Iridium(iii) complexes of 1,2,4-triazines as potential bioorthogonal reagents: metal coordination facilitates luminogenic reaction with strained cyclooctynes.

In this paper we describe unprecedented Ir(iii) complexes of 5-(2-pyridyl)-1,2,4-triazine and their reactivity towards the strained cyclooctyne BCN. The coordination of a 1,2,4-triazine ring to an iridium(iii) ion drastically increases the speed of the reaction, showing the second order rate constant of 8 M-1 s-1, the record value to date for a triazine-BCN reaction.