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To investigate photo-sensitive intramolecular electron transfers in supramolecular coordination compounds, three covalently linked donor ligand acceptor (CLDA) complexes were proposed with the general formula: [dmbRe(CO)₃-μ-L-μ-Re(CO)₃deb]2+, where L=bpa, t-bpe, and 4,4’-bpy. The donor substituent is a rhenium dimethyl polypyridyl linked through a bridging ligand to an acceptor rhenium diester polypyridyl. These three CLDA complexes were broken into six intermediate complexes, which consisted of the donor or acceptor ligand attached to the rhenium (I) center and one of the four bridging ligands. In the CLDA with L= t-bpe, we observe emission only at 600 nm, from the metal-to-ligand charge transfer (MLCT) band of the acceptor deb ligand regardless of which MLCT band was excited. In the CLDA with L=bpa, a wavelength-dependent luminescence is observed depending on which MLCT band was irradiated. Excitation of the Re (I) to the donor dmb ligand MLCT had an emission at 552 nm, while excitation of the Re (I) to the acceptor deb ligand MLCT had an emission at 600 nm. This suggests a lack of conjugation in the bridging ligand which prevents pure electronic communication across the complex.
Schmalbach, Nicole, "Tuning Photo-Sensitive Intramolecular Electron Transfers in Rhenium Coordination Compounds" (2021). Chemistry Honors Papers. 68.