Dirhodium partial paddlewheel complexes featuring electron donating bridging ligands and electron accepting chelating diimine ligands have been shown to act as excellent PDT agents due their ability to bind and photocleave DNA, as well as generate 1O2 upon irradiation. The bridging ligand N,N’-2,6-o-difluoroformamidinate (F2-Form) was used in the synthesis of two new series of the type [Rh2(F2Form)(OAc)(NN)]2+ and [Rh2(F2Form)2(NN)]2+, where NN=1,10-phenathroline, dipyrido[3,2-f:2',3'-h]-quinoxaline, dipyrido[3,2-a:2’,3’-c]phenazine, and benzo[i]dipyrido[3,2-a:2’,3’-h]quinoxaline. Formamidinate bridging ligands pose an advantage over acetate bridging ligands due to their increased electron donating capabilities, resulting in a red-shift of the absorbance of these complexes which is favorable for PDT applications. Dirhodium (II,II) complexes featuring the mixed bridging ligands are unique and unexplored for their biological and photophysical properties. This investigation serves to compare and contrast the mixed bridge ligand series [Rh2(F2Form)(OAc)(NN)]2+ with the bis F2-Form bridged complexes [Rh2(F2Form)2(NN)]2+ and the bis acetate bridged complexes [Rh2(OAc)2(NN)]2+. DNA photocleavage experiments and Resazurin cell viability assays were performed, showing great difference in LC50 irradiated versus LC50 in the dark. Cell microscopy and flow cytometry studies with HeLa cells were also performed to elucidate the mechanism of action of these dirhodium complexes.

Applications of  dirhodium (II,II) photosensitizers for photodynamic therapy featuring formamidinate and acetate bridging ligands

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.