New TBT based conducting polymers functionalized with redox-active tetrazines

Functionalized Triazines and Tetrazines: Synthesis and Applications

The molecules possessing triazine and tetrazine moieties belong to a special class of heterocyclic compounds. Both triazines and tetrazines are building blocks and have provided a new dimension to the design of biologically important organic molecules. Several of their derivatives with fine-tuned electronic properties have been identified as multifunctional, adaptable, switchable, remarkably antifungal, anticancer, antiviral, antitumor, cardiotonic, anti-HIV, analgesic, anti-protozoal, etc. The objective of this review is to comprehensively describe the recent developments in synthesis, coordination properties, and various applications of triazine and tetrazine molecules. The rich literature demonstrates various synthetic routes for a variety of triazines and tetrazines through microwave-assisted, solid-phase, metal-based, [4+2] cycloaddition, and multicomponent one-pot reactions. Synthetic approaches contain linear, angular, and fused triazine and tetrazine heterocycles through a combinatorial method. Notably, the triazines and tetrazines undergo a variety of organic transformations, including electrophilic addition, coupling, nucleophilic displacement, and intramolecular cyclization. The mechanistic aspects of these heterocycles are discussed in a detailed way. The bioorthogonal application of these polyazines with various strained alkenes and alkynes provides a new prospect for investigations in chemical biology. This review systematically encapsulates the recent developments and challenges in the synthesis and possible potential applications of various triazine and tetrazine systems.

Dual-Switching Electrochromism and Electrofluorochromism Derived from Diphenylamine-Based Polyamides with Spirobifluorene/Pyrene as Bridged Fluorescence Units

Electrochromic (EC)/electrofluorochromic (EFC) bifunctional materials are receiving great attention because of their promising applications in optoelectronic devices. However, the development of ideal EC/EFC bifunctional materials is still a great challenge because of the poor integration of EC/EFC performances (optical contrast, response speed, and switching stability). Herein, we reported two novel diphenylamine-based mixed valence (MV) polyamides (S-HPA and P-HPA) with spirobifluorene (2,7-positions) and pyrene (1,6-positions) as bridged fluorescence units, respectively, showing impressive cyclability and fluorescence contrast with rapid switching. Through the formation of an effective electronic coupling between the two nitrogen centers using spirobifluorene/pyrene bridges, we demonstrated that different bridges have significant effects on the thermal and electrooptical characteristics of polyamides. In addition to lower fluorescence quantum yield and glass transition temperature, the S-HPA exhibited superior cyclability (contrast change <3.4%/14% over 500/300 cycles for EC/EFC switching), higher color/fluorescence contrast (64%/304%), and faster switching time (<2.6 s), mainly owing to the shorter conjugated length and more twisted configuration of the spirobifluorene bridge. The design principle of MV polymers with fluorophore bridges proposed here will be a promising way to realize high-performance EC/EFC devices and will also provide new insights into their future development and applications.