Intramolecular Photoinduced Electron Transfer from Nitroxyl Radicals
摘要:
Intramolecular photoinduced electron transfer was observed from a nitroxide radical to a diimide acceptor in N,N'-bis(2,2,6,6-tetramethyl-N-oxidopiperidin-4-yl)-1,4,5,8-naphthalenediimide (DTDI). Irradiation of this substrate produced a zwitterion in which the diimide monoanion, with a lifetime of >200 mu s, was detected by transient absorbance spectroscopy. Slow charge recombination was attributed to the different symmetry constraints for forward electron transfer to an n,pi* state and back electron transfer from a pi,pi* state. The restricted motion of the nitroxide group prevents efficient overlap with the ring pi system, slowing back electron transfer.
A couple of naphthalenediimide 4 and 5 and series of perylenediimide derivatives 6–9 carrying TEMPO radical were prepared and their redox, FET, and magnetic properties were investigated. The radical compounds 4 and 6–9 were found to show antiferromagnetic interactions obeying the Curie–Weiss model, while the naphthalenediimide derivative 5 exhibited a singlet–triplet magnetic behavior and it could be well understood by the short oxygen-to-oxygen distance between the spin centers observed in its crystal structure. Owing presumably to their appropriate reduction potentials and structural motifs, exhibitions of n-type FET properties were disclosed in these radical compounds with mobilities of the order from 10−5 to 10−8 cm2 V−1 s−1 and apparent increase of mobilities was observed in the radical compounds 5 and 7 by the surface treatment with HMDS.
Intramolecular Photoinduced Electron Transfer from Nitroxyl Radicals
作者:Sarah Green、Marye Anne Fox
DOI:10.1021/j100040a026
日期:1995.10
Intramolecular photoinduced electron transfer was observed from a nitroxide radical to a diimide acceptor in N,N'-bis(2,2,6,6-tetramethyl-N-oxidopiperidin-4-yl)-1,4,5,8-naphthalenediimide (DTDI). Irradiation of this substrate produced a zwitterion in which the diimide monoanion, with a lifetime of >200 mu s, was detected by transient absorbance spectroscopy. Slow charge recombination was attributed to the different symmetry constraints for forward electron transfer to an n,pi* state and back electron transfer from a pi,pi* state. The restricted motion of the nitroxide group prevents efficient overlap with the ring pi system, slowing back electron transfer.