Postfunctionalization of a Perfluoroarene-Containing π-Conjugated Polymer via Nucleophilic Aromatic Substitution Reaction

Synthesis and Electrochromic Properties of Ferrocene-Aryl Dicyanovinylene-Based Donor-Acceptor Systems

The favorable redox properties of ferrocene have led to the extensive development of ferrocene-based systems for several electrochemical applications but have scarcely been explored for electrochromism. Here, we report the synthesis and electrochromic properties of novel π-conjugated ferrocene-dicyanovinylene systems (M1-M5 and D1-D3). Monosubstituted (M1-M5) and disubstituted (D1-D3) compounds have been developed via Knoevenagel condensation of methyl-dicyanovinyl ferrocenes (4 or 5) with various aromatic aldehydes. The compounds' optical (λmax = 320-515 nm) and electronic properties (band gap = 2.6-3.1 eV) have been tuned by the appropriate choice of the aryl substituents. The strong D-A interactions between ferrocene and dicyanovinylene moieties rendered intense colors in the solution and thin-film state and demonstrated high-contrast electrochromism. The electrochromic behavior of these compounds is highly reversible (>48 cycles) and fast (0.98-1.06 s) in both solution and thin-film states. These are the first examples of stand-alone ferrocene systems explored for electrochromism.

Post-Functionalization of Fluorinated Dibenzosulfone-Based Conjugated Polymer for Smart 'Turn-off' Sensing of Cu2+ Ions

Post-functionalization of conjugated polymeric backbone with various N-containing heterocycles through nucleophilic aromatic substitution reaction (SNAr) demonstrates crucial tailoring of their photophysical properties. This study explores an approach of post-polymerization modification of a fluorinated dibenzosulfone-based conjugated polymer aiming to incorporate functional groups having coordinating sites to bind metal ions. The resulting polymers, namely BDT-DBTS-IM, BDT-DBTS-TR, and BDT-DBTS-PY revealed successful substitution reactions with imidazole, triazole, and pyridine respectively, and showed significant changes in their absorption and emission properties. Notably, BDT-DBTS-IM demonstrated exceptional performance as a chemosensor, exhibiting a dramatic fluorescence turn-off response specifically to copper ions (Cu2+) with the limit of detection of 26 nM and Stern-Volmer quenching constant (KSV) of 8.2×105 Lmol-1. This high selectivity and sensitivity are attributed to the ability of the imidazole group to form a stable complex with Cu2+, resulting in both static and dynamic quenching efficiently. Our findings underscore the potential of post-polymerization modifications to significantly enhance the functionality of conjugated polymers. The ability of BDT-DBTS-IM to detect trace levels of copper ions with high precision highlights its practical utility in environmental and biological monitoring. This research not only demonstrates an approach for post-polymeric modification through SNAr reaction but also opens new avenues for developing sensors.

Post-polymerisation approaches for the rapid modification of conjugated polymer properties

Post-polymerisation functionalisation provides a facile and efficient way for the introduction of functional groups on the backbone of conjugated polymers. Using post-polymerisation functionalisation approaches, the polymer chain length is usually not affected, meaning that the resulting polymers only differ in their attached functional groups or side chains, which makes them particularly interesting for investigating the influence of the different groups on the polymer properties. For such functionalisations, highly efficient and selective reactions are needed to avoid the formation of complex mixtures or permanent defects in the polymer backbone. A variety of suitable synthetic approaches and reactions that fulfil these criteria have been identified and reported. In this review, a thorough overview is given of the post-polymerisation functionalisations reported to date, with the methods grouped based on the type of reaction used: cycloaddition, oxidation/reduction, nucleophilic aromatic substitution, or halogenation and subsequent cross-coupling reaction. Instead of modifications on the aliphatic side chains of the conjugated polymers, we focus on modifications directly on the conjugated backbones, as these have the most pronounced effect on the optical and electronic properties. Some of the discussed materials have been used in applications, ranging from solar cells to bioelectronics. By providing an overview of this versatile and expanding field for the first time, we showcase post-polymerisation functionalisation as an exciting pathway for the creation of new conjugated materials for a range of applications.

Bis(pentafluorophenyl)-o-carborane and its arylthio derivatives: synthesis, electrochemistry and optical properties

The synthesis of bis(pentafluorophenyl)-o-carborane is reported, which is further thiolated by nucleophilic aromatic substitution (S_NAr) reaction to give emissive materials in the solid state following aggregation-induced emission (AIE) fashion.