19681-25-5Relevant academic research and scientific papers
Photobehavior of copper(I) compounds. 4. Role of the triplet state of (arylphosphine)copper(I) complexes in the photosensitized isomerization of dienes
Liaw, Boryann,Orchard, S. Walter,Kutal, Charles
, p. 1311 - 1316 (2008/10/08)
Photoisomerization of cis- and trans-piperylene can be sensitized with high quantum efficiency by Cu(diphos)BH4 (diphos is 1,2-bis(diphenylphosphino)ethane) and Cu(prophos)BH4 (prophos is 1,3-bis(diphenylphosphino)propane). Sensitization is accompanied by quenching of the emissive 3(σ-aπ) excited state in each copper(I) complex, and the two processes occur with identical Stern-Volmer kinetics. Measurements of the trans/cis diene ratio at the photostationary state can be used to estimate the triplet-state energy as 60-61 kcal for Cu(diphos)BH4 and >61 kcal for Cu(prophos)BH4; additional evidence suggests that 66-67 kcal is a reasonable value for the latter complex. Collectively, the results support the assignment of triplet-triplet energy transfer as the primary mechanism for sensitization and quenching in these systems. This mechanism also can accommodate earlier reports that Cu(diphos)BH4 and Cu(prophos)BH4 sensitize the valence isomerization of norbornadiene to quadricyclene with markedly different quantum efficiencies.
