The optimal catalyst depends on your application and the solvents used. In general, there are three major catalyst systems for copper-catalyzed click reactions that apply the required Cu(I) source:
1) Working in aqueous media: Then we recommend using a CuSO4 (BCMI-004) based system. To generate the catalytic Cu(I) species, please do not forget to add the necessary sodium ascorbate (BCMI-005) and our water soluble THPTA ligand (BCMI-006). As the sodium ascorbate has restricted stability when dissolved, please prepare this solution always fresh.
2) Working in organic medium (mostly DMSO or click solution): Then we recommend using CuBr and TBTA ligand (BCMI-002) for labeling reactions. Please note, that CuBr is sensitive to air. Therefore, we take precautions when aliquoting and sealing this compound. Once opened, please use the compound fast (within a few hours maximum).
3) For small sample amounts from e.g. enzymatic reactions in aqueous media we recommend using our reactor system that is part of our Oligo Link kits. As this catalyst will not dissolve during the reaction and can also be applied in organic media, its handling is very simple as described in the kit user manual. Additionally, the long-term storage is superior compared to the other catalyst systems.