Synthesis, characterization, and biological studies of emissive rhenium–glutamine conjugates
- First Online:
- Cite this article as:
- Huang, R., Langille, G., Gill, R.K. et al. J Biol Inorg Chem (2013) 18: 831. doi:10.1007/s00775-013-1023-3
Two new rhenium complexes containing pyridine–triazole (pyta) and quinoline–triazole (quinta) ligands with attached glutamine-targeting agents have been characterized and tested for uptake in the HT-29 human colon adenocarcinoma cell line. The glutamine moiety in Re(CO)3Br(pyta) (1) and Re(CO)3Br(quinta) (2) remains pendant in solution. Both complexes exhibit absorptions in the 300–400-nm range with metal-to-ligand charge transfer (MLCT) character, as predicted by time-dependent density functional theory calculations. Geometrical analysis by theoretical calculations provides information on the cationic complexes 1+ and 2+ resulting from aquo for halide ligand exchange under aqueous conditions. The emissive properties of both complexes were studied under aqueous conditions, and the measured quantum yields were 0.46 % for 1+ and 0.18 % for 2+. The large Stokes shifts and oxygen sensitivity of the emission suggest a 3MLCT process for both complexes. Cell studies in the HT-29 cell line demonstrate that both complexes are nontoxic over a large concentration range (0–1.4 mM). Preliminary uptake studies show that 2+, but not 1+, displays significant concentration-dependent uptake at 3 and 24 h.