Amine-reactive luminescent metal complexes 30 can be used to label a variety of biomolecules, such as antibodies. However, the amine-reactive groups are unstable in solution and have a tendency to degrade over time. In a 'Chemistry on the complex' approach, the amine-reactive metal complex was synthesised through in situ reaction of the triazine complex with the amine-reactive BCN derivative, prior to bioconjugation (Scheme 1). Such an approach is very convenient for testing libraries of novel Ir(III) complexes in search of the most efficient luminescent probes. The triazine complex 3 was added to the amine-reactive BCN-PNP and incubated overnight at 50°C to synthesise the amine-reactive complex 9 (Figure ). The IEDDA reaction was performed in an NMR tube using DMSO-d6 as the solvent, facilitating both the monitoring of the reaction and preparation of the amine-reactive Ir(III) complex for subsequent bioconjugation. DMSO is routinely utilised to dissolve fluorophores for antibody labelling due to the relatively high tolerance of DMSO by antibodies, documented to be approximately 10% v/v. An excess of 3 in respect to BCN-PNP was used to make sure that only aminereactive complex 9 conjugated to the antibody. H NMR confirmed that the reaction had run to completion due to the absence of signals of BCN-PNP and a yield of 74% of the desired product 9 was calculated, the remaining portion being the starting complex 3. However, the presence of the triazine starting material is not problematic as it is incapable of reacting with an antibody due to the lack of the amine-reactive handle and is easily removed after the conjugation reaction during protein purification.