Diiron propanedithiolate complex bearing the pyridyl-functionalized phosphine ligand axially coordinated to a photosensitizer zinc tetraphenylporphyrin: "Publication year: 2011
Source: Journal of Organometallic Chemistry, In Press, Accepted Manuscript, Available online 23 May 2011
Xu-Feng, Liu , Xun-Wen, Xiao
Treatment of the starting material (μ-PDT)Fe2(CO)6 (PDT=SCH2CH2CH2S) with 4-diphenylphosphinoaminopyridine (PyNHPPh2) in the presence of the decarbonylating agent Me3NO∙2H2O afforded (μ-PDT)Fe2(CO)5(PyNHPPh2) (1) in 56% yield. Further treatment of 1 with Zinc tetraphenylporphyrin (ZnTPP) yielded the target light-driven model compound (μ-PDT)Fe2(CO)5(PyNHPPh2)(ZnTPP) (2) in 94% yield. The new complexes 1 and 2 were characterized by elemental analysis, NMR, IR, and X-ray crystallography. The molecular structure of 2 revealed its precursor 1 and a photosensitizer ZnTPP joined together through axial coordination. Furthermore, the fluorescence emission spectra and electrochemistry were also investigated."
I do not think the so-called quenching is caused by the photoinduced electron transfer between the ZnTPP and Fe2S2 as a red shift is observed after the addition of Fe2S2 to a ZnTPP solution. The shift is caused by the formation of the supramolecular Fe2S2_ZnTPP while the N coordinated to Zn, and the decrease of the emission intensity can be cause by two reasons: 1) the quantum yield of ZnTPP_N is lower than free ZnTPP, 2) the inner filter effect caused by the excess Fe2S2 molecules.
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