Reactive & Efficient: Organic Azides as Cross-Linkers in Material Sciences

Abstract

The exceptional reactivity of the azide group makes organic azides a highly versatile family of compounds in chemistry and the material sciences. One of the most prominent reactions employing organic azides is the regioselective copper(I)-catalyzed Huisgen 1,3-dipolar cycloaddition with alkynes yielding 1,2,3-triazoles. Other named reactions include the Staudinger reduction, the aza-Wittig reaction, and the Curtius rearrangement. The popularity of organic azides in material sciences is mostly based on their propensity to release nitrogen by thermal activation or photolysis. On the one hand, this scission reaction is accompanied with a considerable output of energy, making them interesting as highly energetic materials. On the other hand, it produces highly reactive nitrenes that show extraordinary efficiency in polymer crosslinking, a process used to alter the physical properties of polymers and to boost efficiencies of polymer-based devices such as membrane fuel cells, organic solar cells (OSCs), light-emitting diodes (LEDs), and organic field-effect transistors (OFETs). Thermosets are also suitable application areas. In most cases, organic azides with multiple azide functions are employed which can either be small molecules or oligo- and polymers. This review focuses on nitrene-based applications of multivalent organic azides in the material and life sciences.

Nitrene formation is the first step of the thermal and photochemical decomposition reactions of organic azides

“…For example, they are important components in click chemistry [1][2][3] or synthesis of energetic materials. [4][5][6][7][8][9][10][11][12] Most of these applications as well as their exceptional reactivity arise from their ability to generate nitrene intermediates after N 2 extrusion. [13][14][15][16][17] Although organic azides are known for more than a century, 18 the decomposition reaction mechanism at an atomistic level is still under discussion.…”

“…[4][5][6][7][8][9][10][11][12] Most of these applications as well as their exceptional reactivity arise from their ability to generate nitrene intermediates after N 2 extrusion. [13][14][15][16][17] Although organic azides are known for more than a century, 18 the decomposition reaction mechanism at an atomistic level is still under discussion. More specifically, there is a lack of agreement in the nature (concerted or asynchronous) of the so-called migration reaction in azides (Refs.…”

Covalent Networking of a Conjugated‐Polymer Photocatalyst to Promote Exciton Diffusion in the Aqueous Phase for Efficient Hydrogen Production

“…This results in a 3D covalent network. [33,34] When this is achieved with a mixture of azide molecules and CPs in a nanoparticle, most alkyl side-chains of CPs are chemically bound to each other, and only a few are exposed to the outermost aqueous environment; the performance of the organic semiconductor is not compromised. [34] More importantly, such 3D covalent networking of CPs is expected to limit swelling behavior (even in a colloidal phase in which the CPs are mixed with residual organic solvents), enabling more efficient exciton diffusion.…”

4-Azidocinnoline—Cinnoline-4-amine Pair as a New Fluorogenic and Fluorochromic Environment-Sensitive Probe

“…The chemistry of azides is a fast-growing research area. Organic azides are in great demand for the development of new synthetic methodologies [1][2][3], bioconjugation [4-9], photoaffinity labeling [10], synthesis of biologically active 1,2,3-triazole derivatives [11] and creation of different materials [12,13].…”