Electrochemical, Spectroscopic, and 1 O 2 Sensitization Characteristics of 10,10-Dimethylbiladiene Complexes of Zinc and Copper

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Vol. 118; no. 45; pp. 10639 - 10648
• Main Authors: Pistner, Allen J., Pupillo, Rachel C., Yap, Glenn P. A., Lutterman, Daniel A., Ma, Ying-Zhong, Rosenthal, Joel
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 13.11.2014
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp506412r

The synthesis, electrochemistry and photophysical characterization of a 10,10- dimethylbiladiene tetrapyrrole bearing ancillary pentafluorophenyl groups at the 5 and 15-meso positions (DMBil1) is presented. This non-macrocyclic tetrapyrrole platform is robust and can serve as an excellent ligand scaffold for Zn2+ and Cu2+ centers. X-ray diffraction studies conducted for DMBil1 along with the corresponding Zn[DMBil1] and Cu[DMBil1] complexes show that this ligand scaffold binds a single metal ion within the tetrapyrrole core. Additionally, electrochemical experiments revealed that all three of the aforementioned compounds display an interesting redox chemistry, as the DMBil1 framework can be both oxidized and reduced by two electrons. Spectroscopic and photophysical experiments carried out for DMBil1, Zn[DMBil1] and Cu[DMBil1] provide a basic picture of the electronic properties of these platforms. All three biladiene derivatives strongly absorb light in the visible region and are weakly emissive. The ability of these compounds to sensitize the formation of 1O2 at wavelengths longer than 500 nm was probed. Both the freebase and Zn2+ 10,10-dimethylbiladiene architectures show modest efficiencies for 1O2 sensitization. The combination of structural, electrochemical and photophysical data detailed herein, provides a basis for the design of additional biladiene constructs for the activation of O2 and other small molecules.