Cycloaddition Huisgen, immobilization

The utility of ionic liquid conjugate catalysts such as 32 and 33 can be ascribed to their recyclability [195-199]. On the other hand, triazole-based catalysts such as 34 and 35 are readily accessible via Huisgen 1,3-dipolar cycloadditions, so-called click reactions, from azidomethyl-pyrroHdine and acetylenic precursors, and hence make it possible to design new immobilized catalysts [200-207]. 

Fig. 4 Chemoselective ligation methods a maleimide linker, b silyl linker, c Diels-Alder ligation, d glyoxylyl linker, e diazobenzylidene linker, f Staudinger ligation, g Huisgen [3 + 2] cycloaddition, h hydrazide linker, i glycal immobilization...

Rather than using a covalent reaction to immobilize the small molecule to a surface, a small molecule tagged with a tail having special physical properties could adhere to a surface by physiosorption. This was demonstrated for the preparation of carbohydrate arrays in microtiter plates where carbohydrate labeled at the anomeric position with saturated carbon chains between 13 and 15 carbons were retained on a hydrophobic surface and were resistant to aqueous washing. The viabihty of this immobihzation was demonstrated with the detection of several carbohydrate-lectin interactions [59]. Conversely, it was also shown that such lipophilic tails could be introduced via Huisgen cycloaddition [60]. 

---