Polymeric Chemosensors: A Conventional Platform with New Click Chemistry

Abstract

Polymers are a good platform for the production of various functional materials, since functional moieties can be introduced into both the main chain backbone and side chain pendants by elegant molecular design and utilizing efficient synthetic protocols. Highly colored and fluorescent π-systems have often been employed as ion sensing units especially when heteroaromatic rings are included. The heteroaromatic rings can form supramolecular complexes with metal ions or anions, resulting in the visual color changes of absorption and fluorescence. Conjugated polymers have been traditionally employed to this end, because they are highly emissive and very sensitive to various ions. However, most of such conjugated polymers are synthesized by costly cross-coupling polycondensations, which do not meet the green chemistry concepts of this century. Click chemistry is a new concept representing an efficient and atom-economic synthesis, and one of the most common reactions is the Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) yielding 1,2,3-triazole rings. The 1,2,3-triazole derivatives are electronically almost inert, but they possess fluorescent chemosensor properties. Recent examples of polymeric chemosensors based on the 1,2,3-triazole derivatives are introduced. Furthermore, an emerging click chemistry reaction, i.e., the alkyne-acceptor click chemistry, is also introduced. This reaction produces highly colored donor-acceptor (D-A) chromophores on a polymer platform, enabling visual detection of the ion sensing behavior. The polymeric chemosensors with the D-A chromophores show a specific discrimination between hard and soft metal ions by different color changes. These polymers are also useful for anion sensing.

Electron Donor-Acceptor Organic Polymers by “Click” Type Cycloaddition/Retroelectrocyclization Reaction

“…Upon the completion of electric poling, the second-order nonlinear optical responses of the polymer films were observed. Furthermore, all these polystyrene-based electron donor-acceptor nonconjugated polymers exhibited very specific colorimetric ion sensing behaviors [73][74][75][76]. The hard basic aniline nitrogen atoms preferred to interact with hard acidic metal ions like Fe 3+ , leading to the decrease in the charge-transfer absorption band and thereby resulting in decolorization.…”

Materials Nanoarchitectonics for Mechanical Tools in Chemical and Biological Sensing

“…In many cases, these molecular and supramolecular sensing systems are coupled with various device‐based tools, such as electrodes, transistors, and advanced nanotechnology devices . In addition to conventional chemical approaches, nanoscience tools based on the nanostructure‐driven fabrication of sensing materials have been explored for advanced sensors, as seen in layered nanomaterials, polymer‐based structural platforms, gel assemblies, nano‐optode structures, hybrid architectures with nanocarbons, DNA arrays on surfaces, and nanoporous materials …”

“…In many cases, these molecular and supramolecular sensings ystems are coupled with variousd evice-based tools, such as electrodes, transistors, and advanced nanotechnology devices. [13] In addition to conventionalc hemical approaches, nanoscience tools based on the nanostructure-driven fabrication of sensing materials have been explored for advanced sensors, as seen in layered nanomaterials, [14] polymer-based structuralp latforms, [15] gel assemblies, [16] nano-optode structures, [17] hybrid architectures with nanocarbons, [18] DNA arrays on surfaces, [19] and nanoporous materials. [20] Representing an advanced conceptual paradigm for the designa nd synthesis of functional materials with nanosized structuralf eatures, the novel term "nanoarchitectonics"w as coinedb yM asakazu Aono, who first proposed this concept in the conferencet itled "1st International Symposium on Nanoarchitectonics Using Suprainteractions" in 2000.…”

Linear-type carbazoledioxazine-based organic semiconductors: the effect of backbone planarity on the molecular orientation and charge transport properties

“…[10][11][12][13][14][15][16][17][18] In particular, due to their solution processability and mechanical exibility, organic semiconductors would become fundamental components for novel mobile electronic devices, such as exible displays, biocompatible sensors, and radio frequency identication (RFID) tags. [19][20][21] In order to realize such next-generation devices, signicant efforts have been devoted to the development of new organic semiconducting materials, some of which already demonstrated charge carrier mobilities beyond the benchmark of industry standard inorganic materials, such as amorphous silicon (0.1-1 cm 2 V À1 s À1 ). [22][23][24][25] One important strategy of designing the organic/polymeric semiconducting materials is to envision more promising building blocks.…”