecture of a polymer would dramatically expand the accessible architecture-property space of polymeric materials. Herein, we disclose a backbone rearrangement approach to tune the short-chain branching of polymers. Specifically, we demonstrate that palladium(II)-catalyzed [3,3]-sigmatropic oxo-rearrangements can transform branched polyesters and polyurethanes to their linear counterparts. While the effects on materials properties are generally subtle in the case of polyesters, more dramatic changes are observed in the case of polyurethanes: two polyurethanes undergo a soluble-to-insoluble transition, and one exhibits a dramatic increase in both strain at break and toughness after rearrangement. Additionally, the incorporation of alkenes in the polymer backbone through the rearrangement enables facile deconstruction via ethenolysis. In all, we disclose a powerful and broad-scope strategy to edit the architecture of polymer backbones and thereby tune their physical and chemical properties.

Editing of polymer backbones

Polymers are at the epicentre of modern technological progress and the associated environmental pollution. Considerations of both polymer functionality and lifecycle are crucial in these contexts, and the polymer backbone - the core of a polymer - is at the root of these considerations. Just as the meaning of a sentence can be altered by editing its words, the function and sustainability of a polymer can also be transformed via the chemical modification of its backbone. Yet, polymer modification has primarily been focused on the polymer periphery. In this Review, we focus on the transformations of the polymer backbone by defining some concepts fundamental to this topic (for example, 'polymer backbone' and 'backbone editing') and by collecting and categorizing examples of backbone editing scattered throughout a century's worth of chemical literature, and outline critical directions for further research. In so doing, we lay the foundation for the field of polymer backbone editing and hope to accelerate its development.

Rongalite as C1 Synthon in the Synthesis of Divergent Pyridines and Quinolines

Rongalite has been used as a cheap and efficient carbon synthon for the synthesis of divergent N-heteroaromatics, including different pyridines and quinolines. The selective synthesis of different products can be achieved by employing enaminones or enaminones/anilines as reaction partners. In addition, compared with the reaction using conventional aldehyde synthons, rongalite displays an evident advantage in providing products with considerably higher product yields under milder conditions. The GC-MS analysis of the reaction process has been performed to probe the possible reaction mechanism.

A Rapid Fluorescence Sensor for the Direct Quantification of Rongalite in Foodstuffs

Rongalite was reported illegally used as a food additive for bleaching purposes and improving the tenderness of foodstuffs, which may endanger public health. At present, rongalite was mostly detected by indirect methods via derivatization or determining its decomposition products. In this study, we developed a new fluorescence sensor for the direct quantification of rongalite based on the principles: (1) dopamine reacts with resorcinol and generates strong fluorophore (azamonardine); (2) rongalite could inhibit the production of fluorophores and then result in lower fluorescence intensity. Hence, the rongalite concentration was inversely proportional to fluorescence intensity of fluorophore. Several crucial reaction conditions of fluorescence sensor were further optimized, such as dopamine and resorcinol concentration, pH values, and reaction time. Under the optimal conditions, the limit of detection of fluorescence sensor was 0.28–0.38 μg/g in vermicelli, wheat and rice powder samples, exhibiting almost 3.5-fold improvement compared to that of lateral flow immunoassay. Moreover, the detection time was substantially decreased to 20 min. The recoveries in spiked samples were 80.7–102.1% with a coefficient of variation of less than 12.6%. In summary, we developed a direct, high throughput, selective and accurate fluorescence sensor that poses a promising application for the rapid detection of rongalite in foodstuffs.

Conjugated microporous polymers using a copper-catalyzed [4 + 2] cyclobenzannulation reaction: promising materials for iodine and dye adsorption

A new design strategy is disclosed to synthesize conjugated microporous polymers using a Cu-catalyzed [4 + 2] cyclobenzannulation reaction. The polymers reveal BET surface areas up to 794 m² g⁻¹ and promising uptake of iodine and methylene blue.

Synthesis of conjugated polymers via cyclopentannulation reaction: promising materials for iodine adsorption

A new class of conjugated polymers is prepared by means of a versatile palladium-catalyzed cyclopentannulation reaction using a series of specially designed diethynyl aryl synthons with the commercially available 9,10-dibromoanthracene DBA monomer.