New polyalkynyl dendrons and dendrimers: "click" chemistry with azidomethylferrocene and specific anion and cation electrochemical sensing properties of the 1,2,3-triazole-containing dendrimers.

The synthesis and use of the new tris-alkynyl dendrons 2 to 5 are reported, including the Williamson reaction of 5 with 9-iodo (9), 27-iodo (11), and 81-iodo (12) dendritic cores to yield 27-alkynyl (13), 81-alkynyl (14), and 243-alkynyl (15) dendrimers. So-called "click" reactions of these three dendrimers with azidomethylferrocene (20) give 27-ferrocenyl (16), 81-ferrocenyl (17), and 243-ferrocenyl (18) dendrimers. Electrochemical recognition of oxo-anions (H(2)PO(4)(-) and ATP(2-)) and Pd(2+) cation has been compared using the three polyferrocenyl dendrimers. Derivatization of Pt electrodes with the dendrimers for recognition becomes more facile with increasing size of the dendrimer. This first "click" dendrimer bearing 243-ferrocenyl groups is the best one in the series to obtain robust, recyclable modified Pt electrodes, whereas previous "click" ferrocenyl dendrimers have not been suitable for this purpose.