Click'' methodologies: efficient, simple and greener routes to design dendrimers

Designing dendrimers that are monodisperse hyperbranched macromolecules and offer significant potential in numerous scientific fields, is becoming a major topical area in modern research. Among the challenges of the 21st century, synthetic methodologies that increase efficiency of conversion and a greener chemistry approach, are expected to lead the way in the quest to build novel nanomaterials. The recent entry of so-called click'' reactions that include Diels-Alder, Cu-I-catalyzed Huisgen cycloaddition and thiol-ene coupling, have generated real stimulus not only in developing elegant materials of choice, but also in making the leap to industrial scale build-up of dendritic macromolecules. This tutorial review takes on the task of demonstrating the simplicity of these click'' reactions and the advantages they offer from a synthetic view point in developing mono- to multifunctional dendrimers. A brief introduction to click'' chemistry is followed by a chronological survey of developments in the field, and the impact these have had in designing novel dendritic macromolecules. The review is intended to introduce scientists to these highly efficient methodologies with demonstrated potential, and provide impetus for further growth of the area.