Photoinduced electron transfer from zinc tetraphenylporphyrin to 2-nitrofluorene in polar solvent acetonitrile

作者：Ghosh Mihir; Mora Aruna K; Nath Sukhendu; Kumar P Hemant; Bangal Prakriti Ranjan; Sinha Subrata^*

来源：Journal of Photochemistry and Photobiology A: Chemistry , 2015, 306: 55-65.

DOI：10.1016/j.jphotochem.2015.03.019

• Zinc tetraphenylporphyrin
• 2-Nitrofluorene
• Electron transfer
• Marcus theory

The possibility of intermolecular photoinduced ET (PET) is investigated in a novel donor-acceptor CD-A) system consisting of zinc tetraphenylporphyrin (ZnTPP) as donor and 2-nitrofluorene (2NF) as acceptor upon photoexcitation of the former moieties in polar solvent acetonitrile (ACN). The observed values (7.23 x 10(9) L/(mol s) and 7.04 x 10(9) L/(mol s)) of the fluorescence quenching rate constant from steady state and time-resolved data, respectively, are in good agreement with that (5.65 x 10(9) L/(mol s)) obtained from Marcus theory. Excited state absorption (ESA) from the S-2 state of Soret excited ZnTPP to higher electronic states gives rise to broad transient absorption spectra in 560-700 nm region. Presence of 2NF leads to a faster decay (up to 100 ps time delay) of the ESA signal of ZnTPP at a probe wavelength of 620 nm. This indicates ultrafast ET from the S-2 state (zero vibrational level) as well as the higher vibrational levels of the S-1 state of ZnTPP to 2NF. Moreover, transient absorption kinetics at longer time delays (up to 7 ns) at a probe wavelength of 620 nm show the formation of a charge separated state due to ET from the S-1 state (zero vibrational level) of the Soret excited ZnTPP to 2NF.

• 出版日期2015-6-15