Click chemistry, a term now recognized in many branches of chemistry

The term click chemistry refers to a synthetic strategy that focuses on “ easy-to-make” chemical compounds and materials from modular “blocks.” In 2001, Sharpless, Kolb, and Finn introduced this term to label a chemical synthesis approach conceptualized to advance fast, modular, process-driven design and application-oriented molecular discovery [1/de,1/en]. They defined a set of criteria that a useful process (reaction scheme) must meet in the context of click chemistry:

The reaction must be modular, wide in scope, give very high yields, generate only inoffensive byproducts that can be removed by nonchromatographic methods, and be stereospecific (but not necessarily enantio-selective). The required process characteristics include simple reaction conditions (ideally, the process should be insensitive to oxygen and water), readily available starting materials and reagents, the use of no solvent or a solvent that is benign (such as water) or easily removed, and simple product isolation. Purification—if required—must be by nonchromatographic methods, such as crystallization or distillation, and the product must be stable under physiological conditions.

In various aspects, the goals of click chemistry overlap with those of sustainable chemistry (green chemistry). Although originally demonstrated and discussed within applications in biochemistry and medicine, click chemistry today is recognized in many other areas including materials science, biotechnology, nanotechnology and photovoltaics. References to selected articles, communicating and reviewing research in and applications of click chemistry in such fields, are given below.

Keywords: chemical synthesis, library synthesis, thermodynamics, kinetics, pharmaceutical chemistry, drug design, material design, chemical reaction types, cycloaddition, nucleophile addition

References
[1/de] H. C. Kolb, M. G. Finn and K. B. Sharpless: Click Chemie: diverse chemische Funktionalität mit einer Handvoll guter Reaktionen. Angew. Chem. 2001, 113 (11), pp. 2056-2075.
DOI: 10.1002/1521-3757(20010601)113:11<2056::aid-ange2056>3.0.CO;2-W.
[1/en] H. C. Kolb, M. G. Finn and K. B. Sharpless: Click Chemistry: Diverse Chemical Function from a Few Good Reactions. Angew. Chem. Int. Ed. 2001, 40, pp. 2004-2021.
DOI: 10.1002/1521-3773(20010601)40:11<2004::aid-anie2004>3.0.CO;2-5.
[2] A. J. Dirks, J. J. L. M. Cornelissen, F. L. van Delft, J. C. M. van Hest, R. J. M. Nolte, A. E. Rowan and F. P. J. T. Rutjes: From (bio)Molecules to Biohybrid Materials with the Click Chemistry Approach. QSAR & Combinatorial Science 2007, 26 (11-12), pp. 1200-1210.
DOI: 10.1002/qsar.200740085.
[3] W. Zhan, W. Wu, J. Hua, Y. Jing, F. Meng and He Tian: Photovoltaic properties of new cyanine-naphthalimide dyads synthesized by ‘Click’ chemistry. Tetrahedron Lett. 2007, 48 (14), pp. 2461-2465.
DOI: 10.1016/j.tetlet.2007.02.034.
[4] J. Lutz and H. G. Bömer: Modern trends in polymer bioconjugates design. Prog. Polym. Sci. 2008, 33 (1), pp. 1-39.
DOI: 10.1016/j.progpolymsci.2007.07.005.
[5] Special Issue: Click Chemistry in Polymer Science. Macromol. Rapid Commun. 2008. Table of Contents.
[6] D. Kunz: Klick-Chemie. Synthesen, die gelingen. Chemie in unserer Zeit (ChiuZ) 2009, 43 (4), pp. 224-230.
DOI: 10.1002/ciuz.200900475.